WorldWideScience

Sample records for abutment screw loosening

  1. Effect of surface coating on the screw loosening of dental abutment screws

    Science.gov (United States)

    Park, Chan-Ik; Choe, Han-Cheol; Chung, Chae-Heon

    2004-12-01

    Regardless of the type of performed restoration, in most cases, a screw connection is employed between the abutment and implant. For this reason, implant screw loosening has remained a problem in restorative practices. The purpose of this study was to compare the surface of coated/plated screws with titanium and gold alloy screws and to evaluate the physical properties of coated/plated material after scratch tests via FE-SEM (field emission scanning electron microscopy) investigation. GoldTite, titanium screws provided by 3i (Implant Innovation, USA) and TorqTite, titanium screws by Steri-Oss (Nobel Biocare, USA) and gold screws and titanium screws by AVANA (Osstem Implant, Korea) were selected for this study. The surface, crest, and root of the abutment screws were observed by FE-SEM. A micro-diamond needle was also prepared for the scratch test. Each abutment screw was fixed, and a scratch on the surface of the head region was made at constant load and thereafter the fine trace was observed with FE-SEM. The surface of GoldTite was smoother than that of other screws and it also had abundant ductility and malleability compared with titanium and gold screws. The scratch tests also revealed that teflon particles were exfoliated easily in the screw coated with teflon. The titanium screw had rough surface and low ductility. The clinical use of gold-plated screws is recommended as a means of preventing screw loosening.

  2. Loosening torque of Universal Abutment screws after cyclic loading: influence of tightening technique and screw coating.

    Science.gov (United States)

    Bacchi, Atais; Regalin, Alexandre; Bhering, Claudia Lopes Brilhante; Alessandretti, Rodrigo; Spazzin, Aloisio Oro

    2015-10-01

    The purpose of this study was to evaluate the influence of tightening technique and the screw coating on the loosening torque of screws used for Universal Abutment fixation after cyclic loading. Forty implants (Titamax Ti Cortical, HE, Neodent) (n=10) were submerged in acrylic resin and four tightening techniques for Universal Abutment fixation were evaluated: A - torque with 32 Ncm (control); B - torque with 32 Ncm holding the torque meter for 20 seconds; C - torque with 32 Ncm and retorque after 10 minutes; D - torque (32 Ncm) holding the torque meter for 20 seconds and retorque after 10 minutes as initially. Samples were divided into subgroups according to the screw used: conventional titanium screw or diamond like carbon-coated (DLC) screw. Metallic crowns were fabricated for each abutment. Samples were submitted to cyclic loading at 10(6) cycles and 130 N of force. Data were analyzed by two-way ANOVA and Tukey's test (5%). The tightening technique did not show significant influence on the loosening torque of screws (P=.509). Conventional titanium screws showed significant higher loosening torque values than DLC (P=.000). The use of conventional titanium screw is more important than the tightening techniques employed in this study to provide long-term stability to Universal Abutment screws.

  3. Does Abutment Collar Length Affect Abutment Screw Loosening After Cyclic Loading?

    Science.gov (United States)

    Siadat, Hakimeh; Pirmoazen, Salma; Beyabanaki, Elaheh; Alikhasi, Marzieh

    2015-07-01

    A significant vertical space that is corrected with vertical ridge augmentation may necessitate selection of longer abutments, which would lead to an increased vertical cantilever. This study investigated the influence of different abutment collar heights on single-unit dental implant screw-loosening after cyclic loading. Fifteen implant-abutment assemblies each consisted of an internal hexagonal implant were randomly assigned to 3 groups: Group1, consisting of 5 abutments with 1.5 mm gingival height (GH); Group2, 5 abutments with 3.5 mm GH; and Group3, 5 abutments with 5.5 mm GH. Each specimen was mounted in transparent auto-polymerizing acrylic resin block, and the abutment screw was tightened to 35 Ncm with an electric torque wrench. After 5 minutes, initial torque loss (ITL) was recorded for all specimens. Metal crowns were fabricated with 45° occlusal surface and were placed on the abutments. A cyclic load of 75 N and frequency of 1 Hz were applied perpendicular to the long axis of each specimen. After 500 000 cycles, secondary torque loss (STL) was recorded. One-way ANOVA analysis was used to evaluate the effects of abutment collar height before and after cyclic loading. One-way ANOVA showed that ITL among the groups was not significantly different (P = .52), while STL was significantly different among the groups (P = .008). Post-hoc Tukey HSD tests showed that STL values were significantly different between the abutments with 1.5 mm GH (Group1) and with 5.5 mm GH (Group3) (P = .007). A paired comparison t-test showed that cyclic loading significantly influenced the STL in comparison with the ITL in each group. Within the limitations of this study, it can be concluded that increase in height of the abutment collar could adversely affect the torque loss of the abutment screw.

  4. Abutment screw loosening of endosseous dental implant body/abutment joint by cyclic torsional loading test at the initial stage.

    Science.gov (United States)

    Katsuta, Yasuhiro; Watanabe, Fumihiko

    2015-01-01

    Cyclic torsional loading tests were carried out in the laboratory using various implant systems, in order to clarify differences between the systems in loosening of abutment screws. Six samples from six commercially available abutment systems were used, giving a total of 36 samples. Four of the systems used internal connections, and two used external connections. The abutment screw for each system was tightened to a torque value specified by the manufacturer, and after 5 min, the loosening torque was measured using a digital torque meter. Measurements were taken twice, and a second measurement was taken as a reference value. A cyclic torsional loading test with 100,000 cycles was performed on the sample, and the loosening torque was again measured after the test. In conclusion, loosening of the abutment screw occurred as a result of cyclic torsional loading, and the degree of loosening varied with each implant system.

  5. Influence of implant/abutment joint designs on abutment screw loosening in a dental implant system.

    Science.gov (United States)

    Kitagawa, Tsuyoshi; Tanimoto, Yasuhiro; Odaki, Misako; Nemoto, Kimiya; Aida, Masahiro

    2005-11-01

    The objective of this study was to investigate the influence of implant/abutment joint designs on abutment screw loosening in a dental implant system, using nonlinear dynamic analysis of the finite element method (FEM). This finite element simulation study used two dental implant systems: the Ankylos implant system (Degusa Dental, Hanau, German) with a taper joint (taper joint-type model), and the Bränemark implant system (Nobel Biocare, Gothenburg, Sweden) with an external hex joint (external hex joint-type model). The nonlinear dynamic analysis was performed using three-dimensional finite element analysis. In comparing the movement of the taper type-joint model and external hex type-joint model, it was found that the external hex type-joint model had greater movement than the taper type-joint model. The external hex joint-type model showed rotation movement, whereas the movement of the taper joint-type model showed no rotation. It was concluded that the nonlinear dynamic analysis used in this study clearly demonstrated the differences in rotation of components in dental implant systems with taper or external hex joints. Copyright (c) 2005 Wiley Periodicals, Inc.

  6. Biomechanical Analysis of Tapered Integrated Screw and Sensitivity Analysis on Abutment Loosening in Dental Implants

    Directory of Open Access Journals (Sweden)

    Milad Farzadi

    2013-02-01

    Full Text Available Background and Aims: Different mechanisms have been developed for connecting abutment to implant. One of the most popular mechanisms is Tapered Integrated Screw (TIS, which is a Tapered Interference Fit (TIF with a screw integrated at the bottom of that. The aim of this study was to investigate the mechanism of TIS and effective factors in employing TIS during design and implementation processes using an analytic method.Materials and Methods: Relevant equations were developed to predict tightening and loosening torques, contactpressure and preloads with and without bone tissue in this analysis. The efficiency is defined as the ratio of the loosening torque to the tightening torque. The effects of the change in elastic modulus and thickness of the bone on operation of this mechanism were investigated.Results: In this study, 14 independent parameters such as taper angle, friction coefficient, abutment and implantgeometry that are effective on performance of TIS mechanism were presented. The role of some factors was shown in the performance of ITI implant using sensitivity analysis.Conclusion: It was shown that friction coefficient, contact length, and implant radius play major roles on tightening and loosening torques and efficiency of the mechanism. Furthermore, the results revealed that the change in the elastic modulus and thickness of the bone influenced the efficiency of the mechanism less than 15%.

  7. DLC screw preload. Loosening prevention

    Directory of Open Access Journals (Sweden)

    Ivete Aparecida de Mattias Sartori

    2008-01-01

    Full Text Available The screw loosening is a reason to prosthetic rehabilitation failure. However, the DLC (Diamond-like carbon screw treatment lead thefriction decrease and sliding between the components, which increases the screw preload benefit and decreases the chance of looseningoccurrence. This case shows a clinical indication of the association of the correct preload applied and the DLC screw, which can be considered an optimized protocol to solve screw loosening recidivate of unitary prosthesis in anterior maxillary site.

  8. [Fracture of implant abutment screws and removal of a remaining screw piece

    NARCIS (Netherlands)

    Broeke, S.M. van den; Baat, C. de

    2008-01-01

    Fracture of the implant abutment screws is a complication which can render an implant useless. The prevalence of abutment screw fracture does not exceed 2.5% after 10 years. Causes are loosening of implant abutment screw, too few, too short or too narrow implants, implants not inserted perpendicular

  9. Carbon film coating of abutment surfaces: effect on the abutment screw removal torque.

    Science.gov (United States)

    Corazza, Pedro Henrique; de Moura Silva, Alecsandro; Cavalcanti Queiroz, José Renato; Salazar Marocho, Susana María; Bottino, Marco Antonia; Massi, Marcos; de Assunção e Souza, Rodrigo Othávio

    2014-08-01

    To evaluate the effect of diamond-like carbon (DLC) coating of prefabricated implant abutment on screw removal torque (RT) before and after mechanical cycling (MC). Fifty-four abutments for external-hex implants were divided among 6 groups (n = 9): S, straight abutment (control); SC, straight coated abutment; SCy, straight abutment and MC; SCCy, straight coated abutment and MC; ACy, angled abutment and MC; and ACCy, angled coated abutment and MC. The abutments were attached to the implants by a titanium screw. RT values were measured and registered. Data (in Newton centimeter) were analyzed with analysis of variance and Dunnet test (α = 0.05). RT values were significantly affected by MC (P = 0.001) and the interaction between DLC coating and MC (P = 0.038). SCy and ACy showed the lowest RT values, statistically different from the control. The abutment coated groups had no statistical difference compared with the control. Scanning electron microscopy analysis showed DLC film with a thickness of 3 μm uniformly coating the hexagonal abutment. DLC film deposited on the abutment can be used as an alternative procedure to reduce abutment screw loosening.

  10. Measurements of Repeated Tightening and Loosening Torque of Seven Different Implant/Abutment Connection Designs and Their Modifications: An In Vitro Study.

    Science.gov (United States)

    Butkevica, Alena; Nathanson, Dan; Pober, Richard; Strating, Herman

    2018-02-01

    Repeated tightening and loosening of the abutment screw may alter its mechanical and physical properties affecting the optimal torque and ultimate reliability of an implant/abutment connection. The purpose of this study was to evaluate the effect of repeated tightening and loosening of implant/abutment screws on the loosening torque of implant/abutment connections of commercially available implant systems. Seven different implant/abutment connections and their modifications were tested. The screws of each system were tightened according to the manufacturer's specifications. After 20 minutes the screws were loosened. This procedure was repeated ten times, and the differences between the 1st and 10th cycle were expressed as a percentage change RTq(%) and correlated with initial torque, the number of threads, the length of shank, and thread surface area employing Spearman's analysis. All systems showed significant differences in residual torque (RTq) value (p 0.05). All connections but group 3 (p = 1.000) showed a significant change from the initial torque (ITq) to the RTq values. The first successive RTq values increased in two connection groups 1 and 2. The remaining connections showed reduced RTq values ranging from -1.2 % (group 5) to -23.5% (group 6). The RTq values declined gradually with every repeated tightening in groups 1, 2, 3, 8, 9, 11, 12. In group 2, after the tenth tightening the RTq was still above the ITq value. Only length of shank demonstrated a correlation with the RTq(%) change over the successive tightening loosening cycles (p implant/abutment screws caused varying torque level changes among the different systems. These observations can probably be attributed to connection design. Limiting the number of tightening/loosening cycles in clinical and laboratory procedures is advisable for most of the implant systems tested. © 2016 by the American College of Prosthodontists.

  11. Effectiveness of screw surface coating on the stability of zirconia abutments after cyclic loading.

    Science.gov (United States)

    Basílio, Mariana de Almeida; Butignon, Luis Eduardo; Arioli Filho, João Neudenir

    2012-01-01

    Different surface treatments have been developed in attempts to prevent the loosening of abutment screws. The aim of the current study was to compare the effectiveness of titanium alloy screws with tungsten-doped diamond-like carbon (W-DLC) coating and uncoated screws in providing stability to zirconia (ZrO2) ceramic abutments after cyclic loading. Twenty prefabricated ZrO2 ceramic abutments on their respective external-hex implants were divided into two groups of equal size according to the type of screw used: uncoated titanium alloy screw (Ti) or titanium alloy screw with W-DLC coating (W-DLC/Ti). The removal torque value (preload) of the abutment screw was measured before and after loading. Cyclic loading between 11 and 211 N was applied at an angle of 30 degrees to the long axis of the implants at a frequency of 15 Hz. A target of 0.5 X 106 cycles was defined. Group means were calculated and compared using analysis of variance and the F test (α = .05). Before cyclic loading, the preload for Ti screws was significantly higher than that for W-DLC/Ti screws (P = .021). After cyclic loading, there was no significant difference between them (P = .499). Under the studied conditions, it can be concluded that, after cyclic loading, both abutment screws presented a significant reduction in the mean retained preload and similar effectiveness in maintaining preload.

  12. Hollow Abutment Screw Design for Easy Retrieval in Case of Screw Fracture in Dental Implant System

    Directory of Open Access Journals (Sweden)

    Bo Kyun Sim

    2017-01-01

    Full Text Available The prosthetic component of dental implant is attached on the abutment which is connected to the fixture with an abutment screw. The abutment screw fracture is not frequent; however, the retrieval of the fractured screw is not easy, and it poses complications. A retrieval kit was developed which utilizes screw removal drills to make a hole on the fractured screw that provides an engaging drill to unscrew it. To minimize this process, the abutment screw is modified with a prefabricated access hole for easy retrieval. This study aimed to introduce this modified design of the abutment screw, the concept of easy retrieval, and to compare the mechanical strengths of the conventional and hollow abutment screws by finite element analysis (FEA and mechanical test. In the FEA results, both types of abutment screws showed similar stress distribution in the single artificial tooth system. A maximum load difference of about 2% occurred in the vertical load by a mechanical test. This study showed that the hollow abutment screw may be an alternative to the conventional abutment screws because this is designed for easy retrieval and that both abutment screws showed no significant difference in the mechanical tests and in the FEA.

  13. Identification of risk factors for fracture of veneering materials and screw loosening of implant-supported fixed partial dentures in partially edentulous cases.

    Science.gov (United States)

    Noda, K; Arakawa, H; Maekawa, K; Hara, E S; Yamazaki, S; Kimura-Ono, A; Sonoyama, W; Minakuchi, H; Matsuka, Y; Kuboki, T

    2013-03-01

    This retrospective study identified the risk factors for fracture of veneering materials and screw loosening of implant-supported fixed partial dentures in partially edentulous cases. The study group included a total of 182 patients who were installed 219 suprastructures at the Fixed Prosthodontic Clinic of Okayama University Dental Hospital between February 1990 and March 2005 and were subdivided in two subgroups: 120 patients (149 facing suprastructures) were included in the subgroup to investigate the risk factors of fracture of veneering materials, and 81 patients (92 suprastructures) were included in the subgroup to identify the risk factors of abutment screw loosening. Each patient was followed up from the day of suprastructure installation until March, 2005. A Cox proportional hazards regression model was used to identify the risk factors related to technical complications, and eight factors were regarded as candidate risk factors. Screw retention was the significant risk factor for fracture of veneering materials, whereas connection of suprastructures with natural tooth was the significant risk factor for screw loosening. It was suggested that screw retention was a significant risk factor for the fracture of veneering materials, and connection of suprastructures with natural tooth was a significant risk factor for screw loosening. Future studies, involving dynamic factors (e.g. bruxism) as predictors as well, are more helpful to discuss the risk factor of fracture of veneering materials and screw loosening. © 2013 Blackwell Publishing Ltd.

  14. Abutments with reduced diameter for both cement and screw retentions: analysis of failure modes and misfit of abutment-crown-connections after cyclic loading.

    Science.gov (United States)

    Moris, Izabela Cristina Maurício; Faria, Adriana Cláudia Lapria; Ribeiro, Ricardo Faria; Rodrigues, Renata Cristina Silveira

    2017-04-01

    The aim of this study was to analyze failure modes and misfit of abutments with reduced diameter for both cement and screw retentions after cyclic loading. Forty morse-taper abutment/implant sets of titanium were divided into four groups (N = 10): G4.8S-4.8 abutment with screw-retained crown; G4.8C-4.8 abutment with cemented crown; G3.8S-3.8 abutment with screw-retained crown; and G3.8C-3.8 abutment with cemented crown. Copings were waxed on castable cylinders and cast by oxygen gas flame and injected by centrifugation. After, esthetic veneering ceramic was pressed on these copings for obtaining metalloceramic crowns of upper canine. Cemented crowns were cemented on abutments with provisional cement (Temp Bond NE), and screw-retained crowns were tightened to their abutments with torque recommended by manufacturer (10 N cm). The misfit was measured using a stereomicroscope in a 10× magnification before and after cyclic loading (300,000 cycles). Tests were visually monitored, and failures (decementation, screw loosening and fractures) were registered. Misfit was analyzed by mixed linear model while failure modes by chi-square test (α = 0.05). Cyclic loading affected misfit of 3.8C (P ≤ 0.0001), 3.8S (P = 0.0055) and 4.8C (P = 0.0318), but not of 4.8S (P = 0.1243). No differences were noted between 3.8S with 4.8S before (P = 0.1550) and after (P = 0.9861) cyclic loading, but 3.8C was different from 4.8C only after (P = 0.0015) loading. Comparing different types of retentions at the same diameter abutment, significant difference was noted before and after cyclic loading for 3.8 and 4.8 abutments. Analyzing failure modes, retrievable failures were present at 3.8S and 3.8C groups, while irretrievable were only present at 3.8S. The cyclic loading decreased misfit of cemented and screw-retained crowns on reduced diameter abutments, and misfit of cemented crowns is greater than screw-retained ones. Abutments of reduced diameter failed more than

  15. [Current status of implant-abutment--part 1: abutments for cemented versus screw retained restorations].

    Science.gov (United States)

    Harel, N; Livne, S; Piek, D; Marku-Cohen, S; Ormianer, Z

    2012-01-01

    Fixed implant supported single crowns and fixed dental prostheses (FDPs) have become an accepted treatment option for replacing and restoring missing teeth. Recent systematic reviews summarized excellent 5- and 10-year survival rates for both reconstruction types. In screw-retained restorations, the fastening screw provides a solid joint between the restoration and the implant abutment or between the restoration and the implant itself. With cement-retained prostheses, this restorative screw is eliminated for many reasons: esthetics, occlusal stability, and fabrication of passively fitting restorations. The purpose of this article is to review the variety of implant-abutments available for fabrication of fixed implant-supported restoration and compare between the various abutment forms (screw vs. cement retained).

  16. Tightening techniques for the retaining screws of universal abutment

    Directory of Open Access Journals (Sweden)

    Alexandre Wittcinski REGALIN

    Full Text Available Abstract Purpose This study evaluated the torque maintenance of universal abutment retaining screws using different tightening techniques, and coated or uncoated screws. Material and method The screws were tightened to implants as following: Control – 32 Ncm torque; H20 – holding 32 Ncm torque for 20 s; R – 32 Ncm torque, repeated after 10 min (retorque; and H20+R – combining the two tightening techniques. Titanium and coated screws were also evaluated. Result Statistical analysis showed higher maintained torque for titanium screws (p<0.001. The H20+R technique showed the highest maintained torque (p=0.003, but the H20 technique’s maintained torque was similar. Conclusion Titanium screws associating the two tightening techniques can improve maintained torque.

  17. Effect of lubricant on the reliability of dental implant abutment screw joint: An in vitro laboratory and three-dimension finite element analysis.

    Science.gov (United States)

    Wu, Tingting; Fan, Hongyi; Ma, Ruiyang; Chen, Hongyu; Li, Zhi; Yu, Haiyang

    2017-06-01

    Biomechanical factors play a key role in the success of dental implants. Fracture and loosening of abutment screws are major issues. This study investigated the effect of lubricants on the stability of dental implant-abutment connection. As lubricants, graphite and vaseline were coated on the abutment screw surface, respectively, and a blank without lubricant served as the control. The total friction coefficient (μ tot ), clamping force, fatigue behavior and detorque of the joint combined with dynamic cyclic loading were measured under different lubricating conditions. Further, a three-dimensional finite element analysis was used to investigate stress distribution, in conjunction with experimental images. The results showed that the lubricant reduced μ tot , which in turn led to an increase in clamping force. Decrease in loading increased the fatigue life of the screw. However, use of lubricant at high load reduced the fatigue life. Ductile fracture at the first thread of the screw was the chief failure mode, which was due to maximum von Mises stress. Higher stress levels occurred in the lubricant groups. Lubricated screws resulted in lower detorque which made the joint easier to loosen. In conclusion, the lubricant cannot effectively improve the reliability of dental implant-abutment connection. Keeping the interfaces of implant-screw uncontaminated and strengthening the surface of the screw may be recommend for clinical operation and future design. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Preload, Coefficient of Friction, and Thread Friction in an Implant-Abutment-Screw Complex.

    Science.gov (United States)

    Wentaschek, Stefan; Tomalla, Sven; Schmidtmann, Irene; Lehmann, Karl Martin

    To examine the screw preload, coefficient of friction (COF), and tightening torque needed to overcome the thread friction of an implant-abutment-screw complex. In a customized load frame, 25 new implant-abutment-screw complexes including uncoated titanium alloy screws were torqued and untorqued 10 times each, applying 25 Ncm. Mean preload values decreased significantly from 209.8 N to 129.5 N according to the number of repetitions. The overall COF increased correspondingly. There was no comparable trend for the thread friction component. These results suggest that the application of a used implant-abutment-screw complex may be unfavorable for obtaining optimal screw preload.

  19. Effect of a locking triple pelvic osteotomy plate on screw loosening in 26 dogs.

    Science.gov (United States)

    Rose, Scott A; Peck, Jeffrey N; Tano, Cheryl A; Uddin, Nizam; de Haan, Jacek J

    2012-01-01

    To evaluate the complication rate of the double (DPO) and triple pelvic osteotomy (TPO) procedure (unilateral and bilateral) with a locking purpose-specific plate. Retrospective case series Dogs (n = 26; 38 hips) Medical records (January 2007-January 2011) of dogs that had unilateral or bilateral DPO or TPO were evaluated. Signalment, age, body weight, estimated preoperative subluxation and reduction angles, lameness, and complications were evaluated. Follow-up radiographs were evaluated for implant loosening or failure, femoral head coverage (FCH), pelvic dimensions, and radiographic evidence of healing. Screw loosening occurred in 1 of 266 (0.4%) screws placed and in 1 of 38 hips (2.6%). The rate of screw loosening was significantly lower than previously reported. Only 1 hip (2.6%) developed a major complication. Minor complications involving implants occurred in 2 hips (5.3%). Three to 5 locking screws were used per plate. There was a significant increase in FCH and Norberg angle (NA) compared with preoperative values. No clinically significant change in pelvic canal dimensions measured at 3 locations was identified. Locking 7-hole TPO plates with 3-5 locking screws resulted in a lower rate of major and minor implant associated complications than the reported complication rate for conventional 6-hole plates. En bloc pullout of the caudal aspect of the plate is an infrequent but repeatable complication associated with the locking TPO implant. © Copyright 2011 by The American College of Veterinary Surgeons.

  20. The effect of polyethylene creep on tibial insert locking screw loosening and back-out in prosthetic knee joints.

    Science.gov (United States)

    Sanders, Anthony P; Raeymaekers, Bart

    2014-10-01

    A prosthetic knee joint typically comprises a cobalt-chromium femoral component that articulates with a polyethylene tibial insert. A locking screw may be used to prevent micromotion and dislodgement of the tibial insert from the tibial tray. Screw loosening and back-out have been reported, but the mechanism that causes screw loosening is currently not well understood. In this paper, we experimentally evaluate the effect of polyethylene creep on the preload of the locking screw. We find that the preload decreases significantly as a result of polyethylene creep, which reduces the torque required to loosen the locking screw. The torque applied to the tibial insert due to internal/external rotation within the knee joint during gait could thus drive locking screw loosening and back-out. The results are very similar for different types of polyethylene. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Fracture resistance of abutment screws made of titanium, polyetheretherketone, and carbon fiber-reinforced polyetheretherketone

    Directory of Open Access Journals (Sweden)

    Eduardo Aloisio Fleck NEUMANN

    2014-08-01

    Full Text Available Fractured abutment screws may be replaced; however, sometimes, the screw cannot be removed and the entire implant must be surgically removed and replaced. The aim of this study was to compare the fracture resistance of abutment retention screws made of titanium, polyetheretherketone (PEEK and 30% carbon fiber-reinforced PEEK, using an external hexagonal implant/UCLA-type abutment interface assembly. UCLA-type abutments were fixed to implants using titanium screws (Group 1, polyetheretherketone (PEEK screws (Group 2, and 30% carbon fiber-reinforced PEEK screws (Group 3. The assemblies were placed on a stainless steel holding apparatus to allow for loading at 45o off-axis, in a universal testing machine. A 200 N load (static load was applied at the central point of the abutment extremity, at a crosshead speed of 5 mm/minute, until failure. Data was analyzed by ANOVA and Tukey’s range test. The titanium screws had higher fracture resistance, compared with PEEK and 30% carbon fiber-reinforced PEEK screws (p 0.05. Finally, visual analysis of the fractions revealed that 100% of them occurred at the neck of the abutment screw, suggesting that this is the weakest point of this unit. PEEK abutment screws have lower fracture resistance, in comparison with titanium abutment screws.

  2. Fracture resistance of abutment screws made of titanium, polyetheretherketone, and carbon fiber-reinforced polyetheretherketone.

    Science.gov (United States)

    Neumann, Eduardo Aloisio Fleck; Villar, Cristina Cunha; França, Fabiana Mantovani Gomes

    2014-01-01

    Fractured abutment screws may be replaced; however, sometimes, the screw cannot be removed and the entire implant must be surgically removed and replaced. The aim of this study was to compare the fracture resistance of abutment retention screws made of titanium, polyetheretherketone (PEEK) and 30% carbon fiber-reinforced PEEK, using an external hexagonal implant/UCLA-type abutment interface assembly. UCLA-type abutments were fixed to implants using titanium screws (Group 1), polyetheretherketone (PEEK) screws (Group 2), and 30% carbon fiber-reinforced PEEK screws (Group 3). The assemblies were placed on a stainless steel holding apparatus to allow for loading at 45o off-axis, in a universal testing machine. A 200 N load (static load) was applied at the central point of the abutment extremity, at a crosshead speed of 5 mm/minute, until failure. Data was analyzed by ANOVA and Tukey's range test. The titanium screws had higher fracture resistance, compared with PEEK and 30% carbon fiber-reinforced PEEK screws (p 0.05). Finally, visual analysis of the fractions revealed that 100% of them occurred at the neck of the abutment screw, suggesting that this is the weakest point of this unit. PEEK abutment screws have lower fracture resistance, in comparison with titanium abutment screws.

  3. Influence of abutment type and esthetic veneering on preload maintenance of abutment screw of implant-supported crowns.

    Science.gov (United States)

    Delben, Juliana Aparecida; Barão, Valentim Adelino Ricardo; Dos Santos, Paulo Henrique; Assunção, Wirley Gonçalves

    2014-02-01

    The effect of veneering materials on screw joint stability remains inconclusive. Thus, this study evaluated the preload maintenance of abutment screws of single crowns fabricated with different abutments and veneering materials. Sixty crowns were divided into five groups (n = 12): UCLA abutment in gold alloy with ceramic (group GC) and resin (group GR) veneering, UCLA abutment in titanium with ceramic (group TiC) and resin (group TiR) veneering, and zirconia abutment with ceramic veneering (group ZiC). Abutment screws made of gold were used with a 35 Ncm insertion torque. Detorque measurements were obtained initially and after mechanical cycling. Data were analyzed by ANOVA and Fisher's exact test at a significance level of 5%. For the initial detorque means (in Ncm), group TiC (21.4 ± 1.78) exhibited statistically lower torque maintenance than groups GC (23.9 ± 0.91), GR (24.1 ± 1.34), and TiR (23.2 ± 1.33) (p < 0.05, Fisher's exact test). Group ZiC (21.9 ± 2.68) exhibited significantly lower torque maintenance than groups GC, GR, and TiR (p < 0.05, Fisher's exact test). After mechanical cycling, there was a statistically significant difference between groups TiC (22.1 ± 1.86) and GR (23.8 ± 1.56); between groups ZiC (21.7 ± 2.02) and GR; and also between groups ZiC and TiR (23.6 ± 1.30) (p < 0.05, Fisher's exact test). Detorque reduction occurred regardless of abutment type and veneering material. More irregular surfaces in the hexagon area of the castable abutments were observed. The superiority of any veneering material concerning preload maintenance was not established. © 2013 by the American College of Prosthodontists.

  4. Influence of sizes of abutments and fixation screws on dental implant system: a non-linear finite element analysis.

    Science.gov (United States)

    Mao, Zhihong; Yi, Dake; Cao, Guo

    2017-08-28

    The purpose of this study is to discuss the influence of sizes of abutments and fixation screws on immediately loaded dental implants in mandibular bones using nonlinear finite element methods. Abutments with three unilateral wall thicknesses and fixation screws with three diameters are analyzed to compare the stresses and deformations under a vertical or oblique force of 130 N. The nonlinearity due to friction contacts between the fixation screw, the abutment, the implant, and the bone is taken into account. The results showed that improper sizes of abutments and fixation screws would increase the stress and deformation of the dental implant system. If possible, the diameter of fixation screw should not be smaller than Φ1.0 mm, the diameter between Φ1.0 mm and Φ1.2 mm is acceptable. The fixation screw diameter preferably exceeds Φ1.4 mm. The unilateral wall thickness >0.5 mm is optimal selection for abutments.

  5. Influence of Liquid Lubrication on the Screw-Joint Stability of Y-TZP Implant Abutment Systems.

    Science.gov (United States)

    Basílio, Mariana de Almeida; Abi-Rached, Filipe de Oliveira; Butignon, Luis Eduardo; Arioli Filho, João Neudenir

    2017-12-01

    To evaluate the effectiveness of abutment screws coated with liquid Vaseline on the screw-joint stability of yttria-stabilized tetragonal zirconia (Y-TZP) abutment systems. Forty Y-TZP prefabricated abutments, 20 Neodent and 20 Bionnovation, were tightened to 20 Ncm on their respective external hexagon implants, and divided into four groups (n = 10) according to the screws: coated with Vaseline or uncoated. The removal torque (RT) value of the abutment screw was measured before and after loading. A cyclic loading (0.5 × 10 6 cycles; 15 Hz) between 11 and 211 N was applied. Means were compared using a repeated-measures ANOVA (α = 0.05). There was no significant difference between coated and uncoated screws (p = 0.822). Significant differences were found between the abutment systems (p implant restorations. © 2016 by the American College of Prosthodontists.

  6. Using a porcelain furnace to debond cement-retained implant crown from the abutment after screw fracture: a clinical report.

    Science.gov (United States)

    Saponaro, Paola C; Heshmati, Reza H; Lee, Damian J

    2015-04-01

    When a screw fracture occurs on a cement-retained, implant-supported restoration, the abutment and restoration are completely separated from the implant's internal connection. Traditionally, an access hole is drilled through the crown to retrieve the broken screw, and the restoration can be placed again as a screw-retained restoration. This clinical report documents a patient whose broken abutment screw was retrieved from the restoration by burning off the cement and separating from the abutment without drilling an access hole. © 2014 by the American College of Prosthodontists.

  7. The value of {sup 18}F-fluoride PET/CT in the assessment of screw loosening in patients after intervertebral fusion stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Seifen, Tanja; Rodrigues, Margarida; Rettenbacher, Lukas; Holzmannhofer, Johannes; Pirich, Christian [Paracelsus Medical University Salzburg, Department of Nuclear Medicine and Endocrinology, Salzburg (Austria); Piotrowski, Wolfgang [Paracelsus Medical University Salzburg, Department of Neurosurgery, Salzburg (Austria); Mc Coy, Mark [Paracelsus Medical University Salzburg, Division of Neuroradiology, Salzburg (Austria)

    2014-09-16

    We evaluated {sup 18}F-fluoride PET/CT for the diagnosis of screw loosening after intervertebral fusion stabilization and compared the results with those from functional radiography. A group of 59 patients with pain in the region of previous intervertebral fusion stabilization and suspicion of implant instability due to screw loosening were investigated with {sup 18}F-fluoride PET/CT and functional radiography, 30.1 ± 3.4 and 29.3 ± 3.2 months, respectively, after surgery. The criterion for loosening was increased focal uptake surrounding the screw entry point and shaft. SUV{sub max} and SUV{sub mean} were measured in a region of interest (ROI) drawn around each screw (334 screws analysed). The final diagnosis was established by surgical exploration in 27 patients and clinical follow-up after intervertebral fusion stabilization in 32 patients. Of the 59 patients, 20 were proven positive for implant failure due to screw loosening and 39 were confirmed negative. The sensitivity, specificity and accuracy of {sup 18}F-fluoride PET/CT were 75 %, 97.4 % and 89.8 % in the patient-based analysis, and 45.6 %, 100 % and 80 % in the screw-based analysis, respectively. The positive and negative predictive values were 93.8 % and 100 % in the patient-based analysis, and 88.4 and 76 % in the screw-based analysis, respectively. CT signs in PET/CT allowed screw breakage to be detected in three patients. SUV{sub max}, SUV{sub mean} and SUV{sub max}/SUV{sub mean} ratios in screw ROIs and respective values in reference regions were all found to be significantly different between screws positive for loosening (58 screws) and screws negative for loosening (276 screws). The ratio between SUV{sub max} in screw ROIs and the values in reference regions was the most significant parameter for distinguishing screws positive and screws negative for loosening. {sup 18}F-Fluoride PET/CT imaging is useful for the diagnosis of screw loosening in patients with persistent symptoms after

  8. Use of next generation sequencing to detect biofilm bacteria in a patient with pedicle screw loosening after spine surgery

    DEFF Research Database (Denmark)

    Xu, Yijuan; Thomsen, Trine Rolighed; Lorenzen, Jan

    2016-01-01

    implant-related infection is believed to be linked to pedicle screw loosening after spine surgery. Low-grade bacterial infection can be hard to diagnose and may be undetected by conventional culture based methods. Next generation sequencing (NGS) could help to uncover hidden bacterial infections...... (v.1.20).” Results: “Clinically there were no signs of local or general infection. Serum parameters were normal (C-reactive protein 0.7 mg/L, WBC 6.2 Gpt/L) at revision surgery. No other infectious foci were noticed. Histology showed no signs of infection. Routine microbial culturing was negative......Title: Use of next generation sequencing to detect biofilm bacteria in a patient with pedicle screw loosening after spine surgery: a case report Yijuan Xu1, Trine Rolighed Thomsen1,2, Jan Lorenzen1, Kathrin Chamaon3, Per Trobisch4, Steffen Drange3 1. Danish Technological Institute, Aarhus, Denmark...

  9. Accuracy of bone SPECT/CT for identifying hardware loosening in patients who underwent lumbar fusion with pedicle screws

    Energy Technology Data Exchange (ETDEWEB)

    Hudyana, Hendrah; Maes, Alex [AZ Groeninge, Department of Nuclear Medicine, Kortrijk (Belgium); University Hospital Leuven, Department of Morphology and Medical Imaging, Leuven (Belgium); Vandenberghe, Thierry; Fidlers, Luc [AZ Groeninge, Department of Neurosurgery, Kortrijk (Belgium); Sathekge, Mike [University of Pretoria, Department of Nuclear Medicine, Pretoria (South Africa); Nicolai, Daniel [AZ Groeninge, Department of Nuclear Medicine, Kortrijk (Belgium); Wiele, Christophe van de [AZ Groeninge, Department of Nuclear Medicine, Kortrijk (Belgium); University Ghent, Department of Radiology and Nuclear Medicine, Ghent (Belgium)

    2016-02-15

    The aim of this retrospective study was to evaluate the accuracy of bone SPECT (single photon emission computed tomography)/CT (computed tomography) in diagnosing loosening of fixation material in patients with recurrent or persistent back pain that underwent lumbar arthrodesis with pedicle screws using surgery and clinical follow-up as gold standard A total of 48 patients (median age 49 years, range 21-81 years; 17 men) who had undergone lumbar spinal arthrodesis were included in this retrospective analysis. SPECT/CT results were compared to the gold standard of surgical evaluation or clinical follow-up. Positive SPECT/CT results were considered true positives if findings were confirmed by surgery or if clinical and other examinations were completely consistent with the positive SPECT/CT finding. They were considered false positives if surgical evaluation did not find any loose pedicle screws or if symptoms subsided with non-surgical therapy. Negative SPECT/CT scans were considered true negatives if symptoms either improved without surgical intervention or remained stable over a minimum follow-up period of 6 months. Negative SPECT/CT scans were determined to be false negatives if surgery was still required and loosening of material was found. The median length of time from primary surgery to bone SPECT/CT referral was 29.5 months (range 12-192 months). Median follow-up was 18 months (range 6-57) for subjects who did not undergo surgery. Thirteen of the 48 patients were found to be positive for loosening on bone SPECT/CT. Surgical evaluation (8 patients) and clinical follow-up (5 patients) showed that bone SPECT/CT correctly predicted loosening in 9 of 13 patients, while it falsely diagnosed loosening in 4 patients. Of 35 negative bone SPECT/CT scans, 12 were surgically confirmed. In 18 patients, bone SPECT/CT revealed lesions that could provide an alternative explanation for the symptoms of pain (active facet degeneration in 14 patients, and disc and sacroiliac

  10. Evaluation of torque loss value of MAD/MAM zirconia abutments with prefabricated titanium abutments

    Directory of Open Access Journals (Sweden)

    Marzieh Alikhasi

    2013-04-01

    Full Text Available Background and Aims: In response to esthetic demand of patients, ceramic abutments have been developed. Despite esthetic of zirconia abutments, machining accuracy of these abutments has always been a question. Any misfit in the abutment-implant interface connection can lead to detorque and screw loosening. The aim of this study was to compare torque loss value of manually aided design/manually aided manufacture (MAD/MAM zirconia abutments with prefabricated titanium abutments. Materials and Methods: Seven titanium abutments (Branemark RP, Easy abutment and seven copy milled abutments which were duplicated from the prefabricated Zirkonzhan (ZirkonZahn, Sand in Taufers, Italy were prepared. After sintering process of zirconia abutment, all abutments were fastened with a torque screw under 35 Ncm. Detorque measurements were performed per group pushing the reverse button of the Torque controller soon after screw tightening with values registered. The mean torque loss were calculated and compared using Student's t test. Results: The mean of torque loss was 12.71 Ncm with standard deviation of 1.70 for prefabricated titanium abutments and 15.50 Ncm with standard deviation of 4.67 for MAD-MAM abutments. The difference between the two groups was not statistically significant (P=0.23. Conclusion: Within the limitation of this study, MAD-MAM ceramic abutments could maintain the applied torque comparing to the prefabricated abutments.

  11. Noninvasive method for retrieval of broken dental implant abutment screw

    Directory of Open Access Journals (Sweden)

    Jagadish Reddy Gooty

    2014-01-01

    Full Text Available Dental implants made of titanium for replacement of missing teeth are widely used because of ease of technical procedure and high success rate, but are not free of complications and may fail. Fracturing of the prosthetic screw continues to be a problem in restorative practice and great challenge to remove the fractured screw conservatively. This case report describes and demonstrates the technique of using an ultrasonic scaler in the removal of the fracture screw fragment as a noninvasive method without damaging the hex of implants.

  12. The Effect of Lumbar Lordosis on Screw Loosening in Dynesys Dynamic Stabilization: Four-Year Follow-Up with Computed Tomography

    Directory of Open Access Journals (Sweden)

    Chao-Hung Kuo

    2015-01-01

    Full Text Available Introduction. This study aimed to evaluate the effects of Dynesys dynamic stabilization (DDS on clinical and radiographic outcomes, including spinal pelvic alignment. Method. Consecutive patients who underwent 1- or 2-level DDS for lumbar spondylosis, mild degenerative spondylolisthesis, or degenerative disc disease were included. Clinical outcomes were evaluated by Visual Analogue Scale for back and leg pain, Oswestry Disability Index, and the Japanese Orthopedic Association scores. Radiographic outcomes were assessed by radiographs and computed tomography. Pelvic incidence and lumbar lordosis (LL were also compared. Results. In 206 patients with an average follow-up of 51.1 ± 20.8 months, there were 87 screws (8.2% in 42 patients (20.4% that were loose. All clinical outcomes improved at each time point after operation. Patients with loosened screws were 45 years older. Furthermore, there was a higher risk of screw loosening in DDS involving S1, and these patients were more likely to have loosened screws if the LL failed to increase after the operation. Conclusions. The DDS screw loosening rate was overall 8.2% per screw and 20.4% per patient at more than 4 years of follow-up. Older patients, S1 involvement, and those patients who failed to gain LL postoperatively were at higher risk of screw loosening.

  13. Screw Joint Stability in Conventional and Abutment-Free Implant-Supported Fixed Restorations.

    Science.gov (United States)

    Scherg, Stefan; Karl, Matthias

    2016-01-01

    Procera Implant Bridges (PIBs) do not engage supporting implant shoulders and are fixed using comparably long retention screws. The aim of this in vitro clinical study was to determine the detorque values in PIBs and conventionally fabricated fixed dental prostheses (FDPs). Two groups of screw-retained implant-supported three-unit FDPs (n=10) were fabricated by means of conventional casting or computer-aided design/computer-assisted manufacture to fit an in vitro situation with two implants. Following fixation, the restorations were subjected to masticatory simulation (100,000 cycles, 100 N) and subsequent detorquing of the retention screws. In the clinical part, a total of 10 patients received PIB restorations in the premolar/molar region that were detorqued after 2, 4, and 6 months. One-sample t tests adjusted for multiple testing by the Bonferroni-Holm method were applied for statistical analysis based on percentage detorque values (α=.05). 60% of the initial torque values were maintained in screws directly retaining restorations, while the abutment screws used in the conventional restorations showed detorque levels in the range of 80%. No significant difference in detorque levels between screws retaining PIBs and conventional FDPs could be detected (P=.5186). The abutment screws showed significantly greater detorque values compared with screws directly retaining restorations (P=.0002; P=.0000). In vivo, a significant increase in detorque values ranging from 21.64 Ncm after 2 months to 27.81 Ncm after 6 months was recorded. Prosthetic screws retaining implant-supported FDPs show torque loss during the initial period of service. Retightening reduces the amount of future torque loss.

  14. A technique for the management of screw access opening in cement-retained implant restorations

    Directory of Open Access Journals (Sweden)

    Hamid Kermanshah

    2014-01-01

    Full Text Available Introduction: Abutment screw loosening has been considered as a common complication of implant-supported dental prostheses. This problem is more important in cement-retained implant restorations due to their invisible position of the screw access opening. Case Report: This report describes a modified retrievability method for cement-retained implant restorations in the event of abutment screw loosening. The screw access opening was marked with ceramic stain and its porcelain surface was treated using hydrofluoric acid (HF, silane, and adhesive to bond to composite resin. Discussion: The present modified technique facilitates screw access opening and improves the bond between the porcelain and composite resin.

  15. Evaluation of the sealing capability of implants to titanium and zirconia abutments against Porphyromonas gingivalis, Prevotella intermedia, and Fusobacterium nucleatum under different screw torque values.

    Science.gov (United States)

    Smith, Nicole A; Turkyilmaz, Ilser

    2014-09-01

    When evaluating long-term implant success, clinicians have always been concerned with the gap at the implant-abutment junction, where bacteria can accumulate and cause marginal bone loss. However, little information regarding bacterial leakage at the implant-abutment junction, or microgap, is available. The purpose of this study was to evaluate sealing at 2 different implant-abutment interfaces under different screw torque values. Twenty sterile zirconia abutments and 20 sterile titanium abutments were screwed into 40 sterile implants and placed in test tubes. The ability of a bacterial mixture of Prevotella intermedia, Porphyromonas gingivalis, and Fusobacterium nucleatum to leak through an implant-titanium abutment seal under 20 and 35 Ncm torque values and an implant-zirconia abutment seal under 20 and 35 Ncm torque values was evaluated daily until leakage was noted. Once a unit demonstrated leakage, a specimen was plated. After 4 days, the number of colonies on each plate was counted with an electronic colony counter. Plating was used to verify whether or not bacterial leakage occurred and when leakage first occurred. The implant-abutment units were removed and rinsed with phosphate buffered saline solution and evaluated with a stereomicroscope. The marginal gap between the implant and the abutment was measured and correlated with the amount of bacterial leakage. The data were analyzed with ANOVA. Bacterial leakage was noted in all specimens, regardless of material or screw torque value. With titanium abutments, changing the screw torque value from 20 to 35 Ncm did not significantly affect the amount of bacterial leakage. However, with zirconia abutments, changing the screw torque value from 20 to 35 Ncm was statistically significant (P<.017). Overall, the marginal gap noted was larger at the zirconia-abutment interface (5.25 ±1.99 μm) than the titanium-abutment interface (12.38 ±3.73 μm), irrespective of the screw torque value. Stereomicroscopy revealed a

  16. Loosening torque of prosthetic screws in metal-ceramic or metal-acrylic resin implant-supported dentures with different misfit levels.

    Science.gov (United States)

    Bacchi, Ataís; Paludo, Litiane; Ferraz Mesquita, Marcelo; Schuh, Christian; Federizzi, Leonardo; Oro Spazzin, Aloísio

    2013-04-26

    The aim of this study was to evaluate the effect of the prosthesis material (metal-acrylic resin or metal-ceramic) on loosening torque of the prosthetic screws in an implant-supported mandibular denture under two levels of vertical misfit. Ten frameworks were fabricated with commercially pure titanium, and five of them received acrylic resin and acrylic artificial teeth as veneering material and the other five were veneered with porcelain. Two levels of vertical fit were also created by fabricating 20 cast models to obtain four experimental groups according to the prosthesis material and misfit: Group 1 (metal-acrylic resin prosthesis with a passive fit); Group 2 (metal-acrylic resin prosthesis with a non-passive fit); Group 3 (metal-ceramic prosthesis with a passive fit); and Group 4 (metal-ceramic prosthesis with a non-passive fit). Two hundred prosthetic titanium-alloy screws were divided in 40 sets (five screws per set, n=10). After 24h, the loosening torque of the screws was evaluated using a digital torque meter. The results were submitted to two-way ANOVA analysis of variance followed by a Tukey's test (α=0.05). The mean values and standard deviations for each group were G1=7.05 (1.64), G2=5.52 (0.90), G3=6.46 (1.34), and G4=4.35 (0.99). Overall, the prosthesis material and misfit factors showed a statistically significant influence on the loosening torque (p<0.05). Metal-ceramic prosthesis and misfits decreased the loosening of the torque of the prosthetic screws. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. The effect of different implant-abutment connection on screw joint stability.

    Science.gov (United States)

    Michalakis, Konstantinos; Calvani, Pasquale; Muftu, Sinan; Pissiotis, Argirios; Hirayama, Hiroshi

    2012-03-06

    Abstract Dental implants with an internal connection have been designed in order to establish a better stress distribution when lateral external forces act on the prosthesis and minimize the forces transmitted to the fastening screw. In the present study, ten externally and ten internally hexed implants were tested with a compressive force applied with an Instron Universal machine. Four cycles of loading-unloading were applied to each specimen, in order to achieve displacements of 0.5, 1, 2 and 2.5 mm. The mean loads for the first cycle were 256.70 N for the external connection and 256 N for the internal connection implants. The independent t test did not reveal any significant differences among the two tested groups (P=.780). For the second cycle, the mean loads needed for a displacement of 1mm were 818.19 N and 780.20 N, for the external connection and the internal connection implants respectively. The independent t test revealed significant differences among the two tested groups (Pimplants. These loads were required for a displacement of 2.5mm. The independent t test revealed significant differences among the two tested groups (Pimplant system could not prevent screw loosening during overloading. No implant or prosthesis failure was noticed in either group.

  18. The effect of different implant-abutment connections on screw joint stability.

    Science.gov (United States)

    Michalakis, Konstantinos X; Calvani, Pasquale Lino; Muftu, Sinan; Pissiotis, Argiris; Hirayama, Hiroshi

    2014-04-01

    Dental implants with an internal connection have been designed to establish a better stress distribution when lateral external forces act on the prosthesis and minimize the forces transmitted to the fastening screw. In the present study, 10 externally and 10 internally hexed implants were tested with a compressive force applied with an Instron Universal machine. Four cycles of loading-unloading were applied to each specimen to achieve displacements of 0.5, 1, 2, and 2.5 mm. The mean loads for the first cycle were 256.70 N for the external connection and 256 N for the internal connection implants. The independent t test did not reveal any significant differences among the 2 tested groups (P = .780). For the second cycle, the mean loads needed for a displacement of 1 mm were 818.19 N and 780.20 N for the external connection and the internal connection implants, respectively. The independent t test revealed significant differences among the 2 tested groups (P implants. These loads were required for a displacement of 2.5 mm. The independent t test revealed significant differences among the 2 tested groups (P implant system could not prevent screw loosening during overloading. No implant or prosthesis failure was noticed in either group.

  19. A rationale method for evaluating unscrewing torque values of prosthetic screws in dental implants

    Directory of Open Access Journals (Sweden)

    Felipe Miguel Saliba

    2011-02-01

    Full Text Available OBJECTIVES: Previous studies that evaluated the torque needed for removing dental implant screws have not considered the manner of transfer of the occlusal loads in clinical settings. Instead, the torque used for removal was applied directly to the screw, and most of them omitted the possibility that the hexagon could limit the action of the occlusal load in the loosening of the screws. The present study proposes a method for evaluating the screw removal torque in an anti-rotational device independent way, creating an unscrewing load transfer to the entire assembly, not only to the screw. MATERIAL AND METHODS: Twenty hexagonal abutments without the hexagon in their bases were fixed with a screw to 20 dental implants. They were divided into two groups: Group 1 used titanium screws and Group 2 used titanium screws covered with a solid lubricant. A torque of 32 Ncm was applied to the screw and then a custom-made wrench was used for rotating the abutment counterclockwise, to loosen the screw. A digital torque meter recorded the torque required to loosen the abutment. RESULTS: There was a significant difference between the means of Group 1 (38.62±6.43 Ncm and Group 2 (48.47±5.04 Ncm, with p=0.001. CONCLUSION: This methodology was effective in comparing unscrewing torque values of the implant-abutment junction even with a limited sample size. It confirmed a previously shown significant difference between two types of screws.

  20. Fracture Strength of Implant-Supported Ceramic Crowns with Customized Zirconia Abutments: Screw Retained vs. Cement Retained.

    Science.gov (United States)

    Nogueira, Lorenna Bastos Lima Verde; Moura, Carmem Dolores Vilarinho Soares; Francischone, Carlos Eduardo; Valente, Valdimar Silva; Alencar, Suyá Moura Mendes; Moura, Walter Leal; Soares Martins, Gregorio Antonio

    2016-01-01

    To compare the fracture resistance before and after cyclic fatigue assays of ceramic crowns with customized zirconia abutments when screw retained and cemented onto implants. The sample of this study consisted of 40 ceramic crowns with zirconia infrastructure fixed onto external hexagonal implants. The crowns were distributed into two groups (n = 20): Screw-retained and cemented crowns. Half the crowns of each group (n = 10) underwent compression until fracture and the other half (n = 10) underwent cyclic fatigue and subsequent compression until fracture. The cyclic fatigue test was carried out using an electromechanical fatigue device (loads from 0 to 100 N, 2 Hz frequency, in distilled water, at 37 °C for a period of 1 million cycles). The compression test was carried out using a universal testing machine with a 0.5 mm/min speed and 5 KN load cell. After fracture, the crowns were classified according to the type of fracture. Student's t test (p crowns (before = 1068.31 N, after = 891.49 N; p > 0.05) nor that of the cemented crowns (before = 2117.78 N; after = 2094.81 N; p > 0.05); however, the mean fracture resistance of the cemented crowns was higher than that of the screw-retained crowns both before (p crowns cemented onto the customized zirconia abutments offered greater fracture resistance than ceramic crowns with customized zirconia abutments screw retained onto implants. The cyclic fatigue did not seem to influence the fracture resistance of these crowns, whether cemented or screw retained onto implants. Fracture of the veneering ceramic was the predominant failure in this study. © 2015 by the American College of Prosthodontists.

  1. The effect of DLC-coating deposition method on the reliability and mechanical properties of abutment's screws.

    Science.gov (United States)

    Bordin, Dimorvan; Coelho, Paulo G; Bergamo, Edmara T P; Bonfante, Estevam A; Witek, Lukasz; Del Bel Cury, Altair A

    2018-04-10

    To characterize the mechanical properties of different coating methods of DLC (diamond-like carbon) onto dental implant abutment screws, and their effect on the probability of survival (reliability). Seventy-five abutment screws were allocated into three groups according to the coating method: control (no coating); UMS - DLC applied through unbalanced magnetron sputtering; RFPA-DLC applied through radio frequency plasma-activated (n=25/group). Twelve screws (n=4) were used to determine the hardness and Young's modulus (YM). A 3D finite element model composed of titanium substrate, DLC-layer and a counterpart were constructed. The deformation (μm) and shear stress (MPa) were calculated. The remaining screws of each group were torqued into external hexagon abutments and subjected to step-stress accelerated life-testing (SSALT) (n=21/group). The probability Weibull curves and reliability (probability survival) were calculated considering the mission of 100, 150 and 200N at 50,000 and 100,000 cycles. DLC-coated experimental groups evidenced higher hardness than control (p1 indicating that fatigue contributed to failure. High reliability was depicted at a mission of 100N. At 200N a significant decrease in reliability was detected for all groups (ranging from 39% to 66%). No significant difference was observed among groups regardless of mission. Screw fracture was the chief failure mode. DLC-coating have been used to improve titanium's mechanical properties and increase the reliability of dental implant-supported restorations. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

  2. Influence of occlusal forces on stress distribution in preloaded dental implant screws.

    Science.gov (United States)

    Alkan, Ibrahim; Sertgöz, Atilla; Ekici, Bülent

    2004-04-01

    Abutment and prosthetic loosening of single and multiple screw-retained, implant-supported fixed partial dentures is a concern. The purpose of this study was to investigate stress distribution of preloaded dental implant screws in 3 implant-to-abutment joint systems under simulated occlusal forces. Three abutment-to-implant joint systems were simulated by using the 3-dimensional finite element analysis method: (1) Branemark external hexagonal screw-retained abutment, (2) ITI 8-degree Morse tapered cemented abutment, and (3) ITI 8-degree Morse tapered plus internal octagonal screw-retained abutment. A thermal load and contact analysis method were used to simulate the preload resulting from the manufacturers' recommended torques in implant screw joint assemblies. The simulated preloaded implants were then loaded with 3 simulated static occlusal loads (10 N; horizontal, 35 N; vertical, 70 N; oblique) on the crown position onto the implant complex. Numeric and graphical results demonstrated that the stresses increased in both the abutment and prosthetic screws in the finite element models after simulated horizontal loading. However, when vertical and oblique static loads were applied, stresses decreased in the external hexagonal and internal octagonal plus 8-degree Morse tapered abutment and prosthetic screws with the exception of the prosthetic screw of ITI abutment after 70-N oblique loading. Stresses increased in the ITI 8-degree Morse tapered cemented abutment after both vertical and oblique loads. Although an increase or decrease was demonstrated for the maximum calculated stress values in preloaded screws after occlusal loads, these maximum stress values were well below the yield stress of both abutment and prosthetic screws of 2 implant systems tested. The results imply that the 3 implant-to-abutment joint systems tested may not fail under the simulated occlusal forces.

  3. Stability of the screw joints in patients with implant-supported fixed prostheses in edentulous jaws: a 1-year follow-up study.

    Science.gov (United States)

    Ekfeldt, Anders; Eriksson, Anders; Johansson, Lars-Ake

    2004-01-01

    The purpose of this follow-up study was to evaluate the stability of the screw joint in edentulous patients 1 year after treatment with implant-supported fixed prostheses (Brånemark system). A total of 20 patients were included, 10 treated in the maxilla and 10 in the mandible. The fixed prostheses were removed approximately 1 year after insertion, and the stability of the screw joints was evaluated using a rating scale based upon the CDA quality evaluation criteria of dental care. All implant-supported fixed prostheses were recorded as stable before the prosthetic screws (gold screws) were unscrewed. "Unacceptable loosening" was observed in 4% of the prosthetic screws and in 29% of the abutment screws. In this study, only a few of the prosthetic screws showed unacceptable loosening after 1 year of function. The clinical relevance of the observed high occurrence of loose abutment screws could be questioned, as all fixed prostheses were initially recorded as stable.

  4. Evaluation of torque loss in Co-Cr castable abutments after cyclic loading

    Directory of Open Access Journals (Sweden)

    Somayeh Zeighami

    2018-03-01

    Conclusion: Misfit between the castable implant components can cause torque loss before and after cyclic loading. However, it is more appropriate to relate the results of this study to the screw loosening of the above mentioned abutments than judging their clinical performance.

  5. Effect of the Coronal Wall Thickness of Dental Implants on the Screw Joint Stability in the Internal Implant-Abutment Connection.

    Science.gov (United States)

    Lee, Ji-Hye; Huh, Yoon-Hyuk; Park, Chan-Jin; Cho, Lee-Ra

    2016-01-01

    To evaluate the effect of implant coronal wall thickness on load-bearing capacity and screw joint stability. Experimental implants were customized after investigation of the thinnest coronal wall thickness of commercially available implant systems with a regular platform diameter. Implants with four coronal wall thicknesses (0.2, 0.3, 0.4, and 0.5 mm) were fabricated. Three sets of tests were performed. The first set was a failure test to evaluate load-bearing capacity and elastic limit. The second and third sets were cyclic and static loading tests. After abutment screw tightening of each implant, vertical cyclic loading of 250 N or static loading from 250 to 800 N was applied. Coronal diameter expansion, axial displacement, and removal torque values of the implants were compared. Repeated measures analysis of variance (ANOVA) was used for statistical analysis (α = .05). Implants with 0.2-mm coronal wall thickness demonstrated significantly low load-bearing capacity and elastic limit (both P implants also showed significantly large coronal diameter expansion and axial displacement after screw tightening (both P implant, axial displacement of the abutment, and removal torque loss of the abutment screw (all P Implant coronal wall thickness of 0.2 mm produces significantly inferior load-bearing capacity and screw joint stability.

  6. The role of implant/abutment system on torque maintenance of retention screws and vertical misfit of implant-supported crowns before and after mechanical cycling.

    Science.gov (United States)

    Jorge, Juliana Ribeiro Pala; Barao, Valentim Adelino Ricardo; Delben, Juliana Aparecida; Assuncao, Wirley Goncalves

    2013-01-01

    This study aimed to evaluate the role of the implant/abutment system on torque maintenance of titanium retention screws and the vertical misfit of screw-retained implant-supported crowns before and after mechanical cycling. Three groups were studied: morse taper implants with conical abutments (MTC group), external-hexagon implants with conical abutments (EHC group), and external-hexagon implants with UCLA abutments (EHU group). Metallic crowns casted in cobalt-chromium alloy were used (n = 10). Retention screws received insertion torque and, after 3 minutes, initial detorque was measured. Crowns were retightened and submitted to cyclic loading testing under oblique loading (30 degrees) of 130 ± 10 N at 2 Hz of frequency, totaling 1 × 106 cycles. After cycling, final detorque was measured. Vertical misfit was measured using a stereomicroscope. Data were analyzed by analysis of variance, Tukey test, and Pearson correlation test (P cycling. No statistically significant difference was observed among groups before mechanical cycling. After mechanical cycling, a statistically significantly lower loss of detorque was verified in the MTC group in comparison to the EHC group. Significantly lower vertical misfit values were noted after mechanical cycling but there was no difference among groups. There was no significant correlation between detorque values and vertical misfit. All groups presented a significant decrease of torque before and after mechanical cycling. The morse taper connection promoted the highest torque maintenance. Mechanical cycling reduced the vertical misfit of all groups, although no significant correlation between vertical misfit and torque loss was found.

  7. Eleven-Year Follow-Up of a Prospective Study of Zirconia Implant Abutments Supporting Single All-Ceramic Crowns in Anterior and Premolar Regions.

    Science.gov (United States)

    Zembic, Anja; Philipp, Alexander Otto Hermann; Hämmerle, Christoph Hans Franz; Wohlwend, Arnold; Sailer, Irena

    2015-10-01

    Clinical studies on zirconia abutments report very good survival rates and biological and technical results, but few have an observation period of more than 5 years. The aim of this study was to assess the long-term performance of customized zirconia implant abutments supporting all-ceramic crowns. Twenty-seven patients receiving 54 single implants were included (25 incisors, 14 canines, 15 premolars in both jaws). Yttria-stabilized zirconia abutments were screwed to the implants with a defined torque. All-ceramic crowns were adhesively cemented onto the abutments. The implants, abutments, and crowns were clinically and radiographically examined after 11 years of use. Modified United States Public Health Service (USPHS) criteria were used to assess technical outcomes: fracture of abutment/crown framework/veneering ceramic, loosening of abutment screw/crown, marginal adaptation, anatomical form, occlusal wear, and abutment fit. The biological parameters were pocket probing depth, plaque control record, bleeding on probing, papilla index, and gingival/mucosal recession at implants and neighboring natural teeth. The cumulative success rate of abutments and crowns was calculated by the Kaplan-Meier method. The results of the USPHS criteria were analyzed descriptively. Sixteen patients with 31 zirconia abutments were examined at 11.3 (±0.9) years after implantation. No abutment or crown was lost. The cumulative success rate was 96.3% for abutments and 90.7% for crowns. Two abutment screws loosened, and three crowns exhibited minor chipping. There were no biological complications. Customized zirconia single implant abutments exhibited excellent long-term outcomes in anterior and premolar regions. © 2014 Wiley Periodicals, Inc.

  8. An esthetic solution for single-implant restorations - type III porcelain veneer bonded to a screw-retained custom abutment: a clinical report.

    Science.gov (United States)

    Magne, Pascal; Magne, Michel; Jovanovic, Sascha A

    2008-01-01

    A new esthetic solution to restore dental implants in combination with limited interdental, facial or labial, or interocclusal space is presented. This article describes the translational application of novel-design porcelain veneers and adhesive restorative principles in the implant realm. A patient is presented who was treated with a single implant-supported restoration replacing a missing mandibular lateral incisor and partially collapsed interdental space. A screw-retained custom metal ceramic abutment was combined with a bonded porcelain restoration. This unique design was motivated by the limited restorative space and subgingival implant shoulder. It was also developed as a solution to the interference of the screw-access channel with the incisal edge, therefore providing the surgeon with more options during implant axis selection. The porcelain-to-porcelain adhesive approach was used instead of traditional principles of retention and resistance form of the abutment.

  9. Clinical outcomes of implant abutments in the anterior region: a systematic review.

    Science.gov (United States)

    Bidra, Avinash S; Rungruanganunt, Patchanee

    2013-06-01

    The clinical outcomes of anterior implant abutments are not well reported. Purpose of the Study To systematically review the existing literature to identify survival, mechanical, biological, and esthetic outcomes of anterior implant abutments. An electronic search was performed using PubMed/MEDLINE with specific search terms and predetermined criteria. After application of inclusion and exclusion criteria, the final list of articles was reviewed in-depth to meet the objectives of this review. Systematic application of inclusion and exclusion criteria resulted in identification of 27 studies that described outcomes of anterior implant abutments. Because of substantial heterogeneity of data, true survival, or cumulative survival of abutments could not be calculated. However, the mean failure of abutments was 1.15%, attributable to fractures restricted to ceramic abutments. Mechanical complications included abutment screw loosening, primarily restricted to external hex implants. Biological complications included fistulas and mucosal recession. Esthetic outcomes showed lesser gingival discoloration for zirconia abutments compared with metal abutments. Minimal anterior abutment fractures have been reported and are restricted to ceramic abutments. Studies using spectrophotometry showed lesser gingival discoloration with zirconia abutments, but there is no evidence for difference in patient's esthetic satisfaction between ceramic and metal abutments. For the anterior region, selection of an implant with internal connection and a customized metal abutment (titanium or cast metal) can have the least mechanical complications. Limited existing clinical data indicate reduced peri-implant mucosal discoloration from zirconia abutments, which may be preferable over metal abutments, in patients with thinner mucosal tissues or patients with high or gummy smiles. © 2013 Wiley Periodicals, Inc.

  10. Effect of Preseating, Screw Access Opening, and Vent Holes on Extrusion of Excess Cement at the Crown-Abutment Margin and Associated Tensile Force for Cement-Retained Implant Restorations.

    Science.gov (United States)

    Jimenez, Rodrigo A; Vargas-Koudriavtsev, Tatiana

    2016-01-01

    This study sought to (1) compare the effects of crown preseating prior to cementation, (2) determine whether maintenance of screw access openings on titanium abutments and open vent holes on cast crowns affects the amount of excess cement at the crown-abutment margin, and (3) analyze the associated tensile force after cementation. Three independent variables were tested: (1) abutment screw access (open or closed), (2) crown coping modification (with or without a vent hole in the palatal aspect), and (3) crown preseating on an abutment analog. Ten implant crown copings were cemented using temporary cement on ten straight implant abutments for each combination of the three independent variables. The amount of excess cement at the crown margins was measured by weight. Axial tensile load was measured 24 hours after cementation. Results were statistically analyzed using linear regression and univariate three-way analysis of variance (α = .05). Open screw access, presence of a vent hole on the crown, and preseating of the crown had significant effects on the amount of excess cement at the crown margin (P cement at the margins and tensile strength values. Placement of vent holes on the crown or open screw access may be considered for cementing crowns on implant abutments using temporary cement in order to minimize excess cement at the crown margin. A preseating protocol is not advisable, either alone or combined with open screw access, since it significantly reduces the retentive strength of cemented restorations (P < .001).

  11. Scanning Electron Microscopy Analysis of the Adaptation of Single-Unit Screw-Retained Computer-Aided Design/Computer-Aided Manufacture Abutments After Mechanical Cycling.

    Science.gov (United States)

    Markarian, Roberto Adrian; Galles, Deborah Pedroso; Gomes França, Fabiana Mantovani

    To measure the microgap between dental implants and custom abutments fabricated using different computer-aided design/computer-aided manufacture (CAD/CAM) methods before and after mechanical cycling. CAD software (Dental System, 3Shape) was used to design a custom abutment for a single-unit, screw-retained crown compatible with a 4.1-mm external hexagon dental implant. The resulting stereolithography file was sent for manufacturing using four CAD/CAM methods (n = 40): milling and sintering of zirconium dioxide (ZO group), cobalt-chromium (Co-Cr) sintered via selective laser melting (SLM group), fully sintered machined Co-Cr alloy (MM group), and machined and sintered agglutinated Co-Cr alloy powder (AM group). Prefabricated titanium abutments (TI group) were used as controls. Each abutment was placed on a dental implant measuring 4.1× 11 mm (SA411, SIN) inserted into an aluminum block. Measurements were taken using scanning electron microscopy (SEM) (×4,000) on four regions of the implant-abutment interface (IAI) and at a relative distance of 90 degrees from each other. The specimens were mechanically aged (1 million cycles, 2 Hz, 100 N, 37°C) and the IAI width was measured again using the same approach. Data were analyzed using two-way analysis of variance, followed by the Tukey test. After mechanical cycling, the best adaptation results were obtained from the TI (2.29 ± 1.13 μm), AM (3.58 ± 1.80 μm), and MM (1.89 ± 0.98 μm) groups. A significantly worse adaptation outcome was observed for the SLM (18.40 ± 20.78 μm) and ZO (10.42 ± 0.80 μm) groups. Mechanical cycling had a marked effect only on the AM specimens, which significantly increased the microgap at the IAI. Custom abutments fabricated using fully sintered machined Co-Cr alloy and machined and sintered agglutinated Co-Cr alloy powder demonstrated the best adaptation results at the IAI, similar to those obtained with commercial prefabricated titanium abutments after mechanical cycling. The

  12. Experimental zirconia abutments for implant-supported single-tooth restorations in esthetically demanding regions: 4-year results of a prospective clinical study.

    Science.gov (United States)

    Glauser, Roland; Sailer, Irena; Wohlwend, Arnold; Studer, Stephan; Schibli, Monica; Schärer, Peter

    2004-01-01

    This prospective clinical study evaluated an experimental implant abutment made of densely sintered zirconia with respect to peri-implant hard and soft tissue reaction as well as fracture resistance over time. Twenty-seven consecutively treated patients with 54 single-tooth implants were included. Zirconia abutment ingots were individually shaped and set on the implants with gold screws. All-ceramic (Empress I) crowns were cemented using a composite cement. At the 1- and 4-year examinations, reconstructions were evaluated for technical problems (fracture of abutment or crown, loosening of abutment screw). Modified Plaque and simplified Gingival Indices were recorded at implants and neighboring teeth, and peri-implant bone levels were radiographically determined. All but 1 of the 27 patients with 53 restorations could be evaluated at 1 year, and 36 restorations in 18 patients were evaluated 4 years after abutment and crown insertion. The median observation period for the reconstructions was 49.2 months. No abutment fractures occurred. Abutment screw loosening was reported for 2 restorations at 8 months and 27 months, respectively. Mean Plaque Index was 0.4 (SD 0.6) at abutments and 0.5 (SD 0.6) at teeth; mean Gingival Index was 0.7 (SD 0.5) at abutments and 0.9 (SD 0.5) at teeth. Mean marginal bone loss measured 1.2 mm (SD 0.5) after 4 years of functional loading. Zirconia abutments offered sufficient stability to support implant-supported single-tooth reconstructions in anterior and premolar regions. The soft and hard tissue reaction toward zirconia was favorable.

  13. Long-term cumulative survival and mechanical complications of single-tooth Ankylos Implants: focus on the abutment neck fractures.

    Science.gov (United States)

    Shim, Hye Won; Yang, Byoung-Eun

    2015-12-01

    To evaluate the cumulative survival rate (CSR) and mechanical complications of single-tooth Ankylos® implants. This was a retrospective clinical study that analyzed 450 single Ankylos® implants installed in 275 patients between December 2005 and December 2012. The main outcomes were survival results CSR and implant failure) and mechanical complications (screw loosening, fracture, and cumulative fracture rate [CFR]). The main outcomes were analyzed according to age, sex, implant length or diameter, bone graft, arch, and position. The 8-year CSR was 96.9%. Thirteen (2.9%) implants failed because of early osseointegration failure in 3, marginal bone loss in 6, and abutment fracture in 4. Screw loosening occurred in 10 implants (2.2%), and 10 abutment fractures occurred. All abutment fractures were located in the neck, and concurrent screw fractures were observed. The CSR and rate of screw loosening did not differ significantly according to factors. The CFR was higher in middle-aged patients (5.3% vs 0.0% in younger and older patients); for teeth in a molar position (5.8% vs 0.0% for premolar or 1.1% for anterior position); and for larger-diameter implants (4.5% for 4.5 mm and 6.7% for 5.5 mm diameter vs 0.5% for 3.5 mm diameter) (all Ptooth restoration in Koreans. However, relatively frequent abutment fractures (2.2%) were observed and some fractures resulted in implant failures. Middle-aged patients, the molar position, and a large implant diameter were associated with a high incidence of abutment fracture.

  14. The management of an edentulous maxilla using a CAD/CAM-guided immediately loaded provisional implant prosthesis with screw-retained and cement-retained abutments: a clinical report.

    Science.gov (United States)

    Tee-Khin, Neo; Cheng, Ansgar C; Lee, Helena; Wee, Alvin G

    2009-12-01

    Functional rehabilitation of edentulous jaws using a CAD/CAM-guided implant protocol is commonly recommended as a definitive treatment modality. A patient with an edentulous maxilla received 7 endosseous implants using a CAD/CAM surgical template. A provisional maxillary acrylic resin fixed complete denture was connected immediately after implant placement using a combination of screw-retained and cement-retained abutments.

  15. Influence of space size of abutment screw access channel on the amount of extruded excess cement and marginal accuracy of cement-retained single implant restorations.

    Science.gov (United States)

    Al Amri, Mohammad D; Al-Johany, Sulieman S; Al-Qarni, Mohammed N; Al-Bakri, Ahmed S; Al-Maflehi, Nassr S; Abualsaud, Haythem S

    2018-02-01

    The detrimental effect of extruded excess cement on peri-implant tissue has been well documented. Although several techniques have been proposed to reduce this effect by decreasing the amount of extruded cement, how the space size of the abutment screw access channel (SAC) affects the amount of extruded cement and marginal accuracy is unclear. The purpose of this in vitro study was to evaluate the effect of the size of the unfilled space of the abutment SAC on the amount of extruded excess cement and the marginal accuracy of zirconia copings. Twelve implant replicas and corresponding standard abutments were attached and embedded in acrylic resin blocks. Computer-aided design and computer-aided manufacturing (CAD-CAM) zirconia copings with a uniform 30-μm cement space were fabricated by 1 dental technician using the standard method. The copings were temporarily cemented 3 times at different sizes of the left space of the SAC as follows: the nonspaced group (NS), in which the entire SAC was completely filled, the 1-mm-spaced group (1MMS), and the 2-mm-spaced group (2MMS). Abutments and crowns were ultrasonically cleaned, steam cleaned, and air-dried. The excess cement was collected and weighed. To measure the marginal accuracy, 20 measurements were made every 18 degrees along the coping margin at ×300 magnification and compared with the pre-cementation readings. One-way ANOVA was calculated to determine whether the amount of extruded excess cement differed among the 3 groups, and the Tukey test was applied for multiple comparisons (α=.05). The mean weights (mg) of extruded excess cement were NS (33.53 ±1.5), 1MMS (22.97 ±5.4), and 2MMS (15.17 ±5.9). Multiple comparisons showed significant differences in the amount of extruded excess cement among the 3 test groups (Pextruded excess cement by 55% in comparison with the nonspaced abutments. However, no effect was found on the marginal accuracy of zirconia copings. Copyright © 2017 Editorial Council for the

  16. Biomechanical evaluation of different abutment-implant connections - A nonlinear finite element analysis

    Science.gov (United States)

    Ishak, Muhammad Ikman; Shafi, Aisyah Ahmad; Rosli, M. U.; Khor, C. Y.; Zakaria, M. S.; Rahim, Wan Mohd Faizal Wan Abd; Jamalludin, Mohd Riduan

    2017-09-01

    The success of dental implant surgery is majorly dependent on the stability of prosthesis to anchor to implant body as well as the integration of implant body to bone. The attachment between dental implant body and abutment plays a vital role in attributing to the stability of dental implant system. A good connection between implant body cavity to abutment may minimize the complications of abutment loosening and implant fractures as widely reported in clinical findings. The aim of this paper is to investigate the effect of different abutment-implant connections on stress dispersion within the abutment and implant bodies as well as displacement of implant body via three-dimensional (3-D) finite element analysis (FEA). A 3-D model of mandible was reconstructed from computed tomography (CT) image datasets using an image-processing software with the selected region of interest was the left side covering the second premolar, first molar and second molar regions. The bone was modelled as compact (cortical) and porous (cancellous) structures. Besides, three implant bodies and three generic models of abutment with different types of connections - tapered interference fit (TIF), tapered integrated screwed-in (TIS) and screw retention (SR) were created using computer-aided design (CAD) software and all models were then analysed via 3D FEA software. Occlusal forces of 114.6 N, 17.2 N and 23.4 N were applied in the axial, lingual and mesio-distal directions, respectively, on the top surface of first molar crown. All planes of the mandibular bone model were rigidly fixed. The result exhibited that abutment with TIS connection produced the most favourable stress and displacement outcomes as compared to other attachment types. This is due to the existence of integrated screw at the bottom portion of tapered abutment which increases the motion resistance.

  17. Prospective assessment of CAD/CAM zirconia abutment and lithium disilicate crown restorations: 2.4 year results.

    Science.gov (United States)

    Cooper, Lyndon F; Stanford, Clark; Feine, Jocelyne; McGuire, Michael

    2016-07-01

    Single-tooth implant restorations are commonly used to replace anterior maxillary teeth. The esthetic, functional, and biologic outcomes are, in part, a function of the abutment and crown. The purpose of this clinical study was to describe the implant, abutment, and crown survival and complication rates for CAD/CAM zirconia abutment and lithium disilicate crown restorations for single-tooth implants. As part of a broader prospective investigation that enrolled and treated 141 participants comparing tissue responses at the conical interface (CI; AstraTech OsseoSpeed), flat-to-flat interface (FI; NobelSpeedy), and platform-switch interface (PS; NanoTite Certain Prevail) of single-tooth implants, computer-aided design and computer-aided manufacturing (CAD/CAM) zirconia abutments (ATLANTIS Abutment) and cemented lithium disilicate (e.max) crowns were used in the restoration of all implants. After 2.4 years in function (3 years after implant placement), the implant, abutment, and crown of 110 participants were evaluated. Technical and biologic complications were recorded. Demographic results were tabulated as percentages with mean values and standard deviations. Abutment survival was calculated with the Kaplan-Meier method. After 2.4 years, no abutments or crowns had been lost. Abutment complications (screw loosening, screw fracture, fracture) were absent for all 3 implant groups. Crown complications were limited to 2 crowns debonding and 1 with excess cement (2.5%). Five biological complications (4.0%) were recorded. The overall complication rate was 6.5%. CAD/CAM zirconia abutments restored with cemented lithium disilicate crowns demonstrated high survival on 3 different implant-abutment interface designs. No abutment or abutment screw fracture occurred. The technical complications observed after 2.4 years were minor and reversible. The use of CAD/CAM zirconia abutments with cemented lithium disilicate crowns is associated with high technical and biologic success at 2

  18. Clinical Performance of One-Piece, Screw-Retained Implant Crowns Based on Hand-Veneered CAD/CAM Zirconia Abutments After a Mean Follow-up Period of 2.3 Years.

    Science.gov (United States)

    Schnider, Nicole; Forrer, Fiona Alena; Brägger, Urs; Hicklin, Stefan Paul

    The aim of this study was to evaluate the clinical performance of one-piece, screw-retained implant crowns based on hand-veneered computer-aided design/computer-aided manufacture (CAD/CAM) zirconium dioxide abutments with a crossfit connection at least 1 year after insertion of the crown. Consecutive patients who had received at least one Straumann bone level implant and one-piece, screw-retained implant crowns fabricated with CARES zirconium dioxide abutments were reexamined. Patient satisfaction, occlusal and peri-implant parameters, mechanical and biologic complications, radiologic parameters, and esthetics were recorded. A total of 50 implant crowns in the anterior and premolar region were examined in 41 patients. The follow-up period of the definitive reconstructions ranged from 1.1 to 3.8 years. No technical and no biologic complications had occurred. At the reexamination, 100% of the implants and reconstructions were in situ. Radiographic evaluation revealed a mean distance from the implant shoulder to the first visible bone-to-implant contact of 0.06 mm at the follow-up examination. Screw-retained crowns based on veneered CAD/CAM zirconium dioxide abutments with a crossfit connection seem to be a promising way to replace missing teeth in the anterior and premolar region. In the short term, neither failures of components nor complications were noted, and the clinical and radiographic data revealed stable hard and soft tissue conditions.

  19. In vitro performance of implant-supported monolithic zirconia crowns: Influence of patient-specific tooth-coloured abutments with titanium adhesive bases.

    Science.gov (United States)

    Rosentritt, Martin; Rembs, Andreas; Behr, Michael; Hahnel, Sebastian; Preis, Verena

    2015-07-01

    To investigate the influence of the combination of patient-specific abutments and titanium adhesive bases on the long-term in vitro performance of anterior crowns. Ten systems of screw-retained implant and adhesive base combinations (n=8/group) were restored with zirconia or polyetherketone (PEEK) abutments and identical full-anatomical zirconia crowns. For simulating clinical anterior loading, implants were fixed at an angle of 135° and submitted to prolonged thermal cycling and mechanical loading (TC: 6×3000 cycles, 5°C/55°C; ML: 100N, 3.6×10(6) cycles) to cause and register fatigue failure. Failed restorations were examined by means of scanning electron microscopy. Surviving restorations were loaded to fracture. Data (mean±standard deviation) were statistically analyzed (ANOVA; Bonferroni; Kaplan-Meier-Log-Rank; α=0.05). Seven systems survived TCML without any failure. The other three systems showed loosening and fracturing of the screw (0.4-1.6×10(6) loadings) or debonding between base and abutment (0.002-3.4×10(6) loadings). None of the systems showed any fracture of the crown or failed bonding between abutment and crown. The Log-Rank test showed significant (p=0.000) differences. Fracture data significantly varied (ANOVA p=0.000) between the individual systems (minimum: 371N; maximum: 763N). Failures were mostly caused by bending or fracturing of the screw and in three cases by fracture of the abutment. Anterior implant-supported zirconia crowns on titanium adhesive bases and bonded patient-specific zirconia abutments provided good in vitro performance and high fracture resistance. Sufficient high torque moments and early re-screwing may be advised. Most adhesive base and abutment combinations may be appropriate for anterior application. Individual improvements may contribute to enduring success. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Compatible CAD-CAM titanium abutments for posterior single-implant tooth replacement: A retrospective case series.

    Science.gov (United States)

    Hsu, Kuang-Wei; Shen, Yu-Fu; Wei, Pein-Chi

    2017-03-01

    In addition to the original abutments provided by implant companies, compatible computer-aided design and computer-aided manufacturing (CAD-CAM) abutments are also available from different manufacturers. However, the combination of abutments and implant systems from different manufacturers may lead to mechanical problems between components. Little has been reported on the clinical performance of this treatment option. The purpose of this retrospective case series was to evaluate the outcome of compatible CAD-CAM titanium abutments (TiAs) for posterior single-implant tooth replacement (PSITR) up to 6 years after insertion. Eighty-one patients (34 men, 47 women) who received PSITR restored with compatible CAD-CAM TiAs and had a final recall examination between May 2014 and April 2015 were included in this study. Clinical and radiographic examinations were documented. Retrospective evaluation of the patient records was also performed. Correlations between bone-level changes and variables were calculated using the Spearman correlation. Implant and prosthesis survival rates were 100%. Twenty technical complications were observed, including 9 decementations of the crown, 6 screw loosenings, and 5 ceramic fractures. Periimplant mucositis was diagnosed in 36 patients (44.4%) and periimplantitis in 6 patients (7.4%). Correlation analysis showed a significant effect of the extent of periodontal bone loss of the remaining teeth on the marginal bone-level changes around implants (r=0.548, P<.001). Compatible CAD-CAM TiAs provide a viable treatment option for PSITR. However, in light of relatively high screw-loosening and decementation rates, choosing appropriate cements and abutment manufacturers is essential to improve the clinical performance of this treatment option. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  1. The abutment seating jig: a prosthodontic implant adjunct.

    Science.gov (United States)

    Judy, K W

    1997-01-01

    Rapid, accurate seating of screw-retained implant abutment heads, where timing is controlled by internal or external hex designs, can be readily accomplished with individual, custom-cast abutment head location devices. The devices are especially useful when the abutment head-implant body complex is to be permanently cemented. The use and design of abutment seating jigs for single tooth implants and completely implant or implant and natural tooth-supported prostheses are described.

  2. Practice-based clinical evaluation of zirconia abutments for anterior single-tooth restorations.

    Science.gov (United States)

    Rinke, Sven; Lattke, Anja; Eickholz, Peter; Kramer, Katharina; Ziebolz, Dirk

    2015-01-01

    This study aimed to determine the survival rate and prevalence of biologic and technical complications associated with single-tooth implants with all-ceramic abutments in the anterior region. A total of 33 patients were restored with 50 anterior implants and temporarily luted all-ceramic crowns on prefabricated zirconia abutments. All of the patients subsequently received annual supportive maintenance; 27 patients (18 women, 22-74 years) with 42 implants participated in the final maintenance visit and were included in the study (follow-up 78.1 ± 27.0 months). The time-dependent survival rate (Kaplan-Meier) and the frequency of prosthetic complications (abutment fracture [AF], screw loosening [SL], fracture of veneering ceramics [VF], retention loss [RL]) and biologic complications (peri-implantitis) were calculated to determine the success rates. No implant loss (implant-related survival rate 100%) but one abutment fracture occurred throughout the entire observation period; therefore, the survival rate of the superstructures (in situ criterion) was 97.6% (95% confidence interval [CI] 0.930- 1.000) after 7 years. Eleven restorations were affected by prosthetic complications: RL (n = 4), VF (n = 5), and SL (n = 2). Peri-implantitis was diagnosed for two implants (probing depth > 5 mm, bleeding on probing [BOP]/suppuration, and bone loss > 3 mm) (implant-related peri-implantitis rate 4.8%). No restoration required replacement due to complications. The success rate (event-free restoration) was 75.9% (95% CI 0.636- 0.882) after 7 years. Considering the calculated survival rate, the application of all-ceramic zirconia implant abutments in the anterior region can be recommended as a reliable therapy in private practice. Fractures of veneering ceramics were the most common prosthetic complication.

  3. Loosening After Acetabular Revision

    DEFF Research Database (Denmark)

    Beckmann, Nicholas A.; Weiss, Stefan; Klotz, Matthias C.M.

    2014-01-01

    The best method of revision acetabular arthroplasty remains unclear. Consequently, we reviewed the literature on the treatment of revision acetabular arthroplasty using revision rings (1541 cases; mean follow-up (FU) 5.7 years) and Trabecular Metal, or TM, implants (1959 cases; mean FU 3.7 years......) to determine if a difference with regard to revision failure could be determined. Failure rates of the respective implants were compared statistically using a logistic regression model with adjustment for discrepancies in FU time. In our study, TM shows statistically significant decreased loosening rates...... relative to revision rings for all grades including severe acetabular defects and pelvic discontinuity. The severe defects appear to benefit the most from TM....

  4. The pullout performance of pedicle screws

    CERN Document Server

    Demir, Teyfik

    2015-01-01

    This brief book systematically discusses all subjects that affect the pullout strength of pedicle screws. These screws are used in spinal surgeries to stabilize the spine. The holding strength of the pedicle screw is vital since loosening of the pedicle screws can cause revision surgeries. Once the pedicle screw is pulled out, it is harder to obtain same stabilization for the fused vertebrae. The book reviews the effect of screw designs, application techniques, cement augmentation, coating of the screw and test conditions on the pullout strength. The studies with finite element analysis were also included.

  5. Influence of abutment materials on the implant-abutment joint stability in internal conical connection type implant systems

    Science.gov (United States)

    Jo, Jae-Young; Yang, Dong-Seok; Huh, Jung-Bo; Heo, Jae-Chan; Yun, Mi-Jung

    2014-01-01

    PURPOSE This study evaluated the influence of abutment materials on the stability of the implant-abutment joint in internal conical connection type implant systems. MATERIALS AND METHODS Internal conical connection type implants, cement-retained abutments, and tungsten carbide-coated abutment screws were used. The abutments were fabricated with commercially pure grade 3 titanium (group T3), commercially pure grade 4 titanium (group T4), or Ti-6Al-4V (group TA) (n=5, each). In order to assess the amount of settlement after abutment fixation, a 30-Ncm tightening torque was applied, then the change in length before and after tightening the abutment screw was measured, and the preload exerted was recorded. The compressive bending strength was measured under the ISO14801 conditions. In order to determine whether there were significant changes in settlement, preload, and compressive bending strength before and after abutment fixation depending on abutment materials, one-way ANOVA and Tukey's HSD post-hoc test was performed. RESULTS Group TA exhibited the smallest mean change in the combined length of the implant and abutment before and after fixation, and no difference was observed between groups T3 and T4 (P>.05). Group TA exhibited the highest preload and compressive bending strength values, followed by T4, then T3 (Pimplant systems. The strength of the abutment material was inversely correlated with settlement, and positively correlated with compressive bending strength. Preload was inversely proportional to the frictional coefficient of the abutment material. PMID:25551010

  6. Pedicle screw anchorage of carbon fiber-reinforced PEEK screws under cyclic loading.

    Science.gov (United States)

    Lindtner, Richard A; Schmid, Rene; Nydegger, Thomas; Konschake, Marko; Schmoelz, Werner

    2018-03-01

    Pedicle screw loosening is a common and significant complication after posterior spinal instrumentation, particularly in osteoporosis. Radiolucent carbon fiber-reinforced polyetheretherketone (CF/PEEK) pedicle screws have been developed recently to overcome drawbacks of conventional metallic screws, such as metal-induced imaging artifacts and interference with postoperative radiotherapy. Beyond radiolucency, CF/PEEK may also be advantageous over standard titanium in terms of pedicle screw loosening due to its unique material properties. However, screw anchorage and loosening of CF/PEEK pedicle screws have not been evaluated yet. The aim of this biomechanical study therefore was to evaluate whether the use of this alternative nonmetallic pedicle screw material affects screw loosening. The hypotheses tested were that (1) nonmetallic CF/PEEK pedicle screws resist an equal or higher number of load cycles until loosening than standard titanium screws and that (2) PMMA cement augmentation further increases the number of load cycles until loosening of CF/PEEK screws. In the first part of the study, left and right pedicles of ten cadaveric lumbar vertebrae (BMD 70.8 mg/cm 3  ± 14.5) were randomly instrumented with either CF/PEEK or standard titanium pedicle screws. In the second part, left and right pedicles of ten vertebrae (BMD 56.3 mg/cm 3  ± 15.8) were randomly instrumented with either PMMA-augmented or nonaugmented CF/PEEK pedicle screws. Each pedicle screw was subjected to cyclic cranio-caudal loading (initial load ranging from - 50 N to + 50 N) with stepwise increasing compressive loads (5 N every 100 cycles) until loosening or a maximum of 10,000 cycles. Angular screw motion ("screw toggling") within the vertebra was measured with a 3D motion analysis system every 100 cycles and by stress fluoroscopy every 500 cycles. The nonmetallic CF/PEEK pedicle screws resisted a similar number of load cycles until loosening as the contralateral standard

  7. Radionuclide arthrogram to evaluate knee prostheses loosening

    International Nuclear Information System (INIS)

    Ahn, U.

    2009-01-01

    Full text:This case is about a 78 year old lady who had 3TKRs on her left knee. The 2nd revision surgery was performed due to infection. After 6 weeks long procedure, that patient was discharged with satisfactory movement without sign of infection. 15 months after the surgery, the orthopaedic surgeon found that some pressure wave effects and pain with walking. There was no sign of infection clinically. Once X-ray could not confirm any micro-loosening, the surgeon wanted to investigate with radionuclide arthrogram for this difficult case. 40 MBq in 2mls of Calcium phytate colloid (from RADPHARM Australia) was injected into the knee joint space. 30 minutes static views revealed the tracer started to travel below the tibial component. 4 hours statics views clearly indicate the tibial component loosening also there was leakage of tracer through anterior tibial osteotomy screws into the level of ankle subcutaneously. Cobalt57 flood images provided the anatomical localisation. While the surgeon was planning new component for the 3rd revision surgery, the patient's pain disappeared with time. No more revision was considered with satisfactory level of movement. This was the first and only case of radio arthogram to our department, although we perform many bone scans with same reason. On published articles, overall sensitivity and specificity are variable from 85% to 100%. When we take look at other clinical experience, there are a number of reasons in the high accuracy and reliability of radionuclide arthrogram especially for knee prosthesis loosening. Therefore I want to emphasise the benefit of radionuclide arthrogram for both patient and surgeon as a reliable diagnosis with minimum discomfort.

  8. Immediate placement and provisionalization of single-tooth implants involving a definitive individual abutment: a clinical and radiographic retrospective study.

    Science.gov (United States)

    Hartlev, Jens; Kohberg, Peter; Ahlmann, Søren; Gotfredsen, Erik; Andersen, Niels Trolle; Isidor, Flemming; Schou, Søren

    2013-06-01

    To assess with a mean follow-up period of 33 months (median: 31 month, range: 11-89 month) the treatment outcome after immediate placement and provisionalization of single-tooth oral implants involving a definitive individual abutment and a provisional crown followed by later placement of a definitive crown. 68 patients with 68 single-tooth implants in the esthetic zone were consecutively treated; 55 of these patients were included in the study. The treatment involved tooth extraction, implant placement, placement of a definitive individual abutment, and a provisional crown in the same visit in private practice. The definitive crown was placed after a mean period of 7 months. The primary outcome measures included implant survival, definitive implant crown survival, and overall treatment survival. The secondary outcome measures included probing depth, bleeding on probing, peri-implant marginal bone level, marginal bone level of the neighboring tooth surfaces, biological complications, and technical complications. Of the inserted implants 98% survived and of the definitive crowns mounted a survival of 100% was observed. Consequently, the overall treatment survival was 98%. The mean probing depth was 2.9 mm at implant level and 63% of the implants were characterized by no bleeding on probing. The mean peri-implant marginal bone level was 2 mm. A significant mean peri-implant marginal bone level gain of 0.5 mm was observed from implant placement to the follow-up (95% CI: 0.07-0.89 mm, P = 0.022). No significant changes of the marginal bone level at the neighboring tooth surfaces were seen. Four episodes of peri-implant inflammation were identified in three patients, while 46 incidents of loosening of the provisional crown occurred in 33 patients. One abutment screw loosened before placement of the definitive crown. Finally, loosening of four definitive crowns occurred in four patients. Immediate placement and provisionalization of single-tooth oral implants

  9. Load fatigue performance of conical implant-abutment connections.

    Science.gov (United States)

    Seetoh, Y L; Tan, Keson B; Chua, E K; Quek, H C; Nicholls, Jack I

    2011-01-01

    Conical implant-abutment connections for platform switching have been recently introduced in implant systems. This study investigated the load fatigue performance of three conical abutment systems and their corresponding titanium and zirconia abutments. Regular-diameter implants of the Ankylos (AK), PrimaConnex (PC), and Straumann (ST) systems were tested with their corresponding titanium (Ti) and zirconia (Zr) abutments tightened to the recommended torque (n = 5 implant-abutment assemblies per group). A rotational load fatigue machine applied a sinusoidally varying tensile-compressive 21 N load to specimens at a 45-degree angle, producing an effective bending moment of 35 Ncm at a frequency of 10 Hz. The number of cycles to failure was recorded, with the upper limit set at 5 million cycles. Results were evaluated through analyses of variance. Except for the ST Zr group, which showed no failures in four samples and one failure just below the screw head, and the AK Ti group, in which one sample was preserved without fracture, all groups experienced failure of at least one of the components, whether the abutment screw only, the abutment, and/or the implant neck. There were significant differences between systems. There was no difference between systems for the Ti abutments, and the ST group was significantly different from the AK and PC groups for the Zr abutments. Ti conical abutments appear to have poorer load fatigue performance compared with earlier studies of external-hexagon connections. The load fatigue performance of Zr conical abutments varied and seemed to be highly system dependent. Many of the fractures in both the Ti and Zr abutment groups occurred within the implant, and retrieval would pose a significant clinical challenge. The clinician should weigh the mechanical, biologic, and esthetic considerations before selection of any implant system, connection type, or abutment material.

  10. FEA and microstructure characterization of a one-piece Y-TZP abutment.

    Science.gov (United States)

    da Silva, Lucas Hian; Ribeiro, Sebastião; Borges, Alexandre Luís Souto; Cesar, Paulo Francisco; Tango, Rubens Nisie

    2014-11-01

    The most important drawback of dental implant/abutment assemblies is the need for a fixing screw. This study aimed to develop an esthetic one-piece Y-TZP abutment to suppress the use of the screw. Material characterization was performed using a bar-shaped specimen obtained by slip-casting to validate the method prior to prototype abutment fabrication by the same process. The mechanical behavior of the prototype abutment was verified and compared with a conventional abutment by finite element analysis (FEA). The abutment was evaluated by micro-CT analysis and its density was measured. FEA showed stress concentration at the first thread pitch during installation and in the cervical region during oblique loading for both abutments. However, stress concentration was observed at the base of the screw head and stem in the conventional abutment. The relative density for the fabricated abutment was 95.68%. Micro-CT analysis revealed the presence of elongated cracks with sharp edges over the surface and porosity in the central region. In the light of these findings, the behavior of a one-piece abutment is expected to be better than that of the conventional model. New studies should be conducted to clarify the performance and longevity of this one-piece Y-TZP abutment. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  11. Fracture resistance of implant- supported monolithic crowns cemented to zirconia hybrid-abutments: zirconia-based crowns vs. lithium disilicate crowns.

    Science.gov (United States)

    Elshiyab, Shareen H; Nawafleh, Noor; Öchsner, Andreas; George, Roy

    2018-02-01

    The aim of this in vitro study was to investigate the fracture resistance under chewing simulation of implant-supported posterior restorations (crowns cemented to hybrid-abutments) made of different all-ceramic materials. Monolithic zirconia (MZr) and monolithic lithium disilicate (MLD) crowns for mandibular first molar were fabricated using computer-aided design/computer-aided manufacturing technology and then cemented to zirconia hybrid-abutments (Ti-based). Each group was divided into two subgroups (n=10): (A) control group, crowns were subjected to single load to fracture; (B) test group, crowns underwent chewing simulation using multiple loads for 1.2 million cycles at 1.2 Hz with simultaneous thermocycling between 5℃ and 55℃. Data was statistically analyzed with one-way ANOVA and a Post-Hoc test. All tested crowns survived chewing simulation resulting in 100% survival rate. However, wear facets were observed on all the crowns at the occlusal contact point. Fracture load of monolithic lithium disilicate crowns was statistically significantly lower than that of monolithic zirconia crowns. Also, fracture load was significantly reduced in both of the all-ceramic materials after exposure to chewing simulation and thermocycling. Crowns of all test groups exhibited cohesive fracture within the monolithic crown structure only, and no abutment fractures or screw loosening were observed. When supported by implants, monolithic zirconia restorations cemented to hybrid abutments withstand masticatory forces. Also, fatigue loading accompanied by simultaneous thermocycling significantly reduces the strength of both of the all-ceramic materials. Moreover, further research is needed to define potentials, limits, and long-term serviceability of the materials and hybrid abutments.

  12. Simple New Screw Insertion Technique without Extraction for Broken Pedicle Screws.

    Science.gov (United States)

    Kil, Jin-Sang; Park, Jong-Tae

    2018-05-01

    Spinal transpedicular screw fixation is widely performed. Broken pedicle screw rates range from 3%-7.1%. Several techniques have been described for extraction of broken pedicle screws. However, most of these techniques require special instruments. We describe a simple, modified technique for management of broken pedicle screws without extraction. No special instruments or drilling in an adjacent pedicle are required. We used a high-speed air drill with a round burr. With C-arm fluoroscopy guidance, the distal fragment of a broken pedicle screw was palpated using free-hand technique through the screw entry hole. A high-speed air drill with a round burr (not a diamond burr) was inserted through the hole. Drilling began slowly and continued until enough space was obtained for new screw insertion. Using this space, we performed new pedicle screw fixation medially alongside the distal fragment of the broken pedicle screw. We performed the insertion with a previously used entry hole and pathway in the pedicle. The same size pedicle screw was used. Three patients were treated with this modified technique. New screw insertion was successful in all cases after partial drilling of the distal broken pedicle screw fragment. There were no complications, such as screw loosening, dural tears, or root injury. We describe a simple, modified technique for management of broken pedicle screws without extraction. This technique is recommended in patients who require insertion of a new screw. Copyright © 2017. Published by Elsevier Inc.

  13. The behavior of implant-supported dentures and abutments using the cemented cylinder technique with different resinous cements

    Directory of Open Access Journals (Sweden)

    Ivete Aparecida de Mathias Sartori

    2008-01-01

    Full Text Available Objective: Evaluate the behavior of implant-supported dentures and their components, made by cemented cylinder technique, using threetypes of resin cements. Methods: Fifty three patients, of whom 26 were women and 27 men, aged between 25 and 82 years. Results: With partial (54.43% and total (45.57% implant-supported dentures, of the Cone Morse, external and internal hexagon types (Neodent®, Curitiba, Brazil, totaling 237 fixations, were analyzed. The resin cements used were Panavia® (21.94%, EnForce® (58.23% and Rely X® (19.83% and the components were used in accordance with the Laboratory Immediate Loading - Neodent® sequence. The period of time of denture use ranged between 1 and 5 years. The results reported that 5(2.1% cylinders were loosened from metal structure (both belonging to Rely X group, 2(0.48% implants were lost after the first year of use, 16(6.75% denture retention screws wereloosened and 31(13.08% abutment screws were unloosened.Conclusion: The reasons for these failures probably are: metal structure internal retention failure, occlusal pattern, cementation technique and loading conditions. The cemented cylinder technique was effective when used in partial and total implant-supported rehabilitations, keeping prosthetic components stable, despite the resin cement utilized. However, further clinical studies must be conducted.

  14. Experimental research on the relationship between fit accuracy and fracture resistance of zirconia abutments.

    Science.gov (United States)

    Sui, Xinxin; Wei, Huasha; Wang, Dashan; Han, Yan; Deng, Jing; Wang, Yongliang; Wang, Junjun; Yang, Jianjun

    2014-10-01

    The purpose of the study was to investigate the correlation between fit accuracy and fracture resistance of zirconia abutments, as well as its feasibility for clinical applications. Twenty self-made zirconia abutments were tested with 30 Osstem GSII implants. First, 10 Osstem GSII implants were cut into two parts along the long axis and assembled with the zirconia abutments. The microgaps between the implants and the zirconia abutments were measured under a scanning electron microscope. Second, the zirconia abutments were assembled with 20 un-cut implants and photographed before and after being fixed with a central screw of 30-Ncm torque. The dental films were measured by Digora for Windows 2.6 software. Then the fracture resistance of zirconia abutments was measured using the universal testing machine at 90°. All results were analyzed using SPSS13.0 software. The average internal-hexagon microgaps between the implants and zirconia abutments were 19.38±1.34μm. The average Morse taper microgap in the implant-abutment interface was 17.55±1.68μm. The dental film showed that the Morse taper gap in the implant-abutment interface disappeared after being fixed with a central screw of 30-Ncm torque, and the average moving distance of the zirconia abutments to the implants was 0.19±0.02mm. The average fracture resistance of zirconia abutments was 282.93±17.28N. The internal-hexagon microgap between the implants and zirconia abutments was negatively related to the fracture resistance of the abutments (r1=-0.97, pzirconia abutments. The fracture resistance of zirconia abutments can satisfy the clinical application. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. [Dental implant restoration abutment selection].

    Science.gov (United States)

    Bin, Shi; Hao, Zeng

    2017-04-01

    An increasing number of implant restoration abutment types are produced with the rapid development of dental implantology. Although various abutments can meet different clinical demands, the selection of the appropriate abutment is both difficult and confusing. This article aims to help clinicians select the appropriate abutment by describing abutment design, types, and selection criteria.

  16. Marginal Vertical Fit along the Implant-Abutment Interface: A Microscope Qualitative Analysis

    Directory of Open Access Journals (Sweden)

    Nicola Mobilio

    2016-09-01

    Full Text Available The aim of this study was to qualitatively evaluate the marginal vertical fit along two different implant-abutment interfaces: (1 a standard abutment on an implant and (2 a computer-aided-design/computer-aided-machine (CAD/CAM customized screw-retained crown on an implant. Four groups were compared: three customized screw-retained crowns with three different “tolerance” values (CAD-CAM 0, CAD-CAM +1, CAD-CAM −1 and a standard titanium abutment. Qualitative analysis was carried out using an optical microscope. Results showed a vertical gap significantly different from both CAD-CAM 0 and CAD-CAM −1, while no difference was found between standard abutment and CAD-CAM +1. The set tolerance in producing CAD/CAM screw-retained crowns plays a key role in the final fit.

  17. Fracture strength and failure mode of maxillary implant-supported provisional single crowns: a comparison of composite resin crowns fabricated directly over PEEK abutments and solid titanium abutments.

    Science.gov (United States)

    Santing, Hendrik Jacob; Meijer, Henny J A; Raghoebar, Gerry M; Özcan, Mutlu

    2012-12-01

    Polyetheretherketone (PEEK) temporary abutments have been recently introduced for making implant-supported provisional single crowns. Little information is available in the dental literature on the durability of provisional implant-supported restorations. The objectives of this study were to evaluate the fracture strength of implant-supported composite resin crowns on PEEK and solid titanium temporary abutments, and to analyze the failure types. Three types of provisional abutments, RN synOcta Temporary Meso Abutment (PEEK; Straumann), RN synOcta Titanium Post for Temporary Restorations (Straumann), and Temporary Abutment Engaging NobRplRP (Nobel Biocare) were used, and provisional screw-retained crowns using composite resin (Solidex) were fabricated for four different locations in the maxilla. The specimens were tested in a universal testing machine at a crosshead speed of 1 mm/minute until fracture occurred. The failure types were analyzed and further categorized as irreparable (Type 1) or reparable (Type 2). No significant difference was found between different abutment types. Only for the position of the maxillary central incisor, composite resin crowns on PEEK temporary abutments showed significantly lower (p Provisional crowns on PEEK abutments showed similar fracture strength as titanium temporary abutments except for central incisors. Maxillary right central incisor composite resin crowns on PEEK temporary abutments fractured below the mean anterior masticatory loading forces reported to be approximately 206 N. © 2010 Wiley Periodicals, Inc.

  18. Evaluation of microgap size and microbial leakage in the connection area of 4 abutments with Straumann (ITI) implant.

    Science.gov (United States)

    Rismanchian, Mansoor; Hatami, Mahnaz; Badrian, Hamid; Khalighinejad, Navid; Goroohi, Hossein

    2012-12-01

    A microgap between implant and abutment can lead to mechanical and biological problems such as abutment screw fracture and peri-implantitis. The aim of this study was to evaluate microgap size and microbial leakage in the connection area of 4 different abutments to ITI implants. In this experimental study, 36 abutments in 4 groups (including Cast On, Castable, Solid, and Synocta abutments) connected to Straumann fixtures (with their inner part inoculated with bacterial suspension) and microbial leakage were assessed at different times. The size of the microgap in 4 randomized locations was then measured by scanning electron microscope. The data were analyzed by SPSS software and by 1-way variance statistical test, Kruskal-Wallis, and their supplementary tests (Mann-Whitney HSD and Tukey's; α = .05) at the next step. The effect of using different types of abutments was significant on the mean microgap size (P < .001) and on the mean number of leaked colonies (CFU/mL) through the connection area of the implant and abutment within the first 5 hours of the experiment (P = .012); however, it did not significantly influence microleakage at 24 hours, 48 hours, and 14 days (P = .145). Using Synocta abutments compared with Solid abutments will not provide us with more accommodation, and vice versa. Using Solid and Synocta abutments can significantly decrease the microgap size; however, Cast On abutments do not show a significant difference in terms of microgap compared with Castable abutments. Microleakage in the connection area is comparable for these 4 abutments.

  19. Fracture Strength of Standard and Small Diameter Prosthetic Abutments for Full-Arch Implant-Supported Restorations.

    Science.gov (United States)

    de Sá, Bruno Costa Martins; Andrighetto, Augusto Ricardo; Bernardes, Sergio Rocha; Tiossi, Rodrigo

    2017-06-01

    This study tested the fracture strength of prosthetic abutments with different sizes and combinations to support a 5-implant milled framework with distal extension. Prosthetic abutments with different dimensions (4.8-mm diameter mini conical abutment and 3.5-mm diameter microconical abutment) were screwed to 5 threaded implants. The following groups were divided (n = 3): G1 with 5 miniconical abutments (standard size), G2 with 5 microconical abutments (small sized), G3 with a combination of 3 small sized abutments and 2 standard sized abutments, and G4 with a combination of 2 small sized abutments and 3 standard sized abutments. Standardized titanium frameworks for full-arch fixed dental prosthesis were milled with equidistant holes for each of the 5 implants and abutments. A loading point was selected at 18 mm away from both distal implants. A universal testing system was used for the fracture strength tests and load was applied at a crosshead speed of 0.5 mm/min on the previously described loading points until component fracture. Mean fracture strength for each group was statistically compared (α = 0.05). Prosthetic screws were the only fractured components for all tested groups. Mean fracture strength was: G1, 1130.22 N; G2, 1031.36 N; G3, 757.9 N; and G4 792.03 N (P prosthetic abutments and combinations that were tested provide adequate fracture strength for clinical use. However, the combination of standard and small diameter abutments leads to lower fracture strength compared with when only standard sized prosthetic abutments were used, irrespective of the abutment diameter (4.8- or 3.5-mm).

  20. Femoral component loosening after hip resurfacing arthroplasty

    International Nuclear Information System (INIS)

    Zustin, Jozef; Sauter, Guido; Hahn, Michael; Morlock, Michael M.; Ruether, Wolfgang; Amling, Michael

    2010-01-01

    Before the re-introduction of the current generation of total hip resurfacing arthroplasty, component loosening and osteolysis were of great concern to the orthopaedic community. Early, mid- and long-term clinical results are encouraging, but component loosening still exists. Macroscopic, contact radiographic and histopathological analyses after undecalcified preparation of bone tissue specimens were performed. To investigate the frequency and morphological patterns of the loosening of the femoral component, we analysed a series of 190 retrieved femoral remnants that were revised for aseptic failures. Thirty-five (18.4%) hips were revised for clinical and/or radiographic loosening of the femoral component. Pseudoarthrosis (n = 17; median in situ time: 16 weeks, interquartile range [IQR]: 9 to 34), collapsed osteonecrosis (n = 5; median in situ time: 79 weeks, IQR: 63 to 97), cement-socket debonding (n = 3; median in situ time: 89 weeks, IQR: 54 to 97) and at later follow-up bone-cement loosening (n = 10; median in situ time: 175 weeks; IQR 112 to 198; p =0.005) were distinct patterns of the femoral remnant-implant loosening. Fibrocartilaginous metaplasia of interface bone trabeculae (n = 38; median in situ time: 61 weeks, IQR: 32 to 138) was strongly associated with femoral component loosening (p = 0.009). Both the trabecular hyperosteoidosis (n = 32; median in situ time: 71 weeks, IQR 50 to 129) and excessive intraosseous lymphocyte infiltration (n = 12; median in situ time: 75 weeks, IQR 51 to 98) at the bone-cement interface correlated strongly with fibrocartilaginous metaplasia (p = 0.001 and p = 0.016 respectively) and all three lesions were associated with the female gender (p = 0.021, p = 0.009, and p = 0.051). Femoral component loosening at early follow-up was mostly caused by pathological changes of the femoral remnant bone tissue: pseudoarthrosis and collapsed osteonecrosis. Fibrocartilaginous metaplasia was frequently observed in hips with femoral

  1. Effect of Cyclic Loading on Micromotion at the Implant-Abutment Interface.

    Science.gov (United States)

    Karl, Matthias; Taylor, Thomas D

    2016-01-01

    Cyclic loading may cause settling of abutments mounted on dental implants, potentially affecting screw joint stability and implant-abutment micromotion. It was the goal of this in vitro study to compare micromotion of implant-abutment assemblies before and after masticatory simulation. Six groups of abutments (n = 5) for a specific tissue-level implant system with an internal octagon were subject to micromotion measurements. The implant-abutment assemblies were loaded in a universal testing machine, and an apparatus and extensometers were used to record displacement. This was done twice, in the condition in which they were received from the abutment manufacturer and after simulated loading (100,000 cycles; 100 N). Statistical analysis was based on analysis of variance, two-sample t tests (Welch tests), and Pearson product moment correlation (α = .05). The mean values for micromotion ranged from 33.15 to 63.41 μm and from 30.03 to 42.40 μm before and after load cycling. The general trend toward reduced micromotion following load cycling was statistically significant only for CAD/CAM zirconia abutments (P = .036) and for one type of clone abutment (P = .012), with no significant correlation between values measured before and after cyclic loading (Pearson product moment correlation; P = .104). While significant differences in micromotion were found prior to load cycling, no significant difference among any of the abutment types tested could be observed afterward (P > .05 in all cases). A quantifiable settling effect at the implant-abutment interface seems to result from cyclic loading, leading to a decrease in micromotion. This effect seems to be more pronounced in low-quality abutments. For the implant system tested in this study, retightening of abutment screws is recommended after an initial period of clinical use.

  2. Load to failure of different zirconia abutments for an internal hexagon implant.

    Science.gov (United States)

    Yilmaz, Burak; Salaita, Louai G; Seidt, Jeremy D; McGlumphy, Edwin A; Clelland, Nancy L

    2015-09-01

    Various zirconia abutment designs are available to restore implant systems. Fracture resistance is one of the criteria involved in selecting among these options. The purpose of this in vitro study was to measure and compare load to failure for 5 zirconia abutments for an internally hexagon implant. Five 4.1×11.5-mm Zimmer tapered screw-vent implants were individually secured in a loading apparatus, and 3 specimens of each of the 5 different abutments (Zimmer Contour with a Ti ring, anatomic-contour Atlantis-Zr, anatomic-contour Inclusive-Zr, anatomic-contour Astra Tech ZirDesign, Legacy Straight Contoured abutment with Ti core) (N=15) were loaded at a 30-degree angle until the implant abutment complex failed. Data for load to failure were compared with analysis of variance and a Tukey-Kramer post hoc test (α=.05). The custom anatomic-contour abutment (Inclusive) showed the lowest load to fracture, and the stock anatomic-contour (AstraTech ZirDesign) the second lowest load to fracture. These were significantly lower than all other abutments (Pzirconia abutment with a titanium core-hexagon (Legacy Straight Contoured), which was significantly greater than all other abutments (Pzirconia abutments fractured at an average of 275 N compared with the average fracture load of 842 N for zirconia abutments with titanium component (Pzirconia abutment with a titanium ring and the zirconia abutment with a titanium core-hexagon (Legacy Straight Contoured) had significantly greater fracture resistance than that of any of the 1-piece anatomic-contour zirconia abutments tested. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  3. Minimally Invasive Technique for PMMA Augmentation of Fenestrated Screws

    Directory of Open Access Journals (Sweden)

    Jan-Helge Klingler

    2015-01-01

    Full Text Available Purpose. To describe the minimally invasive technique for cement augmentation of cannulated and fenestrated screws using an injection cannula as well as to report its safety and efficacy. Methods. A total of 157 cannulated and fenestrated pedicle screws had been cement-augmented during minimally invasive posterior screw-rod spondylodesis in 35 patients from January to December 2012. Retrospective evaluation of cement extravasation and screw loosening was carried out in postoperative plain radiographs and thin-sliced triplanar computed tomography scans. Results. Twenty-seven, largely prevertebral cement extravasations were detected in 157 screws (17.2%. None of the cement extravasations was causing a clinical sequela like a new neurological deficit. One screw loosening was noted (0.6% after a mean follow-up of 12.8 months. We observed no cementation-associated complication like pulmonary embolism or hemodynamic insufficiency. Conclusions. The presented minimally invasive cement augmentation technique using an injection cannula facilitates convenient and safe cement delivery through polyaxial cannulated and fenestrated screws during minimally invasive screw-rod spondylodesis. Nevertheless, the optimal injection technique and design of fenestrated screws have yet to be identified. This trial is registered with German Clinical Trials DRKS00006726.

  4. Loosening Psychometric Constraints on Educational Assessments

    Science.gov (United States)

    Kane, Michael T.

    2017-01-01

    In response to an argument by Baird, Andrich, Hopfenbeck and Stobart (2017), Michael Kane states that there needs to be a better fit between educational assessment and learning theory. In line with this goal, Kane will examine how psychometric constraints might be loosened by relaxing some psychometric "rules" in some assessment…

  5. The role of prosthetic abutment material on the stress distribution in a maxillary single implant-supported fixed prosthesis

    Energy Technology Data Exchange (ETDEWEB)

    Peixoto, Hugo Eduardo, E-mail: hugo.e.peixoto@hotmail.com [Implantology Team, Latin American Institute of Research and Education in Dentistry, Curitiba, Paraná (Brazil); Bordin, Dimorvan, E-mail: dimorvan_bordin@hotmail.com [Department of Prosthodontics and Periodontology, Piracicaba Dental School, State University of Campinas, Limeira avenue, 901-Vila Rezende, Piracicaba, SP 13414-903 (Brazil); Del Bel Cury, Altair A., E-mail: altcury@fop.unicamp.br [Department of Prosthodontics and Periodontology, Piracicaba Dental School, State University of Campinas, Limeira avenue, 901-Vila Rezende, Piracicaba, SP 13414-903 (Brazil); Silva, Wander José da, E-mail: wanderjose@fop.unicamp.br [Department of Prosthodontics and Periodontology, Piracicaba Dental School, State University of Campinas, Limeira avenue, 901-Vila Rezende, Piracicaba, SP 13414-903 (Brazil); Faot, Fernanda, E-mail: fernanda.faot@gmail.com [Department of Restorative Dentistry, School of Dentistry, Federal University of Pelotas, Gonçalves Chaves, 457, 2nd floor, Pelotas, Rio Grande do Sul 96015-560 (Brazil)

    2016-08-01

    Purpose: Evaluate the influence of abutment's material and geometry on stress distribution in a single implant-supported prosthesis. Materials and Methods: Three-dimensional models were made based on tomographic slices of the upper middle incisor area, in which a morse taper implant was positioned and a titanium (Ti) or zirconia (ZrN) universal abutments was installed. The commercially available geometry of titanium (T) and zirconia (Z) abutments were used to draw two models, TM1 and ZM1 respectively, which served as control groups. These models were compared with 2 experimental groups were the mechanical properties of Z were applied to the titanium abutment (TM2) and vice versa for the zirconia abutment (ZM2). Subsequently, loading was simulated in two steps, starting with a preload phase, calculated with the respective friction coefficients of each materials, followed by a combined preload and chewing force. The maximum von Mises stress was described. Data were analyzed by two-way ANOVA that considered material composition, geometry and loading (p < 0.05). Results: Titanium and zirconia abutments showed similar von Mises stresses in the mechanical part of the four models. The area with the highest concentration of stress was the screw thread, following by the screw body. The highest stress levels occurred in screw thread was observed during the preloading phase in the ZM1 model (931 MPa); and during the combined loading in the TM1 model (965 MPa). Statistically significant differences were observed for loading, the material × loading interaction, and the loading × geometry interaction (p < 0.05). Preloading contributed for 77.89% of the stress (p < 0.05). There were no statistically significant differences to the other factors (p > 0.05). Conclusion: The screw was the piece most intensely affected, mainly through the preload force, independent of the abutment's material. - Highlights: • The abutment's screw was the most impaired piece of the

  6. Implant-abutment interface

    African Journals Online (AJOL)

    healing collars, abutments, transfer copings and analogs, which increases inventory costs and complexity. Limitations of external hex became more evident ..... 0.75mm or bone platform switching which involves an inward bone ring in the coronal part of the implant. 34 that is in continuity with the alveolar bone crest .

  7. Self-Inflicted Drywall Screws in the Sagittal Sinus.

    Science.gov (United States)

    Guppy, Kern H; Ochi, Calvin

    2018-02-01

    A 30-year-old right-handed man with a history of schizophrenia presented with 2 self-inflicted drywall screws in the skull. The patient was sleepy but easily arousable; blood tests showed he had taken methamphetamines. Computed tomography and computed tomography angiography of the head showed the frontal screw abutted left of the superior sagittal sinus, and the posterior screw went through the superior sagittal sinus with no extravasation of contrast material at either site. Both screws were removed with exposure of the sagittal sinus using U-shaped craniectomies. There was no bleeding on the removal of the screws. It appears the posterior screw entered between the leaflets of the sagittal sinus dura mater. The patient had returned to work without any sequelae 1 month after injury. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Stiffness, strength, and failure modes of implant-supported monolithic lithium disilicate crowns: influence of titanium and zirconia abutments.

    Science.gov (United States)

    Joda, Tim; Bürki, Alexander; Bethge, Stefan; Brägger, Urs; Zysset, Philippe

    2015-01-01

    The objective of this study was to evaluate stiffness, strength, and failure modes of monolithic crowns produced using computer-aided design/computer-assisted manufacture, which are connected to diverse titanium and zirconia abutments on an implant system with tapered, internal connections. Twenty monolithic lithium disilicate (LS2) crowns were constructed and loaded on bone level-type implants in a universal testing machine under quasistatic conditions according to DIN ISO 14801. Comparative analysis included a 2 × 2 format: prefabricated titanium abutments using proprietary bonding bases (group A) vs nonproprietary bonding bases (group B), and customized zirconia abutments using proprietary Straumann CARES (group C) vs nonproprietary Astra Atlantis (group D) material. Stiffness and strength were assessed and calculated statistically with the Wilcoxon rank sum test. Cross-sections of each tested group were inspected microscopically. Loaded LS2 crowns, implants, and abutment screws in all tested specimens (groups A, B, C, and D) did not show any visible fractures. For an analysis of titanium abutments (groups A and B), stiffness and strength showed equally high stability. In contrast, proprietary and nonproprietary customized zirconia abutments exhibited statistically significant differences with a mean strength of 366 N (Astra) and 541 N (CARES) (P zirconia abutments (groups C and D) below the implant shoulder. Depending on the abutment design, prefabricated titanium abutment and proprietary customized zirconia implant-abutment connections in conjunction with monolithic LS2 crowns had the best results in this laboratory investigation.

  9. Photoelastic stress analysis of implant-tooth connected prostheses with segmented and nonsegmented abutments.

    Science.gov (United States)

    Ochiai, Kent T; Ozawa, Shogo; Caputo, Angelo A; Nishimura, Russell D

    2003-05-01

    There is some question about whether implant abutment selection affects the transfer of load between connected implants and natural teeth. The purpose of this study was to compare stress transfer patterns with either 1 or 2 posterior implants connected to a single anteriorly located simulated natural tooth with either 1 or 2 segmented and nonsegmented implant abutments under relevant functional loads by use of the photoelastic stress analysis technique. A model of a human left mandible, edentulous posterior to the first premolar, with two 3.75-mm x 13-mm screw-type implants embedded within the edentulous area, was fabricated from photoelastic materials. The implants were in the first and second molar positions. Two fixed partial denture prosthetic restorations were fabricated with either segmented conical abutments or nonsegmented UCLA abutments. Vertical occlusal loads were applied at fixed locations on the restorations. The photoelastic stress fringes that developed in the supporting mandible were monitored visually and recorded photographically. The stress intensity (number of fringes), stress concentrations (closeness of fringes), and their locations were subjectively compared. Loading on the restoration over the simulated tooth generated apical stresses of similar intensity (fringe order) at the tooth and the first molar implant for both abutment types. Low-level stress was transferred to the second molar implant. Loading directed on the implant-supported region of the restoration demonstrated low transfer of stress to the simulated tooth. Nonvertical stress transfer with slightly higher intensity was observed for the nonsegmented abutment. Within the limitations of this simulation study, stress distribution and intensity for the 2 implant conditions was similar for segmented and nonsegmented abutment designs. Magnitude of stresses observed for both abutment designs was similar for the single implant condition. Vertical loading produced more nonaxial stresses

  10. Effect of abutment modification and cement type on retention of cement-retained implant supported crowns.

    Directory of Open Access Journals (Sweden)

    Mitra Farzin

    2014-06-01

    Full Text Available Provisional cements are commonly used to facilitate retrievability of cement-retained fixed implant restorations; but compromised abutment preparation may affect the retention of implant-retained crowns.The purpose of this study was to investigate the effect of abutment design and type of luting agent on the retentive strength of cement-retained implant restorations.Two prefabricated abutments were attached to their corresponding analogs and embedded in an acrylic resin block. The first abutment (control group was left intact without any modifications. The screw access channel for the first abutment was completely filled with composite resin. In the second abutment, (test group the axial wall was partially removed to form an abutment with 3 walls. Wax models were made by CAD/CAM. Ten cast copings were fabricated for each abutment. The prepared copings were cemented on the abutments by Temp Bond luting agent under standardized conditions (n=20. The assemblies were stored in 100% humidity for one day at 37°C prior to testing. The cast crown was removed from the abutment using an Instron machine, and the peak removal force was recorded. Coping/abutment specimens were cleaned after testing, and the testing procedure was repeated for Dycal luting agent (n=20. Data were analyzed with two- way ANOVA (α=0.05.There was no significant difference in the mean transformed retention (Ln-R between intact abutments (4.90±0.37 and the abutments with 3 walls (4.83±0.25 using Dycal luting agent. However, in TempBond group, the mean transformed retention (Ln-R was significantly lower in the intact abutment (3.9±0.23 compared to the abutment with 3 walls (4.13±0.33, P=0.027.The retention of cement-retained implant restoration can be improved by the type of temporary cement used. The retention of cast crowns cemented to implant abutments with TempBond is influenced by the wall removal.

  11. Custom anatomic healing abutments

    Directory of Open Access Journals (Sweden)

    Vinayak S Gowda

    2016-01-01

    Full Text Available Dental implants with their increasing success rates and predictability of final outcome are fast becoming the treatment of choice for replacing missing teeth. Considering the success of immediate implant placement in reducing tissue loss and achieving good esthetic results, is making it a more popular treatment modality in implant dentistry. Understanding the management of gingival tissues in relation to implants to obtain maximum esthetics is of utmost importance. The use of provisional abutments and immediate temporization has a proven track record of their ability to produce optimal esthetics and to guide the tissue response during the healing phase. With careful patient selection and execution, customized healing abutments can provide an effective method to enhance the esthetic and emergence profile for anterior implant restorations.

  12. A mine abutment

    Energy Technology Data Exchange (ETDEWEB)

    Ardashev, K.A.; Borisovets, V.A.; Kozel, A.M.

    1983-01-01

    The purpose of the invention is to increase the service life of the abutment between a mine shaft and near shaft drifts by eliminating the irregularity of the near shaft rock massif. The stated purpose is achieved by the fact that in the mine abutment, which includes a mine shaft and near shaft chambers, the mine shaft is made within the near shaft chambers with an expansion and is equipped with a cylindrical shell installed in its widened part with an inside cross section equal to the cross section of the shaft which with the shaft forms a cavity for positioning the near shaft chambers. Moreover, the mine shaft in the expansion zone may be made in the form of a cone in its upper part and in the form of a cylinder in its lower part.

  13. The Evaluation of Unscrewing Torque Values of Implant-Abutment Connections: An In Vitro Study.

    Science.gov (United States)

    Bruna, Ezio; Fabianelli, Andrea; Mastriforti, Giacomo; Papacchini, Federica

    This study investigated the stability of titanium screws in implant-abutment connections by measuring the force necessary to induce unscrewing. A total of 60 implant-abutment couplings were assigned to two groups (n = 30 each). The sequence 10-20-32 Ncm was tested in Group 1; the sequence 10-20-32-32-32 Ncm was tested in Group 2. The force necessary to unscrew each abutment-implant sample was recorded and statistically analyzed. The significance level was set at P < .05. Significant differences were found between the two sequences. Group 2 required higher forces than Group 1 to unscrew. The stability of the implant-abutment joint may be improved by tightening with the sequence 10-20-32-32-32 Ncm.

  14. Effect of Vertical Misfit on Screw Joint Stability of Implant-Supported Crowns

    Science.gov (United States)

    Assunção, Wirley Gonçalves; Delben, Juliana Aparecida; Tabata, Lucas Fernando; Barão, Valentim Adelino Ricardo; Gomes, Érica Alves

    2011-08-01

    The passive fit between prosthesis and implant is a relevant factor for screw joint stability and treatment success. The aim of this study was to evaluate the influence of vertical misfit in abutment-implant interface on preload maintenance of retention screw of implant-supported crowns. The crowns were fabricated with different abutments and veneering materials and divided into 5 groups ( n = 12): Gold UCLA abutments cast in gold alloy veneered with ceramic (Group I) and resin (Group II), UCLA abutments cast in titanium veneered with ceramic (Group III) and resin (Group IV), and zirconia abutments with ceramic veneering (Group V). The crowns were attached to implants by gold retention screws with 35-N cm insertion torque. Specimens were submitted to mechanical cycling up to 106 cycles. Measurements of detorque and vertical misfit in abutment-implant interface were performed before and after mechanical cycling. ANOVA revealed statistically significant difference ( P 0.05) between vertical misfit and detorque value. It was concluded that vertical misfit did not influence torque maintenance and the abutments cast in titanium exhibited the highest misfit values.

  15. Influence of abutment material on the fracture strength and failure modes of abutment-fixture assemblies when loaded in a bio-faithful simulation.

    Science.gov (United States)

    Apicella, Davide; Veltri, Mario; Balleri, Piero; Apicella, Antonio; Ferrari, Marco

    2011-02-01

    The aim of the present study was to evaluate differences in the ultimate fracture resistance of titanium and zirconia abutments. Twenty titanium fixtures were embedded in 20 resin mandible section simulators to mimic osseointegrated implants in the premolar area. The embedded implants were then randomly divided into two groups. Afterwards, specimens in group A (n=10) were connected to titanium abutments (TiDesign™ 3.5/4.0, 5.5, 1.5 mm), while specimens in group B (n=10) were connected to zirconia abutments (ZirDesign ™ 3.5/4.0, 5.5, 1.5 mm). Both groups were loaded to failure in a dynamometric testing machine. Fractured samples were then analyzed by scanning electron microscopy (SEM). Group A showed a significantly higher fracture strength than that observed in group B. Group A failures were observed at the screw that connects the abutment with the implant while the abutment connection hexagons were plastically bent by the applied load. Group B failures were a result of abutment fractures. SEM analysis showed that in group A the screw failure was driven by crack nucleation, coalescence and propagation, while in group B, the SEM analysis of failed surfaces showed the conchoidal fracture profile characteristic of brittle materials. The strength of both tested systems is adequate to resist physiologic chewing forces in the premolar area. Conversely, the titanium and zirconia failure modes evaluated here occurred at unphysiological loads. In addition, because the abutments were tested without crowns, the presented data have limited direct transfer to the clinical situation. © 2010 John Wiley & Sons A/S.

  16. Short-term retrospective case series of implant-assisted removable partial dentures with locator abutments.

    Science.gov (United States)

    Ortiz-Puigpelat, Octavi; Gargallo-Albiol, Jordi; Hernández-Alfaro, Federico; Cabratosa-Termes, Josep

    2014-01-01

    The purpose of this retrospective case series was to report on the clinical performance of implant-assisted removable partial dentures (IARPDs) with Locator abutments in different partial edentulism situations, with a mean follow-up period of 28.6 months. Twelve consecutive patients were treated with IARPDs. A total of 24 implants were placed in the edentulous area. Minimum follow-up period was 12 months. Overall patient satisfaction, health of peri-implant tissues, survival of implants and abutments, and prosthetic complications were reported. Overall implant survival was 91.6%; two implants failed. No major complications were reported-only one IARPD metal framework broke. No Locator abutment loosening was reported. Within the limitations of this retrospective study, treatment with IARPDs can improve the patient's function, phonetics, and esthetics without the need for extensive bone regeneration surgeries and prosthodontic rehabilitations. However, well-designed prospective clinical studies on IARPDs are needed to support their long-term use.

  17. Pullout performance comparison of pedicle screws based on cement application and design parameters.

    Science.gov (United States)

    Tolunay, Tolga; Başgül, Cemile; Demir, Teyfik; Yaman, Mesut E; Arslan, Arslan K

    2015-11-01

    Pedicle screws are the main fixation devices for certain surgeries. Pedicle screw loosening is a common problem especially for osteoporotic incidents. Cannulated screws with cement augmentation are widely used for that kind of cases. Dual lead dual cored pedicle screw has already given promising pullout values without augmentation. This study concentrates on the usage of dual lead dual core with cement augmentation as an alternative to cannulated and standard pedicle screws with cement augmentation. Five groups (dual lead dual core, normal pedicle screw and cannulated pedicle screw with augmentation, normal pedicle screw, dual lead dual cored pedicle screw) were designed for this study. Healthy bovine vertebrae and synthetic polyurethane foams (grade 20) were used as embedding test medium. Test samples were prepared in accordance with surgical guidelines and ASTM F543 standard testing protocols. Pullout tests were conducted with Instron 3300 testing frame. Load versus displacement values were recorded and maximum pullout loads were stated. The dual lead dual cored pedicle screw with poly-methyl methacrylate augmentation exhibited the highest pullout values, while dual lead dual cored pedicle screw demonstrated similar pullout strength as cannulated pedicle screw and normal pedicle screw with poly-methyl methacrylate augmentation. The dual lead dual cored pedicle screw with poly-methyl methacrylate augmentation can be used for osteoporotic and/or severe osteoporotic patients according to its promising results on animal cadaver and synthetic foams. © IMechE 2015.

  18. A finite element analysis of two different dental implants: stress distribution in the prosthesis, abutment, implant, and supporting bone.

    Science.gov (United States)

    Quaresma, Sergio E T; Cury, Patricia R; Sendyk, Wilson R; Sendyk, Claudio

    2008-01-01

    This study evaluates the influence of 2 commercially available dental implant systems on stress distribution in the prosthesis, abutment, implant, and supporting alveolar bone under simulated occlusal forces, employing a finite element analysis. The implants and abutments evaluated consisted of a stepped cylinder implant connected to a screw-retained, internal, hexagonal abutment (system 1) and a conical implant connected to a solid, internal, conical abutment (system 2). A porcelain-covered, silver-palladium alloy was used as a crown. In each case, a simulated, 100-N vertical load was applied to the buccal cusp. A finite element model was created based on the physical properties of each component, and the values of the von Mises stresses generated in the prosthesis, abutment, implant, and supporting alveolar bone were calculated. In the prostheses, the maximum von Mises stresses were concentrated at the points of load application in both systems, and they were greater in system 1 (148 N/mm2) than in system 2 (55 N/mm2). Stress was greater on the abutment of system 2 than of system 1 on both the buccal (342 N/mm2 x 294 N/mm2) and lingual (294 N/mm2 x 148 N/ mm2) faces. Stress in the cortical, alveolar bone crest was greater in system 1 than in system 2 (buccal: 99.5 N/mm2 x 55 N/mm2, lingual: 55 N/mm2 x 24.5 N/mm2, respectively). Within the limits of this investigation, the stepped cylinder implant connected to a screw-retained, internal hexagonal abutment produces greater stresses on the alveolar bone and prosthesis and lower stresses on the abutment complex. In contrast, the conical implant connected to a solid, internal, conical abutment furnishes lower stresses on the alveolar bone and prosthesis and greater stresses on the abutment.

  19. A prospective, split-mouth study comparing tilted implants with angulated connection versus conventional implants with angulated abutment.

    Science.gov (United States)

    Van Weehaeghe, Manú; De Bruyn, Hugo; Vandeweghe, Stefan

    2017-12-01

    An angulation of the implant connection could overcome the problems related to angulated abutments. This study compares conventional implants with angulated abutment to tilted implants with an angulated connection. Twenty patients were treated in the edentulous mandible. In the posterior jaw locations, one conventional tilted implant with angulated abutment and one angulated implant without abutment were placed. In the anterior jaw, two conventional implants were placed, one with and one without abutment. Implants were immediately loaded and 3 months later, the final bridge (PFM or monolithic zirconia) was placed. After a follow-up of 48 months, 17 patients were available for clinical examination. The mean overall marginal bone loss (MBL) was 1.26 mm. No significant differences in implant survival, MBL, periodontal indices, patients' satisfaction, or complications was found between implants restored on abutment or implant level, between the posteriorly located angulated implant nor angulated abutment, and between both anterior implants with or without abutment. The posterior implants demonstrated less MBL compared to the anterior implants (P implants restored with zirconia or PFM bridges (P = .294). Overall mean pocket depth was 2.83 mm. More plaque was found in the PFM group compared to the full-zirconia group, at the bridge (P = .042) and the implants (P = .029). There was no difference between both materials in pocket depth (P = .635) or bleeding (P = .821). One zirconia bridge fractured, two angulated abutment were replaced and four loose bridge screws connected to the angulated abutments had to be tightened. Patients were overall satisfied (4.74/5). An implant with angulated connection may results in a stronger connection but does not affect the marginal bone loss. No difference in MBL was seen between implants restored on abutment or implant level. Zirconia seems to reduce the amount of plaque. © 2017 Wiley Periodicals, Inc.

  20. In vitro fatigue and fracture resistance of one- and two-piece CAD/CAM zirconia implant abutments.

    Science.gov (United States)

    Gehrke, Peter; Johannson, Dirk; Fischer, Carsten; Stawarczyk, Bogna; Beuer, Florian

    2015-01-01

    All-ceramic abutments are employed increasingly often in implant dentistry for esthetic reasons. In vitro stress testing is required to evaluate the suitability of these constructions, especially in load-bearing posterior regions. The purpose of the study was to assess and compare the fatigue and fracture resistance of one- and two-piece computer-aided design/computer-assisted manufacture (CAD/CAM) zirconia implant abutments with an internal-hex connection and prefabricated commercially available zirconia stock abutments. Twenty-one abutment-crown specimens were prepared for three test groups. Control group 1 (SZ) included specimens with unprepared stock zirconia abutments, test group 2 (OP) included one-piece CAD/CAM zirconia abutments, and test group 3 (TP) included two-piece CAD/CAM zirconia abutments. All 21 specimens underwent thermocycling and fatigue testing. Finally, all specimens were tested for fracture resistance with a universal testing machine. The maximum load was applied to the tapered occlusal area of each crown at a 30-degree angle and a crosshead speed of 0.5 mm/min until the implant-abutment connection failed. Kolmogorov-Smirnov, Shapiro-Wilk, and post-hoc Scheffé tests were used for statistical analysis. All abutments in groups SZ and OP fractured into two or more pieces after fracture resistance testing. None of the TP abutments displayed apparent disintegration, but failure was evidenced by bending of the retention screw. OP abutments (232.1 ± 29.8 N) and SZ abutments (251.8 ± 23.2 N) showed lower fracture loads than the TP abutments (291.4 ± 27.8 N). However, only the difference between the OP and TP groups was statistically significant. Further load-displacement analyses corroborated the higher mechanical stability of the TP abutments. Superior resistance was achieved for two-piece hybrid CAD/CAM zirconia abutments. These abutments might be clinically beneficial in high-load areas, such as premolar and molar regions.

  1. Biomechanical analysis of pedicle screws in osteoporotic bone with bioactive cement augmentation using simulated in vivo multicomponent loading.

    Science.gov (United States)

    Choma, Theodore J; Frevert, Wesley F; Carson, William L; Waters, Nicole P; Pfeiffer, Ferris M

    2011-03-15

    Biomechanical analysis of bioactive cements augmenting pedicle screw resistance to loosening in osteoporotic synthetic bone. To simulate in vivo loading-loosening of pedicle screws in osteoporotic vertebrae; and to compare biomechanical efficacy of the following bioactive cements: calcium phosphate (CP), calcium sulfate (CS), and proprietary mixture (M). Pedicle screw instrumentation in osteoporotic spines is limited by poor bone-screw interface strength, resulting in screw loosening fixation failure. Previous in vivo studies evaluated augmented pedicle screw resistance to pure pullout, not simulating in vivo loading/failure. A pedicle screw-instrumented osteoporotic thoracic vertebra subjected to combined pullout, transverse, moment loading was simulated. Unconstrained 3-dimensional screw motion relative to vertebra was optically measured during quasi-static, and dynamic loading. Augmented groups (CP, CS, M) produced (P CS > M failure initiation force (P < 0.006) was because of differences in cement distribution. Animal studies may be required to characterize the remodeling activity of bioactive cements and their longer term efficacies.

  2. The Effect of Transpedicular Screw Design on Its Performance in Vertebral Bone Under Tensile Loads: A Parametric Study.

    Science.gov (United States)

    Alkaly, Ron N; Bader, Dan L

    2016-12-01

    A biomechanical study using bovine thoracolumbar spines. To study investigated whether thread design parameters aimed at altering the state of stress at the screw-bone interface increase the screw's holding power. Internal spinal fixators utilizing transpedicular screw fixation are used to achieve early stabilization of the injured spine in a range of clinical conditions. Despite advances in the design of internal spinal fixation systems, implant loosening, and catastrophic failures at the screw-bone interface remains a serious complication in adult spine surgery. Although the performance of the screws in the vertebral bone critically depends on ability of screw thread design to provide and maintain adequate bone purchase, the effect of individual thread design parameters on screw performance and the failure process of the screw-bone interface, remains unclear. On the basis of the AO Schanz thread, this parametric study used 96 lumbar bovine vertebrae instrumented with 19 screw designs to investigate the effects of pitch, ratio of major to minor diameter, screw insertion depth, and major diameter, on screw performance under pure tensile loading. The effect of vertebral morphometry on screw performance and the extent of damage within the failed screw-bone interface were evaluated. The increase in screw insertion depth, screw pitch, and the ratio of major to minor diameter, significantly affected screw performance under tensile loads. Complex interactions existed between the major diameter and each of the design variables. Vertebral morphometry had little effect on screw performance while the damage within the failed bone-screw interface confined to the immediate region of the screw threads. Design variables, able to reduce shear stresses or modify the complex stress profile at the bone-screw interface, are more effective in preventing early failure of the interface.

  3. Effect of implant abutment modification on the extrusion of excess cement at the crown-abutment margin for cement-retained implant restorations.

    Science.gov (United States)

    Wadhwani, Chandur; Piñeyro, Alfonso; Hess, Timothy; Zhang, Hai; Chung, Kwok-Hung

    2011-01-01

    To compare the effect of implant abutment modification on the amount of cement extruded at the crown-abutment margin and to evaluate the vertical discrepancy after cementation. Access openings of titanium abutments were modified with an opening (open) and placement of two vent holes 3 mm from the occlusal edge and 180 degrees apart (internal vent). Access openings were filled with resin material (closed) and used as controls. Each abutment was secured to an implant analog. Eugenol-free zinc oxide cement (TempBond NE) was selected to cement the cast crowns (n = 9) onto test abutments. The amount of cement extruded out of the margin was calculated, and vertical seating discrepancies were determined with a linear transducer device before and after cementation. Differences among groups were analyzed statistically. The mean amount of extruded cement ranged from 36% to 90% of the total cement placed within the crowns. The order, from least to greatest amount of excess cement extrusion at the margins, was internal vent, open, and closed; significant differences were observed between test groups. The net vertical discrepancies of tested specimens ranged from -7 μm to +6 μm (mean, 0 μm). No statistically significant differences in vertical discrepancy were found between the groups. Venting the hollow abutment resulted in the least amount of cement extrusion when compared to closing off the screw access channel or leaving it open. Within the limitations of this study, it may be concluded that the use of two, 0.75-mm radius vent holes placed 3 mm apical to the occlusal area of the abutment and 180 degrees apart will limit the amount of cement extruded into the gingival sulcus of implant-retained crowns.

  4. Comparison of fit accuracy between Procera custom abutments and three implant systems.

    Science.gov (United States)

    Alves da Cunha, Tiago de Morais; Correia de Araújo, Roberto Paulo; Barbosa da Rocha, Paulo Vicente; Pazos Amoedo, Rosa Maria

    2012-10-01

    Although increase of misfit has been reported when associating implant and abutment from different manufacturers, Procera® (Nobel Biocare™, Göteborg, Sweden) custom abutment has been universally used in clinical practice. The purpose of this investigation was to compare the vertical gap of zirconia Procera abutment associated with implants from the same manufacturer (Nobel Biocare) and two other implant systems. Twenty-four zirconia Procera abutments were produced using computer-assisted design and manufacture (CAD/CAM) and paired with (1) eight MK Iii RP 4.1 × 10 mm implants (Nobel Biocare) - GNB group; (2) eight Try on, 4.1 × 10 mm implants (Sistema de Implantes, São Paulo, Brazil) - ES group; and (3) eight Master screw, 4.1 × 10 mm implants (Conexão Sistema de Prótese, São Paulo, Brazil) - EC group. A comparison of the vertical misfit at the implant-abutment interface was taken at six measuring sites on each sample using scanning electron microscopy with a magnification of 408×. One-way analysis of variance was used to test for differences, and Tukey's test was used for pairwise comparison of groups (α = 0.05). Significant differences relative to average misfit were found when Procera abutments were associated with other implant manufacturers. The ES group and EC group did not differ significantly, but both demonstrated significantly larger average misfit than the GNB group (p = .001). The average misfit was 5.7 µm ± 0.39, 9.53 µm ± 0.52 and 10.62 µm ± 2.16, respectively, for groups GNB, ES, and EC. The association of Procera zirconia abutment with other implant systems different from its manufacturer demonstrated significant alteration of vertical misfit at implant-abutment interface. © 2010 Wiley Periodicals, Inc.

  5. Comparison of fit accuracy between Procera® custom abutments and three implant systems.

    Science.gov (United States)

    de Morais Alves da Cunha, Tiago; de Araújo, Roberto Paulo Correia; da Rocha, Paulo Vicente Barbosa; Amoedo, Rosa Maria Pazos

    2012-12-01

    Although increase of misfit has been reported when associating implant and abutment from different manufacturers, Procera custom abutment has been universally used in clinical practice. The purpose of this investigation was to compare the vertical gap of zirconia Procera® abutment associated with implants from the same manufacturer (Procera manufacturer) and two other implant systems. Twenty-four zirconia Procera abutments were produced using computer-assisted design and manufacture and paired with (a) eight MK III, RP 4.1 × 10 mm implants (Nobel Biocare™, Göteborg, Sweden) - GNB group (Nobel Biocare group); (b) eight Try on, 4.1 × 10 mm implants (Sistema de Implantes, São Paulo, Brazil) - ES group (SIN experimental group) ; and (c) eight Master screw, 4.1 × 10 mm implants (Conexão® Sistema de Prótese, São Paulo, Brazil) - EC group (Conexão experimental group). A comparison of the vertical misfit at the implant-abutment interface was taken at six measuring sites on each sample using scanning electron microscopy with a magnification of 408×. One-way analysis of variance was used to test for differences, and Tukey's test was used for pair-wise comparison of groups (α = 0.05). Significant differences relative to average misfit were found when Procera abutments were associated with other implant manufacturers. The ES group and EC group did not differ significantly, but both demonstrated significantly larger average misfit than the GNB group (p = .001). The average misfit was 5.7 µm ± 0.39, 9.53 µm ± 0.52, and 10.62 µm ± 2.16, respectively, for groups GNB, ES, and EC. The association of Procera zirconia abutment with other implant systems different from its manufacturer demonstrated significant alteration of vertical misfit at implant-abutment interface. © 2010 Wiley Periodicals, Inc.

  6. Soft tissues stability of cad-cam and stock abutments in anterior regions: 2-year prospective multicentric cohort study.

    Science.gov (United States)

    Lops, Diego; Bressan, Eriberto; Parpaiola, Andrea; Sbricoli, Luca; Cecchinato, Denis; Romeo, Eugenio

    2015-12-01

    Aim of this study was to verify if the type of implant abutment manufacturing, stock or cad-cam, could influence the maintenance of stable gingival margins around single restorations in anterior areas. After 16 weeks of healing, implants (Osseospeed, Astra Tech Dental Implant) were positioned. Depending on the different fixture inclination and the thickness of buccal peri-implant soft tissue, abutment selection resulted in four groups: Group 1 (patients with zirconia ZirDesign(®) stock abutments), Group 2 (titanium stock TiDesign(®) abutments), Group 3 (zirconia cad-cam abutments), and Group 4 (titanium cad-cam abutments). The following parameters were assessed: buccal gingival margin modification (BGM). The modification of the implant gingival margin was followed at 1 and 2 years of follow-up. A computerized analysis was performed for measurements. Differences between soft tissue margin at baseline and after 2 years measured the gingival margin recession. A general linear model was used to evaluate each group in relation to gingival recession after two years. Tukey's post hoc test was used to compare the mean REC indexes of each group of abutments. Seventy-two healthy patients (39 males and 33 females; mean age of 46 years) scheduled for single gap rehabilitation in anterior areas were enrolled. A 100% of implant survival rate was observed after 24 months of function. One failure occurred due to fracture of a Zirconia cad-cam abutment. Moreover, two abutment screw unscrewing were observed. Both for zirconia and titanium stock abutments (Group 1 and 2), the mean recession of implant buccal soft tissue was of 0.3 mm (SD of 0.3 and 0.4 mm, respectively). Soft tissue mean recession of zirconia and titanium cad-cam abutments (Group 3 and 4) was of 0.1 and -0.3 mm, respectively (SD of 0.3 and 0.4 mm, respectively). REC values of cad-cam titanium abutments (Group 4) were significantly lower than that of Group 1 (-0.57 mm), Group 2 (-0.61 mm), and Group 3 (-0.40 mm

  7. Mechanical behavior of provisional implant prosthetic abutments

    Science.gov (United States)

    Serra-Pastor, Blanca; Roig-Vanaclocha, Ana; Román-Rodriguez, Juan-Luis; Fons-Font, Antonio

    2015-01-01

    Introduction: Implant-supported prostheses have to overcome a major difficulty presented by the morphology and esthetics of peri-implant tissues in the anterior sector. Diverse therapeutic techniques are used for managing the mucosa adjacent to the implant and the most noteworthy is immediate/deferred fixed provisionalization. Objectives: In vitro testing of strength and deformation of implant prosthetic abutments made from different materials (Titanium/PEEK/methacrylate). Material and Methods: Forty Sweden&Martina® implant prosthetic abutments (n=40) were divided into five groups: Group MP: methacrylate provisional abutments with machined titanium base; Group PP: Poly ether ether ketone (PEEK) provisional abutments; Group TP: titanium provisional abutments; Group TAD: titanium anti-rotational definitive abutments; Group TRD: titanium rotational definitive abutments. Their mechanical behavior under static loading was analyzed. Samples were examined under a microscope to determine the type of fracture produced. Results and Conclusions: Definitive anti-rotational titanium abutments and definitive rotational titanium abutments achieved the best mean compression strength, while PEEK resin provisional abutments obtained the lowest. The group that showed the greatest elastic deformation was the group of titanium provisional abutments. Key words:Immediate loading, immediate provisionalization, implant prosthetic abutment, definitive implant prosthetic abutment. PMID:25129253

  8. Criteria to manage the technical and biologic success of an implant abutment.

    Science.gov (United States)

    Hermanides, Leon

    2014-01-01

    To maximize esthetics in anterior implant restorations, the initial step in treatment planning should be determining the prosthesis's esthetic integration with the patient's smile in keeping with the patient's anatomical limitations. This article examines the role of the abutment in supporting both esthetics and technical success. Included are discussions regarding cemented versus screw-retained restorations, material selection for anterior tooth replacement, and design parameters.

  9. Resistance of three implant-abutment interfaces to fatigue testing

    Directory of Open Access Journals (Sweden)

    Cleide Gisele Ribeiro

    2011-08-01

    Full Text Available The design and retentive properties of implant-abutment connectors affect the mechanical resistance of implants. A number of studies have been carried out to compare the efficacy of connecting mechanisms between abutment and fixture. Objectives: The aims of this study were: 1 to compare 3 implant-abutment interfaces (external hexagon, internal hexagon and cone-in-cone regarding the fatigue resistance of the prosthetic screw, 2 to evaluate the corresponding mode of failure, and 3 to compare the results of this study with data obtained in previous studies on Nobel Biocare and Straumann connectors. Materials and METHODS: In order to duplicate the alternating and multivectorial intraoral loading pattern, the specimens were submitted to the rotating cantilever beam test. The implants, abutments and restoration analogs were spun around their longitudinal axes while a perpendicular force was applied to the external end. The objective was to determine the force level at which 50% of the specimens survived 10(6 load cycles. The mean force levels at which 50% failed and the corresponding 95% confidence intervals were determined using the staircase procedure. RESULTS: The external hexagon interface presented better than the cone-in-cone and internal hexagon interfaces. There was no significant difference between the cone-in-cone and internal hex interfaces. Conclusion: Although internal connections present a more favorable design, this study did not show any advantage in terms of strength. The external hexagon connector used in this study yielded similar results to those obtained in a previous study with Nobel Biocare and Straumann systems. However, the internal connections (cone-in-cone and internal hexagon were mechanically inferior compared to previous results.

  10. Motor-driven screwing and transporting tool for pressure vessels, especially pressure vessels for nuclear reactors

    International Nuclear Information System (INIS)

    Scholz, M.

    1976-01-01

    A screwing and transporting device for tensioning and loosening the reactor pressure vessel head is described. The advantage of the tool is its ability to unscrew the stud bolts from the lower part of the pressure vessel, too, and therefore make them accessible for in-service inspection. (TK) [de

  11. In vitro validation of a novel mechanical model for testing the anchorage capacity of pedicle screws using physiological load application.

    Science.gov (United States)

    Liebsch, Christian; Zimmermann, Julia; Graf, Nicolas; Schilling, Christoph; Wilke, Hans-Joachim; Kienle, Annette

    2018-01-01

    Biomechanical in vitro tests analysing screw loosening often include high standard deviations caused by high variabilities in bone mineral density and pedicle geometry, whereas standardized mechanical models made of PU foam often do not integrate anatomical or physiological boundary conditions. The purpose of this study was to develop a most realistic mechanical model for the standardized and reproducible testing of pedicle screws regarding the resistance against screw loosening and the holding force as well as to validate this model by in vitro experiments. The novel mechanical testing model represents all anatomical structures of a human vertebra and is consisting of PU foam to simulate cancellous bone, as well as a novel pedicle model made of short carbon fibre filled epoxy. Six monoaxial cannulated pedicle screws (Ø6.5 × 45mm) were tested using the mechanical testing model as well as human vertebra specimens by applying complex physiological cyclic loading (shear, tension, and bending; 5Hz testing frequency; sinusoidal pulsating forces) in a dynamic materials testing machine with stepwise increasing load after each 50.000 cycles (100.0N shear force + 20.0N per step, 51.0N tension force + 10.2N per step, 4.2Nm bending moment + 0.8Nm per step) until screw loosening was detected. The pedicle screw head was fixed on a firmly clamped rod while the load was applied in the vertebral body. For the in vitro experiments, six human lumbar vertebrae (L1-3, BMD 75.4 ± 4.0mg/cc HA, pedicle width 9.8 ± 0.6mm) were tested after implanting pedicle screws under X-ray control. Relative motions of pedicle screw, specimen fixture, and rod fixture were detected using an optical motion tracking system. Translational motions of the mechanical testing model experiments in the point of load introduction (0.9-2.2mm at 240N shear force) were reproducible within the variation range of the in vitro experiments (0.6-3.5mm at 240N shear force). Screw loosening occurred continuously in

  12. Influence of implant angulation on the fracture resistance of zirconia abutments.

    Science.gov (United States)

    Thulasidas, Shreedevi; Givan, Daniel A; Lemons, Jack E; O'Neal, Sandra Jean; Ramp, Lance C; Liu, Perng-Ru

    2015-02-01

    To investigate the effects of abutment design to correct for implant angulation and aging on the fracture resistance of zirconia abutments. Greater understanding of the fracture strength of the zirconia abutments under various clinical conditions may lead to improvement of clinical protocols and possibly limit potential failures of implant prosthetics. Test specimens consisted of an implant-zirconia abutment-zirconia crown assembly with implant apex positioned at 0°, 20° to the facial (20F), and 20° to the lingual (20L) with respect to a constant crown contour. To keep the abutment design as the only variable, CAD/CAM technology was used to generate monolithic zirconia crowns identical both in external and internal dimensions and marginal contours to precisely fit all the abutments in an identical fashion. The monolithic zirconia abutments were designed to fit the constant crown contours and the internal connection of the implant at the three angulations. The customized abutments for the three implant angulations varied in emergence profile, screw hole location, and material thickness around the screw hole. Half the specimens from each group were subjected to steam autoclaving and thermocycling to simulate aging of the restorations in vivo. To mimic the off-axis loading of the central incisor, the specimens were loaded at the recommended cephalometric interincisal relationship of 135° between the long axis of the crown supported by the implant and the Instron force applicator simulating the mandibular incisor. The force applicator was positioned 2 mm from the incisal edge and loaded at a 1 mm/min crosshead speed. Data were evaluated by 2-way ANOVA (α = 0.05) and Tukey's HSD. The 20F group had the highest fracture values followed by the 0° group, and the 20L group had the lowest fracture values. Aging did not yield any significant difference in fracture force magnitudes. Within the limitations of this study, tilting the implant apex to the lingual

  13. An introduction to single implant abutments.

    LENUS (Irish Health Repository)

    Warreth, Abdulhadi

    2013-01-01

    This article is an introduction to single implant abutments and aims to provide basic information about abutments which are essential for all dental personnel who are involved in dental implantology. Clinical Relevance: This article provides a basic knowledge of implants and implant abutments which are of paramount importance, as replacement of missing teeth with oral implants has become a well-established clinical procedure.

  14. Effect of cyclic load on vertical misfit of prefabricated and cast implant single abutment

    Directory of Open Access Journals (Sweden)

    Rudys Rodolfo de Jesus Tavarez

    2011-02-01

    Full Text Available OBJECTIVES: The purpose of this in vitro study was to evaluate misfit alterations at the implant/abutment interface of external and internal connection implant systems when subjected to cyclic loading. MATERIAL AND METHODS: Standard metal crowns were fabricated for 5 groups (n=10 of implant/abutment assemblies: Group 1, external hexagon implant and UCLA cast-on premachined abutment; Group 2, internal hexagon implant and premachined abutment; Group 3, internal octagon implant and prefabricated abutment; Group 4, external hexagon implant and UCLA cast-on premachined abutment; and Group 5, external hexagon implant and Ceraone abutment. For groups 1, 2, 3 and 5, the crowns were cemented on the abutments and in group 4 crowns were screwed directly on the implant. The specimens were subjected to 500,000 cycles at 19.1 Hz of frequency and non-axial load of 133 N in a MTS 810 machine. The vertical misfit (μm at the implant/abutment interface was evaluated before (B and after (A application of the cyclic loading. Data were analyzed statistically by using two-away ANOVA and Tukey's post-hoc test (p<0.05. RESULTS: Before loading values showed no difference among groups 2 (4.33±3.13, 3 (4.79±3.43 and 5 (3.86±4.60; between groups 1 (12.88±6.43 and 4 (9.67±3.08, and among groups 2, 3 and 4. However, groups 1 and 4 were significantly different from groups 2, 3 and 5. After loading values of groups 1 (17.28±8.77 and 4 (17.78±10.99 were significantly different from those of groups 2 (4.83±4.50, 3 (8.07±4.31 and 5 (3.81±4.84. There was a significant increase in misfit values of groups 1, 3 and 4 after cyclic loading, but not for groups 2 and 5. CONCLUSIONS: The cyclic loading and type of implant/abutment connection may develop a role on the vertical misfit at the implant/abutment interface.

  15. A technique for fabricating single screw-retained implant-supported interim crowns in conjunction with implant surgery.

    Science.gov (United States)

    McRory, M Eric; Cagna, David R

    2014-06-01

    This article presents an intraoral technique for fabricating single screw-retained implant-supported interim crowns immediately after surgical implant placement in extraction sites. The technique may be used with any implant system that provides a provisional abutment or an open-tray impression coping that can be modified for use as a provisional abutment. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  16. Effect of implant connection and restoration design (screwed vs. cemented) in reliability and failure modes of anterior crowns.

    Science.gov (United States)

    Freitas, Amilcar C; Bonfante, Estevam A; Rocha, Eduardo P; Silva, Nelson R F A; Marotta, Leonard; Coelho, Paulo G

    2011-08-01

    The mechanical performance of cemented or screw-retained implant-supported crowns with an internal or external configuration is yet to be understood. This in vitro study evaluated the effect of screw-retained and cement-retained prostheses on internal and external implant-abutment connections. Thereby, the reliability and failure modes of crowns were investigated. Eighty-four implants (Emfils; Colosso Evolution system) were divided into four groups (n=21 each): screw-retained and internal connection (Si), screw-retained and external connection (Se), cement-retained and internal connection (Ci), and cement-retained and external connection (Ce). Ti-6Al-4V abutments were torqued (30 Ncm) to the implants, and maxillary central incisor metal crowns were torqued (30 Ncm) or cemented (Rely X Unicem; 3M-ESPE) and subjected to accelerated life-testing in water. Use-level probability Weibull curves and reliability for 50,000 cycles at 150 N were calculated. The β values for Si (1.72), Se (1.50), Ci (1.34), and Ce (1.77) groups indicated that fatigue/damage accumulation accelerated their failure. The Ci group presented the highest reliability, the Se group presented the lowest reliability, and Si and Ce groups presented intermediate reliability. Screw-retained restorations presented mainly abutment fracture. Cement-retained restorations resulted in failures of the screw in the Ce group, but implant/screw fracture in the Ci group. © 2011 Eur J Oral Sci.

  17. Influence of three types of abutments on preload values before and after cyclic loading with structural analysis by scanning electron microscopy.

    Science.gov (United States)

    Butignon, Luis Eduardo; Basilio, Mariana de Almeida; Pereira, Rodrigo de Paula; Arioli Filho, Joao Neudenir

    2013-01-01

    To evaluate the effectiveness of three types of abutments in the maintenance of screw joint preload before and after cyclic loading as well as to observe possible microdamage in the structure of the components using a scanning electron microscope (SEM). Forty-five external-hex implants were embedded in epoxy resin, received their respective abutments, and were randomly divided into three experimental groups (n = 15): (1) machined titanium (Ti) abutments; (2) pre-machined gold (Au) abutments; and (3) machined zirconia (ZrO(2)) abutments. The abutment screws were tightened according to the manufacturer's recommended torque. Initially, a static bending test was performed using five specimens of each group to determine the load applied in the cyclic loading test. Thus, 10 specimens of each group were used to measure the reverse torque value (preload) of the abutment screw before and after loading. A cyclic loading (0.5 × 10(6) cycles; 15 Hz) between 11 and 211 N was applied at an angle of 30 degrees to the long axis of the implants. The group means were compared using analysis of variance and the Tukey test (α = .05). The reverse torque analysis before cyclic loading showed no significant difference among the groups (P > .05). After cyclic loading, all preload means decreased significantly. The lowest decrease in preload was observed in the Ti group, whereas the highest decrease was observed in the ZrO(2) group, with a significant difference noted between them (P = .010). The Au group presented an intermediate decrease, with no significant difference compared to the other groups (P > .05). SEM images showed structural changes in the mating surfaces of the abutments after cyclic loading. The load application reduced the preload means significantly in all groups, and more significantly in the ZrO(2) group.

  18. [Metal ions: important co-players in aseptic loosening].

    Science.gov (United States)

    Cadosch, D; Schlett, C L; Gautschi, O P; Frei, H C; Filgueira, L

    2010-08-01

    The aims of this review were to discuss the different mechanisms of biocorrosion of orthopaedic metal implants in the human body, as well as the effects of the released metal ions on bone metabolism and the immune system in regard to their involvement in the pathophysiological mechanisms of aseptic loosening and metal hypersensitivity. Implant failure due to aseptic loosening is thought to occur in about 10-15% of cases. A review of the literature (using PubMed with the search terms: biocorrosion, metal ions and bone metabolism) was performed. Additionally, we discuss our research results in the field of aseptic loosening. Despite a great effort in developing new implants, metal devices used in orthopaedic and trauma surgery remain prone to biocorrosion by several mechanisms including the direct corrosion by osteoclasts, leading to the production of significant amounts of wear particles and metal ions. In addition to the well documented increased osteolytic activity caused by large (in the nanometer range) wear particles, increasing evidence strongly suggests that the released metal ions contribute to the pathophysiological mechanism of aseptic loosening. Metal ions stimulate both the immune system and bone metabolism through a series of direct and indirect pathways leading to an increased osteolytic activity at the bone-implant interface. To date, revision surgery remains the only option for the treatment of a failed orthopaedic implant caused by aseptic loosening. A better understanding of the complex pathophysiological mechanisms (including the effects caused by the released metal ions) of aseptic loosening may have a significant potential in developing novel implants and therapies in order to reduce the incidence of this complication. Georg Thieme Verlag KG Stuttgart, New York.

  19. Primary stability of three different iliosacral screw fixation techniques in osteoporotic cadaver specimens-a biomechanical investigation.

    Science.gov (United States)

    Oberkircher, Ludwig; Masaeli, Adrian; Bliemel, Christopher; Debus, Florian; Ruchholtz, Steffen; Krüger, Antonio

    2016-02-01

    The incidence of osteoporotic and insufficiency fractures of the pelvic ring is increasing. Closed reduction and percutaneous fixation with cannulated sacroiliac screws is well-established in the operative treatment of osteoporotic posterior pelvic ring fractures. However, osteoporotic bone quality might lead to the risk of screw loosening. For this reason, cement augmentation of the iliosacral screws is more frequently performed and recommended. The aim of the present biomechanical study was to evaluate the primary stability of three methods of iliosacral screw fixation in human osteoporotic sacrum specimens. This study used methodical cadaver study. A total of 15 fresh frozen human cadaveric specimens with osteoporosis were used (os sacrum). After matched pair randomization regarding bone quality (T-score), three operation technique groups were generated: screw fixation (cannulated screws) without cement augmentation (Group A); screw fixation with cement augmentation before screw placement (cannulated screws) (Group B); and screw fixation with perforated screws and cement augmentation after screw placement (Group C). In all specimens both sides of the os sacrum were used for operative treatment, resulting in a group size of 10 specimens per group. One operation technique was used on each side of the sacral bone to compare biomechanical properties in the same bone quality. Pull-out tests were performed with a rate of 6 mm/min. A load versus displacement curve was generated. Subgroup 1 (Group A vs. Group B): Screw fixation without cement augmentation: 594.4 N±463.7 and screw fixation with cement augmentation before screw placement: 1,020.8 N±333.3; values were significantly different (p=.025). Subgroup 2 (Group A vs. Group C): Screw fixation without cement augmentation: 641.8 N±242.0 and perforated screw fixation with cement augmentation after screw placement: 1,029.6 N±326.5; values were significantly different (p=.048). Subgroup 3 (Group B vs. Group C): Screw

  20. A Current Perspective on Screw-Retained Single-Implant Restorations: A Review of Pertinent Literature.

    Science.gov (United States)

    Priest, George

    2017-05-06

    There is a trend toward increased use of screw-retained single-implant restorations. A comprehensive literature review was undertaken to examine the data related to screw- and cement-retention and to objectively evaluate the innovations in implant dentistry that have led to this resurgence. When comparing the two options, survival and complication rates are similar, bone and soft-tissue levels are comparable, and zirconia offers esthetic advantages for both selections. Zirconia abutments with bonded titanium inserts provide esthetic alternatives to titanium abutments for both choices. Bone- and soft-tissue responses are similar, but residual cement of cement-retained restorations is associated with significant soft- and hard-tissue complications. The potential weakness of ceramic discontinuity of screw-access openings can be lessened by the incorporation of stronger ceramic materials such as zirconia and lithium disilicate. The overriding remaining indication for cement-retained restorations is to compensate for angled implants. Screw-retained single-implant crowns should be reconsidered for many clinical situations for the following reasons: Predictable retention and retrievability No potential for the biologic consequences associated with residual cement As with cement-retained restorations, the choice between metal ceramics or all ceramics Only one margin, at the implant/abutment interface A single abutment/crown ceramic margin that can extend gingivally to the implant interface Nearly imperceptible blend of a composite resin in ceramic abutment access openings One component instead of two, which may simplify the restorative process CLINICAL SIGNIFICANCE: Innovations in implant and ceramic technology now give screw-retained prostheses the potential for esthetic, functional, and biologic outcomes that are comparable to those for cement-retained prostheses, while providing the advantages of predictable retrievability and avoidance of residual cement. Angled

  1. A comparative study on microgap of premade abutments and abutments cast in base metal alloys.

    Science.gov (United States)

    Lalithamma, Jaini Jaini; Mallan, Sreekanth Anantha; Murukan, Pazhani Appan; Zarina, Rita

    2014-06-01

    The study compared the marginal accuracy of premade and cast abutments. Premade titanium, stainless steel, and gold abutments formed the control groups. Plastic abutments were cast in nickel-chromium, cobalt-chromium and grade IV titanium. The abutment/implant interface was analyzed. Analysis of variance and Duncan's multiple range test revealed no significant difference in mean marginal microgap between premade gold and titanium abutments and between premade stainless steel and cast titanium abutments. Statistically significant differences (P < .001) were found among all other groups.

  2. Microbial leakage through the implant-abutment interface of Morse taper implants in vitro.

    Science.gov (United States)

    Aloise, João Pedro; Curcio, Ricardo; Laporta, Marcia Zorello; Rossi, Liliane; da Silva, Adriana Madeira Alvares; Rapoport, Abrão

    2010-03-01

    The aim of this study was to determine and compare the frequency of bacterial leakage of Streptococcus sanguinis biotype II along the implant-abutment interface between two systems of morse taper dental implants. Different methods of activation of the taper abutments were used: tapped-in (Bicon) and screwed-in (Ankylos). Twenty sterile assemblies were used and attached, 10 Bicon and 10 Ankylos implants, according to manufacturers' specifications. They were then totally immersed within 20 test tubes containing a sterile nutrient solution brain-heart infusion (BHI). The internal part of the 20 implants was previously inoculated with 0.1 microl of S. sanguinis II (ATCC 10557) and then connected to the respective abutments. The assemblies were incubated under anaerobic conditions for 14 days in an autoclave at 37 degrees C. They were monitored daily for solution cloudiness resultant from microbial leakage on the interface of the assemblies. For statistical analysis, the Fisher test was applied and significance was assigned at the 5% level. There was solution cloudiness, indicating the finding of bacterial growth inside two Bicon assemblies and two Ankylos assemblies 48 h after incubation. Microbial leakage was further substantiated by testing the suspension for the presence of Streptococcus sp. None of the sterility controls were contaminated. The frequency of bacterial leakage along the implant-abutment interface, with the two different morse taper implant systems, was 20% of the assemblies of each system. There were no statistical differences between them. Irrespective of which of the two morse taper implant connection systems of activation was analyzed, tapped-in (Bicon) or screwed-in (Ankylos), this in vitro experiment showed bacterial leakage along the implant-abutment interface.

  3. Abutment selection in implant-supported fixed prosthodontics.

    Science.gov (United States)

    Giglio, G D

    1999-06-01

    Selecting the appropriate abutment can be both complex and confusing with the ever-increasing number of implant choices and transepithelial abutments available. Many restorative dentists resort to fabricating costly custom abutments to avoid the selection process. Although custom abutments are at times necessary, prefabricated abutments are usually more desirable. This article will describe the various abutments available and how to select the correct abutment for a given clinical situation in an organized, systematic fashion. Criteria discussed include implant position, angulation, soft tissue height, and interocclusal space. The latest modifications and developments in implant abutments are reviewed along with an indirect method of selecting abutments in a laboratory setting.

  4. Development of an anti-loosening fastener and comparing its ...

    Indian Academy of Sciences (India)

    Bikash Panja

    2017-09-08

    Sep 8, 2017 ... Abstract. Threaded fasteners are widely used for temporary joining of different components that require occasional disassembling. However, threaded fasteners may have the problem of loosening under vibrating conditions, which may lead to decreasing clamping force and, thereby, a system failure.

  5. Septic Loosening of a Total Hip Replacement: Case Report ...

    African Journals Online (AJOL)

    It can be difficult to differentiate septic from aseptic loosening of prosthesis and especially those due to delayed and late prosthetic-joint infection. In delayed and late prosthetic-joint infection, the acute signs and symptoms of infection such as fever, swelling, erythema and warmth are usually absent and the only ...

  6. Development of an anti-loosening fastener and comparing its ...

    Indian Academy of Sciences (India)

    An adhesive-bonded nut is also tested, where an adhesive is placed between bolt and nut threads. All these fasteners are tested in terms of their loosening characteristics. Accelerated vibrating conditions are used for the test on an indigenously made test rig. A split bolt with taper pin is introduced for the first time to reduce ...

  7. Influence of the screw augmentation technique and a diameter increase on pedicle screw fixation in the osteoporotic spine: pullout versus fatigue testing.

    Science.gov (United States)

    Kueny, Rebecca A; Kolb, Jan P; Lehmann, Wolfgang; Püschel, Klaus; Morlock, Michael M; Huber, Gerd

    2014-10-01

    For posterior spinal stabilization, loosening of pedicle screws at the bone-screw interface is a clinical complication, especially in the osteoporotic population. Axial pullout testing is the standard pre-clinical testing method for new screw designs although it has questioned clinical relevance. The aim of this study was to determine the fixation strength of three current osteoporotic fixation techniques and to investigate whether or not pullout testing results can directly relate to those of the more physiologic fatigue testing. Thirty-nine osteoporotic, human lumbar vertebrae were instrumented with pedicle screws according to four treatment groups: (1) screw only (control), (2) prefilled augmentation, (3) screw injected augmentation, and (4) unaugmented screws with an increased diameter. Toggle testing was first performed on one pedicle, using a cranial-caudal sinusoidal, cyclic (1.0 Hz) fatigue loading applied at the screw head. The initial compressive forces ranged from 25 to 75 N. Peak force increased stepwise by 25 N every 250 cycles until a 5.4-mm screw head displacement. The contralateral screw then underwent pure axial pullout (5 mm/min). When compared to the control group, screw injected augmentation increased fatigue force (27 %, p = 0.045) while prefilled augmentation reduced fatigue force (-7 %, p = 0.73). Both augmentation techniques increased pullout force compared to the control (ps osteoporotic spine, screw injected augmentation showed the best biomechanical stability. Although pullout testing was more sensitive, the differences observed were not reflected in the more physiological fatigue testing, thus casting further doubt on the clinical relevance of pullout testing.

  8. A review of implant abutments--abutment classification to aid prosthetic selection.

    Science.gov (United States)

    Karunagaran, Sanjay; Paprocki, Gregory J; Wicks, Russell; Markose, Sony

    2013-01-01

    With an increase in the availability of implant restorative components, the selection of an appropriate implant abutment for a given clinical situation has become more challenging. This article describes a classification system that will help the practitioner understand the different implant abutments available and therefore be able to understand the selection of abutments for single and multiple unit fixed implant prosthesis.

  9. Long-term cumulative survival and mechanical complications of single-tooth Ankylos Implants: focus on the abutment neck fractures

    OpenAIRE

    Shim, Hye Won; Yang, Byoung-Eun

    2015-01-01

    PURPOSE To evaluate the cumulative survival rate (CSR) and mechanical complications of single-tooth Ankylos? implants. MATERIALS AND METHODS This was a retrospective clinical study that analyzed 450 single Ankylos? implants installed in 275 patients between December 2005 and December 2012. The main outcomes were survival results CSR and implant failure) and mechanical complications (screw loosening, fracture, and cumulative fracture rate [CFR]). The main outcomes were analyzed according to ag...

  10. Behavior and analysis of an integral abutment bridge.

    Science.gov (United States)

    2013-08-01

    As a result of abutment spalling on the integral abutment bridge over 400 South Street in Salt Lake City, Utah, the Utah Department of Transportation (UDOT) instigated research measures to better understand the behavior of integral abutment bridges. ...

  11. Machined and plastic copings in three-element prostheses with different types of implant-abutment joints: a strain gauge comparative analysis.

    Science.gov (United States)

    Nishioka, Renato Sussumu; Nishioka, Lea Nogueira Braulino de Melo; Abreu, Celina Wanderley; de Vasconcellos, Luis Gustavo Oliveira; Balducci, Ivan

    2010-01-01

    Using strain gauge (SG) analysis, the aim of this in vitro study was quantify the strain development during the fixation of three-unit screw implant-supported fixed partial dentures, varying the types of implant-abutment joints and the type of prosthetic coping. The hypotheses were that the type of hexagonal connection would generate different microstrains and the type of copings would produce similar microstrains after prosthetic screws had been tightened onto microunit abutments. Three dental implants with external (EH) and internal (IH) hexagonal configurations were inserted into two polyurethane blocks. Microunit abutments were screwed onto their respective implant groups, applying a torque of 20 Ncm. Machined Co-Cr copings (M) and plastic prosthetic copings (P) were screwed onto the abutments, which received standard wax patterns. The wax patterns were cast in Co-Cr alloy (n=5), forming four groups: G1) EH/M; G2) EH/P; G3) IH/M and G4) IH/P. Four SGs were bonded onto the surface of the block tangentially to the implants, SG 1 mesially to implant 1, SG 2 and SG 3 mesially and distally to implant 2, respectively, and SG 4 distally to implant 3. The superstructure's occlusal screws were tightened onto microunit abutments with 10 Ncm torque using a manual torque driver. The magnitude of microstrain on each SG was recorded in units of microstrain (µε). The data were analyzed statistically by ANOVA and Tukey's test (p0.05). The hypotheses were partially accepted. It was concluded that the type of hexagonal connection and coping presented similar mechanical behavior under tightening conditions.

  12. Micromorphological differences of the implant-abutment junction and in vitro load testing for three different titanium abutments on Straumann tissue level implants.

    Science.gov (United States)

    Mattheos, N; Larsson, C; Ma, L; Fokas, G; Chronopoulos, V; Janda, M

    2017-12-01

    The aim of this study was to investigate the micromorphological differences among three commercially available titanium abutments on Straumann implants. Furthermore, the possible impact of functional loading on the micromorphology and potential complications was investigated with the use of in vitro testing. Three groups of Titanium abutments (A: Straumann Variobase n = 5, B: EBI best Duo n = 5, and C: Implant Direct n = 5) were torqued on Straumann RN implants, as according to each of the manufacturer's instructions. The implant-abutment units were scanned with Micro-CT. Three units of each group were directly sliced in the microtome and photographed under different magnifications (10×-500×) through a Scanning Electron Microscope. Six units (two from each group) were restored with cement-retained crowns, subjected to 2000,000 load cycles with loads between 30 and 300 N at 2 Hz, examined through Micro-CT and finally sliced and photographed as described above. The micromorphology of each unit was studied, and the total length of tight contact (<3 μm) was calculated between the implant, abutment and screw contact areas. Major morphological differences were identified between the three units, as well as differences in the extent of tight contact in all areas examined. Despite the morphological differences, the 2M cycles of loading via in vitro test did not result in any noticeable complications although some changes in the micromorphology were observed. The examined implant-abutment units presented with major morphological differences. Two million cycles of in vitro loading did not appear to affect the stability of the units despite the micromorphological changes. These results need to be interpreted however under the limitations of the small sample size and the specific set-up of the in vitro testing. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  13. Non-linear 3D evaluation of different oral implant-abutment connections.

    Science.gov (United States)

    Streckbein, P; Streckbein, R G; Wilbrand, J F; Malik, C Y; Schaaf, H; Howaldt, H P; Flach, M

    2012-12-01

    Micro-gaps and osseous overload in the implant-abutment connection are the most common causes of peri-implant bone resorption and implant failure. These undesirable events can be visualized on standardized three-dimensional finite element models and by radiographic methods. The present study investigated the influence of 7 available implant systems (Ankylos, Astra, Bego, Brånemark, Camlog, Straumann, and Xive) with different implant-abutment connections on bone overload and the appearance of micro-gaps in vitro. The individual geometries of the implants were transferred to three-dimensional finite element models. In a non-linear analysis considering the pre-loading of the occlusion screw, friction between the implant and abutment, the influence of the cone angle on bone strain, and the appearance of micro-gaps were determined. Increased bone strains were correlated with small (Ankylos) or a smaller cone angle (Bego). The results of our in silico study provide a solid basis for the reduction of peri-implant bone strain and micro-gaps in the implant-abutment connection to improve long-term stability.

  14. Local scour at abutments: A review

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Kwan T F 1988 A study of abutment scour. Rep. No. 451, School of Engineering, University of. Auckland, Auckland, New Zealand. Kwan T F, Melville B W 1994 Local scour and flow measurements at bridge abutments. J. Hydraul. Res. 32: 661–673. Laursen E M 1952 Observations on the nature of scour. Proc. 5th Hydraul.

  15. [Aseptic loosening of total ankle replacement : Two-stage revision with bone augmentation of osseous defects and secondary prosthesis implantation].

    Science.gov (United States)

    Barg, A; Wiewiorski, M; Valderrabano, V

    2017-06-01

    To remove loosened ankle prosthesis components, perform osseous defect augmentation, and reimplant definitive prosthesis components to preserve ankle range of motion. Aseptic loosening of the tibial and/or talar ankle prosthesis components with substantial bone defect. General surgical/anesthesiological risks, infections, critical soft tissue conditions, nonmanageable hindfoot instability, neurovascular impairment of the lower extremity, neuroarthropathy, substantial nonreconstructable osseous defects with or without cysts on the tibial and/or talar side, noncompliance, primary total ankle replacement (TAR) using intramedullary fixation (stem fixation), severely reduced bone quality, insulin-dependent diabetes mellitus, smoking, unrealistic patients' expectations, high activity in sports. Exposure of the ankle joint using the previous incision. Mobilization and removal of loosened prosthesis components. Debridement of bone stock. Assessment and measurement of osseous defects. Harvesting of iliac crest autograft. Screw fixation of iliac crest autograft. Placement of polyethylene inlay as a spacer. Wound closure in layers at the ankle and the iliac crest. Implantation of definitive prosthesis components. A soft wound dressing. Thromboprophylaxis recommended. Mobilization on postoperative day 1 using a stabilizing walking boot/cast for 6 weeks (sole contact but no weight bearing). Clinical and radiographic follow-up 3 months postoperatively including computed tomography to assess osseous consolidation. After the second surgery, patient mobilization on postoperative day 1 with 15 kg partial weight bearing using a stabilizing walking boot/cast for 6 weeks. Following clinical and radiographic follow-up at 6 weeks, full weight bearing is initiated gradually. From January 2007 to December 2012, a two-stage revision TAR was performed in 5 patients (46.8 and 71.4 years). The time between the initial TAR and revision was 2.4-11.5 years. No intra

  16. Dynamic fatigue properties of the dental implant-abutment interface: joint opening in wide-diameter versus standard-diameter hex-type implants.

    Science.gov (United States)

    Hoyer, S A; Stanford, C M; Buranadham, S; Fridrich, T; Wagner, J; Gratton, D

    2001-06-01

    The clinical long-term success of single-tooth implant restorations depends, in part, on a stable connection between the prosthetic restoration and the implant body. The purpose of this experiment was to investigate the fatigue life of UCLA-style abutment screws in wide-diameter versus conventionally sized dental implant restorations. Five 3.75 x 15-mm and five 6.0 x 15-mm hexed dental implants were used. Ten frameworks were fabricated, 5 with a single UCLA-style, 3.75-mm hexed gold alloy cylinder, and 5 with a single UCLA-style, 6.0-mm hexed gold alloy cylinder. To simulate a common laboratory procedure, 2 abutment interfaces were relieved with a one-quarter round bur for both diameters. The 3.75-mm implant used a Gold-Tite central abutment screw torqued to 32 Ncm, and the 6.0-mm implant used a titanium central abutment screw torqued to 25 Ncm. Frameworks were dynamically loaded ( approximately 10 Hz) with a 120 +/- 10-N, 4-mm off-axis force. Liquid metal strain gauges were used to measure joint opening. Measurements were made at intervals of 10(3), 10(4), 10(5), and 5x10(5) cycles. Gauge output data were converted to displacement with a conversion factor determined by calibration. Linear regression analysis then was performed. Two observations were made in this study. Two of three 3.75-mm nonadjusted specimens and all three 6.0-mm nonadjusted specimens maintained joint closure (range of opening 0-20 microm) while measured under dynamic loading. The median joint opening at 5x10(5) cycles for 3.75-mm nonadjusted specimens was 14 +/- 7 microm; for 6.0-mm specimens, it was 11 +/- 10 microm. Both 3.75-mm adjusted specimens and 1 nonadjusted specimen failed to maintain joint closure (excess joint opening >50 microm). One of the 3.75-mm adjusted specimens had abutment screw fracture. One of two 6.0-mm adjusted specimens failed to maintain joint closure because of screw fracture. The dental implant-abutment interface of 3.75-mm and 6.0-mm externally hexed implants

  17. An in vivo assessment of the effects of using different implant abutment occluding materials on implant microleakage and the peri-implant microbiome

    Science.gov (United States)

    Rubino, Caroline

    Microleakage may be a factor in the progression of peri-implant pathology. Microleakage in implant dentistry refers to the passage of bacteria, fluids, molecules or ions between the abutment-implant interface to and from the surrounding periodontal tissues. This creates a zone of inflammation and reservoir of bacteria at the implant-abutment interface. Bone loss typically occurs within the first year of abutment connection and then stabilizes. It has not yet been definitively proven that the occurrence of microleakage cannot contribute to future bone loss or impede the treatment of peri-implant disease. Therefore, strategies to reduce or eliminate microleakage are sought out. Recent evidence demonstrates that the type of implant abutment channel occluding material can affect the amount of microleakage in an in vitro study environment. Thus, we hypothesize that different abutment screw channel occluding materials will affect the amount of observed microleakage, vis-a-vis the correlation between the microflora found on the abutment screw channel occluding material those found in the peri-implant sulcus. Additional objectives include confirming the presence of microleakage in vivo and assessing any impact that different abutment screw channel occluding materials may have on the peri-implant microbiome. Finally, the present study provides an opportunity to further characterize the peri-implant microbiome. Eight fully edentulous patients restored with at dental implants supporting screw-retained fixed hybrid prostheses were included in the study. At the initial appointment (T1), the prostheses were removed and the implants and prostheses were cleaned. The prostheses were then inserted with polytetrafluoroethylene tape (PTFE, TeflonRTM), cotton, polyvinyl siloxane (PVS), or synthetic foam as the implant abutment channel occluding material and sealed over with composite resin. About six months later (T2), the prostheses were removed and the materials collected. Paper

  18. Compressive Force With 2-Screw and 3-Screw Subtalar Joint Arthrodesis With Headless Compression Screws.

    Science.gov (United States)

    Matsumoto, Takumi; Glisson, Richard R; Reidl, Markus; Easley, Mark E

    2016-12-01

    Joint compression is an essential element of successful arthrodesis. Although subtalar joint compression generated by conventional screws has been quantified in the laboratory, compression obtainable with headless screws that rely on variable thread pitch to achieve bony contact has not been assessed. This study measured subtalar joint compression achieved by 2 posteriorly placed contemporary headless, variable-pitch screws, and quantified additional compression gained by placing a third screw anteriorly. Ten, unpaired fresh-frozen cadaveric subtalar joints were fixed sequentially using 2 diverging posterior screws (one directed into the talar dome, the other into the talar neck), 2 parallel posterior screws (both ending in the talar dome), and 2 parallel screws with an additional anterior screw inserted from the plantar calcaneus into the talar neck. Joint compression was quantified directly during screw insertion using a novel custom-built measuring device. The mean compression generated by 2 diverging posterior screws was 246 N. Two parallel posterior screws produced 294 N of compression, and augmentation of that construct with a third, anterior screw increased compression to 345 N (P screw fixation was slightly less than that reported previously for subtalar joint fixation with 2 conventional lag screws, but was comparable when a third screw was added. Under controlled testing conditions, 2 tapered, variable-pitch screws generated somewhat less compression than previously reported for 2-screw fixation with conventional headed screws. A third screw placed anteriorly increased compression significantly. Because headless screws are advantageous where prominent screw heads are problematic, such as the load-bearing surface of the foot, their effectiveness compared to other screws should be established to provide an objective basis for screw selection. Augmenting fixation with an anterior screw may be desirable when conditions for fusion are suboptimal. © The Author

  19. Radiographical evaluation of the gap at the implant-abutment interface.

    Science.gov (United States)

    Papavassiliou, Harris; Kourtis, Stefanos; Katerelou, Julia; Chronopoulos, Vasillios

    2010-08-01

    The detection of marginal gaps at the implant-abutment interface is a common clinical task in prosthodontic treatment. For the detection of the gap intraorally, especially under thick soft tissues the most common method is dental radiography. The objective of this experimental study was to investigate the accuracy of conservative dental radiography to detect marginal gaps at the implant-abutment interface. For these reasons radiographs were taken on internal and external hex implants with different experimental gaps and inclinations. The abutment (with a space created by plastic sheets 0.5 and 0.2 mm in thickness) was screwed on the implant, and the implant was placed into a box filled with silicone impression material. The X-ray film was placed parallel to the implant at the back of the box, the borders of the box were marked to the base and the box. A ruler of 10 cm was fixed at a long X-ray tube to ensure parallelism to the implant, X-ray film. Sets of radiographs were made at 0 degrees, 5 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, 30 degrees (to the abutment) and -5 degrees, -10 degrees, -15 degrees, -20 degrees, -25 degrees, -30 degrees (to the implant) degrees. The X-ray images were observed with visual examination, under magnification, and in higher magnification in a slide projector. The phenomenal and the true gap at the implant-abutment interface were calculated in order to determine the distortion. There were significant differences between the internal and external hex implants because of the different morphology of the implants. The detecting ability to diagnose a gap at the implant-abutment interface varied significantly with the angulation degree of the X-ray tube. At inclinations to the implant (- inclination) the gap diminished earlier than those inclinations to the prosthetic abutment (+ inclinations). In all examinations the gap was not detectable at angulations higher than 20 degrees. In visual examination at 25 degrees and 30

  20. Clinical Evaluation of the Influence of Connection Type and Restoration Height on the Reliability of Zirconia Abutments: A Retrospective Study on 965 Abutments with a Mean 6-Year Follow-Up.

    Science.gov (United States)

    Fabbri, Giacomo; Fradeani, Mauro; Dellificorelli, Gianluca; De Lorenzi, Marco; Zarone, Fernando; Sorrentino, Roberto

    This multicenter retrospective clinical study aimed to evaluate the clinical performance of zirconia abutments in anterior and posterior regions, focusing on implant-abutment connections and restoration vertical height (RVH). Six experienced prosthodontists used 965 computer-aided design/computer-assisted manufacture zirconia abutments in 601 patients. Different surgical approaches were taken according to the needs of each patient. The final restorations were all-ceramic single crowns and short-span fixed dental prostheses. Screw-retained restorations were mainly used in anterior areas, whereas cemented prostheses were chosen in cases where the implant position was not ideal. Different types of implant-abutment connections were compared: external, internal with metal components, and internal full-zirconia conical connection. All the restorations were followed up for 4 to 10 years. Technical and biologic complications were assessed in relation to several biomechanical variables, such as RVH. Differences between groups were statistically analyzed, and longevity of abutments was evaluated according to Kaplan-Meier survival analysis. Zirconia abutments resulted in overall survival and success rates of 98.9% and 94.8%, respectively. External connections reported survival and success rates of 99.7% and 94.5%, internal metal connections 99.8% and 95.5%, and internal zirconia connections 93.1% and 93.1%, respectively. Overall complication rates of 1.14%, 3.42%, and 0.62% were reported for fractures, chipping, and unscrewing, respectively. The external connection showed the longest survival while the internal zirconia connection showed the highest fracture incidence over the observation period. The clinical risk limit of RVH was identified as 14 mm. Zirconia abutments showed satisfactory clinical performance in anterior and posterior regions after 4 to 10 years. RVH and connection type influenced the clinical longevity of restorations; in particular, internal connections

  1. Molecular leakage at implant-abutment connection--in vitro investigation of tightness of internal conical implant-abutment connections against endotoxin penetration.

    Science.gov (United States)

    Harder, Sönke; Dimaczek, Birka; Açil, Yaha; Terheyden, Hendrik; Freitag-Wolf, Sandra; Kern, Matthias

    2010-08-01

    Microleakage has been discussed as a major contributing factor for inflammatory reactions at the implant-abutment connection. In previous studies, the tightness against corpuscular bodies (viable bacteria) has been successfully investigated under static and dynamic conditions. The aim of this study was to investigate the tightness against endotoxins of two implant systems (AstraTech and Ankylos) with conical internal connections under static conditions. The inner parts of eight implants of each system were inoculated with endotoxin. Implants were screwed together with the respective abutments and stored under isostatic conditions in a supernatant of pyrogen-free water for 168 h. Supernatant samples were taken after 5 min, 24 h, 72 h, and 168 h, and endotoxin contamination was determined by the amebocyte-lysate test. Only one implant in the AstraTech group showed no sign of endotoxin contamination after 168 h, while the other implants showed contamination after varying storage times, respectively. The implants in the Ankylos group showed endotoxin contamination after only 5 min of storage in the supernatant solution. The tested internal conical implant-abutment connections appear to be unable to prevent endotoxin leakage. In average, Astra implants showed a higher tightness than Ankylos implants.

  2. Diagnostic Classification and Design Considerations for Implant-Supported Fixed Partial Dentures and Screw Access Channel: The ABC/PBC and SAC Classifications.

    Science.gov (United States)

    AlHelal, Abdulaziz; Kattadiyil, Mathew T; Clark, Jefferson L; AlBader, Bader

    Logical categorization of implant-supported fixed partial dentures (ISFPDs) based on implant angulation, abutment type, and screw access channel (SAC) design for screw-retained restoration is not available in the literature. This article proposes a simple classification system to describe implant angulations and prosthesis design affecting abutment selection (engaging or nonengaging) for ISFPDs. An additional classification that addresses screw access channel designs is also introduced. These classifications provide clear interpretation of clinical scenarios for ISFPD design consideration and a basis for categorization of future complications. The angulation-based and prosthetic-based classifications simplify communication regarding implant angulation and prosthesis design type for ISFPDs. The SAC classification assists in prosthetic design, factoring in function and esthetics when designing the screw access.

  3. Pre-fabricated zirconium dioxide implant abutments for single-tooth replacement in the posterior region: success and failure after 3 years of function.

    Science.gov (United States)

    Nothdurft, Frank P; Nonhoff, Joerg; Pospiech, Peter R

    2014-07-01

    Zirconia implant abutments have gained a much broader clinical use over the past few years. The aim of the present study was to assess the clinical performance of a pre-fabricated zirconium dioxide implant abutment for single-tooth replacement in the posterior region. Forty implants of the XiVE(®) S plus screw type (DENTSPLY Friadent, Mannheim, Germany) were inserted in the posterior region of 24 patients and provided with zirconium dioxide abutments (FRIADENT(®) CERCON(®) Abutment, DENTSPLY Friadent). The following parameters were used to document the state of soft tissue: modified plaque index, modified sulcus bleeding index and pocket depth. Mesial and distal bone levels were determined on radiographs during the prosthetic treatment and at the 36-month recall. Thirty-seven implants could be followed up after 36 months in function. One patient wearing two abutments was lost to follow-up. One abutment exhibited a rotational misfit after 2 years in function. A further abutment showed the same failure at the 36-months recall appointment. In the remaining 36 implants the soft and hard tissue parameters were indicative of a low inflammatory status. Compared to the baseline situation, a partly significant bone apposition could be observed. Chipping of parts of the veneering ceramic was registered in 22% of the remaining implant restorations. The use of zirconia abutments in this study lead to mainly healthy peri-implant hard and soft tissue conditions but, considering the observed failures after 3 years in function, clinical long-term results should be awaited before recommending full zirconia implant abutments in a posterior indication.

  4. Facet Joint Violation During Percutaneous Pedicle Screw Placement: A Comparison of Two Techniques.

    Science.gov (United States)

    Tannous, Oliver; Jazini, Ehsan; Weir, Tristan B; Banagan, Kelley E; Koh, Eugene Y; Greg Anderson, D; Gelb, Daniel E; Ludwig, Steven C

    2017-08-01

    A comparative study of facet joint violation (FJV) using two percutaneous surgical techniques. To compare the rate of iatrogenic FJV and medial pedicle wall breach between two methods of percutaneous pedicle screw instrumentation in the thoracic and lumbar spine. Variable iatrogenic damage to the facet joints has been reported to occur with percutaneous pedicle screw techniques, compared with the open approach, which has been associated with adjacent segment disease. Technical variations of percutaneous pedicle screw placement may pose different risks to the facet joint. Attending spine surgeons percutaneously placed pedicle screws in seven human cadaveric spines from T2 to L5. At each level, screws were instrumented on one side using the 9 or 3 o'clock reference point of the pedicle on the posteroanterior view with a lateral-to-medial trajectory (LMT) and on the contralateral side using the center of the pedicle with an owl's eye trajectory (OET). Postoperative screw placement was assessed with computed tomography and then open cadaveric dissection. Outcome measures included FJV and medial pedicle wall breach. Overall, 17 of 105 screws placed with an LMT versus 49 of 105 screws placed with an OET violated or abutted the facet joint (P L1), and lumbar (L2-L5) levels (P = 0.003, 0.035, and 0.018, respectively). Medial pedicle wall breach occurred with 11 LMT screws and seven OET screws (P = 0.077), and no breach was considered critical. A significantly higher FJV rate was observed using the OET versus the LMT in the thoracic, thoracolumbar, and lumbar spine. No statistically significant differences in medial pedicle wall breach occurred between the techniques. Thus, the LMT of minimally invasive pedicle screw fixation may reduce iatrogenic damage to the facet joints. 3.

  5. Use of locking plate and screws for triple pelvic osteotomy.

    Science.gov (United States)

    Rose, Scott A; Bruecker, Ken A; Petersen, Steve W; Uddin, Nizam

    2012-01-01

    To evaluate the efficacy and complication rate associated with use of a purpose-specific locking triple pelvic osteotomy (LTPO) plate. Prospective study. Dogs (n = 9; 15 hips). Physical examination, plain film radiography, computed tomography (CT) of the pelvis, and coxofemoral arthroscopy were performed before unilateral triple pelvic osteotomy (TPO) or staged bilateral TPO. Radiographs were taken after each procedure and 3-5, 6-8, and ≥12 weeks postoperatively. Pelvic width was measured at 3 locations to evaluate pelvic canal narrowing. No screw loosening occurred. Complications occurred in only 1 hip (7%) where pullout of the locking plate-screw construct from the caudal iliac segment occurred because of a fracture of the cis-cortex; the dog made a full recovery after a salvage procedure. There was no significant reduction in the cranial pelvic width but a small reduction at the level of the acetabuli and ischiatic tuberosities was noted 3-5 weeks after the 2nd TPO. The LTPO plate was associated with a lower complication rate than previously reported for TPOs using Slocum canine pelvic osteotomy plates (CPOP) and warrants further investigation. Pullout of the caudal plate-screw construct is a complication specific to LTPO implants. Bicortical screw purchase is recommended to prevent fracture of the cis-cortex and implant pullout. © Copyright 2011 by The American College of Veterinary Surgeons.

  6. Ball Screw Actuator Including a Compliant Ball Screw Stop

    Science.gov (United States)

    Wingett, Paul T. (Inventor); Hanlon, Casey (Inventor)

    2017-01-01

    An actuator includes a ball nut, a ball screw, and a ball screw stop. The ball nut is adapted to receive an input torque and in response rotates and supplies a drive force. The ball screw extends through the ball nut and has a first end and a second end. The ball screw receives the drive force from the ball nut and in response selectively translates between a retract position and a extend position. The ball screw stop is mounted on the ball screw proximate the first end to translate therewith. The ball screw stop engages the ball nut when the ball screw is in the extend position, translates, with compliance, a predetermined distance toward the first end upon engaging the ball nut, and prevents further rotation of the ball screw upon translating the predetermined distance.

  7. Factors influencing success of cement versus screw-retained implant restorations: a clinical review

    Directory of Open Access Journals (Sweden)

    Ahmad Manawar

    2012-10-01

    Full Text Available Aim: As more and more dental practitioners are focusing on implant-supported fixed restorations, some clinicians favor the use of cement retained restorations while others consider screw retained prosthesis to be the best choice. Discussion: In screw-retained restorations, the fastening screw provides a solid joint between the restoration and the implant abutment, while in cement-retained prostheses the restorative screw is eliminated to enhance esthetics, occlusal stability, and passive fit of the restorations. The factors that influence the type of fixation of the prostheses to the implants like passivity of the framework, ease of fabrication, occlusion, esthetics, accessibility, retention and retrievability are discussed in this article with scientific studies demonstrating superior outcomes of one technique over another. Screwretained implant restorations have an advantage of predictable retention, retrievability and lack of potentially retained subgingival cement. However, a few disadvantages exist such as precise placement of the implant for optimal and esthetic location of the screw access hole and obtaining passive fit. On the other hand, cement retained restorations eliminate unesthetic screw access holes, have passive fit of castings, reduced complexity of clinical and lab procedures, enhanced esthetics, reduced cost factors and non disrupted morphology of the occlusal table. Conclusion: This article compares the advantages, potential disadvantages and limitations of screw and cement retained restorations and their specific implications in the most common clinical situation.

  8. Enhancing pedicle screw fixation in the lumbar spine using allograft bone plug interference fixation.

    Science.gov (United States)

    Chrea, Bopha; Malempati, Harsha; Campbell, Jeffrey R; Khan, Sonja; Ching, Randal P; Lee, Michael J

    2014-05-01

    A within-subjects controlled laboratory study. To examine a biological alternative to cement augmentation for pedicle screw fixation comparing bilateral axial pullout tests of augmented and nonaugmented (controls) pedicle screws. Fixation in the osteoporotic spine remains a difficult challenge with failure by loosening or backout. Pedicle screw augmentation has been attempted using polymethylmethacrylate and bioabsorbable calcium cements; however, the potential for extravasation and embolization of cement are becoming increasingly concerning and merit the search for alternative methods to improve screw-anchoring strength. Twenty-four (24) fresh human lumbar vertebrae were tested to compare the pullout strength of augmented and nonaugmented pedicle screws. Two different augmentation strategies were employed using allograft bone plugs (ABPs) and evaluated using 12 specimens per group. Bone mineral density of each specimen was obtained using dual-energy x-ray absorptiometry. The augmented versus nonaugmented pedicle was randomized for each vertebra, and bilateral testing enabled paired statistical analyses. Axial pullout tests were performed using an materials testing system servohydraulic test system, and peak force, failure displacement, and stiffness was obtained for each test and correlated with bone mineral density. Augmentation using 6-mm-diameter ABPs with 6.25-mm-diameter pedicle screws resulted in statistically weaker average pullout strength (775±455 N) than the nonaugmented controls (1233±826 N). When using smaller (5 mm diameter) AGPs with the same diameter screws, there was no statistical difference between average pullout strength for the augmented pedicle screws (1772±652 N) and the nonaugmented screws (1780±575 N). Preliminary study of pedicle screw augmentation using cannulated ABPs showed no improvement of fixation with pedicles in the spine. This was even true in osteoporotic specimens, where augmentation would seem to be of considerable benefit.

  9. Clinical experience with the screw extraction set for broken screw.

    Science.gov (United States)

    Mitsukawa, Nobuyuki

    2011-01-01

    Titanium plate systems are used frequently for bone fractures and postosteotomy fixation in craniomaxillofacial surgery. However, sometimes the head of the screw for plate fixation is deformed or the screw breaks in the bone. Screw removal can be difficult in these cases. In this study, we examined the utility of the Screw Extraction Set (Synthes Inc) in facilitating the removal of screws broken in craniomaxillofacial bones. In the past, we often encountered screw head sockets that had become deformed. In the removal of such a screw, the extraction screw tip did not engage well with the deformed screw head socket because the extraction screw tip was angled obtusely. Thus, its removal was difficult, and this method was clearly problematic. Using the Screw Extraction Set, the removal method for a screw broken in the bone was relatively easy. In particular, it was very convenient in removing broken screws in the mandibular angle and ramus, where surgery is difficult under direct vision. This system was thought to be useful for craniofacial surgeons if proper patient selection is performed.

  10. Scalloped Implant-Abutment Connection Compared to Conventional Flat Implant-Abutment Connection

    DEFF Research Database (Denmark)

    Starch-Jensen, Thomas; Christensen, Ann-Eva; Lorenzen, Henning

    2017-01-01

    OBJECTIVES: The objective was to test the hypothesis of no difference in implant treatment outcome after installation of implants with a scalloped implant-abutment connection compared to a flat implant-abutment connection. MATERIAL AND METHODS: A MEDLINE (PubMed), Embase and Cochrane library search...

  11. Tissue reactions to abutment shift: an experimental study in dogs.

    Science.gov (United States)

    Abrahamsson, Ingemar; Berglundh, Tord; Sekino, Satoshi; Lindhe, Jan

    2003-01-01

    Standard protocols for the clinical use of dental implants often include the placement of healing abutments prior to standard or custom-made abutments. The tissue response to a single shift from a healing abutment to a permanent abutment has not been studied. The aim of the present experiment was to study tissue reactions that may occur following the removal of a healing abutment and the placement of a permanent abutment. In six beagle dogs, all mandibular premolars were extracted. Three months later three fixtures of the Astra Tech Implants Dental System (Astra Tech AB, Mölndal, Sweden) were installed in each edentulous premolar region. An additional 3 months later, the first abutment connection was performed. In two sites on each side of the mandible, healing abutments were placed; in the remaining site, a Uni-abutment (Astra Tech AB) was used. The two healing abutments were removed 2 weeks later, and one Uni-abutment and one prepable abutment were placed. A plaque-control period was initiated, and 6 months later block biopsies were obtained. The biopsies were prepared for histometric and morphometric examination. Radiographs were obtained at fixture placement, 2 weeks after the first abutment connection, and 6 months later. The length of the barrier epithelium, the height of the connective tissue attachment, and the level of the marginal bone did not differ between the three abutment groups. The major part of the radiographic bone loss during the experiment took place prior to or immediately after abutment connection; only small bone level alterations occurred during the subsequent 6-month period. The shift from a healing abutment to a permanent abutment resulted in the establishment of a transmucosal attachment, the dimension and quality of which did not differ from those of the mucosal barrier formed to a permanent abutment placed during a second-stage surgery.

  12. Accuracy of different abutment level impression techniques in All-On-4 dental implants

    Directory of Open Access Journals (Sweden)

    Marzieh Alikhasi

    2012-01-01

    Full Text Available Background and Aims: Passive fit of prosthetic frameworks is a major concern in implant dentistry. Impression technique is one of the several variables that may affect the outcome of dental implants. The purpose of this study was to compare the three dimensional accuracy of direct and indirect abutment level implant impressions ofALL-ON-4 treatment plan.Materials and Methods: A reference acrylic resin model with four Branemark fixtures was made according to All-On-4 treatment plan. Multiunit abutments were screwed into the fixtures and two special trays were made for direct and indirect impression techniques. Ten direct and ten indirect impression techniques with respective impression transfers were made. Impressions were poured with stone and the positional accuracy of the abutment analogues in each dimension of x, y, and z axes and also angular displacement (Δθ were evaluated using a Coordinate Measuring Machine (CMM. Data were analyzed using T- test.Results: The results showed that direct impression technique was significantly more accurate than indirect technique (P<0.001.Conclusion: The results showed that the accuracy of direct impression technique was significantly more than that of indirect technique in Δθ and Δr coordinate and also Δx, Δy, Δz.

  13. Discrepancies in marginal and internal fits for different metal and alumina infrastructures cemented on implant abutments.

    Science.gov (United States)

    Faot, Fernanda; Suzuki, Dalton; Senna, Plinio M; da Silva, Wander J; de Mattias Sartori, Ivete A

    2015-06-01

    Cemented crowns are increasingly being used on dental implants instead of on screw-retained prostheses because of the reliability of internal Morse taper implant-abutment connections. However, there is a lack of information on the fit of metal ceramic and premachined alumina infrastructures. Therefore, the aim of this study was to evaluate the marginal and internal fits of different metal and alumina infrastructures cemented on universal post abutments. A total of 45 abutments (6 mm in height and 3.3 mm in diameter) were divided into five groups on the basis of their infrastructure material: cobalt-chromium (CoCr), nickel-chromium (NiCr), nickel-chromium-molybdenum-titanium (NiCrMoTi), gold (Au), and premachined alumina. The alumina group showed marginal overextension, and the Au group showed the highest discrepancy in marginal fit among the metal alloys. The CoCr and alumina groups showed the lowest discrepancies in internal fit. In conclusion, the alumina cylinders exhibited the best internal fit, despite their horizontal overextension. Among the metal alloys, CoCr exhibited the best fit at critical regions, such as the cervical and occlusal areas. © 2015 Eur J Oral Sci.

  14. Incidence of undetected cement on CAD/CAM monolithic zirconia crowns and customized CAD/CAM implant abutments. A prospective case series.

    Science.gov (United States)

    Wasiluk, Grzegorz; Chomik, Ewa; Gehrke, Peter; Pietruska, Małgorzata; Skurska, Anna; Pietruski, Jan

    2017-07-01

    The aim of this study was to assess the frequency of cement residues after cementation of CAD/CAM monolithic zirconia crowns on customized CAD/CAM titanium abutments. Sixty premolars and molars were restored on Astra Tech Osseospeed TX ™ implants using single monolithic zirconia crowns fixed on two types of custom-made abutments: Atlantis ™ titanium or Atlantis ™ Gold Hue. Occlusal openings providing access to the abutment screws were designed for retrievability of the crown/abutment connection. After fixation with glass ionomer cement, the crown/abutment units were unscrewed to evaluate the presence of residual cement. Dichotomous assessment of the presence or absence of cement at the crown/abutment unit and peri-implant tissues was performed. Clinically undetected cement excess was visible on 44 of 60 restorations (73.3%). There was no interdependency between residual cement presence and implant location or diameter. However, a dependency between the presence of residual cement and the aspect of the abutment/crown connection could be noted. The majority of the residues were observed on the distal (17.9%) and mesial (15%) aspects. While on the palatal/lingual aspect, the cement was visible in 8.8%; only 3.4% of all surfaces displayed cement residues. Within the limitations of the study, it can be concluded that the use of customized CAD/CAM abutments do not guarantee avoidance of subgingival cement residues after crown cementation. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  15. MONITORING OF DISPLACEMENT ABUTMENTS OF MOTORWAY VIADUCT

    Directory of Open Access Journals (Sweden)

    Krzysztof TROJNAR

    Full Text Available The aim of the paper is controlling the behavior of the bridge supports of the motorway viaduct WA-164 on strengthened subsoil using soil-cement columns made in DSM technology. Monitoring of the construction was carried out for a period of 16 months by measuring the settlement and rotation of the structure. The settlements were measured by means of the geodesic precision leveling method. Changes in the rotation of the supports were recorded using a inclinometer sensors installed on the walls of the abutments. For mapping of the construction work, numerical models of span and abutments were performed. The abutment was modeled in computer program SOFiSTiK. The stiffness of subsoil was calibrated with regard to the measured settlement of the abutment on DSM columns. The results of field measurements shows that after backfilling the abutments, it leaned in the embankments direction. This is also confirmed by numerical analysis. Monitoring conducted in 2014 showed that settlement is stabilized, and the measured values are safe and lower than the SLS limit stage. Numerical modeling along with geotechnical and geodetic monitoring has enabled a better understanding of the behavior of the bridge foundation on strengthened subsoil and verify the calculation assumptions taken at the stage of design calculations.

  16. Magnesium inference screw supports early graft incorporation with inhibition of graft degradation in anterior cruciate ligament reconstruction

    Science.gov (United States)

    Cheng, Pengfei; Han, Pei; Zhao, Changli; Zhang, Shaoxiang; Zhang, Xiaonong; Chai, Yimin

    2016-05-01

    Patients after anterior cruciate ligament (ACL) reconstruction surgery commonly encounters graft failure in the initial phase of rehabilitation. The inhibition of graft degradation is crucial for the successful reconstruction of the ACL. Here, we used biodegradable high-purity magnesium (HP Mg) screws in the rabbit model of ACL reconstruction with titanium (Ti) screws as a control and analyzed the graft degradation and screw corrosion using direct pull-out tests, microCT scanning, and histological and immunohistochemical staining. The most noteworthy finding was that tendon graft fixed by HP Mg screws exhibited biomechanical properties substantially superior to that by Ti screws and the relative area of collagen fiber at the tendon-bone interface was much larger in the Mg group, when severe graft degradation was identified in the histological analysis at 3 weeks. Semi-quantitative immunohistochemical results further elucidated that the MMP-13 expression significantly decreased surrounding HP Mg screws with relatively higher Collagen II expression. And HP Mg screws exhibited uniform corrosion behavior without displacement or loosening in the femoral tunnel. Therefore, our results demonstrated that Mg screw inhibited graft degradation and improved biomechanical properties of tendon graft during the early phase of graft healing and highlighted its potential in ACL reconstruction.

  17. Primary pedicle screw augmentation in osteoporotic lumbar vertebrae: biomechanical analysis of pedicle fixation strength.

    Science.gov (United States)

    Burval, Daniel J; McLain, Robert F; Milks, Ryan; Inceoglu, Serkan

    2007-05-01

    Pedicle screw pullout testing in osteoporotic and control human cadaveric vertebrae, comparing augmented and control vertebrae. To compare the pullout strengths of pedicle screws fixed in osteoporotic vertebrae using polymethyl methacrylate delivered by 2 augmentation techniques, a standard transpedicular approach and kyphoplasty type approach. Pedicle screw instrumentation of the osteoporotic spine carries an increased risk of screw loosening, pullout, and fixation failure. Osteoporosis is often cited as a contraindication for pedicle screw fixation. Augmentation of the vertebral pedicle and body using polymethyl methacrylate may improve fixation strength and construct survival in the osteoporotic vertebrae. While the utility of polymethyl methacrylate has been demonstrated for salvage of screws that have been pulled out, the effect of the cement technique on pullout strength in osteoporotic vertebrae has not been previously studied. Thirteen osteoporotic and 9 healthy human lumbar vertebrae were tested. All specimens were instrumented with pedicle screws using a uniform technique. Osteoporotic pedicles were augmented with polymethyl methacrylate using either a kyphoplasty type technique or a transpedicular augmentation technique. Screws were tested in a paired testing array, randomly assigning the augmentation techniques to opposite sides of each vertebra. Pullout to failure was performed either primarily or after a 5000-cycle tangential fatigue conditioning exposure. After testing, following screw removal, specimens were cut in the axial plane through the center of the vertebral body to inspect the cement distribution. Pedicle screws placed in osteoporotic vertebrae had higher pullout loads when augmented with the kyphoplasty technique compared to transpedicular augmentation (1414 +/- 338 versus 756 +/- 300 N, respectively; P pedicle screws in osteoporotic vertebrae augmented by kyphoplasty showed higher pullout resistance than those placed in healthy control

  18. Minimally invasive treatment of clavicular fractures with cannulated screw.

    Science.gov (United States)

    Sun, Jun-zhan; Zheng, Guo-hai; Zhao, Ke-yi

    2014-05-01

    To evaluate minimally invasive treatment of clavicular fractures with cannulated screw. Data of 65 patients who had undergone minimally invasive treatment with cannulated screws for clavicular fractures from April 2009 to October 2010 were retrospectively analyzed and compared with those of 65 patients with clavicular fractures who had been treated by the same surgeons with plates. In the study group, there were 41 males and 24 females, aged from 19-67 years (mean, 35.8 years). According to Craig's classification, there were 29 group 1 and 36 of group 2-II. Neer scores were used to evaluate shoulder function and radiographs to assess fracture union. The incision length was 4-5 cm in the cannulated screw group (CSG) and 10-11 cm in the reconstructive plate group (RPG). Radiographs showed bone union was achieved in both groups, the bone healing time being 13.2 ± 6.9 weeks in the CSG and 16.3 ± 8.7 weeks in the RPG. All patients were followed up for 6 to 20 months (average, 10.6 months). The average Neer score was 96.6 ± 3.4 in the CSG and 94.2 ± 5.8 in the RPG. In the CSG, screw loosening occurred in five, and fracture displacement in three. There was a significant difference in fracture healing time between two groups but not in Neer score. Minimally invasive treatment of clavicular fractures with cannulated screws has the advantages of minimal invasion, short bone healing time, good clinical outcomes, and being relatively inexpensive. © 2014 Chinese Orthopaedic Association and Wiley Publishing Asia Pty Ltd.

  19. Early clinical results with cortically based pedicle screw trajectory for fusion of the degenerative lumbar spine.

    Science.gov (United States)

    Glennie, R Andrew; Dea, Nicolas; Kwon, Brian K; Street, John T

    2015-06-01

    This study reviews the outcomes and revision rates of degenerative lumbar fusion surgery using cortical trajectory pedicle screws in lieu of traditional pedicle screw instrumentation. Pedicle screw fixation can be a challenge in patients with low bone mineral density. Wide posterior approaches to the lumbar spine exposing lateral to the facet joints and onto transverse processes causes an additional degree of muscular damage and blood loss not present with a simple laminectomy. A cortical bone trajectory pedicle screw has been proposed as an alternative to prevent screw pullout and decrease the morbidity associated with the wide posterior approach to the spine. We present a series of eight consecutive patients using a cortical bone trajectory instead of traditional pedicle screw fixation for degenerative conditions of the lumbar spine. A retrospective review of our institutional registry data identified eight patients who had cortical screws placed with the assistance of O-arm Stealth navigation (Medtronic Sofamor Danek, Memphis, TN, USA) from 2010-2013. We analyzed the need for revision, the maintenance of reduction and the incidence of screw pullout or breakage. Our review demonstrated that two of eight patients were revised at an average of 12months. The reasons for these revisions were pseudarthrosis and caudal adjacent segment failure. All patients who were revised had frank screw loosening. We present early clinical results of a new technique that has been shown to have a better fixation profile in laboratory testing. Our less than favorable early clinical results should be interpreted with caution and highlight important technical issues which should be considered. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Krag versus Caudad trajectory technique for pedicle screw insertion in osteoporotic vertebrae: biomechanical comparison and analysis.

    Science.gov (United States)

    Yuan, Qiang; Han, Xiaoguang; Han, Xiao; He, Da; Liu, Bo; Tian, Wei

    2014-12-15

    To compare in detail the effects of pedicle screw insertion in osteoporotic vertebrae via Krag and Caudad trajectory techniques. To compare the biomechanical stability of 2 pedicle screw fixation techniques and to correlate the stability of the pedicle screw with quantitative computed tomography (QCT). Pedicle screw fixation is commonly used to facilitate fusion and postoperative rehabilitation. Fixation failure and loosening in the metal-bone interface are frequent, with osteoporosis usually a major factor. Pedicle screw fixation in osteoporotic spines is of particular concern regarding implant failure. Few reports have addressed which fixation method provides better biomechanical strength and thus presents less risk of failure. Eleven cadaveric vertebrae were harvested and subjected to dual-energy x-ray absorptiometry and QCT to assess bone mineral density. Matched, polyaxial pedicle screws were inserted into the left and right pedicles of each vertebra. Screws were randomly assigned to the Caudad or Krag group by right or left side. They were inserted under 3-dimensional navigation system assistance. Cyclic loading tests were performed (maximum load 250 N, 3 Hz, up to 30,000 cycles) while recording load and displacement. Pullout tests were performed if the cyclic loading test was completed. Stiffness quotients were calculated. Cycle-displacement curves showed more pedicle screw dislodgement in the Krag than the Caudad group (P osteoporotic lumbar vertebrae using the Caudad trajectory displayed significantly higher biomechanical strength than those inserted using the Krag trajectory, especially during early fixation. Stability of pedicle screw fixation using the Caudad trajectory technique can be estimated by QCT.

  1. In Vivo Cell Wall Loosening by Hydroxyl Radicals during Cress Seed Germination and Elongation Growth

    NARCIS (Netherlands)

    Muller, K.; Linkies, A.; Vreeburg, R.A.M.; Fry, S.C.; Krieger-Liszkay, A.; Leubner-Metzger, G.

    2009-01-01

    Loosening of cell walls is an important developmental process in key stages of the plant life cycle, including seed germination, elongation growth, and fruit ripening. Here, we report direct in vivo evidence for hydroxyl radical (·OH)-mediated cell wall loosening during plant seed germination and

  2. Is monocyte chemotactic protein 1 elevated in aseptic loosening of TKA? A pilot study

    NARCIS (Netherlands)

    Dasa, V.; Kramer, J.M.; Gaffen, S.L.; Kirkwood, K.L.; Mihalko, W.M.

    2012-01-01

    BACKGROUND: Failure of TKA from aseptic loosening is a growing concern, as TKA is performed with increasing frequency. Loosening is multifactorial and may be associated with elevated inflammatory cytokines in addition to biomechanical failure. QUESTIONS/PURPOSES: We asked whether proinflammatory

  3. Evaluation of Heat Transfer to the Implant-Bone Interface During Removal of Metal Copings Cemented onto Titanium Abutments.

    Science.gov (United States)

    Cakan, Umut; Cakan, Murat; Delilbasi, Cagri

    2016-01-01

    The aim of this investigation was to measure the temperature increase due to heat transferred to the implant-bone interface when the abutment screw channel is accessed or a metal-ceramic crown is sectioned buccally with diamond or tungsten carbide bur using an air rotor, with or without irrigation. Cobalt-chromium copings were cemented onto straight titanium abutments. The temperature changes during removal of the copings were recorded over a period of 1 minute. The sectioning of coping with diamond bur and without water irrigation generated the highest temperature change at the cervical part of the implant. Both crown removal methods resulted in an increase in temperature at the implant-bone interface. However, this temperature change did not exceed 47°C, the potentially damaging threshold for bone reported in the literature.

  4. 21 CFR 872.3630 - Endosseous dental implant abutment.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Endosseous dental implant abutment. 872.3630... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3630 Endosseous dental implant abutment. (a) Identification. An endosseous dental implant abutment is a premanufactured prosthetic component...

  5. Randomized controlled clinical trial of customized zirconia and titanium implant abutments for canine and posterior single-tooth implant reconstructions: preliminary results at 1 year of function.

    Science.gov (United States)

    Sailer, Irena; Zembic, Anja; Jung, Ronald Ernst; Siegenthaler, David; Holderegger, Claudia; Hämmerle, Christoph Hans Franz

    2009-03-01

    The aim of this study was to test whether or not customized zirconia abutments exhibit the same survival rates in canine and posterior regions as titanium abutments, and to compare the esthetic result of the two abutment types. Twenty-two patients with 40 implants in posterior regions were included and the implant sites were randomly assigned to 20 customized zirconia and 20 customized titanium abutments. All-ceramic (AC) and metal-ceramic (MC) crowns were fabricated. In all except two cases, the crowns were cemented on the abutments using resin or glass-ionomer cements. Two zirconia reconstructions were screw retained. At baseline, 6 and 12 months, the reconstructions were examined for technical and biological problems. Probing pocket depth (PPD), plaque (Pl) and bleeding on probing (BOP) were assessed and compared with natural control teeth. Furthermore, the difference of color (DeltaE) of the peri-implant mucosa and the gingiva of control teeth was evaluated by means of a spectrophotometer (Spectroshade). The data were analyzed with Student's unpaired t-test, ANOVA and regression analyses. Twenty patients with 19 zirconia and 12 titanium abutments were examined at a mean follow-up of 12.6+/-2.7 months. The survival rate for reconstructions and abutments was 100%. No technical or biological problems were found at the test and control sites. Two chippings (16.7%) occurred at crowns supported by titanium abutments. No difference was found regarding PPD (meanPPD(ZrO2) 3.4+/-0.7 mm, mPPD(Ti) 3.3+/-0.6 mm), Pl (mPl(ZrO2) 0.2+/-0.3, mPl(Ti) 0.1+/-1.8) and BOP (mBOP(ZrO2) 60+/-30%, mBOP(Ti) 30+/-40%) between the two groups. Both crowns on zirconia and titanium abutments induced a similar amount of discoloration of the soft tissue compared with the gingiva at natural teeth (DeltaE(ZrO2) 8.1+/-3.9, DeltaE(Ti) 7.8+/-4.3). At 1 year, zirconia abutments exhibited the same survival and a similar esthetic outcome as titanium abutments.

  6. Debris from cobalt-chrome cable may cause acetabular loosening.

    Science.gov (United States)

    Kelley, S S; Johnston, R C

    1992-12-01

    To address the issue of nonunion with trochanteric osteotomy, surgeons have experimented with various modes of fixation, wire and cable being the two most popular. From a group of 643 primary cemented total hip arthroplasties performed by a single surgeon via the trans-trochanteric approach, minimum four-year roentgenographic follow-up evaluations were performed on 322 hips (50%). The method of fixation was stainless steel monofilament wire in 162 cases and Co-Cr cable in 160. Trochanteric union rates were 75% (122 patients) for the wire group and 79% (126 patients) for the cable. Breakage rates of the entire trochanteric fixation construction (all three wires or cables) were 43% (68 patients) for the wire and 12% (20 patients) for the cable. Unraveled cable was seen in 56% of the hips (90 patients), and in 47% of these hips, there were no broken cables. Blinded roentgenographic analysis of the acetabulum, preformed independently, revealed that loosening of the acetabulum in the cable group was greater than in the wire group. Cables offer no significant benefit over wires and may have potential adverse effects. Generation of significant particulate debris was noted roentgenographically, and marked reaction/destruction was found at the time of revision surgery.

  7. Fracture resistance of implant-supported screw-retained zirconia-based molar restorations.

    Science.gov (United States)

    Honda, Junichi; Komine, Futoshi; Kamio, Shingo; Taguchi, Kohei; Blatz, Markus B; Matsumura, Hideo

    2017-09-01

    The objective of this in vitro study was to investigate fracture loads of screw-retained zirconia-based molar restorations (hybrid abutment crown) fabricated with different restorative materials and designs. Forty-four screw-retained zirconia-based molar restorations were fabricated on dental implants and divided into four groups (n = 11): porcelain-layered zirconia-based restorations (PLZ), indirect composite-layered zirconia-based restorations (ILZ), metal-ceramic restorations (MC), and monolithic zirconia restorations (MONO). The zirconia-based restorations in the PLZ, ILZ, and MONO groups were adhesively bonded on implant abutments with a dual-polymerized resin material. All restorations were tightened on implant bodies with titanium screws and were tested for fracture resistance. The Kruskal-Wallis test and Steel-Dwass test were used to evaluate differences in fracture loads (α = 0.05). As compared with the other groups, the MONO specimens had a significantly higher mean fracture resistance (7.54 kN); no significant differences were found among the PLZ (1.96 kN), ILZ (1.80 kN), and MC (1.45 kN) groups (P > 0.05). For the PLZ, ILZ, and MC groups, all specimens fractured within the layering materials. In contrast, the fracture mode for the MONO group was complete fracture of the restorations. All restorations withstood the masticatory forces. Fracture loads were significantly higher for screw-retained implant-supported monolithic zirconia restorations than for screw-retained bilayered restorations. For the screw-retained bilayered zirconia-based restorations, the fracture resistance of ILZ restorations was comparable to that of PLZ restorations and MC restorations. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  8. [Polymethylmethacrylate augmentation of bone cement-injectable cannulated pedicle screws for the treatment of degenerative lumbar diseases with osteoporosis].

    Science.gov (United States)

    Sun, H L; Li, C D; Yang, Z C; Yi, X D; Liu, H; Lu, H L; Li, H; Wang, Y

    2016-12-18

    To describe the application of polymethylmethacrylate augmentation of bone cement-injectable cannulated pedicle screws for the treatment of degenerative lumbar diseases with osteoporosis. Observation group included 14 cases of degenerative lumbar diseases with osteoporosis received polymethylmethacrylate augmentation of bone cement-injectable cannulated pedicle screws from November 2014 to July 2015, control group included 12 cases of degenerative lumbar diseases with osteoporosis received polymethylmethacrylate augmentation with traditional pedicle screws.The operation time, blood loss, number of pedicle screws and number of augmented pedicle screws in the two groups were compared. The bone cement leakage and pulmonary bone cement embolism in the two groups were also compared. The fusion rate and pedicle screws loosening by lumbar X ray and dynamic X ray were evaluated. The clinical results were assessed by visual analog scale (VAS) of pain on lumbar and lower limbers, lumbar Japanese Orthopaedic Association scores (JOA), Prolo functional scores and Oswestry disability (ODI) scores. Differences of operation time and blood loss in the two groups were not statistically significant. The average number of pedicle screws was 9.9±4.7 and the average number of augmented pedicle screws was 5.9±2.6 in observation group while the average number of pedicle screws was 7.1±2.8 and the average number of augmented pedicle screws was 3.0±1.9 in control group. The ratio of augmented pedicle screws was higher in observation group than in control group (0.69±0.30 vs.0.47±0.30,Pdegenerative lumbar diseases with osteoporosis was effective, with simple working processes and lower risk of bone cement leakage. The short-term clinical result was good.

  9. Improving the pullout strength of pedicle screws by screw coupling.

    Science.gov (United States)

    Suzuki, T; Abe, E; Okuyama, K; Sato, K

    2001-10-01

    The objective of this study was to determine the effect of pedicle screw coupling on the pullout strength of pedicle screws in the osteoporotic spine. The vertebral bone mineral density (BMD) of 33 cadaveric lumbar vertebrae were measured by quantitative computed tomography. Pedicle screws were inserted into each pedicle. The pullout strength and displacement of the screws, without coupling and with single or double couplers, were studied, and the relationship between pullout strength and BMD was analyzed. The average pullout strength of the pedicle screws without screw coupling was 909.3 +/- 188.6 N (n = 9), that coupled with a single coupler was 1,409.0 +/- 469.1 N (n = 9), and that with double couplers was 1,494.0 +/- 691.6 N (n = 9). The pullout strength of the screws coupled with single or double couplers was significantly greater than that of screws without couplers (p pullout strength by screw coupling was significant in a test group with BMD of more than 90 mg/ml (p pedicle screws improves pullout strength; however, the effect tends to be less significant in severely osteoporotic spines.

  10. Ergotropic effect of bone cement on pedicle screw fixation in treatment of osteoporotic thoracolumbar fracture

    Directory of Open Access Journals (Sweden)

    Da LIU

    2017-02-01

    Full Text Available Objective To evaluate the ergotropic effect of bone cement on pedicle screw fixation in treatment of osteopo¬rotic thoracolumbar fracture. Methods Fifty-three patients with osteoporotic thoracolumbar fracture, admitted from Jun. 2013 to Dec. 2014, were included for treatment by augmentation of pedicle screw fixation with bone cement. All patients underwent pre-operative examination of bone mineral density with T-score ≤-2.5 and augmentation of pedicle screw fixation with injection of 1.5 ml bone cement in adjacent to fractured vertebra. All patients were treated with anti-osteoporosis therapy pre- and post-operation, ob¬served and recorded with basic conditions and complications. At pre-operation, one-week post-operation and last follow-up, pain vi¬sual analogue scale (VAS and neurological function score (ASIA of all patients were recorded, and the compression rats of anterior and posterior edge of fractured vertebra, and compression rats of spinal canal and Cobb angel of all patients were measured. Results All the 53 patients were successfully undergone operation in about 90-140 min with blood loss of about 150-350 ml. No spinal cord or nerve injury, dural tear and obvious leakage of bone cement and screw loosening occurred during operation. All patients were followed up for 12 to 36 months and the neurological function obviously recovered contrasted with pre-operation. X-ray and CT examination at last follow-up showed good fractures healing, good position and non-loosening of internal fixation device and non-leakage of bone cement. At one week post-operation and last follow-up, VAS, compression rats of anterior edge and posterior edge of fractured vertebra, compression rats of spinal canal and Cobb angel were significantly lower than those at pre-operation (P0.05. Conclusions Augmentation of pedicle screw fixation with bone cement can effectively strengthen the initial stability of pedicle screw in osteo¬porosis, restore the

  11. [Study of friction and loosening in hip endoprostheses].

    Science.gov (United States)

    Dovzak Bajs, Ivana; Cvjetko, Ivan; Car, Dolores; Kokić, Visnja

    2002-01-01

    Like any other operative procedure, the implantation of hip prosthesis is associated with certain complications, which diminishes the value and purpose of such a procedure. One of the complications in artificial hip implantation is loosening of the alloplastic material. Therefore, the aim of this study was to examine the effect of lubrication on the torsional moment and its role in the loosening of the femoral component, using an experimental mechanical model. The following hypothesis was tested: the magnitude of torsional loading in the "bone-endoprosthesis-bone cement system" is similar to any other known loading. The testing device was constructed with the possibility of simulation of positions similar to original performances in the implanted hip prosthesis. It refers primarily to the possibilities of achieving definite forces and velocities. The intention was to point quantitatively to the role of friction moment between the acetabular and femoral endoprosthesis part. Trials were conducted by combining 7 types of loading and 4 kinds of lubrication: dry, water, plasma, and light oil. The testing joint (Ring's prosthesis) was connected through tensometric measuring shaft upon the working forepart oscillating mechanism. Graded by the changeable static loading by means of the pendulum and via lever mechanism the testing joint was loaded by force from 610 to 7137 N. As the cause of friction resistance in the moving joint, torque deformaties of the measuring shaft occurred. The testing joint enabled oscillating movement using a four-part mechanism. In this way, it was possible to define not only the maximum values of the frictional moment (or the coefficient of friction) during one movement cycle but also to examine its relation to the kind of lubrication. Change in the measuring torsional moment were computer recorded. Before each trial, the gauging of the complete outfit was performed. Thereafter, cleaning of the frictional surfaces of the whole outfit was done

  12. Fracture load of different crown systems on zirconia implant abutments.

    Science.gov (United States)

    Albrecht, T; Kirsten, A; Kappert, H F; Fischer, H

    2011-03-01

    The purpose of this study was to evaluate the fracture load of single zirconia abutment restorations using different veneering techniques and materials. The abutment restorations were divided into 6 groups with 20 samples each: test abutments (control group A), lithium disilicate ceramic crowns bonded on incisor abutments (group B), leucite ceramic crowns bonded on incisor abutments (group C), premolar abutments directly veneered with a fluor apatite ceramic (group D (layered) and group E (pressed)) and premolar abutments bonded with lithium disilicate ceramic crowns (group F). The fracture load of the restorations was evaluated using a universal testing machine. Half of each group was artificially aged (chewing simulation and thermocycling) before evaluating the fracture load with the exception of the test abutments. The fracture load of the test abutments was 705 ± 43N. Incisor abutments bonded with lithium disilicate or leucite ceramic crowns (groups B and C) showed fracture loads of about 580N. Premolar restorations directly veneered with fluor apatite ceramic (groups D and E) showed fracture loads of about 850N. Premolar restorations bonded with lithium disilicate ceramic crowns (group F) showed fracture loads of about 1850N. The artificial ageing showed no significant influence on the strength of the examined restorations. All ceramic crowns made of lithium disilicate glass-ceramic, adhesively bonded to premolar abutments showed the highest fracture loads in this study. However, all tested groups can withstand physiological bite forces. Copyright © 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  13. One-piece internal zirconia abutments for single-tooth restorations on narrow and regular diameter implants: A 5-year prospective follow-up study.

    Science.gov (United States)

    Nilsson, Andrée; Johansson, Lars-Åke; Lindh, Christina; Ekfeldt, Anders

    2017-10-01

    Studies have reported an increased risk for fractures of zirconia abutments compared with titanium abutments. The aim of this study was to evaluate single-tooth implant restorations with one-piece yttria-stabilized internal zirconia abutments on narrow and regular diameter implants up to 6 years after insertion. This study comprises 52 consecutively treated patients, with a median age of 19 years. In total, 59 narrow (3.3 mm) and 10 regular (4.1 mm) diameter implants were installed. Sixty-five all-ceramic crowns were cemented on implant-supported one-piece internal zirconia abutments and 4 restorations were screw-retained. Thirty-five patients with 48 implant restorations participated in the final examination and another 14 patients with 16 implant restorations were possible to reach and could be interviewed. The implant survival was 100% but the survival rate for the implant-supported ceramic restorations was lower, 87.5%. Three crowns (4.7%) were remade for different reasons. Five restorations (7.8%) were remade due to fracture of the internal one-piece zirconia abutment. Four of these fractures occurred in 3.3 mm implant abutments. Narrow diameter implants offer an opportunity to restore small single-tooth edentulous gaps. For esthetical reasons the choice of an abutment in zirconia can be favorable, but at least with the used implant system, there seems to be an increased risk for fracture. Most patients were very satisfied with the esthetics and function of their implant restorations. © 2017 Wiley Periodicals, Inc.

  14. Upper bound of abutment scour in laboratory and field data

    Science.gov (United States)

    Benedict, Stephen

    2016-01-01

    The U.S. Geological Survey, in cooperation with the South Carolina Department of Transportation, conducted a field investigation of abutment scour in South Carolina and used those data to develop envelope curves that define the upper bound of abutment scour. To expand on this previous work, an additional cooperative investigation was initiated to combine the South Carolina data with abutment scour data from other sources and evaluate upper bound patterns with this larger data set. To facilitate this analysis, 446 laboratory and 331 field measurements of abutment scour were compiled into a digital database. This extensive database was used to evaluate the South Carolina abutment scour envelope curves and to develop additional envelope curves that reflected the upper bound of abutment scour depth for the laboratory and field data. The envelope curves provide simple but useful supplementary tools for assessing the potential maximum abutment scour depth in the field setting.

  15. Surgical treatment of degenerative and traumatic spinal diseases with expandable screws in patients with osteoporosis: 2-year follow-up clinical study.

    Science.gov (United States)

    Gazzeri, Roberto; Roperto, Raffaelino; Fiore, Claudio

    2016-11-01

    OBJECTIVE Pedicle screw instrumentation of the osteoporotic spine carries an increased risk of screw loosening, pullout, and fixation failure. A variety of techniques have been used clinically to improve pedicle screw fixation in the presence of compromised bone. Pedicle screws may be augmented with cement, but this may lead to cement leakage and result in disastrous consequences. To avoid these complications, a multiaxial expandable pedicle screw has been developed. This was a prospective, single-center study designed to evaluate the clinical results of patients with osteoporosis with traumatic and degenerative spinal diseases treated with expandable pedicle screws. METHODS Thirty-three patients (mean age 61.4 years) with osteoporosis and traumatic or degenerative spinal diseases underwent spinal posterior fixation with expandable screws. Preoperative and postoperative visual analog scale (VAS) for pain and Oswestry Disability Index (ODI) questionnaire scores were obtained. The immediate postoperative screw position was measured and compared with the final position on lateral plain radiographs and axial CT scans at the 1- and 2-year follow-up examinations. RESULTS A total of 182 pedicle screws were used, including 174 expandable and 8 regular screws. The mean preoperative patient VAS score improved from 8.2 to 3.6 after surgery. The mean ODI score improved from 83.7% before surgery to 29.7% after the operation and to 36.1% at the final follow-up. No screw migration had occurred at the 1-year follow-up, but 1 screw breakage/migration was visualized on spinal radiography at the 2-year follow-up. CONCLUSIONS The results of this study show that the multiaxial expandable pedicle screw is a safe and practical technique for patients with osteoporosis and various spinal diseases and adds a valuable tool to the armamentarium of spinal instrumentation.

  16. Strength comparison of allogenic bone screws, bioabsorbable screws, and stainless steel screw fixation.

    Science.gov (United States)

    Rano, James A; Savoy-Moore, Ruth T; Fallat, Lawrence M

    2002-01-01

    Allogenic bone screws are new to the fixation market and have yet to be tested against current fixation materials. An in vitro comparison of the same sizes of stainless steel, bioabsorbable, and allogenic bone screws was undertaken to assess screw resistance to the forces of bending, pullout, and shear. Using aluminum plates to support the screws, forces up to 1000 Newtons were applied to six to eight samples of each type of screw. During each test, stainless steel screws withstood the maximum force that could be exerted by the testing apparatus without failing (bending, 113.9 +/- 11.8 N mean +/- SE; pullout 999.1 +/- 33.7 N; and shear, 997.5 +/- 108.8 N). In each test, compared to bioabsorbable screws, allogenic bone screws failed faster (pullout, allogenic: 12.4 +/- 1.1 seconds vs. bioabsorbable, 120.6 +/- 13.8 seconds; p = .001; bending, allogenic: 53.4 +/- 4.8 seconds vs. bioabsorbable, 201.9 +/- 11.1 seconds; p = .001; shear, allogenic 13.5 +/- 1.4 seconds vs. bioabsorbable, 43.8 +/- 0.9 seconds; p = .001) under equivalent (pullout: bioabsorbable, 385.0 +/- 18.4 N vs. allogenic, 401.0 +/- 35.9 N; p = .001) or lower (bending, allogenic: 4.7 +/- 0.2 N vs. bioabsorbable, 11.0 +/- 0.9 N; p = .675; shear, allogenic: 312.1 +/- 15.5 N vs. bioabsorbable 680.9 +/- 8.5 N; p = .001) loads, and in a highly variable fashion. Overall, the bioabsorbable screws withstood the forces of bending, pullout, and shear better than the allogenic screws, and stainless steel screws outperformed both bioabsorbable and allogenic screws. Despite these results, allogenic screws could still be useful in compliant patients who would benefit from their osteoconductive properties.

  17. ROTARY SCREW SYSTEMS IN CEMENT

    OpenAIRE

    Taratuta V. D.; Belokur K. A.; Serga G. V.

    2016-01-01

    The article presents results of research of rotary-screw systems in relation to the creation of rotary kilns for the annealing of-cuttings in the preparation of cement clinker. Using the proposed design, in comparison with known designs of similar purpose, it significantly improves performance, reduces size and power consumption through the use of rotary screw systems in the form of screw rotors and drums made hollow with sidewalls assembled from separate strips or plates of different geometr...

  18. A New Trend in Recording Subgingival Tissue around an Implant While Making a Direct Abutment Impression

    Directory of Open Access Journals (Sweden)

    Suryakant C. Deogade

    2014-01-01

    Full Text Available A successful implant-supported restoration must provide adequate function and esthetics. Osseointegrated implants have given an alternative choice for patients who have lost their teeth. Most commonly encountered problems while doing a transfer from patient to the master cast in restoring implant-supported crowns are an uneven distribution of occlusal loads and undue torquing forces on the various elements of implant. This is caused due to poor fit of frameworks connected to implant, which further leads to marginal bone loss, loosening of screws, fatigue fracture of implant components, and ultimately implant failure. This paper presents a simplified and easy solution to overcome such problems by introducing an innovative gingival retraction system for restoring implant-supported crowns to achieve superior and predictable long-term outcomes.

  19. Biomechanical Comparison of External Fixation and Compression Screws for Transverse Tarsal Joint Arthrodesis.

    Science.gov (United States)

    Latt, L Daniel; Glisson, Richard R; Adams, Samuel B; Schuh, Reinhard; Narron, John A; Easley, Mark E

    2015-10-01

    Transverse tarsal joint arthrodesis is commonly performed in the operative treatment of hindfoot arthritis and acquired flatfoot deformity. While fixation is typically achieved using screws, failure to obtain and maintain joint compression sometimes occurs, potentially leading to nonunion. External fixation is an alternate method of achieving arthrodesis site compression and has the advantage of allowing postoperative compression adjustment when necessary. However, its performance relative to standard screw fixation has not been quantified in this application. We hypothesized that external fixation could provide transverse tarsal joint compression exceeding that possible with screw fixation. Transverse tarsal joint fixation was performed sequentially, first with a circular external fixator and then with compression screws, on 9 fresh-frozen cadaveric legs. The external fixator was attached in abutting rings fixed to the tibia and the hindfoot and a third anterior ring parallel to the hindfoot ring using transverse wires and half-pins in the tibial diaphysis, calcaneus, and metatarsals. Screw fixation comprised two 4.3 mm headless compression screws traversing the talonavicular joint and 1 across the calcaneocuboid joint. Compressive forces generated during incremental fixator foot ring displacement to 20 mm and incremental screw tightening were measured using a custom-fabricated instrumented miniature external fixator spanning the transverse tarsal joint. The maximum compressive force generated by the external fixator averaged 186% of that produced by the screws (range, 104%-391%). Fixator compression surpassed that obtainable with screws at 12 mm of ring displacement and decreased when the tibial ring was detached. No correlation was found between bone density and the compressive force achievable by either fusion method. The compression across the transverse tarsal joint that can be obtained with a circular external fixator including a tibial ring exceeds that

  20. Prosthetic Hip Loosening Due to Brucellar Infection: Case Report and Literature Review

    Directory of Open Access Journals (Sweden)

    Anis Tebourbi

    2016-12-01

    Full Text Available Context: Brucellosis is actually considered to be the commonest zoonotic infection worldwide; conversely prosthetic infection due to brucella is extremely rare. Although diagnostic is easily achieved, management of such situations is extremely challenging. Aims: To report the case of prosthetic hip loosening due to brucellar infection, discuss management manners and to summarize data about 19 cases reported in the literature. Methods: We report the case of a 73-year-old woman with brucellar prosthetic hip loosening treated with 2-stage exchange of the prosthesis and prolonged double antibiotherapy Results: At two years follow up the patient is pain free with total functional recovery and no clinical and radiographic signs of prosthetic loosening Conclusions: Brucella should be evocated as a cause of total joint arthroplasty infection especially in patients from endemic regions and with occupational exposure. Antibiotic treatment alone can be followed if there are no signs of implant loosening. Tow stage revision should be considered in other cases.

  1. Effect of Screw Access Channel Filling Method and Cement Type on Retention of Implant-Supported Fixed Restorations

    Directory of Open Access Journals (Sweden)

    Meysam Mahabadi

    2017-09-01

    Full Text Available Introduction: There is limited data on the factors affecting the retention of cemented fixed prostheses to implant abutment. The aim of this study was to evaluate the effect of screw access channel filling method and cement type on retention of implant-supported fixed restorations.  Materials and Methods: In this experimental study, 40 implant analogs were mounted in autopolymerizing acrylic resin blocks, and two-piece titanium abutments were placed in each implant analog. Twenty abutment samples were completely filled with silicone, and 20 other samples were filled partially. In each of the study groups, Temp Bond® eugenol-containing temporary cement was used for 10 samples, while in another 10 samples non-eugenol temporary cements were utilized. Prior to the retention test, samples were placed in the rmocycling machine with 1000 cycles for 24 h. Each sample was stretched using a Universal Pull-out Test Machine with a force of 5000 N. The required load for removing the crown was recorded. The data was analyzed USING two-way ANOVA and least square difference (α=0.05. Results: Among the four groups, the highest retention rate was observed in the group of partial screw access channel filling with eugenol cement. Also, the rate of retention in the group of complete screw access channel filling with non-eugenol cement was significantly lower than in any other group. A significant difference was observed between all the groups except for the groups of complete screw access channel filling with eugenol cement and partial screw access channel filling with non-eugenol cement (P=0.27. Conclusion: The mean rate of retention in partial access cavity filling group was greater than that of the complete access cavity filling group; moreover, this rate was higher in the eugenol cement group than the non-eugenol cement group.

  2. SCREW SELECTION FOR SCREW OPERATION USING EXPERT SYSTEM APPROACH

    Directory of Open Access Journals (Sweden)

    Hüdayim BAŞAK

    1999-01-01

    Full Text Available In this study, a expert system has been developed using Leonardo expert system package programming for screw operation, According to DIN standard norm. The designed program decide the most suitable screw type considering to material, cutting speed, working condition etc. This program also directs to user.

  3. Abutment Coating With Diamond-Like Carbon Films to Reduce Implant-Abutment Bacterial Leakage.

    Science.gov (United States)

    Cardoso, Mayra; Sangalli, Jorgiana; Koga-Ito, Cristiane Yumi; Ferreira, Leandro Lameirão; da Silva Sobrinho, Argemiro Soares; Nogueira, Lafayette

    2016-02-01

    The influence of diamond-like carbon (DLC) films on bacterial leakage through the interface between abutments and dental implants of external hexagon (EH) and internal hexagon (IH) designs was evaluated. Film deposition was performed by plasma-enhanced chemical vapor deposition. Sets of implants and abutments (n = 30 per group, sets of 180 implants) were divided according to connection design and treatment of the abutment base: 1) no treatment (control); 2) DLC film deposition; and 3) Ag-DLC film deposition. Under sterile conditions, 1 μL Enterococcus faecalis was inoculated inside the implants, and abutments were tightened. The sets were tested for immediate external contamination, suspended in test tubes containing sterile culture broth, and followed for 5 days. Turbidity of the broth indicated bacterial leakage. At the end of the period, the abutments were removed and the internal content of the implants was collected with paper points and plated in Petri dishes. After 24-hour incubation, they were assessed for bacterial viability and colony-forming unit counting. Bacterial leakage was analyzed by χ(2) and Fisher exact tests (α = 5%). The percentage of bacterial leakage was 16.09% for EH implants and 80.71% for IH implants (P DLC and Ag-DLC films do not significantly reduce the frequency of bacterial leakage and bacteria load inside the implants.

  4. Frictional performance of ball screw

    International Nuclear Information System (INIS)

    Nakashima, Katuhiro; Takafuji, Kazuki

    1985-01-01

    As feed screws, ball screws have become to be adopted in place of trapezoidal threads. The structure of ball screws is complex, but those are the indispensable component of NC machine tools and machining centers, and are frequently used for industrial robots. As the problems in the operation of ball screws, there are damage, life and the performance related to friction. As to the damage and life, though there is the problem of the load distribution on balls, the results of the research on rolling bearings are applied. The friction of ball screws consists of the friction of balls and a spiral groove, the friction of a ball and a ball, the friction in a ball-circulating mechanism and the viscous friction of lubricating oil. It was decided to synthetically examine the frictional performance of ball screws, such as driving torque, the variation of driving torque, efficiency, the formation of oil film and so on, under the working condition of wide range, using the screws with different accuracy and the nuts of various circuit number. The experimental setup and the processing of the experimental data, the driving performance of ball screws and so on are reported. (Kako, I.)

  5. [Design and experimental study of individual drill templates for atlantoaxial pedicle screw fixation].

    Science.gov (United States)

    Qin, Wei; Quan, Zhengxue; Liu, Yang; Ou, Yunsheng

    2010-10-01

    To explore and evaluate the accuracy and feasibility of individual rapid prototype (RP) drill templates for atlantoaxial pedicle screw implantation. Volumetric CT scanning was performed in 8 adult cadaveric atlas and axis to collect Dicom format datas. Then three-dimensional (3D) images of atlas and axis were reconstructed and the parameters of pedicles of 3D model were measured by using software Mimics 10.01. The 3D model was saved by STL format in Mimics. The scattered point cloud data of 3D model were processed and the 3D coordinate system was located in software Imageware 12.1. The curves and surfaces of 3D model were processed in software Geomagic Studio 10. The optimal trajectory of pedicle screw was designed and a template was constructed which accorded with the anatomical morphology of posterior arch of atlas and lamina of axis by using software Pro/Engineer 4.0. The optimal trajectory of pedicle screw and the template were integrated into a drill template finally. The drill template and physical models of atlas and axis were manufactured by RP (3D print technology). The accuracy of pilot holes of drill templates was assessed by visually inspecting and CT scanning. The individual drill template was used conveniently and each template could closely fit the anatomical morphology of posterior arch of atlas and lamina of axis. Template loosening and shifting were not found in the process of screw implantation. Thirty-two pedicle screws were inserted. Imaging and visual inspection revealed that the majority of trajectories did not penetrate the pedicle cortex, only 1 cortical penetration was judged as noncritical and did not injury the adjacent spinal cord, nerve roots, and vertebral arteries. The accuracy of atlas pedicle screw was grade 0 in 15 screws and grade I in 1 screw, and the accuracy of axis pedicle screw was grade 0 in 16 screws. The potential of individual drill templates to aid implantation of atlantoaxial pedicle screw is promising because of its

  6. Fixture-abutment connection surface and micro-gap measurements by 3D micro-tomographic technique analysis

    Directory of Open Access Journals (Sweden)

    Deborah Meleo

    2012-01-01

    Full Text Available X-ray micro-tomography (micro-CT is a miniaturized form of conventional computed axial tomography (CAT able to investigate small radio-opaque objects at a-few-microns high resolution, in a nondestructive, non-invasive, and tri-dimensional way. Compared to traditional optical and electron microscopy techniques, which provide two-dimensional images, this innovative investigation technology enables a sample tri-dimensional analysis without cutting, coating or exposing the object to any particular chemical treatment. X-ray micro-tomography matches ideal 3D microscopy features: the possibility of investigating an object in natural conditions and without any preparation or alteration; non-invasive, non-destructive, and sufficiently magnified 3D reconstruction; reliable measurement of numeric data of the internal structure (morphology, structure and ultra-structure. Hence, this technique has multi-fold applications in a wide range of fields, not only in medical and odontostomatologic areas, but also in biomedical engineering, materials science, biology, electronics, geology, archaeology, oil industry, and semi-conductors industry. This study shows possible applications of micro-CT in dental implantology to analyze 3D micro-features of dental implant to abutment interface. Indeed, implant-abutment misfit is known to increase mechanical stress on connection structures and surrounding bone tissue. This condition may cause not only screw preload loss or screw fracture, but also biological issues in peri-implant tissues.

  7. Temporal variation of clear-water scour at compound Abutments

    OpenAIRE

    Aminuddin Ab. Ghani; Reza Mohammadpour

    2016-01-01

    Most of actual abutments in rivers are built on foundation, while there is limited number of study available on the effects of the foundation on the local scour. In this study, temporal variation of local scour around compound abutment was investigated experimentally under clear-water conditions. The results showed that a suitable level of foundation is able to decrease the scour depth and increase scour time during the flood events. The trend of temporal scour depth at compound pier and abut...

  8. [Clinical effect modified Chevron osteotomy combined with lateral tissue loosening in treating mild-moderate hallux valgus through internal signal approach].

    Science.gov (United States)

    Chen, Xue-Qiang; Wu, Qun-Feng; Dong, Wei-Qin; Yu, Li-Xin; Li, Xiong-Feng

    2018-03-25

    To explore clinical effect of modified Chevron osteotomy combined with lateral tissue loosening for the treatment of mild-moderate hallux valgus through internal signal approach. From July 2015 to June 2016, 26 patients with mild-moderate hallux valgus treated with modified Chevron osteotomy combined with lateral tissue loosening through internal signal approach, including 2 males and 24 females aged from 45 to 65 years old with an average of(54.6±4.8) years old;the courses of diseases ranged from 1 to 5 months with an average of (7.5±3.3) months. Hallux valgus angle(HVA), inter metatarsal angle(IMA) were measured at 12 months after operation, and AOFAS score was applied to evaluate clinical effect before and after operation. All incisions were healed at stage I. No incision occurred infection, metatarsal necrosis and recurrence of hallux valgus deformity. Two patients occurred skin numbness caused by musculocutaneous nerve injury. Twenty-six patients were followed up from 6 to 12 months with an average of(9.12±2.06) months. HVA, IMA were(30.01±3.71)°, (14.00±1.50)° before operation and(9.41±4.16)°, (7.00±0.60)° after operation, which had significant difference. There was statistical significance in AOFAS score before operation 54.77±9.59 and after operation 92.73±5.47, and 19 cases obtained excellent results and 7 moderate. Modified Chevron osteotomy combined with full thread headless pressure screw fixation and lateral tissue loosening for the treatment of mild-moderate hallux valgus has advantages of excellent exposure, simple operation, stable fixation, rapid recovery. Akin osteotomy with internal capsulorrhaphy were used with lateral loosening and could recover soft tissue balance between lateral and internal, and could receive satisfied clinical effects. Copyright© 2018 by the China Journal of Orthopaedics and Traumatology Press.

  9. An in vitro comparison of the accuracy of implant impressions with coded healing abutments and different implant angulations.

    Science.gov (United States)

    Al-Abdullah, Khaled; Zandparsa, Roya; Finkelman, Matthew; Hirayama, Hiroshi

    2013-08-01

    Fabricating implant definitive casts with CAD/CAM technology (Robocasts) from coded healing abutment impressions represents a simpler and innovative alternative to conventional implant impression techniques. However, information about the accuracy of the impressions and the resultant definitive casts is limited. The purpose of the study was to evaluate the accuracy of the Robocasts and compare them to those definitive casts fabricated with conventional implant impression techniques (open tray with splinted impression copings technique). A reference epoxy resin cast was fabricated and shaped to simulate a dental arch. Two regular platform implant replicas (Biomet 3i Certain, 4.1 mm diameter and 15 mm length) with internal connections were placed 10 mm apart with a 10-degree convergence for one side of the reference resin cast and a 30-degree convergence for the other. Coded healing abutments (Encode) were placed at 3 different heights above the level of the soft tissue replication material (approximately 1, 2, and 4 mm) and served as test groups (E1, E2, and E4), and open trays with splinted impression copings (OTSC) served as a control group. The control group was compared to the impressions of the coded healing abutments by using a standardized measurement protocol. Impressions were made for each group (n=18) and poured with vacuum mixed (100 g powder/20 mL water) Type IV dental stone. The vertical discrepancy (Z axis) between 2 prefabricated passively fitting titanium reference frameworks and the platforms of the implant replicas was measured with an optical comparator applying the 1 screw test. Data were analyzed with Kruskal-Wallis and post-hoc Mann-Whitney U tests, as well as the Wilcoxon signed-rank tests. The Bonferroni correction was used to account for multiple comparisons. The significance level (α) used in a given set of tests was equal to .05 divided by the number of tests performed in that set. The median vertical discrepancy of each coded healing

  10. Clinical Characteristics of Abutment Teeth with Gingival Discoloration.

    Science.gov (United States)

    Ristic, Ljubisa; Dakovic, Dragana; Postic, Srdjan; Lazic, Zoran; Bacevic, Miljana; Vucevic, Dragana

    2017-04-06

    The grey-bluish discoloration of gingiva (known as "amalgam tattoo") does not appear only in the presence of amalgam restorations. It may also be seen in cases of teeth restored with cast dowels and porcelain-fused-to-metal (PFM) restorations. The aim of this article was to determine the clinical characteristics of abutment teeth with gingival discoloration. This research was conducted on 25 patients referred for cast dowel and PFM restorations. These restorations were manufactured from Ni-Cr alloys. Ninety days after cementing the fixed prosthodontic restorations, the abutment teeth (n = 61) were divided into a group with gingival discoloration (GD) (n = 25) and without gingival discoloration (NGD) (n = 36). The control group (CG) comprised the contralateral teeth (n = 61). Plaque index, gingival index, clinical attachment level, and probing depth were assessed before fabrication and also 90 days after cementation of the PFM restorations. The gingival index, clinical attachment level, and probing depths of the abutment teeth that had GD were statistically higher before restoration, in comparison with the abutment teeth in the NGD and control groups. Ninety days after cementation, the abutment teeth with GD had significantly lower gingival indexes and probing depths, compared to the abutment teeth in the NGD group. Both abutment teeth groups (GD and NGD) had significantly higher values of clinical attachment levels when compared to the control group. There were no statistically significant differences in plaque index values between the study groups. The results of this study indicated that impairment of periodontal status of abutment teeth seemed to be related to the presence of gingival discolorations. Therefore, fabrication of fixed prosthodontic restorations requires careful planning and abutment teeth preparation to minimize the occurrence of gingival discolorations. With careful preparation of abutment teeth for cast dowels and crown restorations it may be

  11. Comparison of radiographic and radionuclide hip arthrography in determination of femoral component loosening of hip arthroplasties

    International Nuclear Information System (INIS)

    Capello, W.N.; Uri, B.G.; Wellman, H.N.; Robb, J.A.; Stiver, P.L.

    1985-01-01

    Radiographic examination of a patient experiencing pain following total hip arthroplasty is an important step in the systematic approach to evaluating component loosening, even though the information yielded is often equivocal and nondiagnostic in assessing component loosening. The radiographic criteria for loosening are especially difficult to assess following revision surgery, for radiolucent lines frequently exist at the bone-cement interface immediately following implantation. The advent of noncemented hip prostheses poses another problem: the routinely noted disruption of bone-cement of prosthesis-cement interfaces is not present with uncemented prostheses. As the criteria for loosening of the noncemented prostheses are still evolving, plain radiographic examination is frequently nondiagnostic. Femoral component loosening is difficult to detect with standard contrast arthrography because the bone, metal, surrounding radiopaque cement and contrast agents have similar or identical radiographic appearances. In contrast arthrography, if the prosthesis is loose the injected agent opacifies the radiolucent zone encircling the prosthesis or cement mangle. Because of the similarity in the appearances of these agents and the surrounding structures on x-ray films, interpretation is difficult. The inclusion of subtraction techniques in routine contrast arthrography has improved its accuracy; however, these techniques require special equipment and demand precise patient positioning. The purpose of this study is to introduce a new form of hip arthrography using a radionuclide agent in place of the contrast agent. A comparison of the results using these two techniques is presented

  12. Influence of abutment tooth position and adhesive point dimension on the rigidity of a dental trauma wire-composite splint.

    Science.gov (United States)

    Zhu, Yuqing; Chen, Hui; Cen, Lian; Wang, Jun

    2016-06-01

    The influence of abutment tooth position and adhesive point dimension on rigidity of wire-composite splints, used in dental trauma, was evaluated in vitro. A commercial artificial resin model was used. The central incisors served as injured teeth with increased mobility (degrees of loosening II tooth 21 and III tooth 11), whereas teeth 12/22 or teeth 13/23 served as non-injured teeth with physiological mobility. Horizontal and vertical tooth mobility before and after splinting was assessed, using a universal testing machine. Teeth were splinted with a wire-composite splint (0.8 mm). Four groups were assigned with respective abutment tooth position and adhesive point dimension: group 1 (13-11-21-23, 2 × 2 mm(2) ), group 2 (12-11-21-22, 2 × 2 mm(2) ), group 3 (12-11-21-22, 3 × 3 mm(2) ), group 4 (12-11-21-22, 4 × 4 mm(2) ). For each group, tooth mobility after splinting was significantly higher than the physiological tooth mobility (P 0.05) were found in tooth mobility after splinting. Significant differences were found in horizontal tooth mobility after splinting of tooth 11 between Group 2 and 3, Group 2 and 4 and Group 3 and 4, respectively (P vertical dimension for tooth 11 only between Group 2 and 4 (P vertical mobility in most cases. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  13. Designing screws for polymer compounding in twin-screw extruders =

    Science.gov (United States)

    Teixeira, Cristina Ferreira

    Considering its modular construction, co-rotating twin screw extruders can be easily adapted to work with polymeric systems with more stringent specifications. However, their geometrical flexibility makes the performance of these machines strongly dependent on the screw configuration. Therefore, the definition of the adequate screw geometry to use in a specific polymer system is an important process requirement which is currently achieved empirically or using a trial-and-error basis. The aim of this work is to develop an automatic optimization methodology able to define the best screw geometry/configuration to use in a specific compounding/reactive extrusion operation, reducing both cost and time. This constitutes an optimization problem where a set of different screw elements are to be sequentially positioned along the screw in order to maximize the extruder performance. For that, a global modeling program considering the most important physical, thermal and rheological phenomena developing along the axis of an intermeshing co-rotating twin screw extruder was initially developed. The accuracy and sensitivity of the software to changes in the input parameters was tested for different operating conditions and screw configurations using a laboratorial Leistritz LSM 30.34 extruder. Then, this modeling software was integrated into an optimization methodology in order to be possible solving the Twin Screw Configuration Problem. Multi-objective versions of local search algorithms (Two Phase Local Search and Pareto Local Search) and Ant Colony Optimization algorithms were implemented and adapted to deal with the combinatorial, discrete and multi-objective nature of the problem. Their performance was studied making use of the hypervolume indicator and Empirical Attainment Function, and compared with the Reduced Pareto Search Genetic Algorithm (RPSGA) previously developed and applied to this problem. In order to improve the quality of the results and/or to decrease the

  14. Time-wise variation of scouring at bridge abutments

    Indian Academy of Sciences (India)

    Accurate estimation of the maximum possible depth of scour at bridge abutments is important in decision-making for the safe depth of burial of footings. Besides, investigation of the geometric features of scour holes around abutments provides useful information for the degree of scour counter-measure to be implemented ...

  15. Velocity and turbulence at a wing-wall abutment

    Indian Academy of Sciences (India)

    Experimental investigation of the 3D turbulent flow field around a 45° wing-wall abutment, resting on a rough rigid bed, is reported. The experiment was conducted ... The shear stresses acting on the bed around the abutment are estimated from the Reynolds stresses and velocity gradients. The data presented in this study ...

  16. Velocity and turbulence at a wing-wall abutment

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Kwan T F 1989 A study of abutment scour. Rep. No. 451, School of Engineering, University of. Auckland, Auckland, New Zealand. Kwan T F, Melville B W 1994 Local scour and flow measurements at bridge abutments. J. Hydraul. Res. 32: 661–673. Melville B W, Raudkivi R J 1977 Flow characteristics in local scour at bridge ...

  17. Microleakage Evaluation at Implant-Abutment Interface Using Radiotracer Technique

    Directory of Open Access Journals (Sweden)

    Hakimeh Siadat

    2016-10-01

    Full Text Available Objectives: Microbial leakage through the implant-abutment (I-A interface results in bacterial colonization in two-piece implants. The aim of this study was to compare microleakage rates in three types of Replace abutments namely Snappy, GoldAdapt, and customized ceramic using radiotracing.Materials and Methods: Three groups, one for each abutment type, of five implants and one positive and one negative control were considered (a total of 17 regular body implants. A torque of 35 N/cm was applied to the abutments. The samples were immersed in thallium 201 radioisotope solution for 24 hours to let the radiotracers leak through the I-A interface. Then, gamma photons received from the radiotracers were counted using a gamma counter device. In the next phase, cyclic fatigue loading process was applied followed by the same steps of immersion in the radioactive solution and photon counting.Results: Rate of microleakage significantly increased (P≤0.05 in all three types of abutments (i.e. Snappy, GoldAdapt, and ceramic after cyclic loading. No statistically significant differences were observed between abutment types after cyclic loading.Conclusions: Microleakage significantly increases after cyclic loading in all three Replace abutments (GoldAdapt, Snappy, ceramic. Lowest microleakage before and after cyclic loading was observed in GoldAdapt followed by Snappy and ceramic.Keywords: Dental Implants; Dental Implant-Abutment Design; Thallium Chloride

  18. Velocity and turbulence at a wing-wall abutment

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    When a wing-wall abutment is placed vertically on a rigid-bed rectangular channel by attach- ing it to one of the vertical sidewalls of the channel, the approaching turbulent boundary layer undergoes separation and rolles up to form the well-known primary vortex, which swept out by the side of the abutment. Limited research ...

  19. An investigation of the aseptic loosening of an AISI 316L stainless steel hip prosthesis.

    Science.gov (United States)

    Godec, Matjaz; Kocijan, Aleksandra; Dolinar, Drago; Mandrino, Djordje; Jenko, Monika; Antolic, Vane

    2010-08-01

    The total replacement of joints by the implantation of permanently indwelling prosthetic components has been one of the major successes of modern surgery in terms of relieving pain and correcting deformity. However, the aseptic loosening of a prosthetic-joint component is the most common reason for joint-revision surgery. Furthermore, it is thought that wear particles are one of the major contributors to the development and perpetuation of aseptic loosening. The aim of the present study was to identify the factors related to the aseptic loosening of an AISI 316L stainless steel total hip prosthesis. The stem was evaluated by x-ray photoelectron spectroscopy, with polished and rough regions being analyzed in order to establish the differences in the chemical compositions of both regions. Specific areas were examined using scanning electron microscopy with energy dispersive x-ray spectroscopy and light microscopy.

  20. Diabetes Mellitus and Hyperglycemia and the Risk of Aseptic Loosening in Total Joint Arthroplasty.

    Science.gov (United States)

    Maradit Kremers, Hilal; Schleck, Cathy D; Lewallen, Eric A; Larson, Dirk R; Van Wijnen, Andre J; Lewallen, David G

    2017-09-01

    It is unknown to what extent diabetes mellitus modifies the long-term risk of aseptic loosening in total hip arthroplasty (THA) and total knee arthroplasty (TKA). We examined the association between diabetes mellitus, perioperative hyperglycemia, and the likelihood of revisions for aseptic loosening. We studied 16,085 primary THA and TKA procedures performed at a large tertiary care hospital between 2002 and 2009. All blood glucose values around the time of surgery (within 1 week) were retrieved. Subsequent revision surgeries and the reasons for revision were ascertained through the institutional joint registry. Multivariate Cox models were used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) for aseptic loosening associated with diabetes mellitus and hyperglycemia adjusting for age, gender, body mass index, and surgery type. A total of 2911 (18%) surgeries had a diagnosis of diabetes mellitus at the time of surgery. Glucose testing was performed at least once in 7055 (44%) procedures within ±1 week of surgery. Although diabetic patients did not experience a higher risk of revision for aseptic loosening (HR, 0.87; 95% CI, 0.55-1.38), higher preoperative glucose values on the day before surgery were significantly associated with both the overall risk of revisions (HR, 2.80; 95% CI, 1.00-7.85) and revisions for aseptic loosening (HR, 4.95; 95% CI, 1.26-19.54). High preoperative hyperglycemia is a potential risk factor for aseptic loosening in THA and TKA. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Retention of crowns cemented on implant abutments with temporary cements.

    Science.gov (United States)

    Nagasawa, Yuko; Hibino, Yasushi; Nakajima, Hiroshi

    2014-01-01

    This study was to examine the retentive force of crowns to implant abutments with commercial temporary cements. Six different temporary cements were investigated. Cast crowns were cemented to the abutments using each cement and their retentive forces to abutments were determined 7 or 28 days after cementing (n=10). The retentive force of the cements to abutments varied widely among the products [27-109 N (7-day), 18-80 N (28-days)]. The retentive force of all the cements was not reduced as the time elapsed, except for two products tested. The polycarboxylate cements and paste-mixing type eugenol-free cements revealed comparable retentive force after 28 days of storage. The powder-liquid type cements showed a positive correlation (pcement between the retentive force and compressive strength. Mechanical strength of temporary cements could not be a prominent predicting factor for retention of the crowns on the abutments.

  2. Scour around vertical wall abutment in cohesionless sediment bed

    Science.gov (United States)

    Pandey, M.; Sharma, P. K.; Ahmad, Z.

    2017-12-01

    At the time of floods, failure of bridges is the biggest disaster and mainly sub-structure (bridge abutments and piers) are responsible for this failure of bridges. It is very risky if these sub structures are not constructed after proper designing and analysis. Scour is a natural phenomenon in rivers or streams caused by the erosive action of the flowing water on the bed and banks. The abutment undermines due to river-bed erosion and scouring, which generally recognized as the main cause of abutment failure. Most of the previous studies conducted on scour around abutment have concerned with the prediction of the maximum scour depth (Lim, 1994; Melvill, 1992, 1997 and Dey and Barbhuiya, 2005). Dey and Barbhuiya (2005) proposed a relationship for computing maximum scour depth near an abutment, based on laboratory experiments, for computing maximum scour depth around vertical wall abutment, which was confined to their experimental data only. However, this relationship needs to be also verified by the other researchers data in order to support the reliability to the relationship and its wider applicability. In this study, controlled experimentations have been carried out on the scour near a vertical wall abutment. The collected data in this study along with data of the previous investigators have been carried out on the scour near vertical wall abutment. The collected data in this study along with data of the previous have been used to check the validity of the existing equation (Lim, 1994; Melvill, 1992, 1997 and Dey and Barbhuiya, 2005) of maximum scour depth around the vertical wall abutment. A new relationship is proposed to estimate the maximum scour depth around vertical wall abutment, it gives better results all relationships.

  3. Screw retained vs. cement retained implant-supported fixed dental prosthesis.

    Science.gov (United States)

    Wittneben, Julia-Gabriela; Joda, Tim; Weber, Hans-Peter; Brägger, Urs

    2017-02-01

    A fixed dental prosthesis can be secured to an endosseous implant via cementation (using a provisional or definitive cement) on an implant abutment that is screw retained to the implant or directly in the implant via screw retention. The clinical decision as to which retention system best suits the individual patient depends on several factors. The aim of this review is to present a detailed overview of the factors potentially influencing whether to choose screw retention or cement retention. These factors include the individual indication, advantages and disadvantages of the different retention mechanisms, the retention provided, retrievability, provisionalization, esthetics and clinical performance, including failures and complications. The results of recently published systematic reviews on this topic are discussed and an overview is provided. A decision tree is presented to facilitate the clinical selection of the retention type. This overview concludes that the choice of retention type (screw retained or cement retained) might not influence the overall survival of the implant-supported fixed dental prosthesis, but may be responsible for the development of certain complications. The decision may depend on technical feasibility and on weighing the pros and cons. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  4. Biofilm formation on titanium alloy and anatase-Bactercline® coated titanium healing screws: an in vivo human study

    Directory of Open Access Journals (Sweden)

    Antonio Scarano

    2013-03-01

    Full Text Available Aim Bacterial adherence to implants is considered to be an important event in the pathogenesis of bacterial infections. In fact, this infection process is a first stage of peri-implant mucositis and peri-implantitis, and a positive correlation has been found between oral hygiene and marginal bone loss around implants in the edentulous mandible. Surface properties of transgingival implant components are important determinants in bacterial adhesion. The purpose of this study was to characterize the biofilm formation, in vivo, on healing screws made of titanium alloy or coated with a combination of anatase and Bactercline® product. Materials and methods Twenty-five patients, between 21- 37 years, in excellent systemic health, participated in this study. In each of the 25 participants, one anatase-Bactercline® coated healing screw (Test and one titanium alloy (TI6Al4V healing screw (Control were adapted to two different implants. Quantitative and qualitative biofilm formation on healing abutments was analyzed by culture method.Results Bacterial adherence to the two different healing screws used in this study were compared. Statistically significant differences were found between the Control and the Test group for both aerobic and anaerobic bacterial counts (p<0,05. The microflora consisted both of Gram-positive and Gram-negative bacteria, and displayed a high variability. The anaerobic S. intermedius, potentially “pathogenic”, was isolated only from the Control group. Both healing screws harbored primarily Gram-positive rods as Actinomyces spp, A. naeslundii, A. viscosus and the Gram-negative rods (Fusobacterium spp, Prevotella spp, Capnocythophaga spp were mostly found on the Control healing screws.Conclusion Anatase-Bactercline® coated healing screws reduce the number of initially adhering bacteria, formed mainly of Gram-positive microorgnisms, while, on the contrary, the microflora covering the titanium alloy healing screws was, for the

  5. Lumbar pedicle screw salvage: pullout testing of three different pedicle screw designs.

    Science.gov (United States)

    McLain, R F; Fry, M F; Moseley, T A; Sharkey, N A

    1995-02-01

    Although research has determined pedicle screw pullout strengths for normal and osteoporotic bone, this study provides the first biomechanical analysis of pedicle screw salvage. Ten fresh frozen human lumbar spines were separated into individual vertebrae; 6.0 x 40 mm pedicle screws were placed in each pedicle; and an axial pullout test was performed to establish control values. Ultimate load, initial stiffness, work, and displacement data were calculated. Each vertebra was reinstrumented with one 7.0 x 40 mm variable screw placement (VSP) screw side by side with either a 7.0 mm Cotrel Dubousset sacral screw (CD) or a 7.0 mm Compact Cotrel Dubousset pedicle screw (CCD). Pullout tests were repeated and compared to control data for individual screws and for each VSP/CD or VSP/CCD pair. Vertebrae were then reinstrumented with 8.0 mm VSP and CD screws and paired pullouts repeated. Statistical analysis was carried out using a paired T test. Analysis of intravertebral and intergroup variation of controls was carried out using a Paired Two Sample T test. The 7.0 mm CCD screws restored pullout strength to 62% of control pullouts; 7.0 mm CD screws, to 85%; 7.0 mm VSP screws, to 99%; 8.0 mm CD screws, to 109%; and 8.0 mm VSP screws, to 148% of control pullouts. The 7.0 mm VSP salvage screws exceeded CD screws in ultimate load by 22.5% (p screws by 33.5% (p screws significantly increased pullout relative to both controls and all 7.0 mm salvage screws, with 8.0 mm VSP exceeding 8.0 mm CD by 34% (p screws. Although applied in a smaller number of vertebrae, 8.0 mm screws sufficiently outperformed smaller screws to provide statistically significant differences. The 7.0 mm VSP salvage screws restored pullout to control levels, roughly equivalent to outcomes previously obtained with unpressurized polymethylmethacrylate (PMMA).

  6. Pedicle screw "hubbing" in the immature thoracic spine: a biomechanical and micro-computed tomography evaluation.

    Science.gov (United States)

    Kang, Daniel G; Lehman, Ronald A; Bevevino, Adam J; Gaume, Rachel E; Purcell, Richard L; Dmitriev, Anton E; Lenke, Lawrence G

    2014-01-01

    A previous biomechanical study using adult thoracic vertebrae (both normal and osteoporotic bone density) demonstrated the deleterious effect of the pedicle screw hubbing technique. Pedicle screw "hubbing" involves seating and engaging the ventral aspect of the screw head onto the dorsal lamina cortex. This technique is postulated to provide a load-sharing effect by improving pullout resistance, as well as decreasing cephalocaudad toggling and implant loosening. We hypothesized the elastic properties of immature bone may mitigate, and perhaps enhance the purported benefits of the hubbing technique. We set out to evaluate pullout strength of fixed-head pedicle screws after hubbing versus standard insertion in the immature thoracic calf spine. Twenty-two (n=22) single-level disarticulated fresh-frozen immature calf thoracic vertebra specimens (ranging from T2 to T13) were prepared. Twelve specimens were instrumented with pedicle screws in group I (nonhubbed) and group II (hubbed) in the opposite pedicle. Cyclic loading in a cephalocaudad direction was applied for 2000 cycles at a rate of 1 Hz. Pullout testing was performed in-line with the midline of the vertebra and peak pullout strength was measured in Newtons. Ten different specimens underwent micro-computed tomography evaluation to assess for trabecular architecture and incidence of iatrogenic microfractures. Hubbed screws resulted in significantly lower pullout strength (747±197 vs. 922±112 N, P=0.01). With the hubbing technique, the dorsal cortex demonstrated plastic deformation and conformed to the screw head in 83% of cases compared with no visible plastic deformation in the control group. Micro-computed tomography demonstrated microfractures of the dorsal cortex in 10/10 for the hubbed group compared with 1/10 for the control group. This is the largest study ever performed on immature thoracic vertebra to evaluate this topic. Hubbed pedicle screws have significantly decreased pullout strength and

  7. Misplaced Cervical Screws Requiring Reoperation.

    Science.gov (United States)

    Peterson, Jeremy C; Arnold, Paul M; Smith, Zachary A; Hsu, Wellington K; Fehlings, Michael G; Hart, Robert A; Hilibrand, Alan S; Nassr, Ahmad; Rahman, Ra'Kerry K; Tannoury, Chadi A; Tannoury, Tony; Mroz, Thomas E; Currier, Bradford L; De Giacomo, Anthony F; Fogelson, Jeremy L; Jobse, Bruce C; Massicotte, Eric M; Riew, K Daniel

    2017-04-01

    A multicenter, retrospective case series. In the past several years, screw fixation of the cervical spine has become commonplace. For the most part, this is a safe, low-risk procedure. While rare, screw backout or misplaced screws can lead to morbidity and increased costs. We report our experiences with this uncommon complication. A multicenter, retrospective case series was undertaken at 23 institutions in the United States. Patients were included who underwent cervical spine surgery from January 1, 2005, to December 31, 2011, and had misplacement of screws requiring reoperation. Institutional review board approval was obtained at all participating institutions, and detailed records were sent to a central data center. A total of 12 903 patients met the inclusion criteria and were analyzed. There were 11 instances of screw backout requiring reoperation, for an incidence of 0.085%. There were 7 posterior procedures. Importantly, there were no changes in the health-related quality-of-life metrics due to this complication. There were no new neurologic deficits; a patient most often presented with pain, and misplacement was diagnosed on plain X-ray or computed tomography scan. The most common location for screw backout was C6 (36%). This study represents the largest series to tabulate the incidence of misplacement of screws following cervical spine surgery, which led to revision procedures. The data suggest this is a rare event, despite the widespread use of cervical fixation. Patients suffering this complication can require revision, but do not usually suffer neurologic sequelae. These patients have increased cost of care. Meticulous technique and thorough knowledge of the relevant anatomy are the best means of preventing this complication.

  8. Gene therapy and cement injection for the treatment of hip prosthesis loosening in elderly patients

    NARCIS (Netherlands)

    Poorter, Jolanda de

    2010-01-01

    Approximately one million total hip replacement operations are performed worldwide annually, mostly for osteoarthritis and rheumatoid arthritis. A major complication in total hip arthroplasties is loosening of the prosthesis leading to pain and walking difficulties and a higher risk for dislocations

  9. REVISION TOTAL HIP ARTHROPLASTY IN PATIENTS WITH ASEPTIC LOOSENING OF FEMORAL STEM (REVIEW

    Directory of Open Access Journals (Sweden)

    A. V. Sementkovsky

    2011-01-01

    Full Text Available The paper presents literature data with regard to the classification of femoral bone loss defects. It also describes the contemporary techniques of revision total hip arthroplasty in patients with aseptic loosening of the femoral component and provides the evaluation of the treatment outcomes of the described approaches.

  10. Comparative study of radiography and scintigraphy for loosening and infection of prosthetic hip replacement

    International Nuclear Information System (INIS)

    Park, Mi Sook; Lee, Sun Wha; Choi, Woo Suk; Lim, Joo Won; Song, Han Joon; Ahn, Chi Yul

    1987-01-01

    Prosthetic hip replacement is associated with certain complications which result in a painful hip. Many of these, e. g. prosthetic dislocation, fracture, trochanteric avulsion, and heterotopic calcification are easily diagnosed by conventional radiography. However, radiographic evaluation for infection and/pr loosening of prosthesis as major complications requiring reoperation often contributes little to the resolution of the diagnostic problem. The authors made a comparative study of plain radiography and scintigraphy of 39 cases performed revision at Kyung Hee University Hospital from Sep. '81-to Aug. '86. The results were as follows: 1. In 39 revised prosthetic hip replacement, 26 cases (67%) of loosening without infection and 11 cases (28%) of infection were proven. 2. In loosening of prosthesis, plain radiography showed true positive rate of 76% and true negative rate of 60%, and scintigraphy showed true positive rate of 75% and true negative rate of 95%. 3. In infection of prosthesis, plain radiography revealed true positive rate of 55% and true negative rate of 96%, and scintigraphy revealed true positive rate of 100% and true negative rate of 83%. 4. Scintigraphy and plain radiography were useful as complementary procedure in evaluating and differentiating loosening and/or infection of prosthetic component

  11. Comparative study of radiography and scintigraphy for loosening and infection of prosthetic hip replacement

    Energy Technology Data Exchange (ETDEWEB)

    Park, Mi Sook; Lee, Sun Wha; Choi, Woo Suk; Lim, Joo Won; Song, Han Joon; Ahn, Chi Yul [College of Medicine, Kyung Hee University, Seoul (Korea, Republic of)

    1987-10-15

    Prosthetic hip replacement is associated with certain complications which result in a painful hip. Many of these, e. g. prosthetic dislocation, fracture, trochanteric avulsion, and heterotopic calcification are easily diagnosed by conventional radiography. However, radiographic evaluation for infection and/pr loosening of prosthesis as major complications requiring reoperation often contributes little to the resolution of the diagnostic problem. The authors made a comparative study of plain radiography and scintigraphy of 39 cases performed revision at Kyung Hee University Hospital from Sep. '81-to Aug. '86. The results were as follows: 1. In 39 revised prosthetic hip replacement, 26 cases (67%) of loosening without infection and 11 cases (28%) of infection were proven. 2. In loosening of prosthesis, plain radiography showed true positive rate of 76% and true negative rate of 60%, and scintigraphy showed true positive rate of 75% and true negative rate of 95%. 3. In infection of prosthesis, plain radiography revealed true positive rate of 55% and true negative rate of 96%, and scintigraphy revealed true positive rate of 100% and true negative rate of 83%. 4. Scintigraphy and plain radiography were useful as complementary procedure in evaluating and differentiating loosening and/or infection of prosthetic component.

  12. Clinical evaluation of isolated abutment teeth in removable partial dentures

    Directory of Open Access Journals (Sweden)

    Zarrati S

    2011-02-01

    Full Text Available "nBackground and Aims: Nowadays, removable partial dentures are applied to patients who are not able to use dental implants or fixed prosthesis. Although based on the studies the users of removable partial dentures are in the risk of plaque accumulation and unacceptable changes such as gingivitis, periodontitis and mobility in abutment tooth. It is not clear whether the negative effects of removable partial dentures are more on the isolated teeth which are a kind of abutment adjacent to endentulous area in both sides. The purpose of this study was to investigate the clinical condition of isolated abutment teeth without splinting in comparison to control abutment from the aspects of B.O.P (bleeding on probing, mobility, pocket depth and gingivitis."nMaterials and Methods: In this cross-sectional study, the prepared questionnaires were filled out by 50 patients who received removable partial dentures in department of removable prosthodontics of dental school of Tehran University of Medical Sciences. The patients had isolated abutment tooth and did not have any systemic disease. The obtained data were analyzed. Using Wilcoxon, exact Fisher and Kruskal-Wallis test."nResults: B.O.P (P=0.004, pocket depth (P=0.035, and mobility (P<0.001 in isolated abutments were more than those in control abutments, but there were not significant differences in the degree of caries (P=0.083 and gingivitis (P=0.07."nConclusion: This study showed that clinical condition of isolated abutments is worse than that of control abutments. More attention should be paid to healthiness of isolated teeth without splinting and periodic follow ups should be done in these cases.

  13. Marginal fit of cemented and screw-retained crowns incorporated on the Straumann (ITI) Dental Implant System: an in vitro study.

    Science.gov (United States)

    Tosches, N A; Brägger, U; Lang, N P

    2009-01-01

    The aim of this study was to assess the marginal fit of crowns on the Straumann (ITI) Dental Implant System with special consideration of different casting dental materials. Sixty porcelain-fused-to-metal crowns were fabricated: 18 crowns on standard cone abutments with an impression cylinder, partially prefabricated analogs, no coping and screw-retained (A); 18 crowns on solid abutments without an impression device, no analogs, no coping and cemented (B); and 18 crowns on solid abutments using an impression transfer cap, an analog with a shoulder, no coping and cemented (C). In each group, six crowns were made on epoxy mastercasts (Bluestar), six on synthetic plaster (Moldasynt) and six on super hard stone (Fujirock). Six additional crowns were fabricated with the transversal screw retention system onto the Octa system with impression transfer caps, metal analogs, gold copings and screw-retained (D). Impregum was used as impression material. Crowns of B and C were cemented with KetacCem. Crowns of A and D were fixed with an occlusal screw torqued at 15 N cm. Crowns were embedded, cut and polished. Under a light microscope using a magnification of x 100, the distance between the crown margin (CM) and the shoulder (marginal gap, MG) and the distance between the CM and the end of the shoulder (crown length, CL) was measured. MGs were 15.4+/-13.2 microm (A), 21.2+/-23.1 microm (B), 11+/-12.1 microm (C) and 10.4+/-9.3 microm (D). No statistically significantly differences using either of the casting materials were observed. CLs were -21.3+/-24.8 microm (A), 3+/-28.9 microm (B), 0.5+/-22 microm (C) and 0.1+/-15.8 microm (D). Crowns were shorter on synthetic casting materials compared with stone casts (Pcemented and screw-retained versions as well as when using no, partial or full analogs.

  14. Micrometer-Sized Titanium Particles Induce Aseptic Loosening in Rabbit Knee

    Directory of Open Access Journals (Sweden)

    Hao Xu

    2018-01-01

    Full Text Available Wear debris induced aseptic loosening is the leading cause of total knee arthroplasty (TKA failure. The complex mechanism of aseptic loosening has been a major issue for introducing effective prevention and treatment methods, so a simplified yet efficient rabbit model was established to address this concern with the use of micrometer-sized titanium particles. 20 New Zealand white rabbits were selected and divided into two groups (control = 10, study = 10. A TKA surgery was then performed for each of them, with implantation of a titanium rod prosthesis which was coated evenly with micrometer-sized titanium in the study group and nothing in the control group, into right femoral medullary cavity. After 12 weeks, all the animals were euthanized and X-ray analyses, H&E staining, Goldner Masson trichrome staining, Von Kossa staining, PCR, and Western blotting of some specific mRNAs and proteins in the interface membrane tissues around the prosthesis were carried out. The implantation of a titanium rod prosthesis coated with 20 μm titanium particles into the femoral medullary cavity of rabbits caused continuous titanium particle stimulation around the prosthesis, effectively inducing osteolysis and aseptic loosening. Titanium particle-induced macrophages produce multiple inflammatory factors able to activate osteoclast differentiation through the OPG/RANKL/RANK signaling pathway, resulting in osteolysis while suppressing the function of osteoblasts and reducing bone ingrowth around the prosthesis. This model simulated the implantation and loosening process of an artificial prosthesis, which is an ideal etiological model to study the aseptic prosthetic loosening.

  15. Missed low-grade infection in suspected aseptic loosening has no consequences for the survival of total hip arthroplasty

    NARCIS (Netherlands)

    Boot, Willemijn; Moojen, Dirk Jan F; Visser, Els; Lehr, A Mechteld; De Windt, Tommy S; Van Hellemondt, Gijs; Geurts, Jan; Tulp, Niek J A; Schreurs, B Wim; Burger, Bart J; Dhert, Wouter J A; Gawlitta, Debby; Vogely, H Charles

    2015-01-01

    BACKGROUND AND PURPOSE: Aseptic loosening and infection are 2 of the most common causes of revision of hip implants. Antibiotic prophylaxis reduces not only the rate of revision due to infection but also the rate of revision due to aseptic loosening. This suggests under-diagnosis of infections in

  16. Missed low-grade infection in suspected aseptic loosening has no consequences for the survival of total hip arthroplasty

    NARCIS (Netherlands)

    Boot, W.; Moojen, D.J.; Visser, E.; Lehr, A.M.; Windt, T.S. De; Hellemondt, G. Van; Geurts, J; Tulp, N.J.; Schreurs, B.W.; Burger, B.J.; Dhert, W.J.; Gawlitta, D.; Vogely, H.C.

    2015-01-01

    Background and purpose - Aseptic loosening and infection are 2 of the most common causes of revision of hip implants. Antibiotic prophylaxis reduces not only the rate of revision due to infection but also the rate of revision due to aseptic loosening. This suggests under-diagnosis of infections in

  17. Fracture strength of zirconia implant abutments on narrow diameter implants with internal and external implant abutment connections: A study on the titanium resin base concept.

    Science.gov (United States)

    Sailer, Irena; Asgeirsson, Asgeir G; Thoma, Daniel S; Fehmer, Vincent; Aspelund, Thor; Özcan, Mutlu; Pjetursson, Bjarni E

    2018-03-11

    There is limited knowledge regarding the strength of zirconia abutments with internal and external implant abutment connections and zirconia abutments supported by a titanium resin base (Variobase, Straumann) for narrow diameter implants. To compare the fracture strength of narrow diameter abutments with different types of implant abutment connections after chewing simulation. Hundred and twenty identical customized abutments with different materials and implant abutment connections were fabricated for five groups: 1-piece zirconia abutment with internal connection (T1, Cares-abutment-Straumann BL-NC implant, Straumann Switzerland), 1-piece zirconia abutment with external hex connection (T2, Procera abutment-Branemark NP implant, Nobel Biocare, Sweden), 2-piece zirconia abutments with metallic insert for internal connection (T3, Procera abutment-Replace NP implant, Nobel Biocare), 2-piece zirconia abutment on titanium resin base (T4, LavaPlus abutment-VarioBase-Straumann BL-NC implant, 3M ESPE, Germany) and 1-piece titanium abutment with internal connection (C, Cares-abutment-Straumann BL-NC implant, Straumann, Switzerland). All implants had a narrow diameter ranging from 3.3 to 3.5 mm. Sixty un-restored abutments and 60 abutments restored with glass-ceramic crowns were tested. Mean bending moments were compared using ANOVA with p-values adjusted for multiple comparisons using Tukey's procedure. The mean bending moments were 521 ± 33 Ncm (T4), 404 ± 36 Ncm (C), 311 ± 106 Ncm (T1) 265 ± 22 Ncm (T3) and 225 ± 29 (T2) for un-restored abutments and 278 ± 84 Ncm (T4), 302 ± 170 Ncm (C), 190 ± 55 Ncm (T1) 80 ± 102 Ncm (T3) and 125 ± 57 (T2) for restored abutments. For un-restored abutments, C and T4 had similar mean bending moments, significantly higher than those of the three other groups (p < .05). Titanium abutments (C) had significantly higher bending moments than identical zirconia abutments (T1) (p < .05). Zirconia

  18. Periodontal Conditions of Abutments and Non-Abutments in Removable Partial Dentures over 7 Years of Use.

    Science.gov (United States)

    da Fonte Porto Carreiro, Adriana; de Carvalho Dias, Kássia; Correia Lopes, Ana Lílian; Bastos Machado Resende, Camila Maria; Luz de Aquino Martins, Ana Rafaela

    2017-12-01

    To evaluate the periodontal conditions and integrity of abutment and non-abutment teeth of patients evaluated 7 years after insertion of the removable partial denture (RPD). Twenty-two patients (17 women, 5 men) were assessed at the moment of denture insertion and 7 years later. The following items were verified in each assessment: bleeding on probing (BP), probing depth (PD), gingival recession (GR), and mobility (M), comparing direct and indirect abutment teeth, and the teeth not involved in the denture design. Tooth integrity was also evaluated and classified as intact when no caries or fractures were observed. The Kruskal-Wallis test was used to reveal statistical significance between the groups (p = 0.05) as well as the Bonferrroni-corrected Mann-Whitney test for post hoc comparison. The Wilcoxon test was used for evaluation within the group over time. Fisher's exact test was applied to cross data about abutment integrity. Statistically significant differences were found for GR (baseline, p < 0.001; 7 years, p < 0.001) and PD (baseline, p = 0.001; 7 years = 0.004) between the three groups at baseline and after 7 years of follow-up. Mean BP and M values increased from initial assessment to after 7 years of RPD use in every group, but no statistically significant difference was found between the groups. For abutment integrity, a statistically significant difference (p = 0.028) was observed, and the direct abutment exhibited more (33.3%) caries and fractures. RPDs generated more periodontal damage to direct abutments, since higher gingival recession probing depth indexes, and presence of caries and fractures were observed in comparison to indirect abutments and non-abutments. © 2016 by the American College of Prosthodontists.

  19. Effect of microthread presence and restoration design (screw versus cemented) in dental implant reliability and failure modes.

    Science.gov (United States)

    Almeida, Erika O; Freitas Júnior, Amilcar C; Bonfante, Estevam A; Rocha, Eduardo Passos; Silva, Nelson R F A; Coelho, Paulo G

    2013-02-01

    This study evaluated the reliability and failure modes of implants with a microthreaded or smooth design at the crestal region, restored with screwed or cemented crowns. The postulated null hypothesis was that the presence of microthreads in the implant cervical region would not result in different reliability and strength to failure than smooth design, regardless of fixation method, when subjected to step-stress accelerated life-testing (SSALT) in water. Eighty four dental implants (3.3 × 10 mm) were divided into four groups (n = 21) according to implant macrogeometric design at the crestal region and crown fixation method: Microthreads Screwed (MS); Smooth Screwed (SS); Microthreads Cemented (MC), and Smooth Cemented (SC). The abutments were torqued to the implants and standardized maxillary central incisor metallic crowns were cemented (MC, SC) or screwed (MS, SS) and subjected to SSALT in water. The probability of failure versus cycles (90% two-sided confidence intervals) was calculated and plotted using a power law relationship for damage accumulation. Reliability for a mission of 50,000 cycles at 150 N (90% 2-sided confidence intervals) was calculated. Differences between final failure loads during fatigue for each group were assessed by Kruskal-Wallis along with Benferroni's post hoc tests. Polarized-light and scanning electron microscopes were used for failure analyses. The Beta (β) value (confidence interval range) derived from use level probability Weibull calculation of 1.30 (0.76-2.22), 1.17 (0.70-1.96), 1.12 (0.71-1.76), and 0.52 (0.30-0.89) for groups MC, SC, MS, and SS respectively, indicated that fatigue was an accelerating factor for all groups, except for SS. The calculated reliability was higher for SC (99%) compared to MC (87%). No difference was observed between screwed restorations (MS - 29%, SS - 43%). Failure involved abutment screw fracture for all groups. The cemented groups (MC, SC) presented more abutment and implant fractures

  20. Integral bridge abutment-to-approach slab connection.

    Science.gov (United States)

    2008-06-01

    The Iowa Department of Transportation has long recognized that approach slab pavements of integral abutment bridges are prone to settlement and cracking, which manifests as the "bump at the end of the bridge". A commonly recommended solution is to in...

  1. Deterioration of J-bar reinforcement in abutments and piers.

    Science.gov (United States)

    2011-12-31

    Deterioration and necking of J-bars has been reportedly observed at the interface of the footing and stem wall during the demolition : of older retaining walls and bridge abutments. Similar deterioration has been reportedly observed between the pier ...

  2. Long-term behavior of integral abutment bridges : [technical summary].

    Science.gov (United States)

    2011-01-01

    Integral abutment bridges, a type of jointless bridge, are the construction option of choice when designing highway bridges in many parts of the country. Rather than providing an expansion joint to separate the substructure from the superstructure to...

  3. Long-term behavior of integral abutment bridges.

    Science.gov (United States)

    2011-01-01

    Integral abutment (IA) construction has become the preferred method over conventional construction for use with typical : highway bridges. However, the use of these structures is limited due to state mandated length and skew limitations. To : expand ...

  4. Prosthetic abutment influences bone biomechanical behavior of immediately loaded implants

    Directory of Open Access Journals (Sweden)

    Germana de Villa CAMARGOS

    2016-01-01

    Full Text Available Abstract This study aimed to evaluate the influence of the type of prosthetic abutment associated to different implant connection on bone biomechanical behavior of immediately and delayed loaded implants. Computed tomography-based finite element models comprising a mandible with a single molar implant were created with different types of prosthetic abutment (UCLA or conical, implant connection (external hexagon, EH or internal hexagon, IH, and occlusal loading (axial or oblique, for both immediately and delayed loaded implants. Analysis of variance at 95%CI was used to evaluate the peak maximum principal stress and strain in bone after applying a 100 N occlusal load. The results showed that the type of prosthetic abutment influences bone stress/strain in only immediately loaded implants. Attachment of conical abutments to IH implants exhibited the best biomechanical behavior, with optimal distribution and dissipation of the load in peri-implant bone.

  5. Automated Erosion System to Protect Highway Bridge Crossings at Abutments

    Science.gov (United States)

    2010-06-01

    A new instrument (Photo-Electronic Erosion Pin, or PEEP) was examined in collecting field data and remotely monitoring bank erosion near bridge abutments during floods. The performance of PEEPs was evaluated through a detailed field study to determin...

  6. Proximal instrumented vertebral body chance fracture after pedicle screw instrumentation in a thoracic kyphosis patient with osteoporosis.

    Science.gov (United States)

    Hu, Xiaobang; Lieberman, Isador H

    2015-02-01

    We present a case of proximal vertebral body chance fracture after pedicle screw instrumentation and fusion in a 67-year-old woman with osteoporosis and thoracic kyphosis. To report the rare and unique complication of proximal vertebral body chance fracture after pedicle screw instrumentation and fusion in a kyphosis patient. Pedicle screw instrumentation has been associated with complications not limited to neurological or vascular injury, loss of curve correction, intraoperative pedicle fracture or loosening, dural laceration, deep infection, and pseudarthrosis. To the best of our knowledge, there are no previous reports describing a chance-type fracture generated by a pedicle screw fixation at the proximal end of a construct. A 67-year-old woman suffered from progressive thoracic kyphosis and mid thoracic pain presented 2 weeks after pedicle screw instrumentation and correction. She developed a vertebral body fracture at the proximal end of the instrumentation construct. Surgical intervention, including removal of the screws in the fractured vertebrae and extension of the instrumented fusion across the cervicothoracic junction, effectively restored the physiological sagittal alignment. Postoperatively, at 12-month follow-up, the patient is doing exceptionally well with near-complete relief of back pain and an excellent maintenance of correction. Chance fracture in osteoporotic bone at the proximal end of a construct due to a pedicle screw is a rare complication but it may result in catastrophic consequences. Early recognition of this complication, reduction of the fraction-dislocation, and an extension of the instrumentation can be utilized for realignment and long-term stabilization.

  7. Mechanical testing of thin-walled zirconia abutments

    Directory of Open Access Journals (Sweden)

    Luigi CANULLO

    2013-01-01

    Full Text Available Although the use of zirconia abutments for implant-supported restorations has gained momentum with the increasing demand for esthetics, little informed design rationale has been developed to characterize their fatigue behavior under different clinical scenarios. However, to prevent the zirconia from fracturing, the use of a titanium connection in bi-component aesthetic abutments has been suggested. Objective Mechanical testing of customized thin-walled titanium-zirconia abutments at the connection with the implant was performed in order to characterize the fatigue behavior and the failure modes for straight and angled abutments. Material and Methods Twenty custom-made bi-component abutments were tested according to ISO 14801:2007 either at a straight or a 25° angle inclination (n=10 each group. Fatigue was conducted at 15 Hz for 5 million cycles in dry conditions at 20°C±5°C. Mean values and standard deviations were calculated for each group. All comparisons were performed by t-tests assuming unequal variances. The level of statistical significance was set at p≤0.05. Failed samples were inspected in a polarized-light and then in a scanning electron microscope. Results Straight and angled abutments mean maximum load was 296.7 N and 1,145 N, the dynamic loading mean Fmax was 237.4 N and 240.7 N, respectively. No significant differences resulted between the straight and angled bi-component abutments in both static (p=0.253 and dynamic testing (p=0.135. A significant difference in the bending moment required for fracture was detected between the groups (p=0.01. Fractures in the angled group occurred mainly at the point of load application, whereas in the straight abutments, fractures were located coronally and close to the thinly designed areas at the cervical region. Conclusion Angled or straight thin-walled zirconia abutments presented similar Fmax under fatigue testing despite the different bending moments required for fracture. The main

  8. Using Ultrasound to Prevent Screw Penetration.

    Science.gov (United States)

    Balfour, George W

    2016-03-01

    Ultrasound is a readily available, inexpensive, easy-to-use, and rapid diagnostic tool. Physicians can use ultrasound to identify excessively long screws or screw penetration into joints. This article illustrates ultrasound identification of problem screws. Copyright © 2016 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  9. Accuracy combining different brands of implants and abutments.

    Science.gov (United States)

    Solá-Ruíz, María-Fernanda; Selva-Otaolaurruchi, Eduardo; Senent-Vicente, Gisela; González-de-Cossio, Inés; Amigó-Borrás, Vicente

    2013-03-01

    To evaluate the vertical misfit between different brands of dental implants and prosthetic abutments, with or without mechanical torque, and to study their possible combination. Five different brands of implant were used in the study: Biofit (Castemaggiore, Italy), Bioner S.A. (Barcelona, Spain), 3i Biomet (Palm Beach, U.S.A.), BTI (Alava, Spain) and Nobel Biocare (Göteborg, Sweden), with standard 4.1 mm heads and external hexagons, and their respective machined prosthetic abutments. The implant-to-abutment fit/misfit was evaluated at four points (vestibular, lingual/palatine, mesial and distal) between implants and abutments of the same brand and different brands, with or without mechanical torque, using SEM micrographs at 5000X. Image analysis was performed using NIS-Elements software (Nikon Instruments Europe B.V.). Before applying torque, vertical misfit (microgaps) of the different combinations tested varied between 1.6 and 5.4 microns and after applying torque, between 0.9 and 5.9 microns, an overall average of 3.46 ± 2.96 microns. For manual assembly without the use of mechanical torque, the best results were obtained with the combination of the 3i implant and the BTI abutment. The Nobel implant and Nobel abutment, 3i-3i and BTI-BTI and the combination of 3i implant with BTI or Nobel abutment provided the best vertical fit when mechanical torque was applied. The vertical fits obtained were within the limits considered clinically acceptable. The application of mechanical torque improved outcomes. There is compatibility between implants and abutments of different brand and so their combination is a clinical possibility.

  10. Creep and shrinkage effects on integral abutment bridges

    Science.gov (United States)

    Munuswamy, Sivakumar

    Integral abutment bridges provide bridge engineers an economical design alternative to traditional bridges with expansion joints owing to the benefits, arising from elimination of expensive joints installation and reduced maintenance cost. The superstructure for integral abutment bridges is cast integrally with abutments. Time-dependent effects of creep, shrinkage of concrete, relaxation of prestressing steel, temperature gradient, restraints provided by abutment foundation and backfill and statical indeterminacy of the structure introduce time-dependent variations in the redundant forces. An analytical model and numerical procedure to predict instantaneous linear behavior and non-linear time dependent long-term behavior of continuous composite superstructure are developed in which the redundant forces in the integral abutment bridges are derived considering the time-dependent effects. The redistributions of moments due to time-dependent effects have been considered in the analysis. The analysis includes nonlinearity due to cracking of the concrete, as well as the time-dependent deformations. American Concrete Institute (ACI) and American Association of State Highway and Transportation Officials (AASHTO) models for creep and shrinkage are considered in modeling the time dependent material behavior. The variations in the material property of the cross-section corresponding to the constituent materials are incorporated and age-adjusted effective modulus method with relaxation procedure is followed to include the creep behavior of concrete. The partial restraint provided by the abutment-pile-soil system is modeled using discrete spring stiffness as translational and rotational degrees of freedom. Numerical simulation of the behavior is carried out on continuous composite integral abutment bridges and the deformations and stresses due to time-dependent effects due to typical sustained loads are computed. The results from the analytical model are compared with the

  11. Displacement of screw-retained single crowns into implants with conical internal connections.

    Science.gov (United States)

    Yilmaz, Burak; Seidt, Jeremy D; McGlumphy, Edwin A; Clelland, Nancy L

    2013-01-01

    Internal conical implant-abutment connections without platforms may lead to axial displacement of crowns during screw tightening. This displacement may affect proximal contacts, incisal edge position, or occlusion. This study aimed to measure the displacement of screw-retained single crowns into an implant in three dimensions during screw tightening by hand or via torque driver. A stereolithic acrylic resin cast was created using computed tomography data from a patient missing the maxillary right central incisor. A 4.0- × 11-mm implant was placed in the edentulous site. Five porcelain-fused-to-metal single crowns were made using "cast-to" abutments. Crowns were tried on the stereolithic model, representing the patient, and hand tightened. The spatial relationship of crowns to the model after hand tightening was determined using three-dimensional digital image correlation (3D DIC), an optical measurement technique. The crowns were then tightened using a torque driver to 20 Ncm and the relative crown positions were again recorded. Testing was repeated three times for each crown, and displacement of the crowns was compared between the hand-tightened and torqued states. Commercial image correlation software was used to analyze the data. Mean vertical and horizontal crown displacement values were calculated after torqueing. The interproximal contacts were evaluated before and after torquing using an 8-μm aluminum foil shim. There were vertical and horizontal differences in crown positions between hand tightening and torqueing. Although these were small in magnitude, detectable displacements occurred in both apical and facial directions. After hand tightening, the 8-μm shim could be dragged without tearing. However, after torque tightening, the interproximal contacts were too tight and the 8-μm shim could not be dragged without tearing. Differences between hand tightening and torque tightening should be taken into consideration during laboratory and clinical

  12. Percutaneous cannulated screw fixation of sacral fractures and sacroiliac joint disruptions with CT-controlled guidewires performed by interventionalists: Single center experience in treating posterior pelvic instability

    International Nuclear Information System (INIS)

    Fischer, Sebastian; Vogl, Thomas J.; Marzi, Ingo; Zangos, Stephan; Wichmann, Julian L.; Scholtz, Jan-Erik; Mack, Martin G.; Schmidt, Sven; Eichler, Katrin

    2015-01-01

    Highlights: • Minimally invasive sacroiliac screw fixation can be performed under CT-imaging. • Guidewires help in precise placement of cannulated sacroiliac screw. • Only a diminishing rate of misplacements can be seen. • The method appears to be a safe and very accurate procedure. - Abstract: Objective: The purpose of our study was to evaluate minimally invasive sacroiliac screw fixation for treatment of posterior pelvic instability with the help of CT controlled guidewires, assess its accuracy, safety and effectiveness, and discuss potential pitfalls. Methods: 100 guidewires and hollow titan screws were inserted in 38 patients (49.6 ± 19.5 years) suffering from 35 sacral fractures and/or 16 sacroiliac joint disruptions due to 33 (poly-)traumatic, 2 osteoporotic and 1 post-infectious conditions. The guidewire and screw positions were analyzed in multiplanar reconstructions. Results: The mean minimal distance between guidewire and adjacent neural foramina was 4.5 ± 2.01 mm, with a distinctly higher precision in S1 than S2. Eight guidewires showed cortical contacts, resulting in a total of 2% mismatched screws with subsequent wall violation. The fracture gaps were reduced from 3.6 ± 0.53 mm to 1.2 ± 0.54 mm. During follow-up 3 cases of minor iatrogenic sacral impaction (<5 mm) due to the bolting and 2 cases of screw loosening were observed. Interventional time was 84.0 min with a mean of 2.63 screws per patient whilst acquiring a mean of 93.7 interventional CT-images (DLP 336.7 mGy cm). Conclusions: The treatment of posterior pelvic instability with a guidewire-based screw insertion technique under CT-imaging results in a very high accuracy and efficacy with a low complication rate. Careful attention should be drawn to radiation levels

  13. Percutaneous cannulated screw fixation of sacral fractures and sacroiliac joint disruptions with CT-controlled guidewires performed by interventionalists: Single center experience in treating posterior pelvic instability

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Sebastian, E-mail: sebastian.fischer@kgu.de [Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany); Vogl, Thomas J. [Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany); Marzi, Ingo [Department of Trauma, Hand and Reconstructive Surgery, University Hospital Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany); Zangos, Stephan; Wichmann, Julian L.; Scholtz, Jan-Erik; Mack, Martin G. [Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany); Schmidt, Sven [Orthopaedic University Hospital Friedrichsheim, Marienburgstraße, 260528 Frankfurt (Germany); Eichler, Katrin [Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt (Germany)

    2015-02-15

    Highlights: • Minimally invasive sacroiliac screw fixation can be performed under CT-imaging. • Guidewires help in precise placement of cannulated sacroiliac screw. • Only a diminishing rate of misplacements can be seen. • The method appears to be a safe and very accurate procedure. - Abstract: Objective: The purpose of our study was to evaluate minimally invasive sacroiliac screw fixation for treatment of posterior pelvic instability with the help of CT controlled guidewires, assess its accuracy, safety and effectiveness, and discuss potential pitfalls. Methods: 100 guidewires and hollow titan screws were inserted in 38 patients (49.6 ± 19.5 years) suffering from 35 sacral fractures and/or 16 sacroiliac joint disruptions due to 33 (poly-)traumatic, 2 osteoporotic and 1 post-infectious conditions. The guidewire and screw positions were analyzed in multiplanar reconstructions. Results: The mean minimal distance between guidewire and adjacent neural foramina was 4.5 ± 2.01 mm, with a distinctly higher precision in S1 than S2. Eight guidewires showed cortical contacts, resulting in a total of 2% mismatched screws with subsequent wall violation. The fracture gaps were reduced from 3.6 ± 0.53 mm to 1.2 ± 0.54 mm. During follow-up 3 cases of minor iatrogenic sacral impaction (<5 mm) due to the bolting and 2 cases of screw loosening were observed. Interventional time was 84.0 min with a mean of 2.63 screws per patient whilst acquiring a mean of 93.7 interventional CT-images (DLP 336.7 mGy cm). Conclusions: The treatment of posterior pelvic instability with a guidewire-based screw insertion technique under CT-imaging results in a very high accuracy and efficacy with a low complication rate. Careful attention should be drawn to radiation levels.

  14. THE USE OF A CODED HEALING ABUTMENT AS AN IMPRESSION COPING TO DESIGN AND MILL AN INDIVIDUALIZED ANATOMIC ABUTMENT : A CLINICAL REPORT

    NARCIS (Netherlands)

    Telleman, Gerdien; Raghoebar, Gerry M.; Vissink, Arjan; Meijer, Henny J. A.

    A coded implant healing abutment makes an impression at the implant level no longer necessary. An impression is made of the healing abutment, which is placed onto the implant directly after implant placement. The codes embedded in the occlusal surface of the healing abutment provide essential

  15. The influence of removable partial dentures on the periodontal health of abutment and non-abutment teeth.

    Science.gov (United States)

    Dula, Linda J; Shala, Kujtim Sh; Pustina-Krasniqi, Teuta; Bicaj, Teuta; Ahmedi, Enis F

    2015-01-01

    The aim of this study was to evaluate the influence of removable partial dentures (RPD) on the periodontal health of abutment and non-abutment teeth. A total 107 patients with RPD participated in this study. It was examined 138 RPD, they were 87 with clasp-retained and 51 were RPD with attachments. The following periodontal parameters were evaluated for abutment and non-abutment teeth, plaque index (PLI), calculus index (CI), bleeding on probing (BOP), probing depth (PD) (mm) and tooth mobility (TM) index. These clinical measurements were taken immediately before insertion the RPD, then one and 3 months after insertion. The level of significance was set at (P 0.05). With carefully planned prosthetic treatment and adequate maintenance of the oral and denture hygiene, we can prevent the periodontal diseases.

  16. Long-term behavior of integral abutment bridges : appendix E, INDOT design manual : selected recommendations for integral abutment bridges.

    Science.gov (United States)

    2011-01-01

    Integral abutment (IA) construction has become the preferred method over conventional construction for use with typical highway bridges. However, the use of these structures is limited due to state mandated length and skew limitations. To expand thei...

  17. Value of scintiscanning in supporting the radiological diagnosis of loosening of total hip endoprotheses

    Energy Technology Data Exchange (ETDEWEB)

    Fritsche, H.J.; Kadner, P.; Schneider, G. (Karl-Marx-Universitaet, Leipzig (German Democratic Republic). Radiologische Klinik)

    1984-01-01

    In 80 cases of total hip endoprotheses with suspicion on loosening bone scintigraphy was performed and compared to clinical and radiological findings. The radiographs of total hip endoprotheses are often dubious and additional bone scintigrams can provide information for the evaluation of the femoral part of the prothesis. Increased radioactivity of the acetabulum can be interpreted only with caution as a sign of loosening of the prothesis. In evaluating the scintigram not only the quantity of the isotope but mainly its distribution and exact localization are of diagnostic relevance. A negative scintigram in painful hip one year following operation does not indicate instability of the prothesis, but it is highly important for the clinician.

  18. Non-Radiological Method for Fabrication of a Screw-Channel Drilling Guide in Cement-Retained Implant Restorations Using Intraoral Digital Scanning and Imaging Superimposition: A Clinical Report.

    Science.gov (United States)

    Mai, Hang-Nga; Kim, Kyung-Rok; Lee, Du-Hyeong

    2017-01-01

    The difficulty of retrieving the abutment screw is a major disadvantage of cement-retained implant restorations. Conventional methods for locating the screw-access hole are based largely on radiography or manual labor, which limits accuracy and clinical feasibility. This clinical report describes a non-radiological method for fabricating an accurate drilling guide for location of the screw channel using intraoral optical scanning, 3D superimposition, and computer-aided design and computer-aided manufacturing (CAD/CAM) technologies. The present technique not only improves the guide fabrication process and the accuracy of screw-channel drilling, but also has wide indications for implant restorations. © 2016 by the American College of Prosthodontists.

  19. A Stereophotogrammetric System For The Detection Of Prosthesis Loosening In Total Hip Arthroplasty

    Science.gov (United States)

    Baumrind, Sheldon; Genant, Harry K.; Hunter, John; Miller, David; Moffitt, Francis; Murray, William R.; Ross, Steven E.

    1980-07-01

    Loosening of the prosthetic device occurs in about 5% of cases following placement of total hip prostheses (THP). Early detection of loosening is much desired but is difficult to achieve using conventional methods. Due to errors of projection, it is quite possible to fail to detect mobility of even as much as 5 mm on single x-ray films. We are attempting to develop a simplified photogrammetric system suitable for general hospital use which could detect loosening of 0.8 mm at the 95 % level of confidence without use of complex stereoplotting equipment. Metal reference markers are placed in the shaft of the femur and in the acetabular region of the pelvis at the time of surgery. The distances between these reference markers and certain unambiguous points on the prostheses are computed analytically using an X-Y acoustical digitizer (accuracy ± 0.1 mm) and software developed previously for craniofacial measurement. Separate stereopairs of the joint region are taken under weight-bearing and nonweight-bearing conditions. Differences in the measured distances between the bo-ne markers and the prosthetic components on the two stereopairs are taken as indicators of prosthesis loosening. Measurements on a phantom using ten different x-ray stereopairs taken from as many different perspectives have established that true linear distances between reference points and prostheses can be measured at the desired reliability with the present low precision system. Preliminary in vivo measurements indicate that the main unresolved problem is the movement of the subject between the two exposures of each single stereopair. Two possible solutions to this problem are discussed.

  20. Association Between Implant-Abutment Microgap and Implant Circularity to Bacterial Leakage: An In Vitro Study Using Tapered Connection Implants.

    Science.gov (United States)

    Lopes de Chaves E Mello Dias, Eduardo Cláudio; Sperandio, Marcelo; Napimoga, Marcelo Henrique

    2017-09-22

    The aim of this study was to evaluate the microgap between the abutment and implant as well as the circularity of implant platforms and associating conformational errors with bacterial microleakage in tapered connection implant systems. Four brands of implants with a tapered abutment connection were tested. Bacterial leakage was assessed using 0.3 μL of Escherichia coli suspension inoculated into the abutment screw chamber of the implants, which were then torqued and incubated at 37°C for 14 days. All specimens used for the microbiologic experiment were then cut lengthwise, and the microgap was measured at three points on each side of the sample using scanning electron microscopy (up to 5,000× magnification). Microtomography was used to assess implant platform circularity to validate the microscopic findings qualitatively. Two samples from the Nobel Biocare system, four from the Ankylos (Dentsply) system, four from the Neodent (Straumann) system, and five from the Conexão system were positive for bacterial leakage, with no significant difference between groups. The Neodent system had the highest mean microgap values (5.84 ± 9.83 μm), followed by the Nobel Biocare systems (5.17 ± 4.10 μm), Ankylos (3.47 ± 3.28 μm), and Conexão (2.72 ± 3.19 μm), with no significant difference between systems. All systems showed conformational errors of circularity on microtomography images. The tapered connection systems evaluated herein were not able to halt bacterial leakage, nor were they free from conformational errors.

  1. The Effect of Compressive Cyclic Loading on the Retention of Cast Single Crowns Cemented to Implant Abutments.

    Science.gov (United States)

    Alvarez-Arenal, Angel; Gonzalez-Gonzalez, Ignacio; Pinés-Hueso, Javier; deLlanos-Lanchares, Hector; del Rio Highsmith, Jaime

    2016-01-01

    The aim of this study was to evaluate and compare the retention strength of three cements commonly used in implant-supported prostheses before and after compressive cyclic loading. The working model consisted of five solid abutments, 7 mm in height and with a 6-degree taper, screw retained to five implant analogs secured in a rectangular block of self-curing acrylic. On the abutments, 30 metal Cr-Ni alloy copings were cemented using three luting agents: glass ionomer, resin urethane-based, and compomer cement (n = 10). Two tensile tests were conducted with a universal testing machine, before and after 100,000 cycles of 100 N and 0.72 Hz compressive cyclic loading in a humid environment. Before applying the compressive load, the retention strength of the resin urethane-based cement was slightly higher than that of the compomer cement and 75% greater than the glass-ionomer cement. After compressive loading, the resin urethane-based cement showed the highest percentage of loss of retention (64.45%, compared with 50% for glass-ionomer and compomer cement). However, the glass-ionomer cement showed the lowest mean retentive strength with 50.35 N as opposed to 75.12 N for the compomer cement and 71.25 N for the resin urethane-based. Compressive cyclic loading significantly influences the retention strength of the luting agents tested. All three cements may favor the retrievability of the crowns.

  2. Investigation of a Passive Sensor Array for Diagnosis of Loosening of Endoprosthetic Implants

    Directory of Open Access Journals (Sweden)

    Rainer Bader

    2012-12-01

    Full Text Available Currently, imaging methods are used to diagnose loosening of endoprosthetic implants, but fail to achieve 100% accuracy. In this study, a passive sensor array which is based on the interaction between magnetic oscillators inside the implant and an excitation coil outside the patient was investigated. The excited oscillators produce sound in the audible range, which varies according to the extent of loosening. By performing several experimental tests, the sensor array was optimized to guarantee reproducible and selective excitation of the sound emission. Variation in the distance between the oscillators demonstrated a definite influence on the quality of the generated sound signal. Furthermore, a numerical design analysis using the boundary element method was generated for consideration of the magnetic field and the selectivity of the oscillators during excitation. The numerical simulation of the coil showed the higher selectivity of a coil with a C-shape compared to a cylindrical coil. Based on these investigations, the passive sensor system reveals the potential for detection of implant loosening. Future aims include the further miniaturization of the oscillators and measurements to determine the sensitivity of the proposed sensor system.

  3. Stability Analysis for Loosened Rock Slope of Jinyang Grand Buddha in Taiyuan, China

    Science.gov (United States)

    SUN, Jinzhong; TIAN, Xiaofu; GUAN, Xudong; YU, Yonggui; YANG, Xiusheng

    On the basis of the status quo of Jinyang Grand Buddha in Taiyuan, some factors such as topography, geological structures, climate, hydrology, and engineering geology that influence the stability of the Buddha slope are considered, and several working situations of the slope that possibly suffered are presented in this article. The Buddha slope stands upright and the rock masses are composed of thick Permian sandstone, which dips slightly inward to the slope. Affected by both the incision of regional joints and the load relief to the free surface, the rock mass of the Buddha slope has turned into loosened blocks. Numerical stability analysis by FLAC-2D on the basis of the strength reduction method reveals that the localized deformation of the rock masses near the vertical surface of the slope may trigger reversing of rock beddings making the back dip slope convert into a dip slope with the possibility of plane sliding failure. Furthermore, the pseudostatic method for the dynamic process and limit equilibrium method for the static process are applied to different working situations of the Buddha slope. The analytical results illustrate that plane sliding failure will not occur when the slope is affected only by seism. However, water filling in the cracks of the loosened rock mass may greatly contribute to the potential plane sliding failure. When horizontal seism-force and hydrostatic pressure are coupled, the Buddha slope can hardly keep stable. Additionally, the loosened rock masses are prone to block toppling failure when influenced by the seism force.

  4. Total Hip Arthroplasty Loosening Due to Mycobacterium Tuberculosis: A Case Report and Review of the Literature

    Directory of Open Access Journals (Sweden)

    Anis Tebourbi

    2017-04-01

    Full Text Available Context: Prosthetic joint infection due to Mycobacterium tuberculosis with no previous history of pulmonary or extra pulmonary tuberculosis is an extremely rare complication. Aims To report the case of a patient with tuberculous mycobacterial prosthetic hip infection, 14 years after surgery for post traumatic osteoarthritis, with no previous history of tuberculosis. Methods A 46-year-old male presented an acetabular loosening of a cemented total hip arthroplasty with subnormal biologic parameters. A one stage revision surgery was planned. Intraoperative findings suggested mycobacterial tuberculous infection with presence of periacetabular yellowish rice-shaped granules. Results A one-stage prosthesis exchange was performed; Culture on Löwenstein-Jensen medium grew MTB days after inoculation and histological examination confirmed tuberculous infection. Patient was treated by antituberculous agents for 12 months with optimal clinical and biological response and no prosthetic loosening signs at eighteen months follow up. Conclusions Total hip arthroplasty loosening due to mycobacterium tuberculosis is a rare entity, which should be evoked even when no inflammatory signs are shown. Discovery of yellowish rice-shaped granules is an indicator to investigate for tuberculosis. Management of prosthetic joint infection due to M.tuberculosis must involve both medical and surgical approach.

  5. Particle-induced osteolysis mediated by endoplasmic reticulum stress in prosthesis loosening.

    Science.gov (United States)

    Wang, Rui; Wang, Zhenheng; Ma, Yutao; Liu, Guoyin; Shi, Hao; Chen, Jiangning; Dong, Lei; Zhao, Jianning; Zhang, Junfeng

    2013-04-01

    We hypothesized that endoplasmic reticulum (ER) stress in macrophages induced by wear particles was one of the reasons for particle-induced osteolysis (PIO) in total hip arthroplasty (THA) failure. In the present study, the expression of ER stress markers was examined by Western blot in macrophages treated with particles from materials used in prosthetics, specimens from PIO animal models and patients suffering from aseptic loosening. To address whether ER stress triggers these inflammatory responses, the effect of an ER stress blocker on the expression of inflammatory cytokines in particle-treated macrophages and PIO animal models was tested. The results demonstrated that ER stress markers were significantly upregulated in particle-treated macrophages, periosteum tissues from PIO animal models and clinical specimens of prosthesis loosening. Blocking ER stress with a specific inhibitor dramatically reduced the particle-induced expression of inflammatory cytokines in vitro and in vivo. Furthermore, in PIO animal models, this ER stress blocker dramatically suppressed the differentiation of osteoclasts and reduced the severity of osteolysis. Thus, the results of the present study suggest that ER stress plays a key role in particle-induced osteolysis and that targeting the ER stress pathway may lead to novel therapeutic approaches for the treatment of aseptic prosthesis loosening. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. A New Computed Tomography-Based Radiographic Method to Detect Early Loosening of Total Wrist Implants

    Energy Technology Data Exchange (ETDEWEB)

    Olivecrona, H.; Noz, M.E.; Maguire, G.Q. Jr; Zeleznik, M.P.; Sollerman, C.; Olivecrona, L. [Dept. of Hand Surgery, Soedersjukhuset, Stockholm (Sweden)

    2007-11-15

    Background: Diagnosis of loosening of total wrist implants is usually late using routine radiographs. Switching modality to computed tomography (CT) should aid in early diagnosis. Purpose: To propose and evaluate the accuracy of a new CT method for assessing loosening of the carpal component in total wrist arthroplasty. Material and Methods: A protocol encompassing volume registration of paired CT scans of patients with unexplained pain in a prosthetically replaced wrist (used in clinical routine) is presented. Scans are acquired as a dynamic examination under torsional load. Using volume registration, the carpal component of the prosthesis is brought into spatial alignment. After registration, prosthetic loosening is diagnosed by a shift in position of the bones relative to the prosthesis. This study is a preclinical validation of this method using a human cadaverous arm with a cemented total wrist implant and tantalum markers. Seven CT scans of the arm were acquired. The scans were combined into 21 pairs of CT volumes. The carpal component was registered in each scan pair, and the residual mismatch of the surrounding tantalum markers and bone was analyzed both visually and numerically. Results: The detection limit for prosthetic movement was less than 1 mm. Conclusion: The results of this study demonstrate that CT volume registration holds promise to improve detection of movement of the carpal component at an earlier stage than is obtainable with plain radiography.

  7. Metallurgical examination of gun barrel screws

    Energy Technology Data Exchange (ETDEWEB)

    Bird, E.L.; Clift, T.L.

    1996-06-01

    The examination was conducted to determine the extent of degradation that had occurred after a series of firings; these screws prevent live rounds of ammunition from being loaded into the firing chamber. One concern is that if the screw tip fails and a live round is accidentally loaded into the chamber, a live round could be fired. Another concern is that if the blunt end of the screw begins to degrade by cracking, pieces could become small projectiles during firing. All screws used in firing 100 rounds or more exhibited some degree degradation, which progressively worsened as the number of rounds fired increased. (SEM, metallography, x-ray analysis, and microhardness were used.) Presence of cracks in these screws after 100 fired rounds is a serious concern that warrants the discontinued use of these screws. The screw could be improved by selecting an alloy more resistant to thermal and chemical degradation.

  8. Findings of a Four-Year Randomized Controlled Clinical Trial Comparing Two-Piece and One-Piece Zirconia Abutments Supporting Single Prosthetic Restorations in Maxillary Anterior Region

    Directory of Open Access Journals (Sweden)

    Guerino Paolantoni

    2016-01-01

    Full Text Available The purpose of this randomized controlled study is to investigate the clinical results obtained over four years and incidence of complications associated with one- versus two-piece custom made zirconia anchorages, in single tooth implant-supported restorations of the maxillary anterior region. Sixty-five patients, with a total of 74 missing maxillary teeth, were selected in the period from February 2007 to July 2010. Two different ways of custom made zirconia abutment and final prosthetic restoration were evaluated: a standard zirconia abutment associated with a pressed layer of lithium disilicate with an all-ceramic cemented restoration versus one-piece restoration with the facing porcelain fired and pressed straight to the custom made zirconia abutment. In 29 cases, the restoration consisted of an all-ceramic restoration for cementation (two pieces; in 45 cases the restoration was a screw-retained restoration (one piece. Three all-ceramic restorations broke during the observation time. Two one-piece restorations fractured after 26 months. At follow-up examination there were no significant differences between one-piece and two-piece groups regarding the PI, BI, and MBL. Awaiting studies with longer follow-up times, a careful conclusion is that zirconia anchorages for single-implant restorations seem to demonstrate good short-term technical and biological results.

  9. Findings of a Four-Year Randomized Controlled Clinical Trial Comparing Two-Piece and One-Piece Zirconia Abutments Supporting Single Prosthetic Restorations in Maxillary Anterior Region

    Science.gov (United States)

    Paolantoni, Guerino; Marenzi, Gaetano; Blasi, Andrea; Mignogna, Jolanda; Sammartino, Gilberto

    2016-01-01

    The purpose of this randomized controlled study is to investigate the clinical results obtained over four years and incidence of complications associated with one- versus two-piece custom made zirconia anchorages, in single tooth implant-supported restorations of the maxillary anterior region. Sixty-five patients, with a total of 74 missing maxillary teeth, were selected in the period from February 2007 to July 2010. Two different ways of custom made zirconia abutment and final prosthetic restoration were evaluated: a standard zirconia abutment associated with a pressed layer of lithium disilicate with an all-ceramic cemented restoration versus one-piece restoration with the facing porcelain fired and pressed straight to the custom made zirconia abutment. In 29 cases, the restoration consisted of an all-ceramic restoration for cementation (two pieces); in 45 cases the restoration was a screw-retained restoration (one piece). Three all-ceramic restorations broke during the observation time. Two one-piece restorations fractured after 26 months. At follow-up examination there were no significant differences between one-piece and two-piece groups regarding the PI, BI, and MBL. Awaiting studies with longer follow-up times, a careful conclusion is that zirconia anchorages for single-implant restorations seem to demonstrate good short-term technical and biological results. PMID:27027093

  10. Findings of a Four-Year Randomized Controlled Clinical Trial Comparing Two-Piece and One-Piece Zirconia Abutments Supporting Single Prosthetic Restorations in Maxillary Anterior Region.

    Science.gov (United States)

    Paolantoni, Guerino; Marenzi, Gaetano; Blasi, Andrea; Mignogna, Jolanda; Sammartino, Gilberto

    2016-01-01

    The purpose of this randomized controlled study is to investigate the clinical results obtained over four years and incidence of complications associated with one- versus two-piece custom made zirconia anchorages, in single tooth implant-supported restorations of the maxillary anterior region. Sixty-five patients, with a total of 74 missing maxillary teeth, were selected in the period from February 2007 to July 2010. Two different ways of custom made zirconia abutment and final prosthetic restoration were evaluated: a standard zirconia abutment associated with a pressed layer of lithium disilicate with an all-ceramic cemented restoration versus one-piece restoration with the facing porcelain fired and pressed straight to the custom made zirconia abutment. In 29 cases, the restoration consisted of an all-ceramic restoration for cementation (two pieces); in 45 cases the restoration was a screw-retained restoration (one piece). Three all-ceramic restorations broke during the observation time. Two one-piece restorations fractured after 26 months. At follow-up examination there were no significant differences between one-piece and two-piece groups regarding the PI, BI, and MBL. Awaiting studies with longer follow-up times, a careful conclusion is that zirconia anchorages for single-implant restorations seem to demonstrate good short-term technical and biological results.

  11. Microleakage at the Different Implant Abutment Interface: A Systematic Review

    Science.gov (United States)

    Chowdhary, Ramesh; Kumari, Shail

    2017-01-01

    Introduction Presence of gap at the implant-abutment interface, leads to microleakage and accumulation of bacteria which can affect the success of dental implants. Aim To evaluate the sealing capability of different implant connections against microleakage. Materials and Methods In January 2017 an electronic search of literature was performed, in Medline, EBSCO host and Pubmed data base. The search was focused on ability of different implant connections in preventing microleakage. The related titles and abstracts available in English were screened, and the articles that fulfilled the inclusion criteria were selected for full text reading. Results In this systematic review, literature search initially resulted in 78 articles among which 30 articles only fulfilled the criteria for inclusion and were finally included in the review. Almost all the studies showed that there was some amount of microleakage at abutment implant interface. Microleakage was very less in Morse taper implants in comparison to other implant connections. Majority of studies showed less microleakage in static loading conditions and microleakage increases in dynamic loading conditions. Conclusion In this systematic review maximum studies showed that there was some amount of microleakage at abutment implant interface. External hexagon implants failed completely to prevent microleakage in both static and dynamic loading conditions of implants. Internal hexagon implants mainly internal conical (Morse taper) implants are very promising in case of static loading and also showed less microleakage in dynamic loading conditions. Torque recommended by manufacturer should be followed strictly to get a better seal at abutment implant interface. Zirconia abutments are more to microleakage than Titanium abutments and there use should be discouraged. Zirconia abutments should be only restricted to cases where there was very high demand of aesthetics. PMID:28764310

  12. Spectrophotometric analysis of fluorescent zirconia abutments compared to "conventional" zirconia abutments: A within subject controlled clinical trial.

    Science.gov (United States)

    Thoma, Daniel S; Gamper, Felix B; Sapata, Vítor M; Voce, Giuseppe; Hämmerle, Christoph H F; Sailer, Irena

    2017-08-01

    Zirconia abutments are frequently used for implant-supported single crowns. Even though demonstrating esthetic benefits compared to metal abutments, zirconia abutments lead to an increased brightness of the peri-implant mucosa compared to natural teeth and are not ideal from an esthetic point of view. To test whether or not a fluorescent hybrid zirconia abutment offers superior esthetics compared to a non-fluorescent one-piece zirconia abutment based on spectrophotometric analysis. In 24 patients with 24 single-tooth implants, 2 types of reconstructions were fabricated: a directly veneered one-piece zirconia abutment/crown (control) and a directly veneered fluorescent hybrid zirconia abutment/crown (test). Spectrophotometric assessment was performed: prior to abutment insertion (WA), at abutment try-in (A), at the try-in of the final crowns (C). Color differences (ΔE) were assessed compared to the gingiva of natural teeth (T) and between the reconstructions. At abutment try-in, ΔE values were 8.49 ± 3.59 for A Control and 8.27 ± 4.03 for A Test compared to T. At crown insertion, ΔE values were 7.61 ± 4.03 for C Control and 8.32 ± 3.57 for C Test compared to T. The difference in ΔE values between A Control and A Test was 0.23 ± 2.54 (P = .37), whereas the difference in ΔE values between C Control and C Test was -0.66 ±3.45 (P = .48). For all cases with a mucosal thickness ≤2 mm, the comparison between C Control and C Test was significant in favor of the control group (P = .03). Both types of reconstructions were similar in terms of esthetics. Incases with a mucosal thickness of compared to the natural gingiva was more pronounced for the fluorescent hybrid zirconia reconstructions. © 2017 Wiley Periodicals, Inc.

  13. The pedicle screw-rod system is an acceptable method of reconstructive surgery after resection of sacroiliac joint tumours

    Directory of Open Access Journals (Sweden)

    Yi-Jun Zhou

    2016-03-01

    Full Text Available Hemipelvic resections for primary bone tumours require reconstruction to restore weight bearing along anatomic axes. However, reconstruction of the pelvic arch remains a major surgical challenge because of the high rate of associated complications. We used the pedicle screw-rod system to reconstruct the pelvis, and the purpose of this investigation was to assess the oncology, functional outcome and complication rate following this procedure. The purpose of this study was to investigate the operative indications and technique of the pedicle screw-rod system in reconstruction of the stability of the sacroiliac joint after resection of sacroiliac joint tumours. The average MSTS (Musculoskeletal Tumour Society score was 26.5 at either three months after surgery or at the latest follow-up. Seven patients had surgery-related complications, including wound dehiscence in one, infection in two, local necrosis in four (including infection in two, sciatic nerve palsy in one and pubic symphysis subluxation in one. There was no screw loosening or deep vein thrombosis occurring in this series. Using a pedicle screw-rod after resection of a sacroiliac joint tumour is an acceptable method of pelvic reconstruction because of its reduced risk of complications and satisfactory functional outcome, as well as its feasibility of reconstruction for type IV pelvis tumour resection without elaborate preoperative customisation. Level of evidence: Level IV, therapeutic study.

  14. Biomechanical Comparison of Inter-fragmentary Compression Pressures: Lag Screw versus Herbert Screw for Anterior Odontoid Screw Fixation.

    Science.gov (United States)

    Park, Jin-Woo; Kim, Kyoung-Tae; Sung, Joo-Kyung; Park, Seong-Hyun; Seong, Ki-Woong; Cho, Dae-Chul

    2017-09-01

    The purpose of the present study was to compare inter-fragmentary compression pressures after fixation of a simulated type II odontoid fracture with the headless compression Herbert screw and a half threaded cannulated lag screw. We compared inter-fragmentary compression pressures between 40- and 45-mm long 4.5-mm Herbert screws (n=8 and n=9, respectively) and 40- and 45-mm long 4.0-mm cannulated lag screws (n=7 and n=10, respectively) after insertion into rigid polyurethane foam test blocks (Sawbones, Vashon, WA, USA). A washer load cell was placed between the two segments of test blocks to measure the compression force. Because the total length of each foam block was 42 mm, the 40-mm screws were embedded in the cancellous foam, while the 45-mm screws penetrated the denser cortical foam at the bottom. This enabled us to compare inter-fragmentary compression pressures as they are affected by the penetration of the apical dens tip by the screws. The mean compression pressures of the 40- and 45-mm long cannulated lag screws were 50.48±1.20 N and 53.88±1.02 N, respectively, which was not statistically significant (p=0.0551). The mean compression pressures of the 40-mm long Herbert screw was 52.82±2.17 N, and was not statistically significant compared with the 40-mm long cannulated lag screw (p=0.3679). However, 45-mm Herbert screw had significantly higher mean compression pressure (60.68±2.03 N) than both the 45-mm cannulated lag screw and the 40-mm Herbert screw (p=0.0049 and p=0.0246, respectively). Our results showed that inter-fragmentary compression pressures of the Herbert screw were significantly increased when the screw tip penetrated the opposite dens cortical foam. This can support the generally recommended surgical technique that, in order to facilitate maximal reduction of the fracture gap using anterior odontoid screws, it is essential to penetrate the apical dens tip with the screw.

  15. Scalloped Implant-Abutment Connection Compared to Conventional Flat Implant-Abutment Connection: a Systematic Review and Meta-Analysis

    Directory of Open Access Journals (Sweden)

    Thomas Starch-Jensen

    2017-03-01

    Full Text Available Objectives: The objective was to test the hypothesis of no difference in implant treatment outcome after installation of implants with a scalloped implant-abutment connection compared to a flat implant-abutment connection. Material and Methods: A MEDLINE (PubMed, Embase and Cochrane library search in combination with a hand-search of relevant journals was conducted. No language or year of publication restriction was applied. Results: The search provided 298 titles. Three studies fulfilled the inclusion criteria. The included studies were characterized by low or moderate risk of bias. Survival of suprastructures has never been compared within the same study. High implant survival rate was reported in all the included studies. Significantly more peri-implant marginal bone loss, higher probing depth score, bleeding score and gingival score was observed around implants with a scalloped implant-abutment connection. There were no significant differences between the two treatment modalities regarding professional or patient-reported outcome measures. Meta-analysis disclosed a mean difference of peri-implant marginal bone loss of 1.56 mm (confidence interval: 0.87 to 2.25, indicating significant more bone loss around implants with a scalloped implant-abutment connection. Conclusions: A scalloped implant-abutment connection seems to be associated with higher peri-implant marginal bone loss compared to a flat implant-abutment connection. Therefore, the hypothesis of the present systematic review must be rejected. However, further long-term randomized controlled trials assessing implant treatment outcome with the two treatment modalities are needed before definite conclusions can be provided about the beneficial use of implants with a scalloped implant-abutment connection on preservation of the peri-implant marginal bone level.

  16. Fatigue induced changes in conical implant-abutment connections.

    Science.gov (United States)

    Blum, Kai; Wiest, Wolfram; Fella, Christian; Balles, Andreas; Dittmann, Jonas; Rack, Alexander; Maier, Dominik; Thomann, Ralf; Spies, Benedikt Christopher; Kohal, Ralf Joachim; Zabler, Simon; Nelson, Katja

    2015-11-01

    Based on the current lack of data and understanding of the wear behavior of dental two-piece implants, this study aims for evaluating the microgap formation and wear pattern of different implants in the course of cyclic loading. Several implant systems with different conical implant-abutment interfaces were purchased. The implants were first evaluated using synchrotron X-ray high-resolution radiography (SRX) and scanning electron microscopy (SEM). The implant-abutment assemblies were then subjected to cyclic loading at 98N and their microgap was evaluated after 100,000, 200,000 and 1 million cycles using SRX, synchrotron micro-tomography (μCT). Wear mechanisms of the implant-abutment connection (IAC) after 200,000 cycles and 1 million cycles were further characterized using SEM. All implants exhibit a microgap between the implant and abutment prior to loading. The gap size increased with cyclic loading with its changes being significantly higher within the first 200,000 cycles. Wear was seen in all implants regardless of their interface design. The wear pattern comprised adhesive wear and fretting. Wear behavior changed when a different mounting medium was used (brass vs. polymer). A micromotion of the abutment during cyclic loading can induce wear and wear particles in conical dental implant systems. This feature accompanied with the formation of a microgap at the IAC is highly relevant for the longevity of the implants. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  17. Abutment emergence modification for immediate implant provisional restorations.

    Science.gov (United States)

    Schoenbaum, Todd R; Chang, Yi-Yuan; Klokkevold, Perry R; Snowden, John S

    2013-04-01

    In their stock form, some titanium provisional implant abutments are not ideally designed for use in immediate placement/immediate provisional restoration treatment. This is largely due to the apical flare design that applies excessive pressure to the peri-implant soft tissue complex and crestal bone. This appears to have the undesirable effect of increasing peri-implant bone resorption and severely impeding the potential for increases in gingival volume. This type of stock titanium abutment will therefore benefit significantly from recontouring. The subgingival portion of the abutment is recontoured from the flared stock shape to a straight or parallel design. This modification minimizes pressure on the surgical site and provides additional space around the subgingival portion of the provisional restoration, within which the gingiva has the potential to remodel and fill. This allows the potential formation of additional peri-implant gingival volume and a coronal maintenance or migration of the soft tissue complex. In order to minimize the "graying effect" of titanium abutments, the retentive portion is opaqued by the technician or clinician. These modifications will improve the potential outcomes for both the peri-implant gingiva and the provisional restoration. Narrowing the emergence profile of implant abutments for use in immediate implant provisional restorations appears to allow for creation of greater peri-implant volume. Thus resulting in increased esthetic potential and predictability of the peri-implant gingiva. © 2012 Wiley Periodicals, Inc.

  18. Minimum 5-year Follow-up Results for Occipitocervical Fusion Using the Screw-Rod System in Craniocervical Instability.

    Science.gov (United States)

    Ando, Kei; Imagama, Shiro; Ito, Zenya; Kobayashi, Kazuyoshi; Yagi, Hideki; Shinjo, Ryuichi; Hida, Tetsuro; Ito, Kenyu; Ishikawa, Yoshimoto; Ishiguro, Naoki

    2017-06-01

    Retrospective clinical study. To evaluate the clinical outcome of patients who had undergone occipitocervical (OC) fusion using pedicle screws and rods over a minimum 5-year follow-up. Few studies have evaluated occipitocervical (OC) fusion using pedicle screws and rods for long-term follow-up. Twenty-seven consecutive patients treated underwent posterior OC fusion using pedicle screws and rods over a minimum 5-year follow-up. The Modified McCormick scale to grade a patient's functional status and the Japanese Orthopaedic Association (JOA) scoring system were used to evaluate preoperative and postoperative neurological function. We assessed fusion by both direct and indirect evidence; bony trabeculae at the graft-recipient interface on lateral cervical radiographs and sagittal computed tomography reconstruction was considered direct evidence of union. The mean follow-up period was 7.2 years (5-14 y). JOA scores were 8.1±3.8 before surgery and 11.7±3.7 at the final follow-up. The recovery rate calculated from the JOA scores was 42.0±30.0%. Functional status did improve at least 1 grade according to the modified McCormick scale in 18 patients (66.7%). There was no deterioration at the final follow-up.There were postoperative implant-related complications in 8 patients (29.6%): loosening of pedicle screws in 2, rod breakage in 2, plate breakage in 1, screw breakage in 1, pullout of pedicle screws in 1, and wiring induced myelopathy in 1 patient. The average duration between surgery and implant failure was 31.2 months (12-60 mo) except for 2. Sufficient bone grafting, proper decortication of the bone bed, using thicker and high stiffness rods, and ultra-high molecular weight polyethylene tape as a fixation or reinforcement of implant may help prevent implant failure.

  19. Helical screw expander evaluation project

    Science.gov (United States)

    McKay, R.

    1982-03-01

    A one MW helical rotary screw expander power system for electric power generation from geothermal brine was evaluated. The technology explored in the testing is simple, potentially very efficient, and ideally suited to wellhead installations in moderate to high enthalpy, liquid dominated field. A functional one MW geothermal electric power plant that featured a helical screw expander was produced and then tested with a demonstrated average performance of approximately 45% machine efficiency over a wide range of test conditions in noncondensing, operation on two-phase geothermal fluids. The Project also produced a computer equipped data system, an instrumentation and control van, and a 1000 kW variable load bank, all integrated into a test array designed for operation at a variety of remote test sites. Data are presented for the Utah testing and for the noncondensing phases of the testing in Mexico. Test time logged was 437 hours during the Utah tests and 1101 hours during the Mexico tests.

  20. Does pedicle screw fixation of the subaxial cervical spine provide adequate stabilization in a multilevel vertebral body fracture model? An in vitro biomechanical study.

    Science.gov (United States)

    Duff, John; Hussain, Mir M; Klocke, Noelle; Harris, Jonathan A; Yandamuri, Soumya S; Bobinski, Lukas; Daniel, Roy T; Bucklen, Brandon S

    2018-03-01

    Cervical vertebral body fractures generally are treated through an anterior-posterior approach. Cervical pedicle screws offer an alternative to circumferential fixation. This biomechanical study quantifies whether cervical pedicle screws alone can restore the stability of a three-column vertebral body fracture, making standard 360° reconstruction unnecessary. Range of motion (2.0 Nm) in flexion-extension, lateral bending, and axial rotation was tested on 10 cadaveric specimens (five/group) at C2-T1 with a spine kinematics simulator. Specimens were tested for flexibility of intact when a fatigue protocol with instrumentation was used to evaluate construct longevity. For a C4-6 fracture, spines were instrumented with 360° reconstruction (corpectomy spacer + plate + lateral mass screws) (Group 1) or cervical pedicle screw reconstruction (C3 and C7 only) (Group 2). Results are expressed as percentage of intact (100%). In Group 1, 360° reconstruction resulted in decreased motion during flexion-extension, lateral bending, and axial rotation, to 21.5%, 14.1%, and 48.6%, respectively, following 18,000 cycles of flexion-extension testing. In Group 2, cervical pedicle screw reconstruction led to reduced motion after cyclic flexion-extension testing, to 38.4%, 12.3%, and 51.1% during flexion-extension, lateral bending, and axial rotation, respectively. The 360° stabilization procedure provided the greatest initial stability. Cervical pedicle screw reconstruction resulted in less change in motion following cyclic loading with less variation from specimen to specimen, possibly caused by loosening of the shorter lateral mass screws. Cervical pedicle screw stabilization may be a viable alternative to 360° reconstruction for restoring multilevel vertebral body fracture. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. Dual X-ray absortiometry(DXA) in the detection of loosening in the total hip replacement arthroplasty: preliminary study

    International Nuclear Information System (INIS)

    Yoon, Hye Kyung; Kang, Heung Sik; Han, Man Chung; Kim, Hee Joong; Kim, Young Min

    1994-01-01

    Algorithms to get cross-sectional bone density pattern(transverse histogram) to predict the loosening of hip prosthesis using DXA(Dual X-ray Absorptiometry) have been developed. We performed this study to analyze the correlation between radiologic findings and densitometric pattern of the THRA(Total Hip Replacement Arthroplasty) patients. Thirty-six hips of 32 THRA patients were evaluated. The duration between THRA and DXA was from 1 year 7 months to 15 years. On transverse histogram, the periprosthetic bone density patterns were classified as 3 types; type I , rigid fixation in 17, type II definite loosening in 8, and type III, partial loosening in 11 cases. Surgical findings, plain X-ray findings and transverse histogram using DXA were correlated. Among 14 cases performing revision for acetabular prosthesis loosening, 5 cases revealed loosening of femoral stems while 9 cases revealed rigid fixation of femoral stems. Sensitivity was 100% for either plain X-ray or DXA. Specificity was 88%, 77% for plain X-ray and DXA respectively. This preliminary study reveals that periprosthetic bone density pattern on transverse histogram on DXA may be useful in the evaluation of the loosening. However, further study will be needed for clinical application

  2. Dual X-ray absortiometry(DXA) in the detection of loosening in the total hip replacement arthroplasty: preliminary study

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Hye Kyung; Kang, Heung Sik; Han, Man Chung; Kim, Hee Joong; Kim, Young Min [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    1994-02-15

    Algorithms to get cross-sectional bone density pattern(transverse histogram) to predict the loosening of hip prosthesis using DXA(Dual X-ray Absorptiometry) have been developed. We performed this study to analyze the correlation between radiologic findings and densitometric pattern of the THRA(Total Hip Replacement Arthroplasty) patients. Thirty-six hips of 32 THRA patients were evaluated. The duration between THRA and DXA was from 1 year 7 months to 15 years. On transverse histogram, the periprosthetic bone density patterns were classified as 3 types; type I , rigid fixation in 17, type II definite loosening in 8, and type III, partial loosening in 11 cases. Surgical findings, plain X-ray findings and transverse histogram using DXA were correlated. Among 14 cases performing revision for acetabular prosthesis loosening, 5 cases revealed loosening of femoral stems while 9 cases revealed rigid fixation of femoral stems. Sensitivity was 100% for either plain X-ray or DXA. Specificity was 88%, 77% for plain X-ray and DXA respectively. This preliminary study reveals that periprosthetic bone density pattern on transverse histogram on DXA may be useful in the evaluation of the loosening. However, further study will be needed for clinical application.

  3. Soil-structure interaction studies for understanding the behavior of integral abutment bridges.

    Science.gov (United States)

    2012-03-01

    Integral Abutment Bridges (IAB) are bridges without any joints within the bridge deck or between the : superstructure and the abutments. An IAB provides many advantages during construction and maintenance of : a bridge. Soil-structure interactions at...

  4. Wear at the Implant-Abutment Interface of Zirconia Abutments Manufactured by Three CAD/CAM Systems.

    Science.gov (United States)

    Pinheiro Tannure, Ana Luiza; Cunha, Alfredo Gonçalves; Borges Junior, Luiz Antônio; da Silva Concílio, Laís Regiane; Claro Neves, Ana Christina

    To evaluate the changes in the external-hexagon surface of the titanium (Ti) implant before and after mechanical cycling, when coupled with zirconia (Zr) abutments (A) manufactured by three computer-aided design/computer-aided manufacturing (CAD/CAM) systems (Neodent Digital, Zirkonzahn, and AmannGirrbach) and the ZrTi abutment manufactured by Neodent. Four groups were formed (n = 6): titanium implant with Zr AmannGirrbach abutment (AZrAG), with Zr Zirkonzahn abutment (AZrZ), with Zr Neodent abutment (AZrN), and with Zr abutment with infrastructure in Ti Neodent (AZrTiN). Standardized abutments were made from three identical abutments milled in wax. Images of the surface of each side of the hexagons of the implant were obtained by scanning electron microscopy, before and after mechanical cycling, to evaluate the parameters: (1) scratches in the hexagon face; (2) hexagon superior shoulder kneading; (3) hexagon shoulder wear; (4) alterations on the hexagon base; and (5) scratches on the hexagon top. The abutments were coupled with the implants, and Cr-Co crowns were cemented. The implant/abutment/crown assemblies were submitted to mechanical cycling (400 N, 8.0 Hz) for 1 million cycles. The observed changes were classified as follows: absence (0), mild (1), moderate (2), and severe (3). The results were analyzed using the Mann-Whitney, Kruskal-Wallis, and Dunn tests (P < .05). For parameter 1, a significant difference (P = .008) was observed between AZrZ and AZrAG, with more scratches in AZrZ; and between AZrN and AZrTiN (P = .006), with more scratches in AZrN. For parameter 2, a significant difference (P < .05) was observed between AZrZ and AZrAG and between AZrZ and AZrN, with greater kneading in AZrZ; among AZrN and AZrTiN, there was no significant difference (P = .103). For parameter 3, a significant difference (P < .05) was observed between AZrZ and the other groups of Zr, with more wear in AZrZ; between AZrN and AZrTiN, there was no significant difference (P

  5. Compression screw fixation of the syndesmosis.

    Science.gov (United States)

    Darwish, Husam H; Glisson, Richard R; DeOrio, James K

    2012-10-01

    Screw fixation of syndesmotic injuries facilitates ligament healing and restoration of ankle stability, but little information regarding screw performance is available. This study quantified the reduction obtained with three common 2-screw configurations using different methods of reduction and novel methods of subsequently provoking and measuring diastasis. Seven fresh-frozen lower extremities were subjected to 100 N medial and lateral tibia loads with the talus restrained. Tibia displacement, indicative of ankle clear space, was recorded. The syndesmosis and distal interosseous ligament were disrupted and measurements repeated. A pressure sensor was inserted into the syndesmosis and three 2-screw fixation methods were evaluated in each specimen: 3.5-mm screws engaging both fibula cortices and the lateral tibial cortex, inserted while using a clamp to achieve syndesmosis reduction; 3.5-mm lag screws engaging both tibia cortices; and 4.5-mm lag screws engaging both tibia cortices. One thousand 100 N medial and lateral loads were applied and clear space and syndesmosis compression were quantified every 100 cycles. Normal ankle clear space averaged 1.98 mm and increased to 3.02 mm after syndesmosis disruption. Fixation decreased the clear space to 1.36 mm, 1.22 mm, and 1.19 mm for the 3.5-mm tricortical, 3.5-mm lag, and 4.5-mm lag screws, respectively, remaining steady throughout cyclic loading. Syndesmosis compression dropped markedly from 61N to 23 N on clamp release after tricortical screw insertion. The 3.5-mm and 4.5-mm lag screws exerted 112 N and 131 N, respectively, after insertion, and maintained compression several-fold greater than the tricortical screws during cyclic loading. No difference was demonstrable between the two lag screw sizes. While all screw configurations successfully reduced ankle clear space, syndesmosis reduction was more effectively maintained by lag screws than by tricortical screws inserted with clamp reduction. The transient nature of

  6. Surgical treatment of osteoporotic thoracolumbar compressive fractures with open vertebral cement augmentation of expandable pedicle screw fixation: a biomechanical study and a 2-year follow-up of 20 patients.

    Science.gov (United States)

    Wu, Zi-xiang; Gao, Ming-xuan; Sang, Hong-xun; Ma, Zhen-sheng; Cui, Geng; Zhang, Yang; Lei, Wei

    2012-03-01

    The incidence of screw loosening increases significantly in elderly patients with severe osteoporosis. Open vertebral cement augmentation of expandable pedicle screw fixation may improve fixation strength in the osteoporotic vertebrae. Twenty cadaveric vertebrae (L1-L5) were harvested from six osteoporotic lumbar spines. Axial pullout tests were performed to compare the maximum pullout strength (Fmax) of four methods: 1. Conventional pedicle screws (CPS), 2. Expandable pedicle screws (EPS), 3. Cement augmentation of CPS (cemented-CPS), 4. Cement augmentation of EPS (cemented-EPS). Thirty-six consecutive patients with single-vertebral osteoporotic compressive fractures received posterior decompression and spinal fusion with cemented-CPS (16 cases) or cemented-EPS (20 cases). Plain film and/or CT scan were conducted to evaluate the spinal fusion and fixation effectiveness. The Fmax and energy absorption of cemented-EPS were significantly greater than three control groups. The mean BMD in the severe osteoporosis group was significantly lower than that in the osteoporosis group (t = 2.04, P = 0.036). In the osteoporosis group, cemented-EPS improved the Fmax by 43% and 21% over CPS and cemented-CPS group. In the severe osteoporosis group, cemented-EPS increased the Fmax by 59%, 22%, and 26% over CPS, EPS, and cemented-CPS, respectively. The clinical results showed that all patients suffered from severe osteoporosis. Six months after operation, the JOA and VAS scores in cemented-EPS group improved from 11.4 ± 2.6 and 7.0 ± 1.4 mm to 24.9 ± 1.6 and 2.1 ± 1.3 mm, respectively. No screw loosening occurred in the cemented-EPS group and spinal fusion was achieved. In the cemented-CPS group, four screws loosened (4.2%) according to the radiolucency. Six months after operation, the JOA and VAS scores improved from 13.1 ± 1.9 and 7.6 ± 1.5 mm to 22.8 ± 2.2 and 2.5 ± 1.6 mm, respectively. No cement leaked into the spinal canal in both groups. Cemented-EPS could increase

  7. The effect of repeated torque tightening on total lengths of implant abutments in different internal implant‒abutment connections

    Directory of Open Access Journals (Sweden)

    Fariba Saleh Saber

    2017-06-01

    Full Text Available Background. Since the misfit of crown has an important role in clinical performance of implant-supported prostheses, and due to the impact of the settling effect on misfit, the aim of this study was to investigate the impact of torque forces on the total lengths of narrow and short implant abutments in different internal implant‒abutment connections. Methods. In four different implant‒abutment connections, 8 analog implants with a normal diameter (4 mm and narrow abutment (4.5 mm were selected from groups of internal hex, internal octagon, morse hex 6° and morse hex 11°. Each of them was mounted within plaster type IV, and 32 samples were obtained. Then, the amount of vertical displacement was measured by closing the impression copings and applying torques of 20 25 and 30 Ncm. This stage was repeated for the abutment. In the next stage, the resin pattern was built and measurements were performed after applying the torques mentioned. Finally, after making the frame, this stage was repeated, and the settling effect was statistically analyzed with ANOVA. Results. In the stages of impression coping, resin pattern and final prosthesis, HEXAGONE had significantly the highest and OCTAGONE had the lowest rates of settling, and the settling of morse hex 11° and 6° was between them. Conclusion. Octagon implant had significantly the lowest settling in various clinical and laboratory stages by applying different torques.

  8. Temporal variation of clear-water scour at compound Abutments

    Directory of Open Access Journals (Sweden)

    Aminuddin Ab. Ghani

    2016-12-01

    Full Text Available Most of actual abutments in rivers are built on foundation, while there is limited number of study available on the effects of the foundation on the local scour. In this study, temporal variation of local scour around compound abutment was investigated experimentally under clear-water conditions. The results showed that a suitable level of foundation is able to decrease the scour depth and increase scour time during the flood events. The trend of temporal scour depth at compound pier and abutment is similar. The scour depth develops to top of foundation quickly, and then the foundation postpones the scour development (lag–time. Duration of lag–time depends on the foundation level, velocity ratio (U/Uc and foundation dimension. This study highlights that proper design of foundation level increases duration of scouring and provides enough time to treat bridge foundation after the flood events.

  9. Effect of screw access hole preparation on fracture load of implant-supported zirconia-based crowns: an in vitro study

    Directory of Open Access Journals (Sweden)

    Hadi Mokhtarpour

    2016-07-01

    Full Text Available Background. Fracture load of implant-supported restorations is an important factor in clinical success. This study evaluated the effect of two techniques for screw access hole preparation on the fracture load of cement-screw-retained implant-supported zirconia-based crowns. Methods. Thirty similar cement-screw-retained implant-supported zirconia-based maxillary central incisor crowns were evaluated in three groups of 10. Group NH: with no screw access holes for the control; Group HBS: with screw access holes prepared with a machine before zirconia sintering; Group HAS: with screw access holes prepared manually after zirconia sintering. In group HBS, the access holes were virtually designed and prepared by a computer-assisted design/computer-assisted manufacturing system. In group HAS, the access holes were manually prepared after zirconia sintering using a diamond bur. The dimensions of the screw access holes were equal in both groups. The crowns were cemented onto same-size abutments and were then subjected to thermocycling. The fracture load values of the crowns were measured using a universal testing machine. Data were analyzed with ANOVA and Tukey test (P < 0.05. Results. The mean fracture load value for the group NH was 888.37 ± 228.92 N, which was the highest among the groups, with a significant difference (P < 0.0001. The fracture load values were 610.48 ± 125.02 N and 496.74 ± 104.10 Nin the HBS and HAS groups, respectively, with no significant differences (P = 0.44. Conclusion. Both techniques used for preparation of screw access holes in implant-supported zirconia-based crowns de-creased the fracture load.

  10. Assessment of different screw augmentation techniques and screw designs in osteoporotic spines

    Science.gov (United States)

    Chavanne, A.; Spitaler, R.; Kropik, K.; Aigner, N.; Ogon, M.; Redl, H.

    2008-01-01

    This is an experimental study on human cadaver spines. The objective of this study is to compare the pullout forces between three screw augmentation methods and two different screw designs. Surgical interventions of patients with osteoporosis increase following the epidemiological development. Biomechanically the pedicle provides the strongest screw fixation in healthy bone, whereas in osteoporosis all areas of the vertebra are affected by the disease. This explains the high screw failure rates in those patients. Therefore PMMA augmentation of screws is often mandatory. This study involved investigation of the pullout forces of augmented transpedicular screws in five human lumbar spines (L1–L4). Each spine was treated with four different methods: non-augmented unperforated (solid) screw, perforated screw with vertebroplasty augmentation, solid screw with vertebroplasty augmentation and solid screw with balloon kyphoplasty augmentation. Screws were augmented with Polymethylmethacrylate (PMMA). The pullout forces were measured for each treatment with an Instron testing device. The bone mineral density was measured for each vertebra with Micro-CT. The statistical analysis was performed with a two-sided independent student t test. Forty screws (10 per group and level) were inserted. The vertebroplasty-augmented screws showed a significant higher pullout force (mean 918.5 N, P = 0.001) than control (mean 51 N), the balloon kyphoplasty group did not improve the pullout force significantly (mean 781 N, P > 0.05). However, leakage occurred in some cases treated with perforated screws. All spines showed osteoporosis on Micro-CT. Vertebroplasty-augmented screws, augmentation of perforated screws and balloon kyphoplasty augmented screws show higher pullout resistance than non-augmented screws. Significant higher pullout forces were only reached in the vertebroplasty augmented vertebra. The perforated screw design led to epidural leakage due to the position of the

  11. Loosening of the femoral component of total hip replacement after plugging the femoral canal.

    Science.gov (United States)

    Harris, W H; McCarthy, J C; O'Neill, D A

    1982-01-01

    A roentgen follow-up study was done of 171 total hip replacements at an average of 3.3 years (range 2 to 5 years) after insertion to assess the loosening rate in older adult patients (average age 60 years) in whom the medullary canal was plugged. The cement (Simplex P) was introduced using a cement gun. The femoral components used were CAD and HD-2 in design, made of chrome cobalt alloy. Evaluation was made according to three categories of loosening: definite (requiring evidence of migration of the component or the cement), probable (requiring a continuous radiolucent zone around the cement mantle in one or more radiographic views), or possible (requiring a radiolucent zone that occupied 50% or more of the cement-bone interface in one or more views but was not continuous). One hip was revised for a loose femoral component. Another patient has asymptomatic subsidence of the femoral component. Thus the total incidence of definitely loose femoral components was 1.1%. No hip was classified as probably loose. Seven hips (4%) were rated as possibly loose. Compared to four other reported series of similar groups of patients followed for like duration, this incidence of definitely loose components is statistically significantly less than in nonplugged canals. The other differences among the series compared, such as stem design, type of cement introduction, modulus of elasticity of the metal used, presence or absence of a collar, and dates during which the surgery was done, are also discussed. Plugging the femoral canal; introducing the cement with a cement gun; using a femoral stem that largely fills the medullary canal, has a collar, and has a rounded rectangular cross section with no medial stress risers made of a superalloy with a modulus of elasticity of about 200 GPa--all these factors were associated with a low (1.1%) incidence of femoral component loosening at 3 years.

  12. "NIMS technique" for minimally invasive spinal fixation using non-fenestrated pedicle screws: A technical note

    Directory of Open Access Journals (Sweden)

    Alugolu Rajesh

    2015-01-01

    Full Text Available Study Design: Case series. Objective: To reduce the cost of minimally invasive spinal fixation. Background: Minimally invasive spine (MIS surgery is an upcoming modality of managing a multitude of spinal pathologies. However, in a resource-limited situations, using fenestrated screws (FSs may prove very costly for patients with poor affordability. We here in describe the Nizam′s Institute of Medical Sciences (NIMS experience of using routine non-FSs (NFSs for transpedicular fixation by the minimally invasive way to bridge the economic gap. Materials and Methods: A total of 7 patients underwent NFS-minimally invasive spine (MIS surgery. Male to female distribution was 6:1. The average blood loss was 50 ml and the mean operating time was 2 and 1/2 h. All patients were mobilized the very next day after confirming the position of implants on X-ray/computed tomography. Results: All 7 patients are doing well in follow-up with no complaints of a backache or fresh neurological deficits. There was no case with pedicle breach or screw pullout. The average cost of a single level fixation by FS and NFS was `1, 30,000/patient and `32,000/patient respectively ($2166 and $530, respectively. At the end of 1-year follow-up, we had two cases of screw cap loosening and with a displacement of the rod cranio-caudally in one case which was revised through the same incisions. Conclusions: Transpedicular fixation by using NFS for thoracolumbar spinal pathologies is a cost-effective extension of MIS surgery. This may extend the benefits to a lower socioeconomic group who cannot afford the cost of fenestrated screw (FS.

  13. Surgical complications in neuromuscular scoliosis operated with posterior- only approach using pedicle screw fixation

    Directory of Open Access Journals (Sweden)

    Singh Surya Udai

    2009-05-01

    Full Text Available Abstract Background There are no reports describing complications with posterior spinal fusion (PSF with segmental spinal instrumentation (SSI using pedicle screw fixation in patients with neuromuscular scoliosis. Methods Fifty neuromuscular patients (18 cerebral palsy, 18 Duchenne muscular dystrophy, 8 spinal muscular atrophy and 6 others were divided in two groups according to severity of curves; group I ( 90°. All underwent PSF and SSI with pedicle screw fixation. There were no anterior procedures. Perioperative (within three months of surgery and postoperative (after three months of surgery complications were retrospectively reviewed. Results There were fifty (37 perioperative, 13 postoperative complications. Hemo/pneumothorax, pleural effusion, pulmonary edema requiring ICU care, complete spinal cord injury, deep wound infection and death were major complications; while atelectesis, pneumonia, mild pleural effusion, UTI, ileus, vomiting, gastritis, tingling sensation or radiating pain in lower limb, superficial infection and wound dehiscence were minor complications. Regarding perioperative complications, 34(68% patients had at least one major or one minor complication. There were 16 patients with pulmonary, 14 with abdominal, 3 with wound related, 2 with neurological and 1 cardiovascular complications, respectively. There were two deaths, one due to cardiac arrest and other due to hypovolemic shock. Regarding postoperative complications 7 patients had coccygodynia, 3 had screw head prominence, 2 had bed sore and 1 had implant loosening, respectively. There was a significant relationship between age and increased intraoperative blood loss (p = 0.024. However it did not increased complications or need for ICU care. Similarly intraoperative blood loss > 3500 ml, severity of curve or need of pelvic fixation did not increase the complication rate or need for ICU. DMD patients had higher chances of coccygodynia postoperatively. Conclusion

  14. Optimal trajectory for the atlantooccipital transarticular screw.

    Science.gov (United States)

    Lee, Kyoung Min; Yeom, Jin S; Lee, Joon Oh; Buchowski, Jacob M; Park, Kun-Woo; Chang, Bong-Soon; Lee, Choon-Ki; Riew, K Daniel

    2010-07-15

    Radiologic evaluation of computed tomography (CT) scans using screw insertion simulation software. To investigate the optimal entry point and trajectory of atlantooccipital transarticular screws. To our knowledge, no large series focusing on the placement of atlantooccipital transarticular screws have been published. We used 1.0-mm sliced CT scans and 3-dimensional screw trajectory software to simulate 4.0-mm screw placement. Four entry points were evaluated. Screw placement success rate, safe range of medial angulation, and screw length using each entry point were determined. CT scans of 126 patients were evaluated, for a total of 252 screws for each entry point. On simulation, the 2 lateral entry points showed significantly higher success rates and safe range of medial angulation than the 2 middle points. The 2 lateral entry points had similar success rates (98.0% for anteriolateral (AL) point and 97.6% for posteriolateral (PL) point). Although the safe range of medial angulation was significantly wider for the AL point (26.1 degrees) than for the PL point (23.7 degrees), the screw lengths were significantly longer for the PL point (32.6 mm) than for the AL point (29.4 mm). For both points, 30 degrees of medial angulation led to highest rate of successful screw placement, but the rate was only 79.4% and 80.2%, respectively. Although there was no significant difference in success rates between AL and PL points, PL is likely the best entry point. Although 30 degrees medial and approximately 5 degrees upward angulation led to the highest rate of successful screw placement, the rate was only around 80%. Given the wide individual variation, we recommend that a preoperative 3-dimensional CT scan be obtained when attempting atlantooccipital transarticular screw fixation.

  15. Biomechanical Analysis of Latarjet Screw Fixation: Comparison of Screw Types and Fixation Methods.

    Science.gov (United States)

    Shin, Jason J; Hamamoto, Jason T; Leroux, Timothy S; Saccomanno, Maristella F; Jain, Akshay; Khair, Mahmoud M; Mellano, Christen R; Shewman, Elizabeth F; Nicholson, Gregory P; Romeo, Anthony A; Cole, Brian J; Verma, Nikhil N

    2017-09-01

    To compare the initial fixation stability, failure strength, and mode of failure of 5 different screw types and fixation methods commonly used for the classic Latarjet procedure. Thirty-five fresh-frozen cadaveric shoulder specimens were allocated into 5 groups. A 25% anteroinferior glenoid defect was created, and a classic Latarjet coracoid transfer procedure was performed. All grafts were fixed with 2 screws, differing by screw type and/or fixation method. The groups included partially threaded solid 4.0-mm cancellous screws with bicortical fixation, partially threaded solid 4.0-mm cancellous screws with unicortical fixation, fully threaded solid 3.5-mm cortical screws with bicortical fixation, partially threaded cannulated 4.0-mm cancellous screws with bicortical fixation, and partially threaded cannulated 4.0-mm captured screws with bicortical fixation. All screws were stainless steel. Outcomes included cyclic creep and secant stiffness during cyclic loading, as well as load and work to failure during the failure test. Intergroup comparisons were made by a 1-way analysis of variance. There were no significant differences among different screw types or fixation methods in cyclic creep or secant stiffness after cyclic loading or in load to failure or work to failure during the failure test. Post-failure radiographs showed evidence of screw bending in only 1 specimen that underwent the Latarjet procedure with partially threaded solid cancellous screws with bicortical fixation. The mode of failure for all specimens analyzed was screw cutout. In this biomechanical study, screw type and fixation method did not significantly influence biomechanical performance in a classic Latarjet procedure. When performing this procedure, surgeons may continue to select the screw type and method of fixation (unicortical or bicortical) based on preference; however, further studies are required to determine the optimal method of treatment. Surgeons may choose the screw type and

  16. Impaction grafting in revision total elbow arthroplasty due to aseptic loosening and bone loss.

    Science.gov (United States)

    Rhee, Yong Girl; Cho, Nam Su; Parke, Chong Suck

    2013-06-05

    With the increase in the number of total elbow arthroplasties being performed, there has been a parallel increase in revision surgery. There is limited information about the outcome of impaction grafting following failed elbow arthroplasty. We retrospectively analyzed sixteen cases of revision arthroplasty performed following aseptic loosening of a semiconstrained total elbow replacement. There were three men and thirteen women with a mean age of 58.4 years (range, twenty-eight to seventy-five years). Fourteen elbows had loosening of both the humeral and the ulnar component, and two elbows had only humeral loosening. Two elbows had perforation of the humeral cortex by the humeral component, and one had perforation of the ulnar cortex. Grade-II bone loss as described by King et al. was found in three elbows; grade III, in six elbows; and grade IV, in seven elbows. The impaction grafting was performed with only allograft in thirteen elbows, and it was done with allograft as well as autograft from the iliac crest in the other three elbows. The mean duration of follow-up was 7.4 years (range, 4.1 to 11.2 years). The mean Mayo Elbow Performance Score (MEPS) for pain significantly improved from 15.0 points preoperatively to 32.8 points at the time of latest follow-up (p = 0.003). The mean arc of flexion also significantly increased, from 60.3° to 115.6° (p < 0.01). Stability according to the MEPS significantly increased from a mean of 2.2 points to a mean of 9.4 points (p = 0.001). The mean total MEPS improved from 41.0 points to 82.8 points (p = 0.001). The result was excellent for four elbows, good for eleven, and fair for one. Follow-up radiographs demonstrated fifteen cases with grade-I resorption of the bone graft and one case with grade-II resorption. A type-I radiolucent line was observed in twelve of the elbows; type II, in three; and type IV, in one. Additional surgery was required in two cases. Impaction grafting is an effective technique when revision total

  17. Unusual way of loosened total hip arthroplasty treatment with an Austin Moore endoprosthesis

    OpenAIRE

    M Erceg; K Becic

    2014-01-01

    A 65-year-old female patient with aseptic loosening of total cemented hip endoprosthesis and pathologic fracture of the femur at the level of the stem of endoprosthesis was presented. As no appropriate endoprosthesis was available due to the war in Croatia and war priority, the problem was managed by femur osteosynthesis and implantation of a partial Austin Moore hip endoprosthesis. The endoprosthesis is still functioning well (for 20 years).To the best of the author′s knowledge, nobody has e...

  18. Unusual way of loosened total hip arthroplasty treatment with an Austin Moore endoprosthesis.

    Science.gov (United States)

    Erceg, M; Becic, K

    2014-01-01

    A 65-year-old female patient with aseptic loosening of total cemented hip endoprosthesis and pathologic fracture of the femur at the level of the stem of endoprosthesis was presented. As no appropriate endoprosthesis was available due to the war in Croatia and war priority, the problem was managed by femur osteosynthesis and implantation of a partial Austin Moore hip endoprosthesis. The endoprosthesis is still functioning well (for 20 years).To the best of the author's knowledge, nobody has ever treated problem like this using this alternative, an unconventional method, with an Austin Moore endoprosthesis.

  19. Unusual way of loosened total hip arthroplasty treatment with an Austin Moore endoprosthesis

    Directory of Open Access Journals (Sweden)

    M Erceg

    2014-01-01

    Full Text Available A 65-year-old female patient with aseptic loosening of total cemented hip endoprosthesis and pathologic fracture of the femur at the level of the stem of endoprosthesis was presented. As no appropriate endoprosthesis was available due to the war in Croatia and war priority, the problem was managed by femur osteosynthesis and implantation of a partial Austin Moore hip endoprosthesis. The endoprosthesis is still functioning well (for 20 years.To the best of the author′s knowledge, nobody has ever treated problem like this using this alternative, an unconventional method, with an Austin Moore endoprosthesis.

  20. Live-bed scour experiments with 45° wing-wall abutments

    Indian Academy of Sciences (India)

    Home; Journals; Sadhana; Volume 39; Issue 5. Live-bed scour experiments with 45° wing-wall abutments ... Keywords. Scour; bridge foundation; abutments; hydraulics; rivers. ... A design equation is proposed for estimating maximum scour depth at 45°wing-wall abutment under live-bed condition. The calculated values of ...

  1. Utilization of Ceramic Inlays for Sealing Implant Prostheses Screw Access Holes: A Case-Control Study.

    Science.gov (United States)

    Mihali, Sorin; Canjau, Silvana; Bratu, Emanuel; Wang, Hom-Lay

    2016-01-01

    The aim of this study was to evaluate, in a case control study, the esthetic and functional clinical performance of ceramic inlays used for covering the screw access hole in single monolithic lithium disilicate full-contour crowns bonded on computer-aided design/computer-aided manufacturing (CAD/CAM) prefabricated titanium abutments in order to eliminate the drawbacks of alternative restorative methods. Twenty-eight patients with missing teeth in the lateral areas (premolars and molars) received screw-retained implant restorations. In half of the restorations (n = 14), composite fillings were used to seal the access hole (control group), while the other half was sealed with ceramic inlays (test group). To determine the restoration occlusal wear, impressions were obtained after the restorations were finalized, at 1 year, and at 2 years follow-up. The casts were scanned with a 3D Scanner Design System recording the anatomical surfaces of the white model replicates. Wear amounts (μm) were calculated as the maximum loss in height of the occlusal surface. The clinical evaluation was carried out using a kit specifically designed for assessing the FDI criteria. Statistics were performed using analysis of variance (ANOVA). A total of 58 restorations were delivered, and after 2 years of follow-up, the wear values were 228.20 ± 54.68 μm for the control group and 65.20 ± 7.24 μm for the ceramic inlay group. One-way ANOVA showed significant differences among the vertical loss between these two groups (P inlays appears to be a predictable, esthetic, and successful method of sealing the screw holes of the screw-retained implant restorations.

  2. Biomechanical comparison of screw versus plate/screw construct for talonavicular fusion.

    Science.gov (United States)

    Jarrell, Shelby E; Owen, John R; Wayne, Jennifer S; Adelaar, Robert S

    2009-02-01

    Talonavicular fusion is performed for a variety of indications. This study examined the effects of fixation techniques on plantar pressures, construct stiffness, and strength. Eight matched pairs of cadaveric lower extremities were axially loaded intact and after talonavicular fixation with a 3.5 reconstruction plate, reconstruction plate plus cancellous screw (plate/screw), or three screws (screws). Recorded plantar pressures were divided into three forefoot, two midfoot, and two hindfoot regions. Cantilevered bending of excised constructs provided stiffness data for plantar and lateral directions, and failure characteristics in plantar bending. Relative to the intact state, all fixations decreased peak pressure in the medial forefoot, while generally increasing it in the lateral forefoot and midfoot. Average pressure shifted laterally for all fixation methods in the forefoot, generally in the hindfoot and the lateral midfoot. Generally, contact areas decreased in the medial forefoot, midfoot, and hindfoot while increasing laterally in the midfoot and hindfoot. The only difference among fixation methods was a decreased medial midfoot contact area for screws. No differences were found between screws and plate/screw in bending stiffness or failure (p screw method averaged approximately 363 N/mm while stiffness of the screw only construct averaged approximately 380 N/mm. The load to failure averaged 946 N for the plate/screw construct and 1099 N for the screw construct. This study showed lateralization of plantar pressures following talonavicular fixation. Minimal differences were found between plate/screw and screws. Fixation across the joint may be key to achieving stability sufficient to resist shear and rotational stresses. Plate/screw or screws would likely be similarly effective in fusing the talonavicular joint. However, the fusion induced lateralization of plantar pressures may unintentionally result in adjacent joint arthritis and foot pain.

  3. A Medical Wireless Measurement System for Hip Prosthesis Loosening Detection Based on Vibration Analysis

    Directory of Open Access Journals (Sweden)

    Sebastian Sauer

    2013-01-01

    Full Text Available Vibration analysis is a promising approach in order to detect early hip prosthesis loosening, with the potential to extend the range of diagnostic tools currently available in clinical routine. Ongoing research efforts and developments in the area of multi-functional implants, which integrate sensors, wireless power supply, communication and signal processing, provide means to obtain valuable in vivo information otherwise not available. In the current work a medical wireless measurement system is presented, which is integrated in the femoral head of a hip prosthesis. The passive miniaturized system includes a 3-axis acceleration sensor and signal pre-processing based on a lock-in amplifier circuit. Bidirectional data communication and power supply is reached through inductive coupling with an operating frequency of 125 kHz in accordance with the ISO 18000-2 protocol standard. The system allows the acquisition of the acceleration frequency response of the femur-prosthesis system between 500 to 2500 Hz. Applied laboratory measurements with system prototypes on artificial bones and integrated prostheses demonstrate the feasibility of the measurement system approach, clearly showing differences in the vibration behavior due to an implant loosening. In addition a possibility to evaluate the non-linear mechanic system behavior is presented.

  4. Does the immune system play a role in loosening and osteolysis of total joint replacements?

    Science.gov (United States)

    Goodman, S B

    1996-01-01

    Total joint replacement is a highly successful surgical procedure with an excellent outcome over many years. However, because this procedure is now being performed in younger patients, and because the average age of our population continues to increase, greater expectations have been placed on joint implants in the hope that they will last forever. Aseptic loosening and osteolysis of total joint replacements are the main processes limiting long-term implant survival. This paper focuses on the possible role of immunological mechanisms in the processes of loosening and osteolysis of joint replacements, with special emphasis on polymeric materials. This topic is very controversial: In vitro experiments and in vivo studies in animals and humans are reviewed and provide evidence for both sides of the debate. In some patients, immunological processes appear to be activated after a total joint replacement has been implanted. Specific materials or their by-products might function as haptens and elicit a T-lymphocyte-mediated, delayed hypersensitivity reaction. Many factors probably are important, including the genetic makeup and immune competence of the patient, prior exposure to the same or similar materials, degree of exposure (rate of generation of particles and the efficacy of clearance mechanisms), and characteristics of the particles themselves.

  5. 26-year follow-up of screw-retained fixed dental prostheses supported by machined-surface Brånemark implants: a case report.

    Science.gov (United States)

    Turkyilmaz, Ilser

    2011-01-01

    Rough-surface implants have become very popular during the last 10 years due to greater reported bone-implant-contact and bone volume between implant threads compared to machined-surface implants. The aim of this clinical report is to present the 26-year clinical outcomes of machined-surface implants supporting screw-retained fixed dental prostheses in a 77-year-old woman. A 51-year-old woman received five mandibular and six maxillary implants supporting screw-retained fixed dental prostheses. The original machined-surface regular platform Branemark implants were placed using a two-stage surgical approach. No implants were lost, and average marginal bone levels between the implant platform and the first bone-implant contact for maxillary and mandibular implants were 3.3 +/- 0.6 mm and 1.7 +/- 0.3 mm after 26 years. The following prosthetic complications were recorded during the follow up period; a) broken acrylic denture tooth (four times), b) loose prosthetic screw (three times), c) loose abutment screw (two times). This case report shows that machined-surface dental implants can successfully support screw-retained fixed dental prostheses over 26 years, which makes dental implants an important dental treatment option compared to the traditional prosthetic treatment methods, especially in elderly edentulous patients.

  6. The BCL2 -938C>A Promoter Polymorphism Is Associated with Risk for and Time to Aseptic Loosening of Total Hip Arthroplasty.

    Directory of Open Access Journals (Sweden)

    Patrick Stelmach

    Full Text Available Aseptic loosening is a major cause of revision surgery of total hip arthroplasty (THA. Only few host factors affecting aseptic loosening have been identified until now, although they are urgently needed to identify and possibly treat those patients at higher risk for aseptic loosening. To determine whether the functional single nucleotide polymorphism (SNP c.-938C>A (rs2279115, located in the promoter region of the BCL2 gene has an impact on aseptic loosening of THA we genotyped and analyzed 234 patients suffering from aseptic loosening and 231 patients after primary THA. The polymorphism is associated with risk for aseptic loosening with the CC genotype at highest risk for aseptic loosening, Odds Ratio CC vs. AA 1.93, 95%CI 1.15-3.25, p = 0.013. In contrast, low risk AA genotype carriers that still developed aseptic loosening showed a significantly shorter time to aseptic loosening than patients carrying the C allele (p = 0.004. These results indicate that the BCL2 -938C>A polymorphism influences the occurrence and course of aseptic loosening and suggests this polymorphism as an interesting candidate for prospective studies and analyses in THA registers.

  7. Precision attachment case restoration with implant abutments: a review with case reports.

    Science.gov (United States)

    Feinberg, Edward

    2011-08-01

    Passively retained precision attachment partial dentures have been used successfully on natural tooth abutments since the 1920s. However, the dental profession has not advocated their use with implant abutments. When used in the passive manner that has proven successful on natural tooth abutments, precision attachment cases on implant abutments can be an excellent treatment option. This type of case has been used successfully for more than 17 years and offers tremendous advantages over the conventional overdenture approach to removal restorations on implant abutments.

  8. The role of the implant impression in abutment selection: a technical note.

    Science.gov (United States)

    Kupeyan, H K; Lang, B R

    1995-01-01

    Selecting the abutment at second-stage implant surgery should combine the experience of both the surgeon and the restorative dentist to avoid complications during prosthetic reconstructions. If an inappropriate abutment is selected, the resultant removal of the abutment and replacement of it with a completely different one is both costly and inefficient. The availability of the healing abutment component has eliminated many of these problems. Making an impression at the implant level allows the dentist ample time to study the restorative needs before selecting the final abutment.

  9. CAD/CAM technology for implant abutments, crowns, and superstructures.

    Science.gov (United States)

    Kapos, Theodoros; Evans, Christopher

    2014-01-01

    The aim of this systematic review was to compare implant prostheses fabricated by computer-assisted design and computer-assisted manufacturing (CAD/CAM) with conventionally fabricated implant prostheses when assessing esthetics, complications (biologic and mechanical), patient satisfaction, and economic factors. Electronic searches for clinical studies focusing on long-term follow-up were performed using the PubMed and Ovid search engines. Concentrating on the restorative aspect of the CAD/CAM technology applicable to implant dentistry, pertinent literature was divided into articles related to implant abutments, crowns, and frameworks. A total of 18 articles satisfied the inclusion criteria. Two articles reported on CAD/CAM crowns, six on abutments, and 10 on implant-supported CAD/CAM frameworks. The mean survival rate for CAD/CAM crowns was 98.85% and for CAD/CAM abutments 100%. The mean survival rate for CAD/CAM frameworks was 95.98%. Based on the current literature, CAD/CAM fabricated crowns, abutments, and frameworks demonstrate survival rates comparable to conventionally fabricated prostheses. Implant survival appears unaffected by fabrication technique. Since this technology encompasses several manufacturing variations, a new definition might be necessary to accurately define the processes under which the CAD/CAM restorations are fabricated. "Complete CAD/CAM product" where no or minimal manual intervention is employed could be a possible term.

  10. Time-wise variation of scouring at bridge abutments

    Indian Academy of Sciences (India)

    provides useful information for the degree of scour counter-measure to be imple- mented against ... time-to-peak value of design flood hydrograph, smaller scour depths may be obtained, which reduce the total cost of ... where KyL is a factor accounting for the effects of flow depth and abutment length, KI is the flow intensity ...

  11. Time-wise variation of scouring at bridge abutments

    Indian Academy of Sciences (India)

    provides useful information for the degree of scour counter-measure to be imple- mented against excessive scouring. Experiments have been performed to investi- gate time-dependent characteristics of scour holes around vertical wall abutments under clear water conditions with uniform bed materials. Temporal variations ...

  12. Assessment of the periapical health of abutment teeth: A ...

    African Journals Online (AJOL)

    Key words: Abutment teeth, apical periodontitis, endodontics, epidemiology, radiology. Date of Acceptance: 29‑Nov‑2014. Introduction. Extensive removal of enamel and dentin is required during the preparation of teeth for fixed partial dentures. This procedure may lead to irreversible damage of the dental pulp if not carried ...

  13. Mechanical performance of cement- and screw-retained all-ceramic single crowns on dental implants.

    Science.gov (United States)

    Obermeier, Matthias; Ristow, Oliver; Erdelt, Kurt; Beuer, Florian

    2018-03-01

    This in-vitro study was performed to compare the contact wear, fracture strength and failure mode of implant-supported all-ceramic single crowns manufactured with various fabrication and fixation concepts. Fifty dental implants (Conelog Ø 4,3mm/L11mm, Camlog Biotechnologies AG) were embedded and treated with all-ceramic molar single-crowns. Three groups received hand-layered zirconia crowns (IPS e.max Ceram/ IPS e.max ZirCAD, Ivoclar Vivadent AG): CZL (cement-retained zirconia-based layered) group crowns were cemented conventionally, SZL (screw-retained zirconia-based layered) group crowns were screw-retained, MZL (modified zirconia-based layered) group crowns showed a different coping design with screw retention. The specimens of SST (screw-retained sintering-technique) and SFL (screw-retained full-contour lithium-disilicate) group were CAD/CAM (Computer-aided design/computer-aided manufacturing) fabricated in the sintering technique (IPS e.max ZirCAD/IPS e.max CAD, Ivoclar Vivadent AG) and full-contour of lithium disilicate (IPS e.max CAD, Ivoclar Vivadent AG) respectively and screw-retained. All specimens underwent artificial aging, load until failure and a scanning electron microscopy (SEM) analysis. The received data were statistically compared (one-way ANOVA; Student-Newman-Keuls test; Mann-Whitney U-test) at a significance level of 5%. Mouth-motion fatigue testing caused two abutment fractures (SST group and SZL group) and two chipping events (CZL group). Specimens of MZL group showed statistically significant less contact wear compared to the other groups (pCAD/CAM fabricated specimens towards manually veneered components. The mode of retention did not influence the fracture resistance but the failure patterns of the specimens. CAD/CAM milled lithium-disilicate crowns seemed to be a preserving factor for dental implants. The mode of retention and veneering influences the mechanical performance of implant-supported single crowns.

  14. Retention of cast crown copings cemented to implant abutments.

    Science.gov (United States)

    Dudley, J E; Richards, L C; Abbott, J R

    2008-12-01

    The cementation of crowns to dental implant abutments is an accepted form of crown retention that requires consideration of the properties of available cements within the applied clinical context. Dental luting agents are exposed to a number of stressors that may reduce crown retention in vivo, not the least of which is occlusal loading. This study investigated the influence of compressive cyclic loading on the physical retention of cast crown copings cemented to implant abutments. Cast crown copings were cemented to Straumann synOcta titanium implant abutments with three different readily used and available cements. Specimens were placed in a humidifier, thermocycled and subjected to one of four quantities of compressive cyclic loading. The uniaxial tensile force required to remove the cast crown copings was then recorded. The mean retention values for crown copings cemented with Panavia-F cement were statistically significantly greater than both KetacCem and TempBond non-eugenol cements at each compressive cyclic loading quantity. KetacCem and TempBond non-eugenol cements produced relatively low mean retention values that were not statistically significantly different at each quantity of compressive cyclic loading. Compressive cyclic loading had a statistically significant effect on Panavia-F specimens alone, but increased loading quantities produced no further statistically significant difference in mean retention. Within the limitations of the current in vitro conditions employed in this study, the retention of cast crown copings cemented to Straumann synOcta implant abutments with a resin, glass ionomer and temporary cement was significantly affected by cement type but not compressive cyclic loading. Resin cement is the cement of choice for the definitive non-retrievable cementation of cast crown copings to Straumann synOcta implant abutments out of the three cements tested.

  15. Simple Technique for Removing Broken Pedicular Screws

    Directory of Open Access Journals (Sweden)

    A Agrawal

    2014-03-01

    Full Text Available The procedure for removing a broken pedicle screw should ideally be technically easy and minimally invasive, as any damage to the pedicle, during removal of the broken screw, may weaken the pedicle, thus compromising on the success of re-instrumentation. We describe the case of a 32-year old man who had undergone surgery for traumatic third lumbar vertebral body fracture three years prior to current admission and had developed the complication of pedicle screw breakage within the vertebral body. The patient underwent re-exploration and removal of the distal screws. Through a paravertebral incision and muscle separation, the screws and rods were exposed and the implants were removed.

  16. Twin screw subsurface and surface multiphase pumps

    Energy Technology Data Exchange (ETDEWEB)

    Dass, P. [CAN-K GROUP OF COMPANIES, Edmonton, Alberta (Canada)

    2011-07-01

    A new subsurface twin screw multiphase pump has been developed to replace ESP and other artificial lift technologies. This technology has been under development for a few years, has been field tested and is now going for commercial applications. The subsurface twin screw technology consists of a pair of screws that do not touch and can be run with a top drive or submersible motor; and it carries a lot of benefits. This technology is easy to install and its low slippage makes it highly efficient with heavy oil. In addition twin screw multiphase pumps are capable of handling high viscosity fluids and thus their utilization can save water when used in thermal applications. It also induces savings of chemicals because asphaltenes do not break down easily as well as a reduction in SOR. The subsurface twin screw multiphase pump presented herein is an advanced technology which could be used in thermal applications.

  17. [Screw arthrodesis of the shoulder].

    Science.gov (United States)

    Lerch, S; Berndt, T; Lipka, W; Rühmann, O

    2011-07-01

    The aim of the procedure is arthrodesis of the shoulder by osteosynthesis of the glenohumeral and the acromiohumeral joint each with three screws, which results in preservation of scapulothoracic motion and pain relief. Traumatic brachial plexus lesions, palsy in infancy, poliomyelitis with preserved or restorable function of the elbow and the hand. Paralysis of the deltoid muscle and the rotator cuff. Nonrestorable vast defect of the rotator cuff with pseudoparalysis. Chronic infectious arthritis resistant to therapy. Unsuccessful attempts to treat glenohumeral instability. Alternative procedure to shoulder arthroplasty in young patients with omarthrosis, who perform hard physical work. Insufficient strength of the scapular muscles (Weaning from the splint after the end of the week 6 postoperatively, full range of motion allowed. In a prospective study from January 2007 to September 2008, 4 patients with a medium age of 35.7 years underwent screw arthrodesis of the shoulder with a follow-up of 1.0 (0.6-1.5) year. Primary fusion of all arthrodesis surfaces was achieved in all patients; no revision surgery was necessary. All patients improved in shoulder function with an average range of motion of 60° abduction and 40° anteversion.

  18. Cannulated screw and cable are superior to modified tension band in the treatment of transverse patella fractures.

    Science.gov (United States)

    Tian, Yun; Zhou, Fang; Ji, Hongquan; Zhang, Zhishan; Guo, Yan

    2011-12-01

    Although the modified tension band technique (eg, tension band supplemented by longitudinal Kirschner wires) has long been the mainstay for fixation of transverse fractures of the patella, it has shortcomings, such as bad reduction, loosening of implants, and skin irritation. We conducted a retrospective comparison of the modified tension band technique and the titanium cable-cannulated screw tension band technique. We retrospectively reviewed 101 patients aged 22 to 85 years (mean, 56.6 years) with AO/OTA 34-C1 fractures (n = 68) and 34-C2 fractures (n = 33). Fifty-two patients were in the modified tension band group and 49 were in the titanium cable-cannulated screw tension band group. Followup was at least 1 year (range, 1-3 years). Comparison criteria were fracture reduction, fracture healing time, and the Iowa score for knee function. The titanium cable-cannulated screw tension band group showed improved fracture reduction, reduced healing time, and better Iowa score, compared with the modified tension band group. In the modified tension band group, eight patients experienced wire migration, three of these requiring a second operation. There were no complications in the titanium cable-cannulated screw tension band group. The titanium cable-cannulated screw tension band technique showed superior results and should be considered as an alternative method for treatment of transverse patellar fractures. Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

  19. Zirconia-Based Screw-Retained Prostheses Supported by Implants: A Retrospective Study on Technical Complications and Failures.

    Science.gov (United States)

    Worni, Andreas; Kolgeci, Lumni; Rentsch-Kollar, Andrea; Katsoulis, Joannis; Mericske-Stern, Regina

    2015-12-01

    Little information is yet available on zirconia-based prostheses supported by implants. To evaluate technical problems and failures of implant-supported zirconia-based prostheses with exclusive screw-retention. Consecutive patients received screw-retained zirconia-based prostheses supported by implants and were followed over a time period of 5 years. The implant placement and prosthetic rehabilitation were performed in one clinical setting, and all patients participated in the maintenance program. The treatment comprised single crowns (SCs) and fixed dental prostheses (FDPs) of three to 12 units. Screw-retention of the CAD/CAM-fabricated SCs and FDPs was performed with direct connection at the implant level. The primary outcome was the complete failure of zirconia-based prostheses; outcome measures were fracture of the framework or extensive chipping resulting in the need for refabrication. A life table analysis was performed, the cumulative survival rate (CSR) calculated, and a Kaplan-Meier curve drawn. Two hundred and ninety-four implants supported 156 zirconia-based prostheses in 95 patients (52 men, 43 women, average age 59.1 ± 11.7 years). Sixty-five SCs and 91 FDPs were identified, comprising a total of 441 units. Fractures of the zirconia framework and extensive chipping resulted in refabrication of nine prostheses. Nearly all the prostheses (94.2%) remained in situ during the observation period. The 5-year CSR was 90.5%, and 41 prostheses (14 SCs, 27 FDPs) comprising 113 units survived for an observation time of more than 5 years. Six SCs exhibited screw loosening, and polishing of minor chipping was required for five prostheses. This study shows that zirconia-based implant-supported fixed prostheses exhibit satisfactory treatment outcomes and that screw-retention directly at the implant level is feasible. © 2014 Wiley Periodicals, Inc.

  20. Percutaneous pedicle screw reduction and axial presacral lumbar interbody fusion for treatment of lumbosacral spondylolisthesis: A case series

    Directory of Open Access Journals (Sweden)

    Miller Larry E

    2011-09-01

    Full Text Available Abstract Introduction Traditional surgical management of lumbosacral spondylolisthesis is technically challenging and is associated with significant complications. The advent of minimally invasive surgical techniques offers patients treatment alternatives with lower operative morbidity risk. The combination of percutaneous pedicle screw reduction and an axial presacral approach for lumbosacral discectomy and fusion offers an alternative procedure for the surgical management of low-grade lumbosacral spondylolisthesis. Case presentation Three patients who had L5-S1 grade 2 spondylolisthesis and who presented with axial pain and lumbar radiculopathy were treated with a minimally invasive surgical technique. The patients-a 51-year-old woman and two men (ages 46 and 50-were Caucasian. Under fluoroscopic guidance, spondylolisthesis was reduced with a percutaneous pedicle screw system, resulting in interspace distraction. Then, an axial presacral approach with the AxiaLIF System (TranS1, Inc., Wilmington, NC, USA was used to perform the discectomy and anterior fixation. Once the axial rod was engaged in the L5 vertebral body, further distraction of the spinal interspace was made possible by partially loosening the pedicle screw caps, advancing the AxiaLIF rod to its final position in the vertebrae, and retightening the screw caps. The operative time ranged from 173 to 323 minutes, and blood loss was minimal (50 mL. Indirect foraminal decompression and adequate fixation were achieved in all cases. All patients were ambulatory after surgery and reported relief from pain and resolution of radicular symptoms. No perioperative complications were reported, and patients were discharged in two to three days. Fusion was demonstrated radiographically in all patients at one-year follow-up. Conclusions Percutaneous pedicle screw reduction combined with axial presacral lumbar interbody fusion offers a promising and minimally invasive alternative for the management

  1. Contributions of human tissue analysis to understanding the mechanisms of loosening and osteolysis in total hip replacement

    DEFF Research Database (Denmark)

    Gallo, Jiri; Vaculova, Jana; Goodman, Stuart B

    2014-01-01

    Aseptic loosening and osteolysis are the most frequent late complications of total hip arthroplasty (THA) leading to revision of the prosthesis. This review aims to demonstrate how histopathological studies contribute to our understanding of the mechanisms of aseptic loosening...... of pathophysiological events that lead to prosthetic loosening and osteolysis. One possible solution is to examine tissues harvested from stable total hip arthroplasties that have been revised at various time periods due to dislocation or periprosthetic fracture in multicenter studies....... molecules of the host response at the protein level (chemokines, cytokines, nitric oxide metabolites, metalloproteinases). However, these studies also have important limitations. Tissues harvested at revision surgery reflect specifically end-stage failure and may not adequately reveal the evolution...

  2. Isolated olecranon fractures in children affected by osteogenesis imperfecta type I treated with single screw or tension band wiring system: Outcomes and pitfalls in relation to bone mineral density.

    Science.gov (United States)

    Persiani, Pietro; Ranaldi, Filippo M; Graci, Jole; De Cristo, Claudia; Zambrano, Anna; D'Eufemia, Patrizia; Martini, Lorena; Villani, Ciro

    2017-05-01

    The purpose of this study is to compare the results of 2 techniques, tension band wiring (TBW) and fixation with screws, in olecranon fractures in children affected with osteogenesis imperfecta (OI) type I. Between 2010 and 2014, 21 olecranon fractures in 18 children with OI (average age: 12 years old) were treated surgically. Ten patients were treated with the screw fixation and 11 with TBW. A total of 65% of olecranon fractures occurred as a result of a spontaneous avulsion of the olecranon during the contraction of the triceps muscle. The average follow-up was 36 months. Among the children treated with 1 screw, 5 patients needed a surgical revision with TBW due to a mobilization of the screw. In this group, the satisfactory results were 50%. In patients treated with TBW, the satisfactory results were 100% of the cases. The average Z-score, the last one recorded in the patients before the trauma, was -2.53 in patients treated with screw fixation and -2.04 in those treated with TBW. TBW represents the safest surgical treatment for patients suffering from OI type I, as it helps to prevent the rigidity of the elbow through an earlier recovery of the range of motion, and there was no loosening of the implant. In analyzing the average Z-score before any fracture, the fixation with screws has an increased risk of failure in combination with low bone mineral density.

  3. [A biomechanical comparison of Acutrak headless compression screw and AO cannulated lag screw for the fixation of Hoffa fracture].

    Science.gov (United States)

    Peng, Jing; Zhang, Shu-Liang; Feng, Pin; Jiang, Yong; Zou, Chang; Zhang, Hui; Tu, Chong-Qi

    2013-03-01

    To compare the stability, strength of Letenneur type I Hoffa fractures fixed by Acutrak headless compression screws and AO cannulated lag screws. 12 models of Letenneur type I Hoffa fractures were randomly divided into 4 groups, which were fixed with two AO cannulated lag screws or Acutrak headless compression screws anteroposteriorly or posteroanteriorly. The stress between two fragments of all specimens was tested. Axial compression test, the cycle load test and the limit load test were successively performed in every specimen. In axial compression test, displacement of Acutrak headless compression screw groups was lower than that of AO cannulated lag screw anteroposteriorly (P AO cannulated lag screws (P AO cannulated lag screw. The direction of screw affects the initial stability for AO cannulated lag screw, other than Acutrak headless compression screw.

  4. Loosen Couple Workflow Mode of Lean Operator Improvement Based on Positive Feedback

    Directory of Open Access Journals (Sweden)

    Yao Li

    2013-04-01

    Full Text Available In order to promote the core competitive power for telecom operating enterprises to face market fine operation, this article compares the ECTA mode (Extension Case Transmission Mode and the LCA mode (Loosen Couple Mode, both of which are promoted by WfMC. By comparing these two modes, the suitable situations for these two modes are determined. We also carry out empirical analysis based on the customization mode of mobile phones between China telecom and mobile phone manufacturers and to expound the ascension effect of mechanism based on the agile telecom loose coupling workflow with positive feedback to the telecom enterprises. Finally, on the basis of positive feedback system, the task complexity and information transparency of LCA mode are improved, so that the semantics of public flow mode is kept unchanged and the sub workflow is optimized when modifying the sub workflow.

  5. Biomechanical comparison of lag screw versus self-drilling screw fixation of oblique metatarsal osteotomy.

    Science.gov (United States)

    Rabenhorst, Brien M; Smith, Michael P; James, C Roger; Grimes, Jerry S

    2011-08-01

    Several fixation methods for a Weil metatarsal osteotomy have been proposed. Lag screw fixation has been described as the preferred fixation technique. The self-drilling screw has been introduced and can be used for fixation of the Weil osteotomy. The current study compared self-drilling screws with lag screw fixation. A Weil metatarsal osteotomy was performed on the second, third, and fourth metatarsals of five matched pairs of fresh frozen cadaver feet. The feet of each pair were randomly assigned ical to fixation with either a 2.0-mm cortical lag screw or a 2.0-mm self-drilling screw. The second metatarsals were stressed using cantilever bending. The third and fourth metatarsals were stressed under a shear force. Yield load, deformation at yield load, structural stiffness, and energy stored at yield load were recorded. There were no statistically significant differences (p screw. There were no significant differences in the stability of fixation of the self-drilling screw and lag screw. There was a trend toward the lag screw fixation being more stable. The clinical significance of this trend is uncertain but suggests there is not a large difference between the two methods of fixation.

  6. Immunoscintigraphy with antigranulocyte monoclonal antibodies for the diagnosis of septic loosening of hip prostheses

    International Nuclear Information System (INIS)

    Boubaker, A.; Bischof Delaloye, A.; Blanc, C.H.; Dutoit, M.; Leyvraz, P.F.; Delaloye, B.

    1995-01-01

    To determine the value of immunoscintigraphy (IS) with antigranulocyte monoclonal antibodies (Mab) in the diagnosis of subacute or chronic infection of hip prostheses, we prospectively studied 57 patients (23 women and 34 men; age 29-92 years, mean 72.7 years) sent to our institution in the past 6 years for clinical suspicion of septic loosening of a hip prosthesis. Nineteen patients had bilateral prostheses and one of them was studied twice. A total of 78 prostheses were examined. All patients had three-phase bone scans followed by IS with technetium-99m antigranulocyte Mab BW 250/183. Intervals between bone scans and IS varied from 2 days to 4 weeks. Final diagnosis was assessed by culture in 48 cases (articular puncture or intraoperative sampling) and by clinical follow-up of at least 8 months in 30 cases. Twelve prostheses were considered septic and 66 non-septic. The overall sensitivity and specificity were 92% and 64% respectively for bone scans, 67% and 75% for IS and 67% and 84% for both modalities together. In three cases, IS was doubtful and the final clinical diagnosis was negative for infection. False-positive results were observed in the presence of massive loosening of the prosthesis or in association with metaplastic peri-articular bone formation. In three of the four false-negative results, infection was proven only after enrichment of the culture, and the bacterium was Staphylococcus epidermidis. In 12/33 (36%) positive bone scans IS allowed the diagnosis of infection to be excluded. Overall accuracy of both modalities together was 81% and the negative predictive value was 93%, which compares favourably with the results reported for other non-invasive methods. (orig.)

  7. Esthetic and Clinical Performance of Implant-Supported All-Ceramic Crowns Made with Prefabricated or CAD/CAM Zirconia Abutments: A Randomized, Multicenter Clinical Trial.

    Science.gov (United States)

    Wittneben, J G; Gavric, J; Belser, U C; Bornstein, M M; Joda, T; Chappuis, V; Sailer, I; Brägger, U

    2017-02-01

    Patients' esthetic expectations are increasing, and the options of the prosthetic pathways are currently evolving. The objective of this randomized multicenter clinical trial was to assess and compare the esthetic outcome and clinical performance of anterior maxillary all-ceramic implant crowns (ICs) based either on prefabricated zirconia abutments veneered with pressed ceramics or on CAD/CAM zirconia abutments veneered with hand buildup technique. The null hypothesis was that there is no statistically significant difference between the 2 groups. Forty implants were inserted in sites 14 to 24 (FDI) in 40 patients in 2 centers, the Universities of Bern and Geneva, Switzerland. After final impression, 20 patients were randomized into group A, restored with a 1-piece screw-retained single crown made of a prefabricated zirconia abutment with pressed ceramic as the veneering material using the cut-back technique, or group B using an individualized CAD/CAM zirconia abutment (CARES abutment; Institut Straumann AG) with a hand buildup technique. At baseline, 6 mo, and 1 y clinical, esthetic and radiographic parameters were assessed. Group A exhibited 1 dropout patient and 1 failure, resulting in a survival rate of 94.7% after 1 y, in comparison to 100% for group B. No other complications occurred. Clinical parameters presented stable and healthy peri-implant soft tissues. Overall, no or only minimal crestal bone changes were observed with a mean DIB (distance from the implant shoulder to the first bone-to-implant contact) of -0.15 mm (group A) and 0.12 mm (group B) at 1 y. There were no significant differences at baseline, 6 mo, and 1 y for DIB values between the 2 groups. Pink esthetic score (PES) and white esthetic score (WES) values at all 3 examinations indicated stability over time for both groups and pleasing esthetic outcomes. Both implant-supported prosthetic pathways represent a valuable treatment option for the restoration of single ICs in the anterior maxilla

  8. Multiobjective optimization design of spinal pedicle screws using neural networks and genetic algorithm: mathematical models and mechanical validation.

    Science.gov (United States)

    Amaritsakul, Yongyut; Chao, Ching-Kong; Lin, Jinn

    2013-01-01

    Short-segment instrumentation for spine fractures is threatened by relatively high failure rates. Failure of the spinal pedicle screws including breakage and loosening may jeopardize the fixation integrity and lead to treatment failure. Two important design objectives, bending strength and pullout strength, may conflict with each other and warrant a multiobjective optimization study. In the present study using the three-dimensional finite element (FE) analytical results based on an L25 orthogonal array, bending and pullout objective functions were developed by an artificial neural network (ANN) algorithm, and the trade-off solutions known as Pareto optima were explored by a genetic algorithm (GA). The results showed that the knee solutions of the Pareto fronts with both high bending and pullout strength ranged from 92% to 94% of their maxima, respectively. In mechanical validation, the results of mathematical analyses were closely related to those of experimental tests with a correlation coefficient of -0.91 for bending and 0.93 for pullout (P design had significantly higher fatigue life (P < 0.01) and comparable pullout strength as compared with commercial screws. Multiobjective optimization study of spinal pedicle screws using the hybrid of ANN and GA could achieve an ideal with high bending and pullout performances simultaneously.

  9. Fracture resistance of zirconia-based implant abutments after artificial long-term aging.

    Science.gov (United States)

    Alsahhaf, Abdulaziz; Spies, Benedikt Christopher; Vach, Kirstin; Kohal, Ralf-Joachim

    2017-02-01

    To investigate the survival rate, fracture strength, bending moments, loading to fracture and fracture modes of different designs of zirconia abutments after dynamic loading with thermocycling, and compare these values to titanium abutments. A total of 80 abutment samples were divided into 5 test groups of 16 samples in each group. The study included the following groups, "Group 1" CAD/CAM produced all-zirconia abutments, "Group 2" titanium abutments, "Group 3" zirconia-abutments adhesively luted to a titanium base, "Group 4" prefabricated all-zirconia abutments and "Group 5" zirconia-abutments glass soldered to a titanium base. Half the number of samples in each group was exposed to 1.2 million loading cycles (5-years simulation) in the chewing simulator. The samples that survived the artificial aging were later tested for fracture strength in a universal testing machine. The remaining 8 samples of the group were directly tested for fracture strength. All samples exposed to the 5-years artificial aging survived except of six samples in one group (Group 1). The surviving samples were later fracture tested in the universal testing machine. The bending moments (Ncm) values were as follow: Exposed groups: "Group 1" 94.5Ncm; "Group 2" 599.2Ncm; "Group 3" 477.5Ncm; "Group 4" 314.4Ncm; "Group 5" 509.4Ncm. Non-exposed groups: "Group 1" 269.3Ncm; "Group 2" 474.2Ncm; "Group 3" 377.6Ncm; "Group 4" 265.4Ncm; "Group 5" 372.4Ncm. Except in Group 1, the values were higher in the exposed groups, although, statistically there was no difference (p>0.05). The one-piece ZrO2-abutment group (Group 1 and Group 4) exhibited lower values, while the two-piece ZrO2-abutment groups (Group 3 and Group 5) showed similar values and fracture modes like the titanium abutment group. The titanium abutment group showed the highest values of bending moments among all groups. The implant-abutment connection area appeared to influence the bending moment value and the fracture mode of the tested

  10. Effect of Steam Autoclaving on the Tensile Strength of Resin Cements Used for Bonding Two-Piece Zirconia Abutments.

    Science.gov (United States)

    Fadanelli, Marcos Alexandre; Amaral, Flávia Lucisano Botelho do; Basting, Roberta Tarkany; Turssi, Cecilia Pedroso; Sotto-Maior, Bruno Salles; França, Fabiana Mantovani Gomes

    2017-04-01

    The purpose of this study was to evaluate the effects of steam autoclave sterilization on the tensile strength of two types of resin cements used to bond customized CAD/CAM zirconia abutments onto titanium bases. Forty sets of zirconia abutments cemented to screwed titanium bases of implants analogs were divided into 4 groups (n = 10). Two groups were treated with a conventional chemically activated resin cement (ML, Multilink Ivoclar Vivadent) and the other two groups with a self-adhesive dual resin cement (RelyX U200, 3M ESPE). One group from each cement was submitted to steam autoclaving. The autoclave sterilization cycle was performed after 72 hours of cementation for 15 minutes at 121°C and 2.1 Kgf/cm 2 . The samples were subjected to tensile strength testing in a universal testing machine (200 Kgf, 0.5 mm/min), from which the means and standard deviations were obtained in Newtons. Results showed (via ANOVA and Tukey's test; α = 0.05) that in the absence of steam autoclaving, no difference was observed in tensile strength between the cements tested: ML: 344.87 (93.79) and U200: 280 (92.42) (P = .314). Steam autoclaving, however, significantly increased tensile strength for the ML: 465.42 (87.87) compared to U200: 289.10 (49.02) (P 0.05). The authors concluded that steam autoclaving increases the mean tensile strength of the chemically activated cement compared to the dual-cure self-adhesive cement. The performance of both cements evaluated was similar if the sterilization step was disconsidered.

  11. Two Different Percutaneous Bone-Anchored Hearing Aid Abutment Systems: Comparative Clinical Study.

    Science.gov (United States)

    Polat, Beldan; İşeri, Mete; Orhan, Kadir Serkan; Yılmazer, Ayça Başkadem; Enver, Necati; Ceylan, Didem; Kara, Ahmet; Güldiken, Yahya; Çomoğlu, Şenol

    2016-04-01

    To compare two different percutaneous bone-anchored hearing aid (BAHA) abutment systems regarding operation time, scar healing, quality of life, implant stability, audiologic results, and complications. The study involves a prospective multi-center clinical evaluation. Thirty-two consecutive patients who had undergone BAHA surgery from January 2011 to January 2013 in two tertiary centers were included in the study. The Glasgow Inventory Benefit Score was used to assess the patients at least 6 months after surgery. The operation time and complications were recorded. Implant stability quotient (ISQ) values were recorded using resonance frequency analysis. Holger's classification was used to evaluate skin reactions. The mean length of the operation was 39.2±4 min for standard abutment and 18.3±5.7 min for hydroxyapatite-coated abutment. ISQ scores were significantly better for standard abutment in all tests. The mean total Glasgow Inventory Benefit Score was 39.3±19 for the standard abutment and 46.3±24.5 for the hydroxyapatite-coated abutment groups, but there was no statistical significance between the two groups. There was no difference in audiological improvement between the two groups after surgery. Hydroxyapatite-coated abutment provided a shorter operation time that was significantly different from standard abutment. There were no significant differences between standard abutment and hydroxyapatite-coated abutment regarding audiologic improvement, quality of life, loading time, and complications.

  12. Bending moments of zirconia and titanium implant abutments supporting all-ceramic crowns after aging.

    Science.gov (United States)

    Mühlemann, Sven; Truninger, Thomas C; Stawarczyk, Bogna; Hämmerle, Christoph H F; Sailer, Irena

    2014-01-01

    To test the fracture load and fracture patterns of zirconia abutments restored with all-ceramic crowns after fatigue loading, exhibiting internal and external implant-abutment connections as compared to restored and internally fixed titanium abutments. A master abutment was used for the customization of 5 groups of zirconia abutments to a similar shape (test). The groups differed according to their implant-abutment connections: one-piece internal connection (BL; Straumann Bonelevel), two-piece internal connection (RS; Nobel Biocare ReplaceSelect), external connection (B; Branemark MkIII), two-piece internal connection (SP, Straumann StandardPlus) and one-piece internal connection (A; Astra Tech AB OsseoSpeed). Titanium abutments with internal implant-abutment connection (T; Straumann Bonelevel) served as control group. In each group, 12 abutments were fabricated, mounted to the respective implants and restored with glass-ceramic crowns. All samples were embedded in acrylic holders (ISO-Norm 14801). After aging by means of thermocycling in a chewing simulator, static load was applied until failure (ISO-Norm 14801). Fracture load was analyzed by calculating the bending moments. Values of all groups were compared with one-way ANOVA followed by Scheffé post hoc test (P-valuecrown occurred in the test groups. In groups BL and A, fractures were located in the internal part of the connection, whereas in groups RS and SP, a partial deformation of the implant components occurred and cracks and fractures of the zirconia abutment were detected. The differently connected zirconia abutments exhibited similar bending moments with the exception of one group. Hence, the type of connection only had a minor effect on the stability of restored zirconia abutments. In general, restored titanium abutments exhibited the highest bending moments. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  13. Fabrication of a Customized Ball Abutment to Correct a Nonparallel Implant Abutment for a Mandibular Implant-Supported Removable Partial Prosthesis: A Case Report

    Directory of Open Access Journals (Sweden)

    Hossein Dasht

    2017-12-01

    Full Text Available Introduction: While using an implant-supported removable partial prosthesis, the implant abutments should be parallel to one another along the path of insertion. If the implants and their attachments are placed vertically on a similar occlusal plane, not only is the retention improved, the prosthesis will also be maintained for a longer period. Case Report: A 65-year-old male patient referred to the School of Dentistry in Mashhad, Iran with complaints of discomfort with the removable partial dentures for his lower mandible. Due to the lack of parallelism in the supporting implants, prefabricated ball abutment could not be used. As a result, a customized ball abutment was fabricated in order to correct the non-parallelism of the implants. Conclusion: Using UCLA abutments could be a cost-efficient approach for the correction of misaligned implant abutments in implant-supported overdentures.

  14. Guidelines for implant abutment selection for partially edentulous patients.

    Science.gov (United States)

    Drago, Carl; Lazzara, Richard J

    2010-01-01

    Dental implant treatments have changed dramatically since the introduction of osseointegration in the 1970s. Placement and restoration of dental implants now are considered to be a basic, important component of dental practices around the world. During the past several decades, there has been a significant increase in the number of dental implant manufacturers and implant restorative components available for clinicians and dental laboratory technicians treating partially edentulous patients. While the increase in components has improved the esthetic and functional results obtainable with dental implants, clinicians also have reported difficulties and confusion in treatment planning dental implant restorations for partially edentulous patients. This article introduces a protocol for implant abutment selection in partially edentulous patients undergoing dental implant treatment by describing a clinical/laboratory protocol for abutment selection in implant dentistry for implant surgeons, restorative dentists, and dental laboratory technicians.

  15. Impact of implant-abutment connection on osteoimmunological and microbiological parameters in short implants: a randomized controlled clinical trial.

    Science.gov (United States)

    Öztürk, Veli Özgen; Emingil, Gülnur; Bostanci, Nagihan; Belibasakis, Georgios N

    2017-09-01

    The study aimed to determine the levels of soluble receptor activator of nuclear factor-кB ligand (sRANKL) and osteoprotegerin (OPG) as well as their relative calculated ratio in peri-implant crevicular fluid (PICF) obtained around two different types of implant-abutment connection on short implants following a 12-month monitoring period. Moreover, the levels of a number of oral bacterial species were investigated in the corresponding submucosal biofilm samples. Thirty short implants were randomly placed in posterior maxillary edentulous sites using a split-mouth design in 15 periodontally healthy subjects. Tapered interference fit (TIF) and taper-integrated screwed-in (TIS) types of implant-abutment connections were selected for investigation. PICF and submucosal biofilm samples were collected 1 month after surgery and repeated 12 months after prosthetic loading. Clinical parameters, including probing depth, dichotomous presence of bleeding on probing, and plaque index, were recorded and digital periapical radiographs were taken at each time point. sRANKL and OPG levels in PICF were analyzed using an enzyme-linked immunosorbent assay. Total bacterial levels, as well as levels of Fusobacterium nucleatum, Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, Prevotella intermedia, and Streptococcus oralis, were analyzed in the corresponding submucosal biofilm samples using quantitative real-time polymerase chain reaction. The total amount of sRANKL in TIF implants was 2.64-fold lower than that in TIS implants at baseline (P  0.05). Accordingly, OPG and RANKL/OPG ratio were similar between the groups at each time point (P > 0.05). Microbiological results were similar in both groups at each time point (P > 0.05). The results of this longitudinal study suggested that sRANKL and OPG in PICF, as well as microbiological parameters in submucosal biofilms, were similar between TIF and TIS implants, after a 12-month monitoring period, despite early

  16. Clinical considerations for selecting implant abutments for fixed prosthodontics.

    Science.gov (United States)

    Solow, Roger A

    2015-01-01

    There is an overwhelming number of designs and components for dentists to choose from when treatment planning implant-supported restorations. The selection process can be simplified by establishing priorities on a site-by-site basis to facilitate a predictable, esthetic, and stable final result. Clinical considerations should include prosthetic support, periodontal stability, reparability, and oral hygiene, which often occur in concert. This article addresses the principles that guide implant abutment selection when treatment planning for fixed prosthodontics.

  17. Accuracy combining different brands of implants and abutments

    OpenAIRE

    Sol?-Ru?z, Mar?a F.; Selva-Otaolaurruchi, Eduardo; Senent-Vicente, Gisela; Gonz?lez-de-Cossio, In?s; Amig?-Borr?s, Vicente

    2012-01-01

    Objective: To evaluate the vertical misfit between different brands of dental implants and prosthetic abutments, with or without mechanical torque, and to study their possible combination. Study design: Five different brands of implant were used in the study: Biofit (Castemaggiore, Italy), Bioner S.A. (Barcelona, Spain), 3i Biomet (Palm Beach, U.S.A.), BTI (Alava, Spain) and Nobel Biocare (G?teborg, Sweden), with standard 4.1 mm heads and external hexagons, and their respective machined prost...

  18. Densitometric evaluation might prevent failure of knee artroplasty for aseptic loosening. An 8-year observational controlled study

    Directory of Open Access Journals (Sweden)

    Gianantonio Saviola

    2016-02-01

    Full Text Available Objectives: To study the correlation between quantitative ultrasound (QUS expressed as stiffness index (SI and the risk of aseptic loosening of knee arthroplasty. Methods: An observational retrospective controlled study was performed on 85 female patients (mean age: 73.3 years divided into 2 groups from January 2007 to March 2015 and carried out at the Orthopedic Rehabilitation Unit, Casa di Cura Eremo, Arco, Trento, Italy. Group A included 42 patients who had undergone a revision of knee prosthesis for aseptic-loosening, and group B included 43 age-matched patients who underwent primary replacement of the knee without following aseptic loosening. Patients in both groups were evaluated for SI with Achilles - QUS system at the same side of the surgery. Results: In group A, 20/42 patients (47.6% had an SI T-score below -2.5. In group B, 14/43 (32.5% patients had a SI T-score below -2.5. The difference between the 2 groups was statistically significant (p=0.015. Conclusion: Stiffness index appears to be an important predictor of aseptic loosening of the knee prosthesis. Therefore, densitometric evaluation, including SI, may be recommended before surgical knee replacement.

  19. Long-term effects of deep soil loosening on root distribution and soil physical parameters in compacted lignite mine soils

    Science.gov (United States)

    Badorreck, Annika; Krümmelbein, Julia; Raab, Thomas

    2015-04-01

    Soil compaction is a major problem of soils on dumped mining substrates in Lusatia, Germany. Deep ripping and cultivation of deep rooting plant species are considered to be effective ways of agricultural recultivation. Six years after experiment start, we studied the effect of initial deep soil loosening (i.e. down to 65 cm) on root systems of rye (Secale cereale) and alfalfa (Medicago sativa) and on soil physical parameters. We conducted a soil monolith sampling for each treatment (deep loosened and unloosened) and for each plant species (in three replicates, respectively) to determine root diameter, length density and dry mass as well as soil bulk density. Further soil physical analysis comprised water retention, hydraulic conductivity and texture in three depths. The results showed different reactions of the root systems of rye and alfalfa six years after deep ripping. In the loosened soil the root biomass of the rye was lower in depths of 20-40 cm and the root biomass of alfalfa was also decreased in depths of 20-50 cm together with a lower root diameter for both plant species. Moreover, total and fine root length density was higher for alfalfa and vice versa for rye. The soil physical parameters such as bulk density showed fewer differences, despite a higher bulk density in 30-40cm for the deep loosened rye plot which indicates a more pronounced plough pan.

  20. Potential Effect of 2% Chlorhexidine Gel in the Implant Screw Hole on Bacterial Count

    Directory of Open Access Journals (Sweden)

    Abd Khudair Ali

    2017-11-01

    Full Text Available Background: Microbial penetration inside the implant’s internal hole creates a bacterial reservoir that is related with an area of inflamed connective tissue opposite the fixture-abutment junction and this can affect with the health of the peri-implant tissue. Chlorhexidine (CHX has been used to prevent internal implant contamination as a 0.2% solution, a varnish or gel. Aim: To evaluate the aerobic/anaerobic bacterial count-reduction potential of 2% CHX gel placed, at the time of surgery, in the implant screw hole over a period of minimum 90 d, and to monitor the periodontal health status of all patients, throughout the study. Material and methods: Ten partially edentulous patients received 30 DI and these implants were randomly allocated in to: Group I (test 15 implants applied by flap or flapless surgery with 2% CHX gel application. Group II (control 15 implants applied by flap or flapless surgery without CHX gel application. All patients were examined clinically to determine their oral health status by examination of their plaque index, PLI, Gingival index GI, Bleeding on probing, BOP, and probing pocket depth, PPD, every two weeks throughout the study. Three months later, the plaque sample was collected from the internal hole of fixture and was sent for bacteriological examination. Results: The present study shows highly significant reduction of aerobic count of bacteria from 52.1% to 100%. Also, anaerobic bacterial count was reduced from 64.6% to 100% for group that received 2% CHX gel in screw hole of implants at time of surgery. When compared, the count of aerobic and anaerobic bacteria (CFU between test and control group, a significant reduction was found. Conclusion: The use of 2% CHX gel at the time of placement can significantly reduce bacterial counts in the implant screw hole, and this effect can be maintained for 90 d or longer.

  1. Twin Screw Mixer/Fine Grind Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The 40-mm Twin-Screw Mixer/Extruder (TSE) pilot plant is a continuous, remotely operated, flexible facility that can significantly enhance safety and environmental...

  2. Load-Bearing Capacity of Fiber-Reinforced Composite Abutments and One-Piece Implants.

    Science.gov (United States)

    Etxeberria, Marina; Abdulmajeed, Aous A; Escuin, Tomas; Vinas, Miguel; Lassila, Lippo V J; Närhi, Timo O

    2015-06-01

    Fiber-reinforced composites (FRC) can potentially help in a physiologic stress transmission due to its excellent biomechanical matching with living tissues. Novel one-piece FRC implants and abutments with two different fiber orientations were loaded until failure to assess the load-bearing capacity, fracture patterns, and precision of fit. The one-piece FRC implants showed significantly higher load-bearing capacity compared to FRC abutments regardless of the fiber orientation (p < 0.001). For FRC abutments, bidirectional abutments showed significantly higher loads compared to unidirectional abutments (p < 0.001). The type of structure and fiber orientation are strong determinant factors of the load-bearing capacity of FRC implants and abutments.

  3. The diagnostic performance of radiographic criteria to detect aseptic acetabular component loosening after revision total hip arthroplasty.

    Science.gov (United States)

    Abrahams, J M; Kim, Y S; Callary, S A; De Ieso, C; Costi, K; Howie, D W; Solomon, L B

    2017-04-01

    This study aimed to determine the diagnostic performance of radiographic criteria to detect aseptic acetabular loosening after revision total hip arthroplasty (THA). Secondary aims were to determine the predictive values of different thresholds of migration and to determine the predictive values of radiolucency criteria. Acetabular component migration to re-revision was measured retrospectively using Ein-Bild-Rontgen-Analyse (EBRA-Cup) and manual measurements (Sutherland method) in two groups: Group A, 52 components (48 patients) found not loose at re-revision and Group B, 42 components (36 patients) found loose at re-revision between 1980 and 2015. The presence and extent of radiolucent lines was also assessed. Using EBRA, both proximal translation and sagittal rotation were excellent diagnostic tests for detecting aseptic loosening. The area under the receiver operating characteristic (ROC) curves was 0.94 and 0.93, respectively. The thresholds of 2.5 mm proximal translation or 2° sagittal rotation (EBRA) in combination with radiolucency criteria had a sensitivity of 93% and specificity of 88% to detect aseptic loosening. The sensitivity, specificity, positive predictive value and negative predictive value (NPV) of radiolucency criteria were 41%, 100%, 100% and 68% respectively. Manual measurements of both proximal translation and sagittal rotation were very good diagnostic tests. The area under the ROC curve was 0.86 and 0.92 respectively. However, manual measurements had a decreased specificity compared with EBRA. Radiolucency criteria had a poor sensitivity and NPV of 41% and 68% respectively. This study shows that EBRA and manual migration measurements can be used as accurate diagnostic tools to detect aseptic loosening of cementless acetabular components used at revision THA. Radiolucency criteria should not be used in isolation to exclude loosening of cementless acetabular components used at revision THA given their poor sensitivity and NPV. Cite this

  4. Fatigue resistance and failure mode of adhesively restored custom metal-composite resin premolar implant abutments.

    Science.gov (United States)

    Boff, Luís Leonildo; Oderich, Elisa; Cardoso, Antônio Carlos; Magne, Pascal

    2014-01-01

    To evaluate the fatigue resistance and failure mode of composite resin and porcelain onlays and crowns bonded to premolar custom metal-composite resin premolar implant abutments. Sixty composite resin mesostructures were fabricated with computer assistance with two preparation designs (crown vs onlay) and bonded to a metal implant abutment. Following insertion into an implant with a tapered abutment interface (Titamax CM), each metal-composite resin abutment was restored with either composite resin (Paradigm MZ100) or ceramic (Paradigm C) (n = 15) and attached with adhesive resin (Optibond FL) and a preheated light-curing composite resin (Filtek Z100). Cyclic isometric chewing (5 Hz) was then simulated, starting with 5,000 cycles at a load of 50 N, followed by stages of 200, 400, 600, 800, 1,000, 1,200, and 1,400 N (25,000 cycles each). Samples were loaded until fracture or to a maximum of 180,000 cycles. The four groups were compared using life table survival analysis (log-rank test). Previously published data using zirconia abutments of the same design were included for comparison. Paradigm C and MZ100 specimens fractured at average loads of 1,133 N and 1,266 N, respectively. Survival rates ranged from 20% to 33.3% (ceramic crowns and onlays) to 60% (composite resin crowns and onlays) and were significantly different (pooled data for restorative material). There were no restoration failures, but there were adhesive failures at the connection between the abutment and the mesostructure. The survival of the metal-composite resin premolar abutments was inferior to that of identical zirconia abutments from a previous study (pooled data for abutment material). Composite resin onlays/crowns bonded to metal-composite resin premolar implant abutments presented higher survival rates than comparable ceramic onlays/crowns. Zirconia abutments outperformed the metal-composite resin premolar abutments.

  5. Case report using the "H" abutment: achieving esthetics, strength, and predictability for the anterior implant.

    Science.gov (United States)

    Hornbrook, David

    2015-03-01

    Replacing an anterior tooth using a dental implant has long been a challenge for most clinicians. Implant abutment selection is a crucial aspect of maximizing esthetics, strength, and customization. The author has experienced significant success in this regard over a period of more than 7 years using a lithium-disilicate "H" ("Hybrid") abutment. In this case presentation, a procedure is described for providing these highly esthetic abutment-supported restorations, which may offer significant advantages over traditional options.

  6. Selection and modification of prefabricated implant abutments according to the desired restoration contour: a case report.

    Science.gov (United States)

    Kourtis, Stefanos G

    2002-05-01

    Implant restorations must fulfill the functional and esthetic demands of the patient. The discrepancy in the diameters of an implant and a natural tooth often leads to compromise. The use of prefabricated abutments that can be individually modified offers certain advantages. Selection and modification of the abutment are simpler when a waxup of the restoration is used as a guideline. This article describes a laboratory technique in which the implant abutment is selected and modified according to the waxup of the restoration.

  7. A technique to determine the preferred use of a custom abutment for an implant supported crown.

    Science.gov (United States)

    Wicks, Russell; Ahuja, Swati; Jain, Vinay

    2012-01-01

    One of the most significant challenges in contemporary dental implant therapy involves managing the transition of the restoration from the implant through the soft tissues by means of an abutment. This article presents a practical technique to visualize if the selection of a custom-made abutment would be favored over the use of a manufactured standard abutment to receive crown restoration supported by a dental implant.

  8. Fracture resistance of inter-joined zirconia abutment of dental implant system with injection molding technique.

    Science.gov (United States)

    Yang, Jianjun; Wang, Ke; Liu, Guangyuan; Wang, Dashan

    2013-11-01

    Zirconia powder in nanometers can be fabricated into inter-joined abutment of dental implant system with the injection shaping technique. This study was to detect the resistance of inter-joined zirconia abutment with different angle loading for clinical applications. The inter-joined abutments were shaped with the technique of injection of zirconia powder in nanometers. Sixty Osstem GSII 5 × 10 mm implants were used with 30 zirconia abutments and 30 Osstem GSII titanium abutments for fixation using 40 N torque force. The loading applications included 90°, 30°, and 0° formed by the long axis of abutments and pressure head of universal test machine. The fracture resistances of zirconia and titanium abutments were documented and analyzed. The inter-joined zirconia abutments were assembled to the Osstem GSII implants successfully. In the 90° loading mode, the fracture resistance of zirconia abutment group and titanium abutment group were 301.5 ± 15.4 N and 736.4 ± 120.1 N, respectively. And those in the 30° groups were 434.7 ± 36.1 N and 1073.1 ± 74 N, correspondingly. Significant difference in the two groups was found using t-test and Wilcoxon test. No damage on the abutments of the two groups but S-shaped bending on the implants was found when the 0° loading was 1300-2000 N. Through the assembly of Zirconia abutments and implants, all the components presented sufficient resistance acquired for the clinical application under loadings with different angle. © 2012 John Wiley & Sons A/S.

  9. Application of reverse engineering in the production of individual dental abutments.

    Science.gov (United States)

    Yunusov, A. V.; Kashapov, R. N.; Kashapov, L. N.; Statsenko, E. O.

    2017-09-01

    The purpose of the research is to develop a method of manufacturing individual dental abutments for a variety of dental implants. System of industrial X-ray microtomography Phoenix V|tome|X S 240 has been applied for creation of highly accurate model of the dental abutment. Scanning of dental abutment and the optimization of model was produced. The program of milling the individual abutment with a standard conical neck of hexagon was produced for the five-axis milling machine imes - icore 450i from the materials titanium and zirconium oxide.

  10. Comparison of 3 luting agents on retention of implant-supported crowns on 2 different abutments.

    Science.gov (United States)

    Güncü, M Bariş; Cakan, Umut; Canay, Senay

    2011-10-01

    For fixed prostheses, retention is one of the most important factors for clinical success. It is unknown whether grooves that increase surface area of implant abutment while retaining the diameter and wall height provide greater uniaxial retention force. The purpose of this study was to determine the retention of 3 different cements on 2 implant abutments with different surface configurations. Thirty samples on 2 different abutments (a total of 60 crowns) with different margin and axial walls configuration and surface area were used. Metal crowns were fabricated on the abutment and cemented with 3 different (zinc-phosphate [ZP], glass ionomer [GI], or eugenol-free zinc oxide [ZO]) cements. After cementation, implant-abutment-casting assemblies were thermal cycled 1000 times with 1-minute dwell-time between 5°C and 55°C then subjected to tensile test with universal testing machine until decementation occurred. The mean force required to dislodge castings from abutment was determined. The luting agents influenced retention of castings on implant abutments, whereas different surface configurations and total surface area of the abutments did not influence the uniaxial retention forces. Among the cements tested, ZP exhibited higher values of retention, followed by GI and eugenol-free ZO. The increase in surface area of abutment did not result in improved retention. The present results suggest using ZP rather than GI and eugenol-free ZO in implant-supported crowns to provide higher retention.

  11. Effect of surface topography of implant abutments on retention of cemented single-tooth crowns.

    Science.gov (United States)

    de Campos, Tomie Nakakuki; Adachi, Lena Katekawa; Miashiro, Karen; Yoshida, Hideki; Shinkai, Rosemary Sadami; Neto, Pedro Tortamano; Frigerio, Maria Luiza Moreira Arantes

    2010-08-01

    This study investigated whether surface topography affects the retentive strength of cemented full crowns, comparing the effects of standard machined, sandblasted, and grooved implant abutments. Five metallic crowns per abutment type were cast and cemented with zinc phosphate. After 24 hours, the specimens were submitted to a tensile test. The retentive strength of the cemented crowns was affected by abutment surface topography. The sandblasted and grooved surface groups had approximately 2.4 times greater mean uniaxial retentive strength than the machined surface group (P < .001). The retentive strength of the sandblasted and grooved abutments was similar, despite marked differences in surface profiles and roughness parameters.

  12. Ball Screw Actuator Including a Stop with an Integral Guide

    Science.gov (United States)

    Wingett, Paul T. (Inventor); Perek, John (Inventor); Geck, Kellan (Inventor)

    2015-01-01

    An actuator includes a housing assembly, a ball nut, a ball screw, and a ball screw stop. The ball nut is rotationally mounted in the housing assembly, is adapted to receive an input torque, and is configured, upon receipt thereof, to rotate and supply a drive force. The ball screw is mounted within the housing assembly and extends through the ball nut. The ball screw has a first end and a second end, and is coupled to receive the drive force from the ball nut. The ball screw is configured, upon receipt of the drive force, to selectively translate between a stow position and a deploy position. The ball screw stop is mounted on the ball screw to translate therewith and is configured to at selectively engage the housing assembly while the ball screw is translating, and engage the ball nut when the ball screw is in the deploy position.

  13. Insertion profiles of 4 headless compression screws.

    Science.gov (United States)

    Hart, Adam; Harvey, Edward J; Lefebvre, Louis-Philippe; Barthelat, Francois; Rabiei, Reza; Martineau, Paul A

    2013-09-01

    In practice, the surgeon must rely on screw position (insertion depth) and tactile feedback from the screwdriver (insertion torque) to gauge compression. In this study, we identified the relationship between interfragmentary compression and these 2 factors. The Acutrak Standard, Acutrak Mini, Synthes 3.0, and Herbert-Whipple implants were tested using a polyurethane foam scaphoid model. A specialized testing jig simultaneously measured compression force, insertion torque, and insertion depth at half-screw-turn intervals until failure occurred. The peak compression occurs at an insertion depth of -3.1 mm, -2.8 mm, 0.9 mm, and 1.5 mm for the Acutrak Mini, Acutrak Standard, Herbert-Whipple, and Synthes screws respectively (insertion depth is positive when the screw is proud above the bone and negative when buried). The compression and insertion torque at a depth of -2 mm were found to be 113 ± 18 N and 0.348 ± 0.052 Nm for the Acutrak Standard, 104 ± 15 N and 0.175 ± 0.008 Nm for the Acutrak Mini, 78 ± 9 N and 0.245 ± 0.006 Nm for the Herbert-Whipple, and 67 ± 2N, 0.233 ± 0.010 Nm for the Synthes headless compression screws. All 4 screws generated a sizable amount of compression (> 60 N) over a wide range of insertion depths. The compression at the commonly recommended insertion depth of -2 mm was not significantly different between screws; thus, implant selection should not be based on compression profile alone. Conically shaped screws (Acutrak) generated their peak compression when they were fully buried in the foam whereas the shanked screws (Synthes and Herbert-Whipple) reached peak compression before they were fully inserted. Because insertion torque correlated poorly with compression, surgeons should avoid using tactile judgment of torque as a proxy for compression. Knowledge of the insertion profile may improve our understanding of the implants, provide a better basis for comparing screws, and enable the surgeon to optimize compression. Copyright

  14. Stereo-radiographic analysis of loosening processes of alloplastic hip joint replacement

    International Nuclear Information System (INIS)

    Probst, K.J.

    1980-01-01

    A computer-aided diagnostic system has been developed by which implant dislocation of an order of 0.2 mm can be detected in all three dimensions. The diagnostic system is based on a point-by-point evaluation of stereoradiographic pictures; precise localisation of the implant relative to its place of insertion is made possible by special mathematical operations which are discussed in detail in the methodical part of the book. The method has been tested in clinical practice in 351 cases (208 patients) in the period between September 1, 1977, and May 31, 1979. By taking functional pictures during adduction and abduction of the extremity carrying the endoprosthesis and then evaluating these pictures, the diagnostic system can detect dislocations of the endoprosthesis inside the bone at a given moment. Also, the fate of hip joints with endoprostheses can be followed in the framework of longitudinal research. The method described here may also help to solve other problems of clinical relevance. The only precondition for this is the imaging of the structures of interest in the X-ray picture. A program to analyze loosening processes of alloplastic knee joint implants is new being worked on which will be of great use to the increasing number of patients with alloplastic knee joint implants. (orig./MG) [de

  15. Surgical treatment of isolated aseptic acetabular loosening of the hip joint

    Directory of Open Access Journals (Sweden)

    Zvereva К.Р.

    2017-09-01

    Full Text Available Aseptic acetabular loosening is one of the most common complications of primary hip arthroplasty Its treatment is possible in the volume of replacement of only the endoprosthesis cup with the preservation of a stable correctly oriented femoral component. The sequence of actions consists of provision of access to the acetabulum component and its replacement, after which the necessary offset is selected by changing the size of the head and installing a new pair of friction. Currently, the vast majority of the installed heads during the primary and revision hip replacement have a standard size forthe cone of the femoral component 12/14mm. According to the observations, in 3% of cases, there are femoral components with non-standard cone sizes 11/13 mm, usually established 7-8 years ago. The absence of heads forthe necessary cone leads to the need to replace the stable correctly oriented femoral component, which is accompanied by an increase in the time of intervention, the volume of intraoperative blood loss and the risk of intraopera-tive peri-prosthetic fracture. We represent the clinical case of a 75-year-old patient with a dislocation of the acetabular component and a stable correctly oriented femoral component, which during the audit intervention due to the lack of heads for an irregular cone size, total replacement of the components was made.

  16. Squatting-Related Tibiofemoral Shear Reaction Forces and a Biomechanical Rationale for Femoral Component Loosening

    Directory of Open Access Journals (Sweden)

    Ashvin Thambyah

    2014-01-01

    Full Text Available Previous gait studies on squatting have described a rapid reversal in the direction of the tibiofemoral joint shear reaction force when going into a full weight-bearing deep knee flexion squat. The effects of such a shear reversal have not been considered with regard to the loading demand on knee implants in patients whose activities of daily living require frequent squatting. In this paper, the shear reversal effect is discussed and simulated in a finite element knee implant-bone model, to evaluate the possible biomechanical significance of this effect on femoral component loosening of high flexion implants as reported in the literature. The analysis shows that one of the effects of the shear reversal was a switch between large compressive and large tensile principal strains, from knee extension to flexion, respectively, in the region of the anterior flange of the femoral component. Together with the known material limits of cement and bone, this large mismatch in strains as a function of knee position provides new insight into how and why knee implants may fail in patients who perform frequent squatting.

  17. Effects of Removal and Reinsertion of Headless Compression Screws.

    Science.gov (United States)

    Donald, Simon M; Niu, Rui; Jones, Christopher W; Smith, Belinda J; Clarke, Elizabeth C; Lawson, Richard D

    2018-02-01

    This study investigates the loss of compression when 3 commonly used headless compression screws are backed out (reversed), and assesses the ability to re-establish compression with screws of greater diameter. Two investigators tested 3 screw designs (Acutrak 2, Synthes HCS, Medartis SpeedTip CCS) in 2 diameters and lengths. Each design had 10 test cycles in a polyurethane foam bone model with compression recorded using a washer load cell. A 28-mm screw of the narrower diameter was inserted until 2 mm recessed and then reversed 30°, 60°, 90°, 180°, 270°, 360°, and 720°. After this the screw was removed completely and a 24-mm screw of greater diameter inserted until recessed 2 mm with the compressive force again recorded. All screws showed an immediate, statistically significant loss of compression at 30° of reversing. The Acutrak 2 Micro screw demonstrated not only the greatest mean compressive force, but also the fastest compressive loss. Insertion of the shorter screw of greater diameter was associated with re-establishment of compression to levels comparable with the original screw. This study reaffirms the importance of establishing the correct screw length before insertion due to the immediate loss of compression with reversal of these devices. If a headless compression screw penetrates the far joint surface, the screw should be completely removed and replaced with a shorter screw of greater diameter. Copyright © 2018 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  18. Axial loading cross screw fixation for the Austin bunionectomy.

    Science.gov (United States)

    Rigby, Ryan B; Fallat, Lawrence M; Kish, John P

    2011-01-01

    The Austin procedure has become a common method of osteotomy for the correction of hallux abductovalgus when indicated. The V-type configuration is intrinsically stable but not without complications. One complication encountered is rotation and/or displacement of the capital fragment. We present the use of an axial loading screw in conjunction with a dorsally placed compression screw. The benefit to this technique lies in the orientation of the axial loading screw, because it is directed to resist the ground reactive forces while also providing a second point of fixation in a crossing screw design. In a head-to-head biomechanical comparison, we tested single dorsal screw fixation versus double screw fixation, including both the dorsal and the axial loading screws in 10 metatarsal Sawbones(®) (Pacific Research Laboratories Inc, Vashon, WA). Five metatarsals received single dorsal screw fixation and five received the dorsal screw and the additional axial loading screw. The metatarsals were analyzed on an Instron compression device for comparison; 100% of the single screw fixation osteotomies failed with compression at an average peak load of 205 N. Four of five axial loading double screw fixation osteotomies did not fail. This finding suggests that the addition of an axial loading screw providing cross screw orientation significantly increases the stability of the Austin osteotomy, ultimately decreasing the likelihood of displacement encountered in the surgical repair of hallux abductovalgus. Copyright © 2011 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  19. Lapidus bunionectomy: Early evaluation of crossed lag screws versus locking plate with plantar lag screw.

    Science.gov (United States)

    Saxena, Amol; Nguyen, Aidan; Nelsen, Elise

    2009-01-01

    We compared outcomes of the Lapidus bunionectomy fixated with crossed lag screws versus a locking plate with a plantar lag screw. Forty patients who underwent Lapidus bunionectomy between August 2001 and May 2006 were evaluated in a combined retrospective and prospective fashion. Crossed lag screws were used in 19 of the patients, and a locking plate with a plantar lag screw was used in 21 of the patients. Other than fixation, the only interventional difference pertained to postoperative weight bearing, where those receiving the plate initiated full weight bearing on the operated foot at 4 weeks postoperative, as compared to 6 weeks for those receiving crossed screws. Overall, the mean preoperative AOFAS hallux score was 41.75 +/- 2.52, and the postoperative score was 90.48 +/- 8.41 (P fixation, use of an adjunct Akin osteotomy and surgery performed before 2003 were statistically significantly associated with crossed screw fixation, and the preoperative AOFAS score was statistically significantly higher in the locking plate fixation group. There were no statistically significant differences related to postoperative complications between the 2 fixation groups. In conclusion, the Lapidus bunionectomy fixated with a locking plate and a plantar lag screw allows earlier weight bearing in comparison with crossed lag screws, without a difference in complications. 2.

  20. An investigation of heat transfer to the implant-bone interface when drilling through a zirconia crown attached to a titanium or zirconia abutment.

    Science.gov (United States)

    Mason, Amy G; Sutton, Alan; Turkyilmaz, Ilser

    2014-11-01

    Thermal injury to the implant-bone interface may lead to bone necrosis and loss of osseointegration. This is a concern during manipulation of the implant throughout the restorative phase of treatment. The risk of heat transfer to the implant-bone interface during abutment preparation or prosthesis removal should be considered. The purpose of the study was to examine the amount of heat transferred to the implant-bone interface when a zirconia crown is drilled to access the screw channel or section a crown with a high-speed dental handpiece. Of the 64 ceramic-veneered zirconia crowns fabricated, 32 had a coping thickness of 0.5 mm and 32 had a coping thickness of 1.0 mm. The crowns were cemented on either titanium stock abutments or zirconia stock abutments. Each group was further subdivided to evaluate heat transfer when the screw channel was accessed or the crown was sectioned with a high-speed handpiece with or without irrigation. Temperature change was recorded for each specimen at the cervical and apical aspect of the implant with thermocouples and a logging thermometer. ANOVA was used to assess the statistical significance in temperature change between the test combinations, and nonparametric Mann-Whitney U tests were used to evaluate the findings. The use of irrigation during both crown removal processes yielded an average temperature increase of 3.59 ±0.35°C. Crown removal in the absence of irrigation yielded an average temperature increase of 18.76 ±3.09°C. When all parameter combinations in the presence of irrigation were evaluated, the maximum temperature change was below the threshold of thermal injury to bone. The maximum temperature change was above the threshold for thermal injury at the coronal aspect of the implant and below the threshold at the apical aspect in the absence of irrigation. Within the limitations of this investigation, the use of irrigation with a high-speed dental handpiece to remove a ceramic-veneered zirconia crown results in

  1. Standard Waste Box Lid Screw Removal Option Testing

    Energy Technology Data Exchange (ETDEWEB)

    Anast, Kurt Roy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-03-11

    This report provides results from test work conducted to resolve the removal of screws securing the standard waste box (SWB) lids that hold the remediated nitrate salt (RNS) drums. The test work evaluated equipment and process alternatives for removing the 42 screws that hold the SWB lid in place. The screws were secured with a red Loctite thread locker that makes removal very difficult because the rivets that the screw threads into would slip before the screw could be freed from the rivet, making it impossible to remove the screw and therefore the SWB lid.

  2. Effect of pedicle screw diameter on screw fixation efficacy in human osteoporotic thoracic vertebrae.

    Science.gov (United States)

    Lai, Dar-Ming; Shih, Yu-Tang; Chen, Yi-Hsing; Chien, Andy; Wang, Jaw-Lin

    2018-03-21

    The selection of an ideal screw size plays a crucial role in the success of spinal instrumentation as larger diameter screws are thought to provide better fixation strength but increase the risk of pedicle failure during insertion. On the other hand, smaller diameter screws are with lesser risk of pedicle breakage but are thought to compromise the stability of the instrumentation. By investigating the relationship between screw diameter and the pullout strength of pedicle screws after fatigue loading, this study seeks to find quantitative biomechanical data for surgeons in determining the most ideal diameter size screws when performing surgical implementations on osteoporotic vertebrae. Twenty-seven osteoporotic (BMD ranged: 0.353-0.848 g/cm 2 ) thoracic vertebrae (T3-T8) were harvested from 5 human cadavers. Two sizes of poly-axial screws (5.0 mm × 35 and 4.35 mm × 35) were implanted into each pedicles of the vertebrae by an experienced surgeon. Specimens were randomly distributed into control group, fatigue group of 5000 and 10,000 cycles with peak-to-peak loadings of 10-100 N at 1 Hz. Each specimen was then axial pullout tested at a constant rate of 5 mm/min. The ultimate pullout strength (N) & stiffness (N/mm) were obtained for analysis. The results showed that although the larger diameter screws achieved superior pullout strength immediately after the implantation, both sizes of screws exhibited comparable pullout strengths post fatigue loading. This indicates that the smaller diameter screws may be considered for surgical techniques performed on osteoporotic vertebrae for reduced risk of pedicle breakage without sacrificing fixation strength. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Stability of medial locking plate and compression screw versus two crossed screws for lapidus arthrodesis.

    Science.gov (United States)

    Klos, Kajetan; Gueorguiev, Boyko; Mückley, Thomas; Fröber, Rosemarie; Hofmann, Gunther O; Schwieger, Karsten; Windolf, Markus

    2010-02-01

    Lapidus (first metatarsocuneiform joint) arthrodesis is an established procedure for the management of hallux valgus. This study investigated the utility of fixation with a medial locking plate with adjunct compression screw versus fixation with two crossed screws. Eight pairs of fresh-frozen human specimens were used in a matched pair test. Bone mineral density (BMD) was measured with peripheral quantitative computed tomography (pQCT). Fixation with two 4-mm-diameter crossed screws was compared versus a medial locking plate (X-Locking Plate 2.4/2.7; Synthes, Solothurn, Switzerland) with adjunct 4-mm-diameter compression screw. The specimens were tested in a four-point bending test. Parameters obtained were initial stiffness; plantar joint-line gapping after one cycle, 100 and 1000 cycles; and number of cycles to failure. Failure was defined as more than or equal to 3 mm plantar gapping. The groups did not differ significantly with regard to BMD (p = 0.866) and initial stiffness (p = 0.889). The plate-and-screw construct showed significantly less movement during testing, and significantly (p = 0.001) more cycles to failure than did the crossed-screw construct. There was a significant correlation (crossed-screw construct: p = 0.014; plate-and-screw construct: p = 0.010) between BMD and the number of cycles to failure. Under cyclic loading conditions, the construct using a medial locking plate with adjunct compression screw was superior to the construct using two crossed screws. The medial locking-plate technique described could help shorten the period of nonweightbearing and reduce the risk of non-union.

  4. Effect of Implant Connection Type and Depth on the Seating Accuracy of Hand-Tightened Abutments.

    Science.gov (United States)

    Siadat, Hakimeh; Belbasi, Simin; Alikhasi, Marzieh; Nazari, Vahideh; Beyabanaki, Elaheh

    2017-12-14

    Improper seating of abutment on the implant is a common problem. This study investigated the effect of the type of implant/abutment interface on the complete seating of the abutments on the head of implants placed at different gingival depths. Three implant systems with three different connections including straight external hexagon, butt-joint internal tri-lobed, and conical internal hexagon were used. Two gingival thicknesses (2 and 7 mm) were created using pink baseplate wax around the straight abutments seated on the implants. After placing the implants in acrylic blocks, the wax was replaced with the gingival mask material to simulate the gingival drape around the implant heads. Afterwards, 15 prosthodontists were asked to hand-tighten the straight abutments in the corresponding implant bodies relying only on their tactile sense. At the final stage, the gingival mask was removed, and the seating quality of the abutments on implant bodies was assessed visually. The effect of implant connection and depth on abutment seating accuracy was analyzed using Kruskal-Wallis and multiple-comparison tests. No significant difference was found regarding the effect of either depth or connection design on the accuracy of the abutment seating (p > 0.05); however, pairwise comparison of the combined effect of the depth and connection design was significant (p = 0.009). Accuracy of abutment seating on the Nobel Active implants at both 2 and 7 mm depths were significantly better than Replace system with 7 mm depth (p = 0.027). The same results were obtained in comparison between Nobel Active system at both 2 and 7 mm depths with Branemark system with 7 mm depth (p = 0.006). An increase in implant placement depth meant a decrease in accuracy of the abutment seating. The internal conical connection design showed the best result in abutment positioning in deep implants as compared with external and internal butt-joint connection designs. © 2017 by the American College of

  5. Antibacterial effect of doxycycline-coated dental abutment surfaces

    International Nuclear Information System (INIS)

    Xing, Rui; Tiainen, Hanna; Shabestari, Maziar; Lyngstadaas, Ståle P; Haugen, Håvard J; Witsø, Ingun L; Lönn-Stensrud, Jessica; Jugowiec, Dawid

    2015-01-01

    Biofilm formation on dental abutment may lead to peri-implant mucositis and subsequent peri-implantitis. These cases are clinically treated with antibiotics such as doxycycline (Doxy). Here we used an electrochemical method of cathodic polarization to coat Doxy onto the outer surface of a dental abutment material. The Doxy-coated surface showed a burst release in phosphate-buffered saline during the first 24 h. However, a significant amount of Doxy remained on the surface for at least 2 weeks especially on a 5 mA–3 h sample with a higher Doxy amount, suggesting both an initial and a long-term bacteriostatic potential of the coated surface. Surface chemistry was analyzed by x-ray photoelectron spectroscopy and secondary ion mass spectrometry. Surface topography was evaluated by field emission scanning electron microscopy and blue-light profilometry. Longer polarization time from 1 h to 5 h and higher current density from 1 to 15 mA cm −2 resulted in a higher amount of Doxy on the surface. The surface was covered by a layer of Doxy less than 100 nm without significant changes in surface topography. The antibacterial property of the Doxy-coated surface was analyzed by biofilm and planktonic growth assays using Staphylococcus epidermidis. Doxy-coated samples reduced both biofilm accumulation and planktonic growth in broth culture, and also inhibited bacterial growth on agar plates. The antibacterial effect was stronger for samples of 5 mA–3 h coated with a higher amount of Doxy compared to that of 1 mA–1 h. Accordingly, an abutment surface coated with Doxy has potential for preventing bacterial colonization when exposed to the oral cavity. Doxy-coating could be a viable way to control peri-implant mucositis and prevent its progression into peri-implantitis. (paper)

  6. The effects of splinting periodontally compromised removable partial denture abutments on bone stresses: a three-dimensional finite element study

    Directory of Open Access Journals (Sweden)

    Allahyar Geramy

    2010-03-01

    Conclusion: Splinting a very weak abutment to an adjacent healthy tooth might not be beneficial. The acceptable crown to root ratio for fixed splinting a weak abutment to an adjacent normal tooth was around 1.65-2.

  7. A novel abutment construction technique for rapid bridge construction : controlled low strength Materials (CLSM) with full-height concrete panels.

    Science.gov (United States)

    2012-01-01

    One of the major obstacles facing rapid bridge construction for typical span type bridges is the time required to construct bridge abutments and foundations. This can be remedied by using the controlled low strength materials (CLSM) bridge abutment. ...

  8. Twin screw wet granulation: Binder delivery.

    Science.gov (United States)

    Saleh, Mohammed F; Dhenge, Ranjit M; Cartwright, James J; Hounslow, Michael J; Salman, Agba D

    2015-06-20

    The effects of three ways of binder delivery into the twin screw granulator (TSG) on the residence time, torque, properties of granules (size, shape, strength) and binder distribution were studied. The binder distribution was visualised through the transparent barrel using high speed imaging as well as quantified using offline technique. Furthermore, the effect of binder delivery and the change of screw configuration (conveying elements only and conveying elements with kneading elements) on the surface velocity of granules across the screw channel were investigated using particle image velocimetry (PIV). The binder was delivered in three ways; all solid binder incorporated with powder mixture, 50% of solid binder mixed with powder mixture and 50% mixed with water, all the solid binder dissolved in water. Incorporation of all solid binder with powder mixture resulted in the relatively longer residence time and higher torque, narrower granule size distribution, more spherical granules, weaker big-sized granules, stronger small-sized granules and better binder distribution compared to that in other two ways. The surface velocity of granules showed variation from one screw to another as a result of uneven liquid distribution as well as shown a reduction while introducing the kneading elements into the screw configuration. Copyright © 2015. Published by Elsevier B.V.

  9. Study of displacements of a bridge abutment using FEM

    Directory of Open Access Journals (Sweden)

    Wymysłowski Michał

    2016-06-01

    Full Text Available Steel sheet piles are often used to support excavations for bridge foundations. When they are left in place in the permanent works, they have the potential to increase foundation bearing capacity and reduce displacements; but their presence is not usually taken into account in foundation design. In this article, the results of finite element analysis of a typical abutment foundation, with and without cover of sheet piles, are presented to demonstrate these effects. The structure described is located over the Więceminka river in the town of Kołobrzeg, Poland. It is a single-span road bridge with reinforced concrete slab.

  10. Live-bed scour experiments with 45 wing-wall abutments

    Indian Academy of Sciences (India)

    Home; Journals; Sadhana; Volume 39; Issue 5. Live-bed scour experiments with 45° wing-wall ... Keywords. Scour; bridge foundation; abutments; hydraulics; rivers. ... A design equation is proposed for estimating maximum scour depth at 45°wing-wall abutment under live-bed condition. The calculated values of scour ...

  11. Soft tissue response to zirconia and titanium implant abutments : an in vivo within-subject comparison

    NARCIS (Netherlands)

    van Brakel, Ralph; Meijer, Gert J.; Verhoeven, Jan Willem; Jansen, John; de Putter, Cornelis; Cune, Marco S.

    2012-01-01

    Aim To compare the health of the soft tissues towards zirconia and titanium abutments in man, as observed using histological data. Material and Methods Twenty patients received two mandibular implants with either a zirconia or titanium abutment (split mouth study design, left-right randomization).

  12. Live-bed scour experiments with 45 wing-wall abutments

    Indian Academy of Sciences (India)

    The armour-layer gradually increases the effective bed shear resistance, which restricts the development of scour hole. 4. Maximum equilibrium local scour depth around 45. ◦ wing-wall abutment. Maximum equilibrium local scour depth at 45. ◦ wing-wall abutment in non-cohesive bed sedi- ments depends on the variables ...

  13. A Simplified Technique for Implant-Abutment Level Impression after Soft Tissue Adaptation around Provisional Restoration

    OpenAIRE

    Ahmad Kutkut; Osama Abu-Hammad; Robert Frazer

    2016-01-01

    Impression techniques for implant restorations can be implant level or abutment level impressions with open tray or closed tray techniques. Conventional implant-abutment level impression techniques are predictable for maximizing esthetic outcomes. Restoration of the implant traditionally requires the use of the metal or plastic impression copings, analogs, and laboratory components. Simplifying the dental implant restoration by reducing armamentarium through incorporating conventional techniq...

  14. Analysis of resistance to fatigue between straight solid and anatomic abutments of Morse taper system

    Directory of Open Access Journals (Sweden)

    Vanessa Tavares de GOIS-SANTOS

    Full Text Available Abstract Background The study of the phenomenon of fatigue is essential because implant failures usually are caused by this process. Purpose The objective of this study was to examine the fatigue resistance of straight and anatomical abutments joints that were submitted to cyclic loads. Material and method We used 37 Morse taper implants and 37 abutments, divided into two groups (n= 16: straight abutment, n= 21 anatomical abutment. The sets were submitted to cyclic loading (5 million using servo-hydraulic equipment. Three sets from each group were subjected to bending tests to determine the maximum load resistance, which served as the parameter for comparison of the cyclic tests. We evaluated number of cycles, load and bending moment. Result Of the 31 abutments cyclically tested, 17 (54.8% fractured in fewer than 5 million cycles; 8 (25.8% of these were straight abutments, and 9 (29% were anatomical. A total of 14 samples (45.2% resisted the cyclic loading. According to Fisher's exact test, there was no difference between groups as the fracture. Conclusion Despite of the straight abutments have higher average load and bending moment on the anatomical, both types of abutments showed similar performance as the fracture strength in vitro.

  15. Fracture Strength and Failure Mode of Maxillary Implant-Supported Provisional Single Crowns : A Comparison of Composite Resin Crowns Fabricated Directly Over PEEK Abutments and Solid Titanium Abutments

    NARCIS (Netherlands)

    Santing, H.J.; Meijer, Henny J.A.; Raghoebar, G.M.; Ozcan, M.

    2012-01-01

    Background: Polyetheretherketone (PEEK) temporary abutments have been recently introduced for making implant-supported provisional single crowns. Little information is available in the dental literature on the durability of provisional implant-supported restorations. Purpose: The objectives of this

  16. Impact of screw configuration on the particle size distribution of granules produced by twin screw granulation.

    Science.gov (United States)

    Vercruysse, J; Burggraeve, A; Fonteyne, M; Cappuyns, P; Delaet, U; Van Assche, I; De Beer, T; Remon, J P; Vervaet, C

    2015-02-01

    Twin screw granulation (TSG) has been reported by different research groups as an attractive technology for continuous wet granulation. However, in contrast to fluidized bed granulation, granules produced via this technique typically have a wide and multimodal particle size distribution (PSD), resulting in suboptimal flow properties. The aim of the current study was to evaluate the impact of granulator screw configuration on the PSD of granules produced by TSG. Experiments were performed using a 25 mm co-rotating twin screw granulator, being part of the ConsiGma™-25 system (a fully continuous from-powder-to-tablet manufacturing line from GEA Pharma Systems). Besides the screw elements conventionally used for TSG (conveying and kneading elements), alternative designs of screw elements (tooth-mixing-elements (TME), screw mixing elements (SME) and cutters) were investigated using an α-lactose monohydrate formulation granulated with distilled water. Granulation with only conveying elements resulted in wide and multimodal PSD. Using kneading elements, the width of the PSD could be partially narrowed and the liquid distribution was more homogeneous. However, still a significant fraction of oversized agglomerates was obtained. Implementing additional kneading elements or cutters in the final section of the screw configuration was not beneficial. Furthermore, granulation with only TME or SME had limited impact on the width of the PSD. Promising results were obtained by combining kneading elements with SME, as for these configurations the PSD was narrower and shifted to the size fractions suitable for tableting. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. The movement of screw dislocations in tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Tian Xiaogeng; Woo Chungho

    2004-03-25

    Using Acland potential for tungsten, the movement of 1/2a<1 1 1> screw dislocation under shear stress was investigated by molecular dynamics simulation. Equilibrated core structure was obtained by relaxation of screw dislocation with proper boundary conditions. We found that the equilibrium dislocation core has three-fold symmetry and spread out in three <1 1 2> direction on {l_brace}1 1 0{r_brace} planes. The screw dislocation core could not keep the original shape when the shear stress applied. The dislocation could not move until the shear stress became large enough. The dislocation moved in zigzag when the shear stress neared the Peierls stress. When the shear stress became larger, the dislocation moved in zigzag at the beginning and than moved almost in straight line in [2-bar11] direction. The large shear stress applied, the long distance moved before the dislocation stilled in z-direction and the large velocity in y-direction.

  18. A Simplified Technique for Implant-Abutment Level Impression after Soft Tissue Adaptation around Provisional Restoration

    Directory of Open Access Journals (Sweden)

    Ahmad Kutkut

    2016-05-01

    Full Text Available Impression techniques for implant restorations can be implant level or abutment level impressions with open tray or closed tray techniques. Conventional implant-abutment level impression techniques are predictable for maximizing esthetic outcomes. Restoration of the implant traditionally requires the use of the metal or plastic impression copings, analogs, and laboratory components. Simplifying the dental implant restoration by reducing armamentarium through incorporating conventional techniques used daily for crowns and bridges will allow more general dentists to restore implants in their practices. The demonstrated technique is useful when modifications to implant abutments are required to correct the angulation of malpositioned implants. This technique utilizes conventional crown and bridge impression techniques. As an added benefit, it reduces costs by utilizing techniques used daily for crowns and bridges. The aim of this report is to describe a simplified conventional impression technique for custom abutments and modified prefabricated solid abutments for definitive restorations.

  19. Interfacial sliding properties of bone screw materials and their effect on screw fixation strength.

    Science.gov (United States)

    Koistinen, Arto P; Korhonen, Hannu; Kröger, Heikki; Lappalainen, Reijo

    2014-09-05

    This study examined the effect of interfacial sliding and test material properties on the fixation strength and insertional properties of self-tapping bone screws. Various substitute materials (polyacetal [POM], poly(methyl methacrylate) [PMMA] and E-glass-filled Epoxy [Sawbones®]) for human bone were evaluated, and the results were compared with the findings for cadaver bone.
 Initial coefficient of friction (CoF) of the screw material stainless steel AISI316 was tested using a pin-on-disk apparatus, and the screws were exposed to pullout tests after insertion torque tests. The effect of a smooth diamond-like carbon (DLC) coating was studied by applying the coating on both CoF test balls and bone screws.
 Mechanical properties of test blocks strongly correlated to both pullout strength and insertion torque of the screws: for noncoated 2.7-mm screws, tensile strength correlated to pullout strength and insertion torque, with Pearson correlation coefficients r=0.977 and r=0.738, respectively. In contrast, CoF correlated strongly to screw insertion torque but not to pullout strength in bone substitute materials (for noncoated 2.7-mm screws, r=0.652 and r=0.248, respectively). There were no significant differences in CoF using noncoated and DLC-coated screw materials against bone substitutes.
 Proper materials for in vitro testing help in evaluating the biomechanics of the implants in advance. However, choosing the material needs attention, as their ability to model human bone depends on test type.

  20. Effect of the number of abutments on biomechanics of Branemark prosthesis with straight and tilted distal implants

    Directory of Open Access Journals (Sweden)

    Marcos Michelon Naconecy

    2010-04-01

    Full Text Available OBJECTIVE: This study aimed to evaluate the bending moments, and compressive and tensile forces in implant-supported prostheses with three, four or five abutments. MATERIAL AND METHODS: Ten Pd-Ag frameworks were tested over two master models with: 1 parallel vertical implants, and 2 tilted distal implants. Strain gauges were fixed on the abutments of each master model to measure the deformation when a static load of 50 N was applied on the cantilever (15 mm. The deformation values were measured when the metallic frameworks were tested over three, four or five abutments, and transformed into force and bending moment values. Data were analyzed by ANOVA and Tukey's test for multiple comparisons at 5% level of significance. RESULTS: Abutment #1 (adjacent to the cantilever had the highest values of force and sagittal bending moment for all tests with three, four or five abutments. Independently from the number of abutments, axial force in abutment #1 was higher in the vertical model than in the tilted model. Total moment was higher with three abutments than with four or five abutments. Independently from the inclination of implants, the mean force with four or five abutments was lower than that with three abutments. CONCLUSION: The results suggest that in the set-ups with four or five abutments tilted distal implants reduced axial force and did not increase bending moments.

  1. Effect of the number of abutments on biomechanics of Branemark prosthesis with straight and tilted distal implants.

    Science.gov (United States)

    Naconecy, Marcos Michelon; Geremia, Tomás; Cervieri, André; Teixeira, Eduardo Rolim; Shinkai, Rosemary Sadami

    2010-01-01

    This study aimed to evaluate the bending moments, and compressive and tensile forces in implant-supported prostheses with three, four or five abutments. Ten Pd-Ag frameworks were tested over two master models with: 1) parallel vertical implants, and 2) tilted distal implants. Strain gauges were fixed on the abutments of each master model to measure the deformation when a static load of 50 N was applied on the cantilever (15 mm). The deformation values were measured when the metallic frameworks were tested over three, four or five abutments, and transformed into force and bending moment values. Data were analyzed by ANOVA and Tukey's test for multiple comparisons at 5% level of significance. Abutment #1 (adjacent to the cantilever) had the highest values of force and sagittal bending moment for all tests with three, four or five abutments. Independently from the number of abutments, axial force in abutment #1 was higher in the vertical model than in the tilted model. Total moment was higher with three abutments than with four or five abutments. Independently from the inclination of implants, the mean force with four or five abutments was lower than that with three abutments. The results suggest that in the set-ups with four or five abutments tilted distal implants reduced axial force and did not increase bending moments.

  2. OSTEOSYNTHESIS OF FEMORAL NECK FRACTURES: TWO OR THREE SCREWS?

    OpenAIRE

    Basile, Ricardo; Pepicelli, Gustavo Roberto; Takata, Edmilson Takehiro

    2012-01-01

    Objectives: To evaluate the efficacy of osteosynthesis on femoral neck fractures using two instead of three screws. Methods: Thirty-nine fractures were retrospectively evaluated, divided into groups in which two screws were used in parallel (n = 28) or three screws (n =11) in an inverted triangle configuration (in accordance with the AO technique). The patients were then followed up until reaching the outcome of either consolidation or failure. Results: In the group in which two screws were u...

  3. A processing method for orthodontic mini-screws reuse

    Directory of Open Access Journals (Sweden)

    Saeed Noorollahian

    2012-01-01

    Conclusion: Cleaning of used mini-screws with phosphoric acid 37% (10 minutes and sodium hypochlorite 5.25% (30 minutes reduces tissue remnants to the level of as-received mini-screws. So it can be suggested as a processing method of used mini-screws. Previous insertion of mini-screws into the bone and above-mentioned processing method and resterilization with autoclave had no adverse effects on insertion, removal, and fracture torque values as mechanical properties indices.

  4. Drag and Torque on Locked Screw Propeller

    Directory of Open Access Journals (Sweden)

    Tomasz Tabaczek

    2014-09-01

    Full Text Available Few data on drag and torque on locked propeller towed in water are available in literature. Those data refer to propellers of specific geometry (number of blades, blade area, pitch and skew of blades. The estimation of drag and torque of an arbitrary propeller considered in analysis of ship resistance or propulsion is laborious. The authors collected and reviewed test data available in the literature. Based on collected data there were developed the empirical formulae for estimation of hydrodynamic drag and torque acting on locked screw propeller. Supplementary CFD computations were carried out in order to prove the applicability of the formulae to modern moderately skewed screw propellers.

  5. Influence of abutment height and surface roughness on in vitro retention of three luting agents.

    Science.gov (United States)

    Cano-Batalla, Jordi; Soliva-Garriga, Joan; Campillo-Funollet, Marc; Munoz-Viveros, Carlos A; Giner-Tarrida, Lluis

    2012-01-01

    This study evaluated the effects of abutment height, airborne-particle abrasion, and type of cement on the tensile resistance to dislodgement of cement-retained implant restorations. Three groups of 12 standardized abutments each were prepared with different heights (4 mm, 5 mm, and 6 mm) using a milling machine. Crowns were cast in cobalt-chrome using the lost-wax technique, airborne particle-abraded using 50-Μm aluminum oxide, and cleaned with acetone. Restorations were cemented using a noneugenol acrylic urethane cement, a resin-modified glass ionomer, or a zinc oxide-noneugenol cement. A 5-kg load was applied for 10 minutes. Samples were kept at 37°C and 100% humidity overnight. A tensile force was applied to the crown using a testing machine at a crosshead speed of 5 mm/minute until failure occurred. Next, the abutments were airborne particle-abraded with 50-Μm aluminum oxide, and the cementation and testing procedures were repeated. The effects of cement, abutment height, and surface treatment were evaluated statistically. There were significant differences among the cements. The resin-modified glass ionomer provided the greatest retention in all the tested conditions, while the zinc oxide-noneugenol cement produced the lowest retention values. Significant differences were also detected between 4-mm and 6-mm abutments, with the 6-mm abutments being more retentive. No differences were found between 4-mm and 5-mm abutments or between 5-mm and 6-mm abutments. The effect of airborne-particle abrasion was also found to be significant. A maximum increase of 90 N in retention force was observed after airborne-particle abrasion for the 5-mm abutments cemented with the acrylic urethane cement. Cement, airborne-particle abrasion, and abutment height can significantly influence retention of implant-supported crowns. Different parameters, including those specific to the patient, should be considered in the selection of a luting agent.

  6. Primary stability following abutment preparation of one-piece dental implants.

    Science.gov (United States)

    Cohen, Omer; Gabay, Eran; Machtei, Eli E

    2013-01-01

    One-piece dental implants are commonly used for the immediate restoration of missing teeth. In most cases, the clinician has to prepare the abutment intraorally to ensure a proper emergence profile and abutment angulation. However, this procedure might impair primary stability and thus potentially compromise osseointegration. The aim of this study was to determine the effect of abutment preparation on the primary stability of a one-piece implant system (UNO MIS). Implant stability was assessed by resonance frequency analysis with a novel custom-made external fixation device, validated previously, developed specifically for resonance frequency measurements of this implant. Thirty 3 × 13-mm implants were inserted in porcine jawbone with insertion torque of 15 Ncm (group A, 15 implants) or 30 Ncm (group B, 15 implants). Abutments were prepared by reducing the facial aspect of the implant abutment with a high-speed dental turbine (400,000 rpm) equipped with a medium-roughness diamond bur. Implant stability quotients (ISQs) were measured before and after abutment preparation. Mean ISQs measured in group A and group B before abutment preparation were very similar (58.2 ± 1.4 and 57.4 ± 0.9, respectively; P > .05). Following abutment preparation, three implants in group A lost primary stability. The mean ISQ value in group A was reduced from 58.2 ± 1.4 to 54.9 ± 7.9 following abutment preparation (P .05). Abutment preparation of a one-piece dental implant inserted with low insertion torque might impair implant primary stability.

  7. An innovative steel-concrete joint for integral abutment bridges

    Directory of Open Access Journals (Sweden)

    Bruno Briseghella

    2015-08-01

    Full Text Available Integral abutment bridges are becoming rather common, due to the durability problems of bearings and expansion joints. At the same time, among short- and medium-span bridges, multi-beam steel-concrete composite deck with hot-rolled girder is an economical and interesting alternative to traditional pre-stressed concrete solutions. The two concepts can be linked together to design integral steel-concrete composite bridges with the benefits of two typologies. The most critical aspect for these bridges is usually the joints between deck and piers or abutments. In this paper, an innovative beam-to-pier joint is proposed and a theoretical and experimental study is introduced and discussed. The analyzed connection is aimed at combining general ease of construction with a highly simplified assembly procedure and a good transmission of hogging and sagging moment at the supports in continuous beams. For this purpose, the traditional shear studs, used at the interface between steel beam and upper concrete slab, are also used at the ends of steel profiles welded horizontally to the end plates. To better understand the behaviour of this kind of joints and the roles played by different components, three large-scale specimens were tested and an FE model was implemented. The theoretical and experimental results confirmed the potential of the proposed connection for practical applications and indicated the way to improve its structural behaviour.

  8. Bond strengths of a porcelain material to different abutment substrates.

    Science.gov (United States)

    Ferrari, M; Mannocci, F; Vichi, A; Goracci, G

    2000-01-01

    The study evaluated the bond strength values of a single-unit all-porcelain material luted with an adhesive-resin cement to different abutment substrates: amalgam, compomer, traditional glass ionomer cement, microhybrid resin composite, two resin composites for abutment build-up, gold, sandblasted gold, dentin and enamel. Syntac enamel-dentin bonding system, in combination with IPS-Empress porcelain material, was used. After thermal cycling, the samples were inserted into a Bencor jig device and sheared in a Controls testing machine. The statistical analysis of the differences between the bond strength values obtained was performed by ANOVA and the Student-Newman-Keuls multiple-comparison test. The type of failure at the interface was evaluated using scanning electron microscopy. The type of failure, such as adhesive, cohesive and adhesive-cohesive, was correlated with bond strength values. Enamel, dentin and the two resin composites for crown build-up showed the highest bond strength values, while amalgam and gold samples showed the lowest.

  9. Hollow Mill for Extraction of Stripped Titanium Screws: An Easy ...

    African Journals Online (AJOL)

    Removal of jammed titanium screws can be difficult due to the problem of stripping of the hexagonal heads of the screws. We present a technique of extraction of stripped screws with the use of a standard 4.5 mm stainless steel hollow mill in a patient of peri‑implant fracture of the radius fixed with a titanium locking plate 2 ...

  10. Hollow Mill for Extraction of Stripped Titanium Screws: An Easy ...

    African Journals Online (AJOL)

    screws. We present a technique of extraction of stripped screws with the use of a standard 4.5 mm stainless steel hollow mill in a patient of peri-implant fracture of the radius fixed with a titanium locking plate 2 years back. The technique is quick, safe, and cost effective. Key words: Hollow mill, stripped screws, titanium locked.

  11. Dual-worm screw compressors; Compresseurs bi-vis

    Energy Technology Data Exchange (ETDEWEB)

    Baleydier, J.P. [Bitzer France, 69 - Lyon (France)

    1997-12-31

    Low power worm-screw moto-compressors are used in any king of refrigerating machineries and more and more in air conditioning systems. This paper presents the principle of dual-screw moto-compressors: worm-screw technology, role of oil (lubrication, tightness, cooling), compression, internal pressure, power reduction, lubrication, economizer, operation, model selection and accessories. (J.S.)

  12. Inadvertent Screw Stripping During Ankle Fracture Fixation in Elderly Bone

    Science.gov (United States)

    Dinah, A. Feroz; Mears, Simon C.; Knight, Trevor A.; Soin, Sandeep P.; Campbell, John T.; Belkoff, Stephen M.

    2011-01-01

    Poor screw purchase because of osteoporosis presents difficulties in ankle fracture fixation. The aim of our study was to determine if cortical thickness, unicortical versus bicortical purchase, and bone mineral density are predictors of inadvertent screw stripping and overtightening. Ten paired cadaver ankles (average donor age, 81.7 years; range, 50-97 years) were used for the study. Computed tomography scanning with phantoms of known density was used to determine the bone density along the distal fibula. A standard small-fragment, 7-hole, one-third tubular plate was applied to the lateral surface of the fibula, with 3 proximal bicortical cortical screws and 2 distal unicortical cancellous screws. A posterior plate, in which all 5 screws were cortical and achieved bicortical purchase, was subsequently applied to the same bones and positioned so that the screw holes did not overlap. A torque sensor was used to measure the torque of each screw during insertion (Ti) and then stripping (Ts). The effect of bone density, screw location, cortical thickness, and unicortical versus bicortical purchase on Ti and Ts was checked for significance (P screws were inadvertently stripped and 12% were overtightened. Despite 21% of the screws being stripped or being at risk for stripping, we found no significant predictors to warn of impending screw stripping. Additional work is needed to identify clinically useful predictors of screw stripping. PMID:23569675

  13. The Effect of Polymethyl Methacrylate Augmentation on the Primary Stability of Cannulated Bone Screws in an Anterolateral Plate in Osteoporotic Vertebrae: A Human Cadaver Study

    Science.gov (United States)

    Rüger, Matthias; Sellei, Richard M.; Stoffel, Marcus; von Rüden, Christian

    2015-01-01

    Study Design Cohort study. Objective Expandable anterolateral plates facilitate the reduction of posttraumatic deformities of thoracolumbar spine injuries and are commonly used in cases of unstable injuries or compromised bone quality. In this in vitro study, the craniocaudal yield load of the osseous fixation of an anterior angular stable plate fixation system and the effect of polymethyl methacrylate (PMMA) screw augmentation on the primary stability of the screw–bone interface during kyphosis reduction was evaluated in 12 osteoporotic human thoracolumbar vertebrae. Methods The anterolateral stabilization device used for this study is comprised of two swiveling flanges and an expandable midsection. It facilitates the controlled reduction of kyphotic deformities in situ with a geared distractor. Single flanges were attached to 12 thoracolumbar vertebrae. Six specimens were augmented with PMMA by means of cannulated bone screws. The constructs were subjected to static, displacement-controlled craniocaudal loading to failure in a servohydraulic testing machine. Results The uncemented screws cut out at a mean 393 ± 66 N, whereas the cemented screws showed significantly higher yield load of 966 ± 166 N (p < 0.02). We detected no significant correlation between bone mineral density and yield load in this setting. Conclusion Our results indicate that PMMA augmentation is an effective method to increase two- to threefold the primary stability of the screw–bone interface of an anterolateral spine stabilization system in osteoporotic bone. We recommend it in cases of severely compromised bone quality to reduce the risk of screw loosening during initial kyphosis correction and to increase long-term construct stability. PMID:26835201

  14. Femoral Component Varus Malposition is Associated with Tibial Aseptic Loosening After TKA.

    Science.gov (United States)

    Lee, Bum-Sik; Cho, Hyun-Ik; Bin, Seong-Il; Kim, Jong-Min; Jo, Byeong-Kyu

    2018-02-01

    survivorship. Although aseptic loosening occurred most commonly on the tibial side, the primary origin of the overall varus malalignment was femoral component varus malpositioning. Aiming for neutral alignment in TKA still seems to be a reasonable strategy in clinical practice. Level III, therapeutic study.

  15. Fracture strength of implant abutments after fatigue testing: A systematic review and a meta-analysis.

    Science.gov (United States)

    Coray, Rafaela; Zeltner, Marco; Özcan, Mutlu

    2016-09-01

    The use of implants and their respective suprastructures to replace missing teeth has become a common therapeutic option in dentistry. Prior to their clinical application, all implant components have to demonstrate suitable durability in laboratory studies. Fatigue tests utilising cyclic loading typically simulate masticatory function in vitro. The objectives of this systematic review were to assess the loading conditions used for fatigue testing of implant abutments and to compare the fracture strength of different types of implant abutment and abutment-connection types after cyclic loading. Original scientific papers published in MEDLINE (PubMed) and Embase database in English between 01/01/1970 and 12/31/2014 on cyclic loading on implant abutments were included in this systematic review. The following MeSH terms, search terms and their combinations were used: "in vitro" or "ex vivo" or experimental or laboratory, "dental implants", "implants, experimental", "dental prosthesis, implant-supported", "fatigue", "dental abutments", "cyclic loading", "cyclic fatigue", "mechanical fatigue", "fatigue resistance", "bending moments", and "fracture". Two reviewers performed screening and data abstraction. Only the studies that reported, static fracture values before and after fatigue cycling of implant abutments, were included that allowed comparison of aging effect through cyclic loading. Data (N) were analyzed using a weighted linear regression analysis (α=0.05). The selection process resulted in the final sample of 7 studies. In general, loading conditions of the fatigue tests revealed heterogeneity in the sample but a meta-analysis could be performed for the following parameters: a) abutment material, b) implant-abutment connection, and (c) number of fatigue cycles. Mean fracture strength of titanium (508.9±334.6N) and for zirconia abutments (698.6±452.6N) did not show significant difference after cyclic loading (p>0.05). Internal implant-abutment connections

  16. Entry zone of iliac screw fixation to maintain proper entry width and screw length.

    Science.gov (United States)

    Park, Soo-An; Kwak, Dai-Soon; You, Sung-Lim

    2015-11-01

    To evaluate the entry zone of iliac screw fixation to maintain proper entry width and screw length. Computed tomography images of pelvic bones from 90 human cadavers were reconstructed into 3-dimensional models. In each model, a sectional image crossing the posterior superior iliac spine (PSIS) and anterior inferior iliac spine (AIIS) and consecutive sectional images up to 20 mm superiorly and inferiorly from the PSIS with 1-mm intervals aiming the AIIS were obtained. One virtual iliac screw with 10-mm diameter was introduced onto the PSIS at the middle and at the lateral and medial 1/4 points on the prominence of the posterior iliac spine. The entry width of the bony prominence and the corresponding maximal screw length available were evaluated for each entry point. The entry width was smallest on the inferior 20 mm (4.7 ± 3.0 mm) and gradually increased up to the superior 10 mm (19.1 ± 3.9 mm) sectional images. The maximal screw length was smallest on the superior 20 mm (76.7 ± 39.7 mm) and gradually increased down to the inferior 10 mm (112.3 ± 15.1 mm) sectional images. The maximal screw lengths were significantly greatest at the most medial point and smallest at the most lateral point on the superior 20- and 10-mm sectional images and at the PSIS. The iliac screw fixation entry zone to maintain proper screw length and entry width is outlined from 20 mm superiorly to 10 mm inferiorly from the PSIS and is located more medially from the prominence of the posterior iliac spine.

  17. Sacroiliac screw fixation for tile B fractures.

    NARCIS (Netherlands)

    Bosch, E.W. van den; Zwienen, C.M. van; Hoek van Dijke, G.A.; Snijders, C.J.; Vugt, A.B. van

    2003-01-01

    BACKGROUND: The purpose of this comparative cadaveric study was to investigate whether the stability of partially unstable pelvic fractures can be improved by combining plate fixation of the symphysis with a posterior sacroiliac screw. METHODS: In six specimens, a Tile B1 (open-book) pelvic fracture

  18. Nylon screws make inexpensive coil forms

    Science.gov (United States)

    Aucoin, G.; Rosenthal, C.

    1978-01-01

    Standard nylon screws act as coil form copper wire laid down in spiral thread. Completed coil may be bonded to printed-circuit board. However, it is impossible to tune coil by adjusting spacing between windings, technique sometimes used with air-core coils.

  19. On Loosening Plastic Composite under Active Load and Its Influence on the Deformation and Strength Properties

    Directory of Open Access Journals (Sweden)

    K. F. Komkov

    2015-01-01

    Full Text Available Processing the test results of the composite, which is a mechanical mixture of metal particles with a plastic polymer binder, has shown that its deformation and strength properties are substantially different from those of stable plastic material. The specimen tests for tensile and compression with measuring transverse deformations, as well as torsion tests of tubular samples have revealed that the process of its deformation is accompanied by a change in the original structure.The composite instability is caused by the fact that during this process, it acquires considerable loosening that depends on the type of the stress-state. Hard metal particles are hardly deformed at any stress-state, but they form a layer of bonds that affect the mixture behavior under force action. The total deformation is the plastic flow of the binder on which deformation, caused both by sliding and by loss of the surface layer bonds, is superimposed.The analysis shows that with destruction at tensile test the non-linear part of the bulk deformation (dilatancy is 6 times more than "conditionally" elastic (3.5 times compressed. The objective of this work is to develop a technique for determining a dilatancy, define its influence on deformation and strength properties of the composite, and improve the mathematical model of the material. The proposed model based on the tensor-nonlinear equations describes loosening, as an additional component of the mean deformation and as a mean stress component, hereinafter referred to as: the first - by the deformation, the second – by the stress. A ratio value of the nonlinear part of deformation with the quadratic tensor argument to the linear part, which reaches 0.3, shows the need for such equations. It also shows the influence of deformation on the relationship between the deviators.To enhance capabilities of mathematical model is possible after including therein the equations for the spherical part of the tensor of deformation

  20. A comparison of screw insertion torque and pullout strength.

    Science.gov (United States)

    Ricci, William M; Tornetta, Paul; Petteys, Timothy; Gerlach, Darin; Cartner, Jacob; Walker, Zakiyyah; Russell, Thomas A

    2010-06-01

    Pullout strength of screws is a parameter used to evaluate plate screw fixation strength. However, screw fixation strength may be more closely related to its ability to generate sufficient insertion because stable nonlocked plate-screw fracture fixation requires sufficient compression between plate and bone such that no motion occurs between the plate and bone under physiological loads. Compression is generated by tightening of screws. In osteoporotic cancellous bone, sufficient screw insertion torque may not be generated before screw stripping. The effect of screw thread pitch on generation of maximum insertion torque (MIT) and pullout strength (POS) was investigated in an osteoporotic cancellous bone model and the relationship between MIT and POS was analyzed. Stainless steel screws with constant major (5.0 mm) and minor (2.7 mm) diameters but with varying thread pitches (1, 1.2, 1.5, 1.6, and 1.75 mm) were tested for MIT and POS in a validated osteoporotic surrogate for cancellous bone (density of 160 kg/m(3) [10 lbs/ft(3)]). MIT was measured with a torque-measuring hex driver for screws inserted through a one-third tubular plate. POS was measured after insertion of screws to a depth of 20 mm based on the Standard Specification and Test Methods for Metallic Medical Bone Screws (ASTM F 543-07). Five screws were tested for each failure mode and screw design. The relationship between MIT and compressive force between the plate and bone surrogate was evaluated using pressure-sensitive film. There was a significant difference in mean MIT based on screw pitch (P compression between the plate and bone surrogate was found for increasing screw torque (R(2) = 0.97). These results indicate that the ability of different screw designs to generate high screw insertion torque in a model of osteoporotic cancellous bone is unrelated to their pullout strength. Therefore, extrapolation of results for POS to identify optimal screw design for osteoporotic bone may not be valid

  1. [Clinical application of percutaneous iliosacral screws combined with pubic ramus screws in Tile B pelvic fracture].

    Science.gov (United States)

    Xu, Qi-Fei; Lin, Kui-Ran; Zhao, Dai-Jie; Zhang, Song-Qin; Feng, Sheng-Kai; Li, Chen

    2017-03-25

    To investigate the application and effect of minimally invasive percutaneous anterior pelvic pubic ramus screw fixation in Tile B fractures. A retrospective review was conducted on 56 patients with posterior pelvic ring injury combined with fractures of anterior pubic and ischiadic ramus treated between May 2010 and August 2015, including 31 males and 25 females with an average age of 36.8 years old ranging from 35 to 65 years old. Based on the Tile classification, there were 13 cases of Tile B1 type, 28 cases of Tile B2 type and 15 cases of Tile B3 type. Among them, 26 patients were treated with sacroiliac screws combined with external fixation (external fixator group) and the other 30 patients underwent sacroiliac screw fixation combined with anterior screw fixation (pubic ramus screw group). Postoperative complications, postoperative ambulation time, fracture healing, blood loss, Majeed pelvic function score and visual analogue scale(VAS) were compared between two groups. Fifty-four patients were followed up from 3 to 24 months with a mean of 12 months. There were no significant difference in the peri-operative bleeding and operation time between two groups( P >0.05). The postoperative activity time and fracture healing time of pubic ramus screw group were shorter than those of the external fixator group, the differences were statistically significant( P safty treatment method to the Tile B pelvic fracture. It has advantages of early ambulation, relief of the pain and few complications.

  2. Method of Retention Control for Compromised Periodontal Bone Support Abutment of Conical Crown Retained Denture

    Directory of Open Access Journals (Sweden)

    Chau-Hsiang Wang

    2010-08-01

    Full Text Available Conical crown-retained dentures (CCRD show a higher survival rate and greater patient satisfaction than transitional removable partial dentures during long-term follow-up. However, unsustainable denture retention force on supporting abutments after initial delivery and loss retention are frequently seen in long-term follow-up of clinical cases. The main causes are insufficient information concerning denture retention designs and the retention-tolerance of the supporting abutments. Monitoring by dental technicians of the quality of dental prostheses is critical. This case report describes an optimal method for CCRD construction that determines and distributes an optimal denture retention force on the supporting abutments to allow the patient to easily remove the denture while ensuring that the CCRD remains in place during physiologic activities. Oral rehabilitation with CCRD should consider the condition of the abutment periodontal support, the interarch occlusal relationship, supplemental fatigue of the terminal abutment, and patient's estimated bite force. The effects of friction on the abutment's inner crown were based on an optimal a angle. The dental laboratory used these measurements to fabricate a CCRD using a Koni-Meter to adjust the retention of the inner crown. This method protects the abutments and reduces the wear between the inner and outer crowns. The CCRD achieved good esthetic results and physiologic functions. Periodic long-term follow-up of the patient and CCRD after initial placement is recommended.

  3. Analysis of the Generating and Influencing Factors of Vertical Cracking in Abutments during Construction

    Directory of Open Access Journals (Sweden)

    Xingwei Xue

    2018-01-01

    Full Text Available In order to analyze the causes of cracking in abutments subject to concrete shrinkage and temperature variation during the construction process and to determine factors affecting the mechanical properties of the abutment, nonlinear calculations capturing abutment behavior are conducted with Midas/FEA software. Using these calculations, the cracking mechanism is identified, and the influence of the evaluated factors is analyzed. It is concluded that the deformation between the pile cap and abutment backwall as constrained by a pile foundation when subjected to concrete shrinkage and temperature changes is the basic cause of abutment cracks during construction; these cracks form over the piles and develop upward. For a given reinforcement ratio, the distribution of horizontal crack-control steel using small, closely spaced bars is more beneficial. When pile-bearing capacity meets the standard, the width of the generated cracks tends to decrease with the decrease in the diameter of the piles. The existence of a postcast strip in the abutment backwall also contributes to the decrease in the depth of the crack. Finally, the impact of age difference between the pile cap concrete and abutment backwall concrete on cracking is inconsequential.

  4. The use of definitive implant abutments for the fabrication of provisional crowns: a case series.

    Science.gov (United States)

    Bilhan, Hakan; Geckili, Onur; Mumcu, Emre

    2011-10-01

    The anterior region is a challenge for most clinicians to achieve optimal esthetics with dental implants. The provisional crown is a key factor in the success of obtaining pink esthetics around restorations with single implants, by soft tissue and inter-proximal papilla shaping. Provisional abutments bring additional costs and make the treatment more expensive. Since one of the aims of the clinician is to reduce costs and find more economic ways to raise patient satisfaction, this paper describes a practical method for chair-side fabrication of non-occlusal loaded provisional crowns used by the authors for several years successfully. Twenty two patients (9 males, 13 females; mean age, 36,72 years) with one missing anterior tooth were treated by using the presented method. Metal definitive abutments instead of provisional abutments were used and provisional crowns were fabricated on the definitive abutments for all of the patients. The marginal fit was finished on a laboratory analogue and temporarily cemented to the abutments. The marginal adaptation of the crowns was evaluated radiographically. The patients were all satisfied with the final appearance and no complications occurred until the implants were loaded with permanent restorations. The use of the definitive abutments for provisional crowns instead of provisional abutments reduces the costs and the same results can be obtained.

  5. Influences of implant neck design and implant-abutment joint type on peri-implant bone stress and abutment micromovement: three-dimensional finite element analysis.

    Science.gov (United States)

    Yamanishi, Yasufumi; Yamaguchi, Satoshi; Imazato, Satoshi; Nakano, Tamaki; Yatani, Hirofumi

    2012-11-01

    Occlusal overloading is one of the causes of peri-implant bone resorption, and many studies on stress distribution in the peri-implant bone by three-dimensional finite element analysis (3D FEA) have been performed. However, the FEA models previously reported were simplified and far from representing what occurs in clinical situations. In this study, 3D FEA was conducted with simulation of the complex structure of dental implants, and the influences of neck design and connections with an abutment on peri-implant bone stress and abutment micromovement were investigated. Three types of two-piece implant CAD models were designed: external joint with a conical tapered neck (EJ), internal joint with a straight neck (IJ), and conical joint with a reverse conical neck (CJ). 3D FEA was performed with the setting of a "contact" condition at the component interface, and stress distribution in the peri-implant bone and abutment micromovement were analyzed. The shear stress was concentrated on the mesiodistal side of the cortical bone for EJ. EJ had the largest amount of abutment micromovement. While the von Mises and shear stresses around the implant neck were concentrated on the labial bone for IJ, they were distributed on the mesiodistal side of the cortical bone for CJ. CJ had the least amount of abutment micromovement. Implants with a conical joint with an abutment and reverse conical neck design may effectively control occlusal overloading on the labial bone and abutment micromovement. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  6. Evaluation of Bond Strength between Grooved Titanium Alloy Implant Abutments and Provisional Veneering Materials after Surface Treatment of the Abutments: An In vitro Study.

    Science.gov (United States)

    Venkat, Gowtham; Krishnan, Murugesan; Srinivasan, Suganya; Balasubramanian, Muthukumar

    2017-01-01

    Titanium has become the material of choice with greater applications in dental implants. The success of the dental implant does not only depend on the integration of the implant to the bone but also on the function and longevity of the superstructure. The clinical condition that demands long-term interim prosthesis is challenging owing to the decreased bond between the abutment and the veneering material. Hence, various surface treatments are done on the abutments to increase the bond strength. This study aimed to evaluate the bond strength between the abutment and the provisional veneering materials by surface treatments such as acid etching, laser etching, and sand blasting of the abutment. Forty titanium alloy abutments of 3 mm diameter and 11 mm height were grouped into four groups with ten samples. Groups A, B, C, and D are untreated abutments, sand blasted with 110 μm aluminum particles, etched with 1% hydrofluoric acid and 30% nitric acid, and laser etched with Nd: YAG laser, respectively. Provisional crowns were fabricated with bis-acrylic resin and cemented with noneugenol temporary luting cement. The shear bond strength was measured in universal testing machine using modified Shell-Nielsen shear test after the cemented samples were stored in water at 25°C for 24 h. Load was applied at a constant cross head speed of 5 mm/min until a sudden decrease in resistance indicative of bond failure was observed. The corresponding force values were recorded, and statistical analysis was done using one-way ANOVA and Newman-Keuls post hoc test. The laser-etched samples showed higher bond strength. Among the three surface treatments, laser etching showed the highest bond strength between titanium alloy implant abutment and provisional restorations. The sand-blasted surfaces demonstrated a significant difference in bond strength compared to laser-etched surfaces. The results of this study confirmed that a combination of surface treatments and bond agents enhances the

  7. Effect of Abutment Height on Retention of Single Cementretained, Wide- and Narrow-platform Implant-supported Restorations

    Directory of Open Access Journals (Sweden)

    Fariba Saleh Saber

    2012-06-01

    Full Text Available Background and aims. In contrast to prepared natural dentin abutments, little is known concerning factors influencing the retention of fixed prostheses cemented to implant abutments. The aim of this study was to investigate the effect of implant abutment height on the retention of single castings cemented to wide and narrow platform implant abutments. Materials and methods. Thirty-six parallel-sided abutments (Biohorizon Straight Abutment of narrow platform (NP and wide platform (WP sizes with their analogs were used. In each group of platform size, abutments were prepared with axial wall heights of 5, 4, 3, 2 mm (n=9. On the whole 72 castings were constructed, which incorporated an attachment to allow removal. Castings were cemented to abutments with TempBond®. A uniaxial tensile force was applied to the crown using an Instron machine until cement failure occurred. Analysis of variance of the models were fit to determine the effect of height of abutment of the restorations on the mean tensile strength (α=0.05. Results. The mean peak removal force for corresponding abutments was significantly different (P NP; (2 with alteration of axial wall height for NP: 5 mm > 4 mm > 3 mm = 2 mm and for WP: 5 mm > 4 mm = 3 mm = 2 mm. Conclusion. The retention of NP cement-retained restorations is influenced by the wall height but not in same manner as WP. Restorations of narrow-platform size with longer abutment exhibited higher tensile resistance to dislodgement.

  8. Assessing accuracy of sustentaculum screw placement during calcaneal fixation.

    Science.gov (United States)

    Gitajn, I Leah; Toussaint, Rull James; Kwon, John Y

    2013-02-01

    The aim of this study was to determine the ability of the Harris heel view to confirm placement of the sustentacular screw during calcaneal fixation. A 4.0 cancellous screw was placed in a cadaveric specimen, from lateral to medial in 5 configurations: (1) within the sustentaculum, (2) misdirected inferiorly to sustentaculum, (3) misdirected superiorly to sustentaculum, (4) misdirected anteriorly to sustentaculum, and (5) misdirected posteriorly to sustentaculum. Harris heel views were obtained at 5 angulations and were analyzed to determine screw placement. A screw placed anatomically was radiographically confirmed by the Harris heel view to be within the sustentaculum in all views. An inferiorly misdirected screw appeared radiographically within the sustentaculum at 30, 40 and 50 degrees but was confirmed misplaced on the 10- and 20-degree views. A posteriorly misdirected screw was confirmed misplaced on all 5 views. An anteriorly misdirected screw appeared radiographically within the sustentaculum on the 10-degree view but was confirmed misplaced on all other views. A superiorly misdirected screw was confirmed misplaced on all views. Clinicians should be aware that several specific axial heel views are required to verify placement of the sustentacular screw. An inferiorly misdirected screw will appear to be within the sustentaculum with the standard Harris heel view. Heel views should be obtained from a range of 10 to 50 degrees to confirm accurate placement of the sustentacular screw.

  9. Abutment Material Effect on Peri-implant Soft Tissue Color and Perceived Esthetics.

    Science.gov (United States)

    Kim, Aram; Campbell, Stephen D; Viana, Marlos A G; Knoernschild, Kent L

    2016-12-01

    The purpose of this study was to evaluate the effect of implant abutment material on peri-implant soft tissue color using intraoral spectrophotometric analysis and to compare the clinical outcomes with patient and clinician perception and satisfaction. Thirty patients and four prosthodontic faculty members participated. Abutments were zirconia, gold-hued titanium, and titanium. Peri-implant mucosa color of a single anterior implant restoration was compared to the patient's control tooth. Spectrophotometric analysis using SpectroShade TM Micro data determined the color difference (ΔE, ΔL*, Δa*, Δb*) between the midfacial peri-implant soft tissue for each abutment material and the marginal gingiva of the control tooth. Color difference values of the abutment groups were compared using ANOVA (α = 0.05). Patient and clinician satisfaction surveys were also conducted using a color-correcting light source. The results of each patient and clinician survey question were compared using chi-square analysis (α = 0.05). Pearson correlation analyses identified the relationship between the total color difference (ΔE) and the patient/clinician perception and satisfaction, as well as between ΔE and tissue thickness. Zirconia abutments displayed significantly smaller spectrophotometric gingival color difference (ΔE) compared to titanium and gold-hued titanium abutments (respectively, 3.98 ± 0.99; 7.22 ± 3.31; 5.65 ± 2.11; p esthetics than crown (white) esthetics (p < 0.05). Peri-implant mucosa with zirconia abutments demonstrated significantly lower mean color difference compared to titanium or gold-hued titanium abutments as measured spectrophotometrically; however, no statistical difference in patient or clinician perception/satisfaction among abutment materials was demonstrated. Patients were significantly more satisfied than clinicians. © 2015 by the American College of Prosthodontists.

  10. EFFECT OF CAST RECTIFIERS ON THE MARGINAL FIT OF UCLA ABUTMENTS

    Science.gov (United States)

    Jaime, Ana Paula Gumieiro; de Vasconcellos, Diego Klee; Mesquita, Alfredo Mikail Melo; Kimpara, Estevão Tomomitsu; Bottino, Marco Antonio

    2007-01-01

    Objectives: This study assessed the effect of cast rectifiers on the marginal misfit of cast UCLA abutments compared to premachined UCLA abutments. The influence of casting and porcelain baking on the marginal misfit of these components was also investigated. Methods: Two groups were analyzed: test group – 10 cast UCLA abutments, finished with cast rectifier and submitted to ceramic application; control group – 10 premachined UCLA abutments, cast with noble metal alloy and submitted to ceramic application. Vertical misfit measurements were performed under light microscopy. In the test group, measurements were performed before and after the use of cast rectifiers, and after ceramic application. In the control group, measurements were performed before and after casting, and after ceramic application. Data were submitted to statistical analysis by ANOVA and Tukey's test (α= 5%). Results: The use of cast rectifiers significantly reduced the marginal misfit of cast UCLA abutments (from 25.68μm to 14.83μm; p<0.05). After ceramic application, the rectified cylinders presented misfit values (16.18μm) similar to those of premachined components (14.3 μm). Casting of the premachined UCLA abutments altered the marginal misfit of these components (from 9.63 μm to 14.6 μm; p<0.05). There were no significant changes after porcelain baking, in both groups. Conclusion: The use of cast rectifiers reduced the vertical misfit of cast UCLA abutments. Even with carefully performed laboratory steps, changes at the implant interface of premachined UCLA abutments occurred. Ceramic application did not alter the marginal misfit values of UCLA abutments. PMID:19089125

  11. Effect of cast rectifiers on the marginal fit of UCLA abutments

    Directory of Open Access Journals (Sweden)

    Ana Paula Gumieiro Jaime

    2007-06-01

    Full Text Available OBJECTIVES: This study assessed the effect of cast rectifiers on the marginal misfit of cast UCLA abutments compared to premachined UCLA abutments. The influence of casting and porcelain baking on the marginal misfit of these components was also investigated. METHODS: Two groups were analyzed: test group - 10 cast UCLA abutments, finished with cast rectifier and submitted to ceramic application; control group - 10 premachined UCLA abutments, cast with noble metal alloy and submitted to ceramic application. Vertical misfit measurements were performed under light microscopy. In the test group, measurements were performed before and after the use of cast rectifiers, and after ceramic application. In the control group, measurements were performed before and after casting, and after ceramic application. Data were submitted to statistical analysis by ANOVA and Tukey's test (a= 5%. RESULTS: The use of cast rectifiers significantly reduced the marginal misfit of cast UCLA abutments (from 25.68mm to 14.83mm; p<0.05. After ceramic application, the rectified cylinders presented misfit values (16.18mm similar to those of premachined components (14.3 mm. Casting of the premachined UCLA abutments altered the marginal misfit of these components (from 9.63 mm to 14.6 mm; p<0.05. There were no significant changes after porcelain baking, in both groups. CONCLUSION: The use of cast rectifiers reduced the vertical misfit of cast UCLA abutments. Even with carefully performed laboratory steps, changes at the implant interface of premachined UCLA abutments occurred. Ceramic application did not alter the marginal misfit values of UCLA abutments.

  12. Influence of implant abutment material on the color of different ceramic crown systems.

    Science.gov (United States)

    Dede, Doğu Ömür; Armağanci, Arzu; Ceylan, Gözlem; Celik, Ersan; Cankaya, Soner; Yilmaz, Burak

    2016-11-01

    Ceramics are widely used for anterior restorations; however, clinical color reproduction still constitutes a challenge particularly when the ceramic crowns are used on titanium implant abutments. The purpose of this in vitro study was to investigate the effect of implant abutment material on the color of different ceramic material systems. Forty disks (11×1.5 mm, shade A2) were fabricated from medium-opacity (mo) and high-translucency (ht) lithium disilicate (IPS e.max) blocks, an aluminous ceramic (VITA In-Ceram Alumina), and a zirconia (Zirkonzahn) ceramic system. Disks were fabricated to represent 3 different implant abutments (zirconia, gold-palladium, and titanium) and dentin (composite resin, A2 shade) as background (11×2 mm). Disk-shaped composite resin specimens in A2 shade were fabricated to represent the cement layer. The color measurements of ceramic specimens were made on composite resin abutment materials using a spectrophotometer. CIELab color coordinates were recorded, and the color coordinates measured on composite resin background served as the control group. Color differences (ΔE 00 ) between the control and test groups were calculated. The data were analyzed with 2-way analysis of variance (ANOVA) and compared with the Tukey HSD test (α=.05). The ceramics system, abutment material, and their interaction were significant for ΔE 00 values (P2.25) were observed for lithium disilicate ceramics on titanium abutments (2.46-2.50). The ΔE 00 values of lithium disilicate ceramics for gold-palladium and titanium abutments were significantly higher than for other groups (P2.25) of an implant-supported lithium disilicate ceramic restoration may be clinically unacceptable if it is fabricated over a titanium abutment. Zirconia may be a more suitable abutment material for implant-supported ceramic restorations. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  13. OSTEOSYNTHESIS OF FEMORAL NECK FRACTURES: TWO OR THREE SCREWS?

    Science.gov (United States)

    Basile, Ricardo; Pepicelli, Gustavo Roberto; Takata, Edmilson Takehiro

    2012-01-01

    To evaluate the efficacy of osteosynthesis on femoral neck fractures using two instead of three screws. Thirty-nine fractures were retrospectively evaluated, divided into groups in which two screws were used in parallel (n = 28) or three screws (n =11) in an inverted triangle configuration (in accordance with the AO technique). The patients were then followed up until reaching the outcome of either consolidation or failure. In the group in which two screws were used, consolidation was observed in 23 of the 28 fractures (82%). In the group in which three screws were used, consolidation was observed in 6 of the 11 fractures (55%). There was no statistically significant difference between these percentages. There was no difference in the prognosis for these fractures when treated using two screws in parallel or three screws in an inverted triangle in accordance with the AO technique. Further studies are needed in order to establish a definitive conclusion.

  14. Dental materials and their performance for the management of screw access channels in implant-supported restorations.

    Science.gov (United States)

    Raab, Philipp; Alamanos, Christos; Hahnel, Sebastian; Papavasileiou, Dimitrios; Behr, Michael; Rosentritt, Martin

    2017-03-31

    Unsuccessfully sealed screw access channels of prosthetic implant abutments may lead to malodor or peri-implant diseases in gingival tissues adjacent to implant-supported restorations. Therefore, 72 sets of screw channel analogs with six different materials incorporated (Polytetrafluoroethylene (PTFE), wax, gutta-percha, cavit, endofrost-pellets and cotton pellets) were exposed (2.5 h, 37°C) to Streptococcus mutans, oralis and Candida albicans suspensions. Bacterial adherence was quantified by using the fluorescence dye, Alamar Blue/resazurin, and an automated multifunctional reader. For quantification of fungal adherence the ATP-based bioluminescence approach was used. High relative fluorescence and luminescence intensities (>10,000), indicating high adhesion of streptococci and fungi were found for cotton and endofrost-pellets and low intensities (cavit and PTFE. The quantity of bacterial and fungal adhesion differed significantly between the assessed various sealing materials. In conclusion and within the limitations of this study, wax, gutta-percha, cavit and PTFE should be preferred as sealing materials.

  15. A Nearly Lethal Screw: An Unusual Cause of Recurrent Bradycardia and Asystole Episodes after Fixation of the Cervical Spine

    Directory of Open Access Journals (Sweden)

    Amit Frenkel

    2017-01-01

    Full Text Available We present a case of a 51-year-old man who was injured in a bicycle accident. His main injury was an unstable fracture of the cervical and thoracic vertebral column. Several hours after his arrival to the hospital the patient underwent open reduction and internal fixation (ORIF of the cervical and thoracic spine. The patient was hospitalized in our critical care unit for 99 days. During this time patient had several episodes of severe bradycardia and asystole; some were short with spontaneous return to sinus and some required pharmacological treatment and even Cardiopulmonary Resuscitation (CPR. Initially, these episodes were attributed to the high cervical spine injury, but, later on, CT scan suggested that a fixation screw abutted on the esophagus and activated the vagus nerve by direct pressure. After repositioning of the cervical fixation, the bradycardia and asystole episodes were no longer observed and the patient was released to a rehabilitation ward. This case is presented in order to alert practitioners to the possibility that, after operative fixation of cervical spine injuries, recurrent episodes of bradyarrhythmia can be caused by incorrect placement of the fixation screws and might be confused with the natural history of the high cervical cord injury.

  16. Research and application of absorbable screw in orthopedics: a clinical review comparing PDLLA screw with metal screw in patients with simple medial malleolus fracture

    OpenAIRE

    TANG Jin; HU Jin-feng; GUO Wei-chun; YU Ling; ZHAO Sheng-hao

    2013-01-01

    【Abstract】Objective: To observe the therapeutic effect of absorbable screw in medial malleolus fracture and discuss its clinical application in orthopedics. Methods: A total of 129 patients with simple medial malleolus fracture were studied. Among them, 64 patients were treated with poly-D, L-lactic acid (PDLLA) absorbable screws, while the others were treated with metal screws. All the patients were followed up for 12-20 months (averaged 18.4 months) and the the...

  17. Biomechanical Analysis of Individual All-Ceramic Abutments Used in Dental Implantology

    Directory of Open Access Journals (Sweden)

    Ziębowicz B.

    2016-09-01

    Full Text Available The paper presents the results of finite element analysis and experimental testing under simulated physiological loading conditions on issues shaping the functional properties of individual all-ceramic abutments manufactured by CAD/CAM technology. The conducted research have cognitive significance showing the all-ceramic abutment behavior, as a key element of the implantological system, under the action of cyclic load. The aim of this study was evaluation the fatigue behavior of yttria-stabilized zirconia abutment submitted to cyclic stresses, conducted in accordance with EN ISO 14801 applies to dynamic fatigue tests of endosseous dental implants.

  18. Biomechanical study of pedicle screw fixation in severely osteoporotic bone.

    Science.gov (United States)

    Cook, Stephen D; Salkeld, Samantha L; Stanley, Tom; Faciane, Albert; Miller, Scot D

    2004-01-01

    Obtaining adequate purchase with standard pedicle screw techniques remains a challenge in poor quality bone. The development of alternate insertion techniques and screw designs was prompted by recognition of potential fixation complications. An expandable pedicle screw design has been shown to significantly improve fixation compared to a conventional screw in poor quality bone. The purpose of this study was to determine if polymethylmethacrylate (PMMA) bone cement augmentation of an expandable pedicle screw can further improve fixation strength compared to the expandable screw alone in severely osteoporotic bone. A technique for cement insertion into the pedicle by means of the cannulated central portion of the expandable screw is also described. The axial pullout strength, stiffness and energy absorbed of cemented and noncemented expandable pedicle screws was determined in cadaveric vertebrae. Twenty-one fresh unembalmed vertebrae from the thoracolumbar spine were used. Radiographs and bone mineral density measurements (BMD) were used to characterize bone quality. Paired cemented and noncemented pedicle screw axial pullout strength was determined through mechanical testing. Mechanical pullout strength, stiffness and energy to failure was correlated with BMD. Overall, there was a 250% increase in mean pullout strength with the cemented expandable screw compared with a noncemented expandable screw including a greater than twofold increase in pullout strength in the most severely osteoporotic bone. The mean stiffness and energy absorbed to failure was also significantly increased. A cemented conventional screw achieved a pullout strength similar to the noncemented expandable screw. PMMA cement augmentation of the expandable pedicle screw may be a viable clinical option for achieving fixation in severely osteoporotic bone.

  19. Screw Versus Plate Fixation for Chevron Osteotomy: A Retrospective Study.

    Science.gov (United States)

    Andrews, Boyd J; Fallat, Lawrence M; Kish, John P

    2016-01-01

    The chevron osteotomy is a popular procedure used for the correction of moderate hallux abducto valgus deformity. Fixation is typically accomplished with Kirschner wires or bone screws; however, in cystic or osteoporotic bone, these could be inadequate, resulting in displacement of the capital fragment. We propose using a locking plate and interfragmental screw for fixation of the chevron osteotomy that could reduce the healing time and decrease the incidence of displacement. We performed a retrospective cohort study for chevron osteotomies on 75 feet (73 patients). The control groups underwent fixation with 1 screw in 30 feet (40%) and 2 screws in 30 feet (40%). A total of 15 feet (20%) were included in the locking plate and interfragmental screw group. The patients were followed up until bone healing was achieved at a median of 7 (range 6 to 14) weeks. Our hypothesis was that those treated with the locking plate and interfragmental screw would have a faster healing time and fewer incidents of capital fragment displacement compared with the 1- or 2-screw groups. The corresponding mean intervals to healing for the 1-screw group was 7.71 ± 1.28 (range 6 to 10) weeks, for the 2-screw group was 7.27 ± 1.57 (range 6 to 14) weeks, and for the locking plate and interfragmental screw group was 7.01 ± 1.00 (range 6 to 9) weeks. One case of capital fragment displacement occurred in the single screw group and one in the 2-screw group. No displacement occurred in the locking plate and interfragmental screw group. Neither finding was statistically significant. However, we believe the locking plate and interfragmental screw could be a viable option in patients with osteoporotic and cystic bone changes for correction of hallux abducto valgus. Copyright © 2016 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  20. Research and application of absorbable screw in orthopedics: a clinical review comparing PDLLA screw with metal screw in patients with simple medial malleolus fracture

    Directory of Open Access Journals (Sweden)

    TANG Jin

    2013-02-01

    Full Text Available 【Abstract】Objective: To observe the therapeutic effect of absorbable screw in medial malleolus fracture and discuss its clinical application in orthopedics. Methods: A total of 129 patients with simple medial malleolus fracture were studied. Among them, 64 patients were treated with poly-D, L-lactic acid (PDLLA absorbable screws, while the others were treated with metal screws. All the patients were followed up for 12-20 months (averaged 18.4 months and the therapeutic effect was evaluated ac-cording to the American Orthopaedic Foot and Ankle Soci-ety clinical rating systems. Results: In absorbable screw group, we obtained excel-lent and good results in 62 cases (96.88%; in steel screw group, 61 cases (93.85% achieved excellent and good results. There was no significant difference between the two groups. Conclusion: In the treatment of malleolus fracture, absorbable screw can achieve the same result compared with metal screw fixation. Absorbable screw is preferred due to its advantages of safety, cleanliness and avoiding the removal procedure associated with metallic implants. Key words: Ankle; Bone screws; Fractures, bone

  1. [Effectiveness of U-shape titanium screw-rod fixation system with bone autografting for lumbar spondylolysis of young adults].

    Science.gov (United States)

    Pu, Xiaobing; Yang, Shuangshi; Cao, Haiquan; Jing, Xingquan; Yin, Jun

    2014-03-01

    To investigate the effectiveness of U-shape titanium screw-rod fixation system with bone autografting for lumbar spondylolysis of young adults. Between January 2008 and December 2011, 32 patients with lumbar spondylolysis underwent U-shape titanium screw-rod fixation system with bone autografting. All patients were male with an average age of 22 years (range, 19-32 years). The disease duration ranged from 3 to 24 months (mean, 14 months). L3 was involved in spondylolysis in 2 cases, L4 in 10 cases, and L5 in 20 cases. The preoperative visual analogue scale (VAS) and Oswestry disability index (ODI) scores were 8.0 +/- 1.1 and 75.3 +/- 11.2, respectively. The operation time was 80-120 minutes (mean, 85 minutes), and the blood loss was 150-250 mL (mean, 210 mL). Primary healing of incision was obtained in all patients without complications of infection and nerve symptom. Thirty-two patients were followed up 12-24 months (mean, 14 months). Low back pain was significantly alleviated after operation. The VAS and ODI scores at 3 months after operation were 1.0 +/- 0.5 and 17.6 +/- 3.4, respectively, showing significant differences when compared with preoperative ones (t = 30.523, P = 0.000; t = 45.312, P = 0.000). X-ray films and CT showed bone fusion in the area of isthmus defects, with the bone fusion time of 6-12 months (mean, 9 months). During follow-up, no secondary lumbar spondyloly, adjacent segment degeneration, or loosening or breaking of internal fixator was found. The U-shape titanium screw-rod fixation system with bone autografting is a reliable treatment for lumbar spondylolysis of young adults because of a high fusion rate, minimal invasive, and maximum retention of lumbar range of motion.

  2. Clinical efficacy of bone cement injectable pedicle screw system combined with intervertebral fusion in treatment of lumbar spondylolysis and osteoporosis

    Directory of Open Access Journals (Sweden)

    Peng-yi DAI

    2016-10-01

    .05. Based on the ODI score, the excellent/fine rate was 90.6% and 92.5% for 3 months after operation and the last follow-up, respectively. During the period of following up, no loss of the correction degrees, no loosening of the screws, and 19 cases were noted bony fusion with the fusion success rate of 90.5%. Conclusion  The treatment effect of bone cement injectable pedicle screw system and intervertebral fusion for lumbar spondylolysis and osteoporosis is satisfied. DOI: 10.11855/j.issn.0577-7402.2016.10.12

  3. Cephalomedullary screws as the standard proximal locking screws for nailing femoral shaft fractures.

    Science.gov (United States)

    Collinge, Cory; Liporace, Frank; Koval, Kenneth; Gilbert, George T

    2010-12-01

    In 2004, we modified our technique for the stabilization of femoral shaft fractures so that all fractures were stabilized using a reconstruction nail with proximal locking screws oriented into the femoral head. The rationale for this was twofold: first, potentially "missed" associated femoral neck fractures would be stabilized. Second, hip fractures that might occur later in life above the intramedullary nail might be avoided. The purpose of this study therefore was to determine whether there were any risks to patients treated for femoral shaft fractures with antegrade nails using cephalomedullary proximal locking screws. Retrospective. Two regional trauma centers. Eighty-seven consecutive patients were treated for a femoral shaft fracture treated with antegrade femoral nailing with a cephalomedullary locked nail. Reamed, trochanteric insertion of an intramedullary nail with proximal locking screws placed in a cephalomedullary direction. Patient and injury data, radiographic analyses, and complications of treatment were assessed at a minimum of 12 months. Sixty-one of 87 patients (70%) were available at a mean of 19.8 months (range, 12-44 months). Sixty of 61 fractures united after the index procedure. Complications included one delayed union successfully treated with exchange nailing, one distal locking screw fracture (allowing dynamization and completion of fracture healing), two patients with postoperative deformity that required a derotation procedure, and two drill bits that broke intraoperatively and were retained. There were no major complications at the hip, no migration or failure of proximal locking screws, and no screws required removal. Using a reconstruction nail and cephalomedullary proximal locking screws for antegrade femoral nailing of femoral shaft fractures was not associated with major complications in this series. This modification of standard femoral nailing offers potential advantages, including fixation of any "missed" associated femoral

  4. Biomechanical analysis of an interference screw and a novel twist lock screw design for bone graft fixation.

    Science.gov (United States)

    Asnis, S; Mullen, J; Asnis, P D; Sgaglione, N; LaPorta, T; Grande, D A; Chahine, N O

    2017-12-01

    Malpositioning of an anterior cruciate ligament graft during reconstruction can occur during screw fixation. The purpose of this study is to compare the fixation biomechanics of a conventional interference screw with a novel Twist Lock Screw, a rectangular shaped locking screw that is designed to address limitations of graft positioning and tensioning. Synthetic bone (10, 15, 20lb per cubic foot) were used simulating soft, moderate, and dense cancellous bone. Screw push-out and graft push-out tests were performed using conventional and twist lock screws. Maximum load and torque of insertion were measured. Max load measured in screw push out with twist lock screw was 64%, 60%, 57% of that measured with conventional screw in soft, moderate and dense material, respectively. Twist lock max load was 78% and 82% of that with conventional screw in soft and moderate densities. In the highest bone density, max loads were comparable in the two systems. Torque of insertion with twist lock was significantly lower than with conventional interference screw. Based on geometric consideration, the twist lock screw is expected to have 35% the holding power of a cylindrical screw. Yet, results indicate that holding power was greater than theoretical consideration, possibly due to lower friction and lower preloaded force. During graft push out in the densest material, comparable max loads were achieved with both systems, suggesting that fixation of higher density bone, which is observed in young athletes that require reconstruction, can be achieved with the twist lock screw. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Achieving interfragmentary compression without special drilling technique or screw design.

    Science.gov (United States)

    Eastman, Jonathan; Deafenbaugh, Bradley; Christiansen, Blaine; Garcia-Nolen, Tanya; Lee, Mark

    2017-09-08

    Traditional fracture fixation teaching suggests that fully threaded screws do not provide interfragmentary compression unless placed through a glide hole. Based on this assumption, pelvic surgeons typically use fully threaded screws in the treatment of comminuted transforaminal sacral fractures to limit iatrogenic neuroforaminal stenosis. Clinical experience with fully threaded screws suggests that interfragmentary compression actually does occur. We hypothesized that the use of a fully threaded screw does not produce any interfragmentary compression and that there is no difference in insertional torque between partially threaded and fully threaded screws. To test this hypothesis, fully and partially threaded 7.0 millimeter (mm) cannulated screws were placed across two synthetic bone blocks fabricated to simulate normal and osteoporotic bone. We compared two groups of normal and osteoporotic blocks for compression achieved and maximal insertional torque generated with fully threaded and partially threaded screw insertion. A micro computed tomography (CT) scan of the composite blocks was obtained to investigate for structural changes created during screw insertion. For both groups, compression was achieved with fully threaded screws and the maximal insertional torque was higher using fully threaded screws. Micro CT analysis demonstrated local bone damage with structural disruption in the near segment of the fully threaded screw path in comparison to the partially threaded. this study demonstrates that compression is generated using fully threaded screws without using a predrilled glide hole. The insertional torque required to generate compression with fully threaded screws is increased but is clinically applicable. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  6. Long-term behavior of integral abutment bridges : appendix A, construction plans.

    Science.gov (United States)

    2011-01-01

    Integral abutment (IA) construction has become the preferred method over conventional construction for use with typical highway bridges. However, the use of these structures is limited due to state mandated length and skew limitations. To expand thei...

  7. Long-term behavior of integral abutment bridges : appendix D, Bowen lab soil borings.

    Science.gov (United States)

    2011-01-01

    Integral abutment (IA) construction has become the preferred method over conventional construction for use with typical highway bridges. However, the use of these structures is limited due to state mandated length and skew limitations. To expand thei...

  8. Thermal behavior of IDOT integral abutment bridges and proposed design modifications.

    Science.gov (United States)

    2013-05-01

    The Illinois Department of Transportation (IDOT) has increasingly constructed integral abutment bridges (IABs) : over the past few decades, similar to those in many other states. Because the length and skew limitations : currently employed by IDOT ha...

  9. Sealing Capability and SEM Observation of the Implant-Abutment Interface.

    Science.gov (United States)

    Lorenzoni, Fabio C; Coelho, Paulo G; Bonfante, Gerson; Carvalho, Ricardo M; Silva, Nelson R F A; Suzuki, Marcelo; Silva, Thelma Lopes; Bonfante, Estevam A

    2011-01-01

    To evaluate the sealing capability of external hexagon implant systems and assess the marginal fit, two groups (n = 10 each) were employed: SIN (Sistema de Implantes Nacional, Brazil) and Osseotite, (Biomet 3i, USA). Sealing capability was determined by placing 0.7 μL of 1% acid-red solution in the implant wells before the torque of their respective abutments. Specimens were then placed into 2.5 mL vials filled with 1.3 mL of distilled water with the implant-abutment interface submerged. Three samples of 100 μL water were collected at previously determinate times. The absorbance was measured with a spectrophotometer, and the data were analyzed by Two-way ANOVA (P implant-abutment interface of both groups. Gaps in the implant-abutment interface were observed along with leakage increased at the 144 hrs evaluation period.

  10. Thermal response of integral abutment bridges with mechanically stabilized earth walls.

    Science.gov (United States)

    2013-03-01

    The advantages of integral abutment bridges (IABs) include reduced maintenance costs and increased useful life spans. : However, improved procedures are necessary to account for the impacts of cyclic thermal displacements on IAB components, : includi...

  11. Peri-implant conditions and marginal bone loss around cemented and screw-retained single implant crowns in posterior regions: A retrospective cohort study with up to 4 years follow-up.

    Directory of Open Access Journals (Sweden)

    Jun-Yu Shi

    Full Text Available The aim of the present study was to identify the peri-implant conditions (bleeding on probing (BOP, pocket probing depth (PPD, modified plaque index (mPI and marginal bone loss (MBL, marginal bone level change between follow-up and occlusal loading around cemented and screw-retained posterior single crowns on tissue-level implants. The study was a retrospective cohort study with up to 4 years (mean 2.5 years follow-up. Patients with either cemented or screw-retained crowns in posterior regions were included. Implant survival, technical complications, BOP, PPD, mPI, MBL, biologic complications (peri-implant mocositis and peri-implantitis were evaluated. Mann-Whitney U test was used to test the difference between the screw-retained group (SG and cemented group (CG. 176 patients (SG: 94, CG: 82 were included. The implant survival rates were 100% in SG and 98.8% in CG. Prosthetic screw loosening was found in 8 restorations (8.7% at follow-up visit. Peri-implant mucositis rate was significantly higher in the SG group (42.1% than that in the CG group (32.2% (P = 0.04. Six patients (6.38% in the screw-retained group and 5 patients (6.10% in the cemented group were diagnosed with peri-implantitis, the difference did not reach statistical significance (P>0.05. No significant difference of PPD, mPI and MBL were found between two groups (P = 0.11, 0.13 and 0.08, respectively. High implant survival rates were achieved in both groups. Cemented single crowns on tissue-level implants showed comparable peri-implant conditions in comparison with two-piece screw-retained crowns. Well-designed prospective cohort or randomized controlled clinical trials with longer follow-up are needed to confirm the result.

  12. Peri-implant conditions and marginal bone loss around cemented and screw-retained single implant crowns in posterior regions: A retrospective cohort study with up to 4 years follow-up.

    Science.gov (United States)

    Shi, Jun-Yu; Jie-Ni; Zhuang, Long-Fei; Zhang, Xiao-Meng; Fan, Lin-Feng; Lai, Hong-Chang

    2018-01-01

    The aim of the present study was to identify the peri-implant conditions (bleeding on probing (BOP), pocket probing depth (PPD), modified plaque index (mPI)) and marginal bone loss (MBL, marginal bone level change between follow-up and occlusal loading) around cemented and screw-retained posterior single crowns on tissue-level implants. The study was a retrospective cohort study with up to 4 years (mean 2.5 years) follow-up. Patients with either cemented or screw-retained crowns in posterior regions were included. Implant survival, technical complications, BOP, PPD, mPI, MBL, biologic complications (peri-implant mocositis and peri-implantitis) were evaluated. Mann-Whitney U test was used to test the difference between the screw-retained group (SG) and cemented group (CG). 176 patients (SG: 94, CG: 82) were included. The implant survival rates were 100% in SG and 98.8% in CG. Prosthetic screw loosening was found in 8 restorations (8.7%) at follow-up visit. Peri-implant mucositis rate was significantly higher in the SG group (42.1%) than that in the CG group (32.2%) (P = 0.04). Six patients (6.38%) in the screw-retained group and 5 patients (6.10%) in the cemented group were diagnosed with peri-implantitis, the difference did not reach statistical significance (P>0.05). No significant difference of PPD, mPI and MBL were found between two groups (P = 0.11, 0.13 and 0.08, respectively). High implant survival rates were achieved in both groups. Cemented single crowns on tissue-level implants showed comparable peri-implant conditions in comparison with two-piece screw-retained crowns. Well-designed prospective cohort or randomized controlled clinical trials with longer follow-up are needed to confirm the result.

  13. Analysis of 18 F-FDG uptake patterns in PET for diagnosis of septic and aseptic loosening after total hip arthroplasty

    International Nuclear Information System (INIS)

    Cremerius, U.; Niethard, F.U.; Mumme, T.; Reinartz, P.; Wirtz, D.; Buell, U.

    2003-01-01

    Aim: Identification of typical patterns for fluorodeoxyglucose (FDG) uptake in positron emission tomography (PET) to detect aseptic loosening of hip prosthesis (acetabular and/or femoral component) and prosthetic infection. Methods: 18 patients with painful hip prosthesis underwent PET using a dedicated full ring scanner after application of 200-300 MBq FDG. The interface between bone and surrounding soft tissue or bone as displayed on coronal slices was divided into 12 segments in accordance with the classifications of Delee and Gruen. FDG uptake in each of the segments was scored (0-3) by two independent observers. Intraoperative findings were regarded as the gold standard. Results: After surgical revision 14 acetabular components and 9 femoral components were found to be loose and prosthetic infection was present in 7 prostheses. Loosening of the acetabular component was correlated to enhanced uptake in the middle of the acetabular interface, while loosening of the femoral component was correlated to enhanced uptake in the proximal and middle segment of the lateral femoral interface and the proximal segment of the medial femoral interface. A similar pattern was found in prosthetic infection with high uptake along the middle portion of the lateral femoral interface. In 6 of 7 infected prostheses loosening of the acetabular and of the femoral component was present. Taking the typical uptake patterns as criteria for loosening and grade 3 uptake as an additional criterion for septic loosening the accuracy of PET imaging in the detection of loosening of the acetabular or the femoral component and of prosthetic infection was 72, 78 and 89%, respectively. Conclusion: This pilot study presents FDG-PET as a promising diagnostic tool for patients with painful hip prostheses. Its clinical value should be evaluated in a larger patient population. (orig.) [de

  14. Twin screw granulation - review of current progress.

    Science.gov (United States)

    Thompson, M R

    2015-01-01

    Twin screw granulation (TSG) is a new process of interest to the pharmaceutical community that can continuously wet granulate powders, doing so at lower liquid concentrations and with better product consistency than found by a high shear batch mixer. A considerable body of research has evolved over the short time since this process was introduced but generally with little comparison of results. A certain degree of confidence has been developed through these studies related to how process variables and many attributes of machinery configuration will affect granulation but some major challenges still lay ahead related to scalability, variations in the processing regimes related to degree of channel fill and the impact of wetting and granulation of complex powder formulations. This review examines the current literature for wet granulation processes studied in twin screw extrusion machinery, summarizing the influences of operational and system parameters affecting granule properties as well as strives to provide some practical observations to newly interested users of the technique.

  15. Screw as a Bladder Foreign Body

    Directory of Open Access Journals (Sweden)

    Seyed Reza Hosseini

    2017-02-01

    Full Text Available Foreign bodies in the bladder are among the strangest differential diagnoses in the lower urinary tract symptoms (LUTS and may be missed in initial medical evaluations. We present a 63-year-old man who was visited in the emergency department because of obstructive and irritative lower urinary tract symptoms. Two months earlier, he had a pelvic fracture due to motor vehicle accident and underwent an open reduction and internal fixation of the pubic rami and right acetabulum by an anterior ilioinguinal approach. After initial evaluation, an abdominopelvic X-ray revealed a 3 cm screw in the suprapubic area. He underwent urethrocystoscopy and a 3 cm screw was extracted by forceps.

  16. Calculating Characteristics of the Screws with Constant And Variable Step

    Directory of Open Access Journals (Sweden)

    B. N. Zotov

    2015-01-01

    Full Text Available This work is devoted to creating a technique for calculating power characteristics of the screws with constant and variable step for the centrifugal pumps. The technique feature is that the reverse currents, which are observed in screws working at low flow, are numerically taken into account. The paper presents a diagram of the stream in the screw with flow to the network Q=0, and the static pressure of the screw in this mode is computed according to reverse current parameters. Maximum flow of screw is determined from the known formulas. When calculating the power characteristics and computing the overall efficiency of the screw, for the first time a volumetric efficiency of the screw is introduced. It is defined as a ratio between the flow into the network and the sum of the reverse current flows and a flow into the network. This approach allowed us to determine the efficiency of the screw over the entire range of flows.A comparison of experimental characteristics of the constant step screw with those of calculated by the proposed technique shows their good agreement.The technique is also used in calculating characteristics of the variable step screws. The variable step screw is considered as a screw consisting of two screws with a smooth transition of the blades from the inlet to the outlet. Screws in which the step at the inlet is less than that of at the outlet as well as screws with the step at the inlet being more than that of at the outlet were investigated. It is shown that a pressure of the screw with zero step and the value of the reverse currents depend only on the parameters of the input section of the screw, and the maximum flow, if the step at the inlet is more than the step at the outlet, is determined by the parameters of the output part of the screw. Otherwise, the maximum flow is determined a little bit differently.The paper compares experimental characteristics with characteristics calculated by the technique for variable step

  17. Optimal trajectory for the occipital condyle screw.

    Science.gov (United States)

    Le, Tien V; Vivas, Andrew C; Baaj, Ali A; Vale, Fernando L; Uribe, Juan S

    2014-04-01

    Retrospective analysis. To understand what may constitute an optimal trajectory for an occipital condyle (OC) screw. OC screws are an alternative to standard occipital plates as a cephalad fixation point in occipitocervical fusion. An optimal trajectory for placement of OC screws has not been described. We conducted a computed tomography-based study of 340 human occipital condyls. All computed tomographies were negative for traumatic, degenerative, and neoplastic pathology. On the basis of the current literature, linear measurements of distances were made based on a constant entry point. Medial angulations of 10, 20, and 25 degrees relative to the sagittal midline were used. In addition, 10-, 5-degree cranial, 10- and 30-degree caudal angulations were studied to evaluate the incidence of hypoglossal canal and atlantooccipital joint compromise. Average distances were 17.1±2.8, 20.4±2.8, and 22.2±2.9 for 10, 20, and 25 degrees of medial angulation, respectively. Right-sided and left-sided measurements for each category were not significantly different. However, the difference in the measured distances between 10 versus 20 degrees, 10 versus 25 degrees, and 20 versus 25 degrees was all significantly different (PAtlantooccipital joint compromise incidence was 21.8% and 99.1% for 10- and 30-degree caudal angulation, respectively. The condylar entry point should be medial to the condylar fossa, midcondylar, and ≥2 mm caudal to the skull base. An optimal trajectory for the OC screw should have a medial angulation of ≥20 degrees relative to the sagittal midline, trying to stay parallel to the skull base. Minor adjustments in angulation can be made, but any adjustment approaching 10 degrees cranial or caudal leads to an increased risk of hypoglossal canal cranially or atlantooccipital joint compromise caudally.

  18. Fracture Strength of Titanium based Lithium Disilicate and Zirconia Abutment Crowns

    Science.gov (United States)

    2017-06-12

    If yes . give date. D N/A 27. COMMENTS ~ APPROVED 0 DISAPPROVED I RB approved presentation of dental materials research w i th appropriate...The specimens were cemented to a titanium-base implant system, subjected to thermocycling and cyclic loading, and fractured in a material testing...zirconia abutment/lithium-disilicate crown. INTRODUCTION Dental implants and the use of esthetic abutments are widely practiced procedures for dentists

  19. Performance of conical abutment (Morse Taper) connection implants: a systematic review.

    Science.gov (United States)

    Schmitt, Christian M; Nogueira-Filho, Getulio; Tenenbaum, Howard C; Lai, Jim Yuan; Brito, Carlos; Döring, Hendrik; Nonhoff, Jörg

    2014-02-01

    In this systematic review, we aimed to compare conical versus nonconical implant-abutment connection systems in terms of their in vitro and in vivo performances. An electronic search was performed using PubMed, Embase, and Medline databases with the logical operators: "dental implant" AND "dental abutment" AND ("conical" OR "taper" OR "cone"). Names of the most common conical implant-abutment connection systems were used as additional key words to detect further data. The search was limited to articles published up to November 2012. Recent publications were also searched manually in order to find any relevant studies that might have been missed using the search criteria noted above. Fifty-two studies met the inclusion criteria and were included in this systematic review. As the data and methods, as well as types of implants used was so heterogeneous, this mitigated against the performance of meta-analysis. In vitro studies indicated that conical and nonconical abutments showed sufficient resistance to maximal bending forces and fatigue loading. However, conical abutments showed superiority in terms of seal performance, microgap formation, torque maintenance, and abutment stability. In vivo studies (human and animal) indicated that conical and nonconical systems are comparable in terms of implant success and survival rates with less marginal bone loss around conical connection implants in most cases. This review indicates that implant systems using a conical implant-abutment connection, provides better results in terms of abutment fit, stability, and seal performance. These design features could lead to improvements over time versus nonconical connection systems. © 2013 Wiley Periodicals, Inc.

  20. Accurate and Simple Screw Insertion Procedure With Patient-Specific Screw Guide Templates for Posterior C1-C2 Fixation.

    Science.gov (United States)

    Sugawara, Taku; Higashiyama, Naoki; Kaneyama, Shuichi; Sumi, Masatoshi

    2017-03-15

    Prospective clinical trial of the screw insertion method for posterior C1-C2 fixation utilizing the patient-specific screw guide template technique. To evaluate the efficacy of this method for insertion of C1 lateral mass screws (LMS), C2 pedicle screws (PS), and C2 laminar screws (LS). Posterior C1LMS and C2PS fixation, also known as the Goel-Harms method, can achieve immediate rigid fixation and high fusion rate, but the screw insertion carries the risk of injury to neuronal and vascular structures. Dissection of venous plexus and C2 nerve root to confirm the insertion point of the C1LMS may also cause problems. We have developed an intraoperative screw guiding method using patient-specific laminar templates. Preoperative bone images of computed tomography (CT) were analyzed using three-dimensional (3D)/multiplanar imaging software to plan the trajectories of the screws. Plastic templates with screw guiding structures were created for each lamina using 3D design and printing technology. Three types of templates were made for precise multistep guidance, and all templates were specially designed to fit and lock on the lamina during the procedure. Surgery was performed using this patient-specific screw guide template system, and placement of the screws was postoperatively evaluated using CT. Twelve patients with C1-C2 instability were treated with a total of 48 screws (24 C1LMS, 20 C2PS, 4 C2LS). Intraoperatively, each template was found to exactly fit and lock on the lamina and screw insertion was completed successfully without dissection of the venous plexus and C2 nerve root. Postoperative CT showed no cortical violation by the screws, and mean deviation of the screws from the planned trajectories was 0.70 ± 0.42 mm. The multistep, patient-specific screw guide template system is useful for intraoperative screw navigation in posterior C1-C2 fixation. This simple and economical method can improve the accuracy of screw insertion, and reduce operation time and

  1. 2D and 3D assessment of sustentaculum tali screw fixation with or without Screw Targeting Clamp.

    Science.gov (United States)

    De Boer, A Siebe; Van Lieshout, Esther M M; Vellekoop, Leonie; Knops, Simon P; Kleinrensink, Gert-Jan; Verhofstad, Michael H J

    2017-12-01

    Precise placement of sustentaculum tali screw(s) is essential for restoring anatomy and biomechanical stability of the calcaneus. This can be challenging due to the small target area and presence of neurovascular structures on the medial side. The aim was to evaluate the precision of positioning of the subchondral posterior facet screw and processus anterior calcanei screw with or without a Screw Targeting Clamp. The secondary aim was to evaluate the added value of peroperative 3D imaging over 2D radiographs alone. Twenty Anubifix™ embalmed, human anatomic lower limb specimens were used. A subchondral posterior facet screw and a processus anterior calcanei screw were placed using an extended lateral approach. A senior orthopedic trauma surgeon experienced in calcaneal fracture surgery and a senior resident with limited experience in calcaneal surgery performed screw fixation in five specimens with and in five specimens without the clamp. 2D lateral and axial radiographs and a 3D recording were obtained postoperatively. Anatomical dissection was performed postoperatively as a diagnostic golden standard in order to obtain the factual screw positions. Blinded assessment of quality of fixation was performed by two surgeons. In 2D, eight screws were considered malpositioned when placed with the targeting device versus nine placed freehand. In 3D recordings, two additional screws were malpositioned in each group as compared to the golden standard. As opposed to the senior surgeon, the senior resident seemed to get the best results using the Screw Targeting Clamp (number of malpositioned screws using freehand was eight, and using the targeting clamp five). In nine out of 20 specimens 3D images provided additional information concerning target area and intra-articular placement. Based on the 3D assessment, five additional screws would have required repositioning. Except for one, all screw positions were rated equally after dissection when compared with 3D examinations

  2. In vitro evaluation of force-expansion characteristics in a newly designed orthodontic expansion screw compared to conventional screws

    Directory of Open Access Journals (Sweden)

    Oshagh Morteza

    2009-01-01

    Full Text Available Objective : Expansion screws like Hyrax, Haas and other types, produce heavy interrupted forces which are unfavorable for dental movement and could be harmful to the tooth and periodontium. The other disadvantage of these screws is the need for patient cooperation for their regular activation. The purpose of this study was to design a screw and compare its force- expansion curve with other types. Materials and Methods : A new screw was designed and fabricated in the same dimension, with conventional types, with the ability of 8 mm expansion (Free wire length: 12 mm, initial compression: 4.5 mm, spring wire diameter: 0.4 mm, spring diameter: 3 mm, number of the coils: n0 ine, material: s0 tainless steel. In this in vitro study, the new screw was placed in an acrylic orthodontic appliance, and after mounting on a stone cast, the force-expansion curve was evaluated by a compression test machine and compared to other screws. Results : Force-expansion curve of designed screw had a flatter inclination compared to other screws. Generally it produced a light continuous force (two to 3.5 pounds for every 4 mm of expansion. Conclusion : In comparison with heavy and interrupted forces of other screws, the newly designed screw created light and continuous forces.

  3. In vitro evaluation of force-expansion characteristics in a newly designed orthodontic expansion screw compared to conventional screws.

    Science.gov (United States)

    Oshagh, Morteza; Momeni Danaei, S H; Hematian, M R; Oshagh, M R; Zade, A Hadiun; Saboori, A A

    2009-01-01

    Expansion screws like Hyrax, Haas and other types, produce heavy interrupted forces which are unfavorable for dental movement and could be harmful to the tooth and periodontium. The other disadvantage of these screws is the need for patient cooperation for their regular activation. The purpose of this study was to design a screw and compare its force- expansion curve with other types. A new screw was designed and fabricated in the same dimension, with conventional types, with the ability of 8 mm expansion (Free wire length: 12 mm, initial compression: 4.5 mm, spring wire diameter: 0.4 mm, spring diameter: 3 mm, number of the coils: n0 ine, material: s0 tainless steel). In this in vitro study, the new screw was placed in an acrylic orthodontic appliance, and after mounting on a stone cast, the force-expansion curve was evaluated by a compression test machine and compared to other screws. Force-expansion curve of designed screw had a flatter inclination compared to other screws. Generally it produced a light continuous force (two to 3.5 pounds) for every 4 mm of expansion. In comparison with heavy and interrupted forces of other screws, the newly designed screw created light and continuous forces.

  4. In vitro evaluation of thermomechanic coupling in conical implant-to-abutment joint.

    Science.gov (United States)

    Traini, Tonino; Di Iorio, Donato; Caputi, Sergio; Degidi, Marco; Iezzi, Giovanna; Piattelli, Adriano

    2007-12-01

    This study investigates the use of thermomechanic abutment-to-implant coupling. Ten 3.5 x 1 mm commercially pure titanium Ankylos implants (Dentsply Friadent, Mannheim, Germany) and 10 standard abutment of titanium alloy Ti6Al4V were used in the present study. All fixtures were mounted on hold specimen provided of a 10-ohm electrical resistance to maintain the fixture at 37 degrees C +/- 3 degrees C during the entire test and to evaluate the influence of the coefficient of thermal expansion on joined conical abutment. The threading part of all abutments was cut off using a diamond disc. All abutment implants were coupled at 35 N using a universal testing machine (Lloyd 30K, Lloyd Instruments Ltd. Segensworth, UK). Five abutments were heated at 37 degrees C +/- 3 degrees C, whereas the reaming were cooled at 0 degrees C +/- 3 degrees C before connection. To measure the difference a pull-out test was performed. The results were statistically analyzed using unpaired t test at P < 0.05. The cooled specimens showed a result (mean +/- SD) of 421.6 +/- 55.20 N, whereas for heated specimens the result was 238.4 +/- 42.27 N. The difference was statistically significant (P = 0.001). The thermomechanic coupling significantly increases the performance of the conical joint.

  5. Epithelial attachment and downgrowth on dental implant abutments--a comprehensive review.

    Science.gov (United States)

    Iglhaut, Gerhard; Schwarz, Frank; Winter, Robert R; Mihatovic, Ilja; Stimmelmayr, Michael; Schliephake, Henning

    2014-01-01

    The soft tissues around dental implants are enlarged compared with the gingiva because of the longer junctional epithelium and the hemidesmosonal attachments are fewer, suggestive of a poorer quality attachment. Inflammatory infiltrates caused by bacterial colonization of the implant-abutment interface are thought to be one of the factors causing epithelial downgrowth and subsequent peri-implant bone loss. Gold alloys and dental ceramics as well as the contamination of the implant surface with amino alcohols, appear to promote epithelial downgrowth. Physical manipulaton of the abutment surfaces, including concave abutment designs, platform switching, and microgrooved surfaces are believed to inhibit epithelial downgrowth and minimizes bone loss at the implant shoulder. This paper reviews the factors that are believed to influence the migration of epithelial attachment the dental implant and abutment surfaces. Exploration of innovative computer-aided design/computer-aided manufacturing-based concepts such as "one abutment-one time" and their effect on epithelial downgrowth are discussed. Based on the review of current literature, the authors recommend inserting definitive abutments at the time of surgical uncovering. To implement this concept, registration of the implant position should to be taken at the time of surgical implant placement. © 2014 Wiley Periodicals, Inc.

  6. Influence of superstructure geometry on the mechanical behavior of zirconia implant abutments: a finite element analysis.

    Science.gov (United States)

    Geringer, Alexander; Diebels, Stefan; Nothdurft, Frank P

    2014-12-01

    To predict the clinical performance of zirconia abutments, it is crucial to examine the mechanical behavior of different dental implant-abutment connection configurations. The international standard protocol for dynamic fatigue tests of dental implants (ISO 14801) allows comparing these configurations using standardized superstructure geometries. However, from a mechanical point of view, the geometry of clinical crowns causes modified boundary conditions. The purpose of this finite element (FE) study was to evaluate the influence of the superstructure geometry on the maximum stress values of zirconia abutments with a conical implant-abutment connection. Geometry models of the experimental setup described in ISO 14801 were generated using CAD software following the reconstruction of computerized tomography scans from all relevant components. These models served as a basis for an FE simulation. To reduce the numerical complexity of the FE model, the interaction between loading stamp and superstructure geometry was taken into account by defining the boundary conditions with regard to the frictional force. The results of the FE simulations performed on standardized superstructure geometry and anatomically shaped crowns showed a strong influence of the superstructure geometry and related surface orientations on the mechanical behavior of the underlying zirconia abutments. In conclusion, ISO testing of zirconia abutments should be accompanied by load-bearing capacity testing under simulated clinical conditions to predict clinical performance.

  7. Hydraulic screw fastening devices - design, maintenance, operational experience

    International Nuclear Information System (INIS)

    Lachner.

    1976-01-01

    With hydraulic screw fastening devices, pretension values with a maximum deviation of +-2.5% from the rated value can be achieved. This high degree of pretension accuracy is of considerable importance with regard to the safety factor required for the screw connection between reactor vessel head and reactor vessel. The operating rhythm of a nuclear power station with its refuelling art regular intervals makes further demands on the screw fastening device, in particular in connection with the transport of screws and for nuts. The necessary installations extend the screw fastening device into a combination of a high-pressure hydraulic cylinder system with an electrical or pneumoelectrical driving unit and an electrical control unit. Maintenance work is complicated by the large number of identical, highly stressed structural elements in connection with an unfavourable relation operating time/outage time. The problems have been perpetually reduced by close cooperation between the manufacturers and users of screw fastening devices. (orig./AK) [de

  8. Translaminar screw fixation in the lumbar spine: technique, indications, results

    OpenAIRE

    Grob, D.; Humke, T.

    1998-01-01

    Translaminar screw fixation of the lumbar spine represents a simple and effective technique for short segment fusion in the degenerative spine. Clinical experience with 173 patients who underwent translaminar screw fixation revealed a fusion rate of 94%. The indications for translaminar screw fixation as a primary fixation procedure are: segmental dysfunction, lumbar spinal stenosis with painful degenerative changes, segmental revision surgery after discectomies, and painful disc-related synd...

  9. The gauge theory of dislocations: A nonuniformly moving screw dislocation

    Energy Technology Data Exchange (ETDEWEB)

    Lazar, Markus, E-mail: lazar@fkp.tu-darmstadt.d [Emmy Noether Research Group, Department of Physics, Darmstadt University of Technology, Hochschulstr. 6, D-64289 Darmstadt (Germany); Department of Physics, Michigan Technological University, Houghton, MI 49931 (United States)

    2010-07-05

    We investigate the nonuniform motion of a straight screw dislocation in infinite media in the framework of the translational gauge theory of dislocations. The equations of motion are derived for an arbitrarily moving screw dislocation. The fields of the elastic velocity, elastic distortion, dislocation density and dislocation current surrounding the arbitrarily moving screw dislocation are derived explicitly in the form of integral representations. We calculate the radiation fields and the fields depending on the dislocation velocities.

  10. Randomized controlled trial of osteoconductive fixation screws for anterior cruciate ligament reconstruction: a comparison of the Calaxo and Milagro screws.

    Science.gov (United States)

    Bourke, Henry E; Salmon, Lucy J; Waller, Alison; Winalski, Carl S; Williams, Heidi A; Linklater, James M; Vasanji, Amit; Roe, Justin P; Pinczewski, Leo A

    2013-01-01

    To compare the outcome of 2 bioabsorbable screws for tibial interference fixation in anterior cruciate ligament reconstruction with reference to rate of absorption, osteoconductive properties, and clinical outcome. Patients undergoing primary anterior cruciate ligament reconstruction with hamstring autograft in a single unit were invited to participate in this study. Patients were randomized to receive either the Calaxo screw (Smith & Nephew, Andover, MA) or Milagro screw (DePuy Mitek, Raynham, MA) for tibial fixation. Patients were reviewed with subjective and objective evaluation by use of the International Knee Documentation Committee form, Lysholm score, KT-1000 arthrometry (MEDmetric, San Diego, CA), and clinical examination. Magnetic resonance imaging was performed at 1 year and computed tomography scanning at 1 week and at 6, 12, and 24 months. Sixty patients agreed to participate in the study, with 32 patients randomized to the Calaxo screw and 28 to the Milagro screw for tibial fixation. There was no significant difference in subjective or objective clinical outcome between the 2 groups. At 24 months, 88% of Calaxo screws showed complete screw resorption compared with 0% of Milagro screws (P Milagro group (P = .001). At 24 months, the mean volume of new bone formation for the Calaxo group was 21% of original screw volume. Ossification of the Milagro screw was unable to be accurately assessed as a result of incomplete screw resorption. Both screws showed similar favorable objective and subjective outcomes at 2 years. The Calaxo screw resorbed completely over a period of 6 months and was associated with a high incidence of intra-tunnel cyst formation. The Milagro screw increased in volume over a period of 6 months, followed by a gradual resorption, which was still ongoing at 2 years. Both screws were associated with tunnel widening, and neither showed evidence of significant tunnel ossification. We conclude that, despite satisfactory clinical outcomes, the

  11. Cervical Pedicle Screw Placement Using Medial Funnel Technique.

    Science.gov (United States)

    Lee, Jung Hwan; Choi, Byung Kwan; Han, In Ho; Choi, Won Gyu; Nam, Kyoung Hyup; Kim, Hwan Soo

    2017-09-01

    Cervical pedicle screw (CPS) placement is very challenging due to high risk of neurovascular complications. We devised a new technique (medial funnel technique) to improve the accuracy and feasibility of CPS placement. We reviewed 28 consecutive patients undergoing CPS instrumentation using the medial funnel technique. Their mean age was 51.4 years (range, 30-81 years). Preoperative diagnosis included degenerative disease (n=5), trauma (n=22), and infection (n=1). Screw perforations were graded with the following criteria: grade 0 having no perforation, grade 1 having 50% of screw diameter. Grades 0 and 1 were considered as correct position. The degree of perforation was determined by 2 junior neurosurgeons and 1 senior neurosurgeon. A total of 88 CPSs were inserted. The rate of correct placement was 94.3%; grade 0, 54 screws; grade 1, 29 screws; grade 2, 4 screws; and grade 3, 1 screw. No neurovascular complications or failure of instrumentation occurred. In perforated screws (34 screws), lateral perforations were 4 and medial perforations were 30. We performed CPS insertion using medial funnel technique and achieved 94.3% (83 of 88) of correct placement. And it can decrease lateral perforation.

  12. Accuracy of pedicle screw placement in patients with Marfan syndrome.

    Science.gov (United States)

    Qiao, Jun; Zhu, Feng; Xu, Leilei; Liu, Zhen; Sun, Xu; Qian, Bangping; Jiang, Qing; Zhu, Zezhang; Qiu, Yong

    2017-03-21

    There is no study concerning safety and accuracy of pedicle screw placement in Marfan syndrome. The objective of this study is to investigate accuracy and safety of pedicle screw placement in scoliosis associated with Marfan syndrome. CT scanning was performed to analyze accuracy of pedicle screw placement. Pedicle perforations were classified as medial, lateral or anterior and categorized to four grades: ≤ 2 mm as Grade 1, 2.1-4.0 mm as Grade 2, 4.1-6.0 mm as Grade 3, ≥6.1 mm as Grade 4. Fully contained screws or with medial wall perforation ≤ 2 mm or with lateral wall perforation ≤ 6 mm and without injury of visceral organs were considered acceptable, otherwise were unacceptable. 976 pedicle screws were placed, 713 screws (73.1%) were fully contained within the cortical boundaries of the pedicle. 924 (94.7%) screws were considered as acceptable, and 52 (5.3%) as unacceptable. The perforation rate was higher using free-hand technique than O-arm navigation technique (30.8% VS. 11.4%, P Marfan syndrome is accuracy and safe. O-arm navigation was an effective modality to ensure the safety and accuracy of screw placement. Special attention should be paid when screws were placed at the lumber spine and the concave side of spine deformity to avoid the higher rate of complications.

  13. Influence of abutment design on clinical status of peri-implant tissues.

    Science.gov (United States)

    Taiyeb-Ali, Tara B; Toh, Chooi Gait; Siar, Chong Huat; Seiz, Doris; Ong, Siew Tin

    2009-10-01

    To compare the clinical soft tissue responses around implant tooth-supported 3-unit bridges using tapered abutments with those using butt-joint abutments. In a split-mouth design study, 8 mm Ankylos (Dentsply Friadent, Germany) implants were placed in the second mandibular molar region of 8 adult Macaca fascicularis monkeys about 1 month after extraction of all mandibular molars. After 3 months of submerged healing, 3-unit metal bridges were constructed. Clinical data was collected by the author who was blind to the abutment selections. Implants were clinically evaluated using Waite plaque index, sulcus bleeding index, probing pocket depth (PPD), probing attachment loss (PAL), and width of keratinized mucosa at baseline (BL) and 3-month and 6-month intervals. Stability of the implant was assessed using Periotest device at BL and after 6 months. At BL, all the clinical variables did not differ statistically between the tapered and the butt-joint groups except for PPD (P < 0.05), where the mean PPD was greater in the butt-joint group (2.75 ± 1.02 mm) as compared with the tapered group (1.97 ± 0.65 mm). At the 3-month assessment, there was no difference in all clinical variables. After 6-month loading, no significant difference between these 2 groups was detected in all these variables, with the exception of PAL (P = 0.05) where mean PAL was greater for implants with the butt-joint abutments (0.91 ± 0.86 mm) in comparison with the tapered abutments (0.50 ± 0.88 mm), and mean Periotest values (PTVs) that indicate the tapered-abutment implants (PTV = -4.5 ± 1.60) were more stable than butt-joint-abutment implants (PTV = -1.5 ± 3.59) with P < 0.05. The differences in these mucogingival responses between these 2 groups at BL (during seating of abutments, especially of butt-joint abutments) and after 6-month loading indicated enhanced peri-implant soft tissue stability around the tapered abutments of this system. There was also enhanced-PTV in the test group for

  14. Multifactorial risk assessment for survival of abutments of removable partial dentures based on practice-based longitudinal study.

    Science.gov (United States)

    Tada, Sayaka; Ikebe, Kazunori; Matsuda, Ken-Ichi; Maeda, Yoshinobu

    2013-12-01

    Predicting the tooth survival is such a great challenge for evidence-based dentistry. To prevent further tooth loss of partially edentulous patients, estimation of individualized risk and benefit for each residual tooth is important to the clinical decision-making. While there are several reports indicating a risk of losing the abutment teeth of RPDs, there are no existing reports exploring the cause of abutment loss by multifactorial analysis. The aim of this practice-based longitudinal study was to determine the prognostic factors affecting the survival period of RPD abutments using a multifactorial risk assessment. One hundred and forty-seven patients had been previously provided with a total of 236 new RPDs at the Osaka University Dental Hospital; the 856 abutments for these RPDs were analyzed. Survival of abutment teeth was estimated using the Kaplan-Meier method. Multivariate analysis was conducted by Cox's proportional hazard modelling. The 5-year survival rates were 86.6% for direct abutments and 93.1% for indirect abutments, compared with 95.8% survival in non-abutment teeth. The multivariate analysis showed that abutment survival was significantly associated with crown-root ratio (hazard ratio (HR): 3.13), root canal treatment (HR: 2.93), pocket depth (HR: 2.51), type of abutments (HR: 2.19) and occlusal support (HR: 1.90). From this practice-based longitudinal study, we concluded that RPD abutment teeth are more likely to be lost than other residual teeth. From the multifactorial risk factor assessment, several prognostic factors, such as occlusal support, crown-root ratio, root canal treatment, and pocket depth were suggested. These results could be used to estimate the individualized risk for the residual teeth, to predict the prognosis of RPD abutments and to facilitate an evidence-based clinical decision making. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Analysis of the peri-implant soft tissues in contact with zirconia abutments: an evidence-based literature review.

    Science.gov (United States)

    de Medeiros, Rodrigo Antonio; Vechiato-Filho, Aljomar José; Pellizzer, Eduardo Piza; Mazaro, Jose Vitor Quinelli; dos Santos, Daniela Micheline; Goiato, Marcelo Coelho

    2013-05-01

    The aim of this study is to evaluate through a literature review, the soft tissue response in contact with zirconia abutments, including case reports comparing prosthetics rehabilitations with zirconia and titanium abutments upto 3 years of follow-up as well as the factors that should be considered on implant's abutment selection. Metallic abutments can provide grayish color when in contact with thin soft tissues which may lead the implant prosthetic treatment to failure. In this context, the abutments of zirconia stand out because there is an excellent linking between esthetics and the health of peri-implant soft tissues. A consult of the published researches was made on the PubMed database from 2000 to September 2012. The including criteria were: literature reviews, clinical studies and case reports in English that focused on the response of the soft tissue in contact with zirconia implant abutments. The studies that were not in English and did not match the tackled issue were excluded. A total of 32 articles were found. According to the search strategy, just 16 articles were selected for this review. Three studies affirmed that zirconia abutments have an excellent soft tissue response; one study showed increased gingival recession with zirconia abutments and nine studies do not stand out any difference on biological behavior between titanium and zirconia abutments. Three studies affirmed that zirconia abutments provide natural gingival appearance, anatomic contour and greater esthetics. The use of zirconia abutments is recommended for anterior regions because of their greater optical properties and esthetic results and more studies should be performed and analyzed longitudinally regarding their biological response. The zirconia abutments have been established to be essential in order to achieve great esthetic results in cases of thin peri-implant soft tissues and in regions where the three-dimensional placement of implants is more superficial.

  16. Finite element analysis of osteosynthesis screw fixation in the bone stock: an appropriate method for automatic screw modelling.

    Directory of Open Access Journals (Sweden)

    Jan Wieding

    Full Text Available The use of finite element analysis (FEA has grown to a more and more important method in the field of biomedical engineering and biomechanics. Although increased computational performance allows new ways to generate more complex biomechanical models, in the area of orthopaedic surgery, solid modelling of screws and drill holes represent a limitation of their use for individual cases and an increase of computational costs. To cope with these requirements, different methods for numerical screw modelling have therefore been investigated to improve its application diversity. Exemplarily, fixation was performed for stabilization of a large segmental femoral bone defect by an osteosynthesis plate. Three different numerical modelling techniques for implant fixation were used in this study, i.e. without screw modelling, screws as solid elements as well as screws as structural elements. The latter one offers the possibility to implement automatically generated screws with variable geometry on arbitrary FE models. Structural screws were parametrically generated by a Python script for the automatic generation in the FE-software Abaqus/CAE on both a tetrahedral and a hexahedral meshed femur. Accuracy of the FE models was confirmed by experimental testing using a composite femur with a segmental defect and an identical osteosynthesis plate for primary stabilisation with titanium screws. Both deflection of the femoral head and the gap alteration were measured with an optical measuring system with an accuracy of approximately 3 µm. For both screw modelling techniques a sufficient correlation of approximately 95% between numerical and experimental analysis was found. Furthermore, using structural elements for screw modelling the computational time could be reduced by 85% using hexahedral elements instead of tetrahedral elements for femur meshing. The automatically generated screw modelling offers a realistic simulation of the osteosynthesis fixation with

  17. Finite element analysis of osteosynthesis screw fixation in the bone stock: an appropriate method for automatic screw modelling.

    Science.gov (United States)

    Wieding, Jan; Souffrant, Robert; Fritsche, Andreas; Mittelmeier, Wolfram; Bader, Rainer

    2012-01-01

    The use of finite element analysis (FEA) has grown to a more and more important method in the field of biomedical engineering and biomechanics. Although increased computational performance allows new ways to generate more complex biomechanical models, in the area of orthopaedic surgery, solid modelling of screws and drill holes represent a limitation of their use for individual cases and an increase of computational costs. To cope with these requirements, different methods for numerical screw modelling have therefore been investigated to improve its application diversity. Exemplarily, fixation was performed for stabilization of a large segmental femoral bone defect by an osteosynthesis plate. Three different numerical modelling techniques for implant fixation were used in this study, i.e. without screw modelling, screws as solid elements as well as screws as structural elements. The latter one offers the possibility to implement automatically generated screws with variable geometry on arbitrary FE models. Structural screws were parametrically generated by a Python script for the automatic generation in the FE-software Abaqus/CAE on both a tetrahedral and a hexahedral meshed femur. Accuracy of the FE models was confirmed by experimental testing using a composite femur with a segmental defect and an identical osteosynthesis plate for primary stabilisation with titanium screws. Both deflection of the femoral head and the gap alteration were measured with an optical measuring system with an accuracy of approximately 3 µm. For both screw modelling techniques a sufficient correlation of approximately 95% between numerical and experimental analysis was found. Furthermore, using structural elements for screw modelling the computational time could be reduced by 85% using hexahedral elements instead of tetrahedral elements for femur meshing. The automatically generated screw modelling offers a realistic simulation of the osteosynthesis fixation with screws in the adjacent

  18. Biomechanical efficacy of monoaxial or polyaxial pedicle screw and additional screw insertion at the level of fracture, in lumbar burst fracture: An experimental study

    Directory of Open Access Journals (Sweden)

    Hongwei Wang

    2012-01-01

    Conclusions: The addition of intermediate screws at the level of a burst fracture significantly increased the stability of short-segment pedicle screw fixation in both the MPS and PPS groups. However, in short-segment fixation group, monoaxial pedicle screw exhibited more stability in flexion and extension than the polyaxial pedicle screw.

  19. The Effect of Abutment Surface Roughness on the Retention of Implant-Supported Crowns Cemented with Provisional

    Directory of Open Access Journals (Sweden)

    Seyyed Mohammad Abrisham

    2012-09-01

    Full Text Available Introduction: Surface roughness can increase the retention of castings by ridges and grooves that are microretentive. This study compared the retention of implant-supported crowns when used with 3 different surface roughness abutments and one temporary cement. Methods: Thirty solid abutments (ITI, 4 mm high, were divided into three groups randomly. In the first group, 10 abutments were roughened with sandblast (50-µm aluminum oxide and in the second group, 10 abutments were roughened with diamond bur. The third group had no surface treatment. Then, thirty implant fixture analogs (ITI were placed in the center of acrylic cylinders. After that a solid abutment was tightened on the each fixture analog with 35 N/cm force. Thirty base metal crowns were made on the 4 mm ITI abutment analogs using plastic coping. The prepared copings were cemented on the abutments by TempBond temporary cement and finally, crowns were pulled from the abutment in a universal test machine at a cross speed of 0.5cm/min. Results: The mean tensile strength in sandblasted, bur treated, and control group were 64.38±8, 91.37±7.19, and 58.61±1.93, respectively. Bur treated group showed higher tensile strength in comparison with two other groups. Conclusion: Surface modification of implant abutment by diamond bur may be an effective method to increase retention of crown when TempBond is used.

  20. The Effect of Abutment Surface Roughness on the Retention of Implant-Supported Crowns Cemented with Provisional Luting Cement

    Directory of Open Access Journals (Sweden)

    Jalil Ganbarzadeh

    2013-01-01

    Full Text Available Introduction: Surface roughness can increase the retention of castings by ridges and grooves that are microretentive. This study compared the retention of implant-supported crowns when used with 3 different surface roughness abutments and one temporary cement. Methods: Thirty solid abutments (ITI, 4 mm high, were divided into three groups randomly. In the first group, 10 abutments were roughened with sandblast (50-µm aluminum oxide and in the second group, 10 abutments were roughened with diamond bur. The third group had no surface treatment. Then, thirty implant fixture analogs (ITI were placed in the center of acrylic cylinders. After that a solid abutment was tightened on the each fixture analog with 35 N/cm force. Thirty base metal crowns were made on the 4 mm ITI abutment analogs using plastic coping. The prepared copings were cemented on the abutments by TempBond temporary cement and finally, crowns were pulled from the abutment in a universal test machine at a cross speed of 0.5cm/min. Results: The mean tensile strength in sandblasted, bur treated, and control group were 64.38±8, 91.37±7.19, and 58.61±1.93, respectively. Bur treated group showed higher tensile strength in comparison with two other groups. Conclusion: Surface modification of implant abutment by diamond bur may be an effective method to increase retention of crown when TempBond is used.

  1. The Influence of Post in Endodontically Treated Molar Abutment on Fixed Dentures Success Rate

    Directory of Open Access Journals (Sweden)

    Pralita Kusumawardhini

    2013-05-01

    Full Text Available Many dentists believe that the tooth need reinforcement provided by post before the definite restoration is placed. However, others suggest not to use post when posterior teeth especially molars, still have significant amount of tooth structure. Therefore, when endodontically treated molar is considered to be used as fixed denture abut-ment, clinicians must have proper knowledge about the impact of post placement. This literature will describe considerations regarding post placement in endodontically treated molar abutment in fixed partial dentures and their influence to the success rate. Previous studies implied the need of proper measurement of the amount of remaining tooth structure, the type of intracoronal reinforcement of the abutment, and the functional loads to ensure the success of fixed denture treatment. When planning definitive restorations for endodontically treated abutment teeth, some even suggest to use post and core to fulfill the need of reinforcement. On the contrary, others find that when a post is use in endodontically treated abutment teeth, the failure of custom made-tapered cast post and core is relatively high, whereas the use of amalgam or composite core in posterior teeth especially molars with adequate amount of tooth structure is sufficient due to post system’s limited influence on the suc-cess rate. Based on literature review, for cases with adequate tooth stucture, it can be concluded that the influ-ence of post placement in endodontically treated molar abutment to fixed partial dentures success rate is very limited.DOI: 10.14693/jdi.v18i2.64

  2. Wear of Morse taper and external hexagon implant joints after abutment removal.

    Science.gov (United States)

    Prado, Abraão M; Pereira, Jorge; Silva, Filipe S; Henriques, Bruno; Nascimento, Rubens M; Benfatti, Cesar A M; López-López, José; Souza, Júlio C M

    2017-05-01

    The aim of this in vitro study was to evaluate the removal torque values on abutments and the morphological wear aspects of two different dental implant joints after immersion in a medium containing biofilm from human saliva. Twenty implant-abutment assemblies were divided into four groups in this study: (A) Morse taper free of medium containing biofilm, and (B) after contact with a medium containing biofilm from human saliva; (C) External Hexagon free of medium containing biofilm, and (D) after contact with medium containing biofilm from human saliva. The abutments were firstly torqued to the implants according to the manufacturer´s recommendations, using a handheld torque meter. Groups B and D were immersed into 24 well-plates containing 2 ml BHI medium with microorganisms for 72 h at 37 °C under microaerophilic conditions. After detorque evaluation, the abutments were removed and the implants were analyzed by scanning electron microscopy (SEM) and profilometry. On the detorque evaluation, the torque values decreased for the external hexagon implants and increased for the Morse taper implants. However, the values were lower when both implant-abutment assemblies were in contact with a medium containing biofilm from human saliva. The wear areas of contacting surfaces of the implants were identified by SEM. The highest average roughness values were recorded on the surfaces free of biofilm. The medium containing biofilm from human saliva affected the maintenance of the torque values on Morse taper and external hexagon abutments. Additionally, the removal of abutment altered the inner implant surfaces resulting in an increase of wear of the titanium-based connection.

  3. Low Rates of Aseptic Tibial Loosening in Obese Patients With Use of High-Viscosity Cement and Standard Tibial Tray: 2-Year Minimum Follow-Up.

    Science.gov (United States)

    Crawford, David A; Berend, Keith R; Nam, Denis; Barrack, Robert L; Adams, Joanne B; Lombardi, Adolph V

    2017-09-01

    Total knee arthroplasty is overall a very successful surgery, but complications do occur. These complications include aseptic loosening of the tibial component, and obese patients are among the highest risk group. High-viscosity cement (HVC) has been implicated as a possible cause for aseptic loosening of the tibial component. The purpose of this study was to evaluate the incidence of aseptic loosening of the tibial component in obese patients with the use of HVC and standard tibial tray. We identified 1366 obese patients (1851 knees) with a body mass index >35 kg/m 2 and 2-year minimum follow-up who underwent primary total knee arthroplasty using HVC and a symmetrical, grit-blasted, cobalt-chrome tibial component with 40-mm stem. Preoperative and postoperative range of motion, Knee Society (KS) scores, complications, and reoperations were evaluated. Specifically, we assessed the rate of tibial aseptic loosening. At a mean 5.4 years follow-up, only 1 in 1851 knees had aseptic loosening of the tibial component for an incidence of 0.054%. There was a mean increase of 3.3 degrees of knee range of motion. KS pain level decreased by 38.6 points (50 point scale). KS clinical scores improved by 52.2, Knee Society functional scores improved by 19.5, University of California, Los Angeles, activity score improved by 0.9, and Oxford Knee Score by 15.7. All these improvements were statistically significant with P < .001. Standard tibial components and HVC can be used in most patients, including the high-risk obese group, with low rates of tibial aseptic loosening. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Evaluation of bond strength between grooved titanium alloy implant abutments and provisional veneering materials after surface treatment of the abutments: An in vitro study

    Directory of Open Access Journals (Sweden)

    Gowtham Venkat

    2017-01-01

    Full Text Available Introduction: Titanium has become the material of choice with greater applications in dental implants. The success of the dental implant does not only depend on the integration of the implant to the bone but also on the function and longevity of the superstructure. The clinical condition that demands long-term interim prosthesis is challenging owing to the decreased bond between the abutment and the veneering material. Hence, various surface treatments are done on the abutments to increase the bond strength. Aim: This study aimed to evaluate the bond strength between the abutment and the provisional veneering materials by surface treatments such as acid etching, laser etching, and sand blasting of the abutment. Materials and Methods: Forty titanium alloy abutments of 3 mm diameter and 11 mm height were grouped into four groups with ten samples. Groups A, B, C, and D are untreated abutments, sand blasted with 110 μm aluminum particles, etched with 1% hydrofluoric acid and 30% nitric acid, and laser etched with Nd: YAG laser, respectively. Provisional crowns were fabricated with bis-acrylic resin and cemented with noneugenol temporary luting cement. The shear bond strength was measured in universal testing machine using modified Shell–Nielsen shear test after the cemented samples were stored in water at 25°C for 24 h. Load was applied at a constant cross head speed of 5 mm/min until a sudden decrease in resistance indicative of bond failure was observed. The corresponding force values were recorded, and statistical analysis was done using one-way ANOVA and Newman–Keuls post hoc test. Results: The laser-etched samples showed higher bond strength. Conclusion: Among the three surface treatments, laser etching showed the highest bond strength between titanium alloy implant abutment and provisional restorations. The sand-blasted surfaces demonstrated a significant difference in bond strength compared to laser-etched surfaces. The results of this

  5. Statistical time series methods for damage diagnosis in a scale aircraft skeleton structure: loosened bolts damage scenarios

    International Nuclear Information System (INIS)

    Kopsaftopoulos, Fotis P; Fassois, Spilios D

    2011-01-01

    A comparative assessment of several vibration based statistical time series methods for Structural Health Monitoring (SHM) is presented via their application to a scale aircraft skeleton laboratory structure. A brief overview of the methods, which are either scalar or vector type, non-parametric or parametric, and pertain to either the response-only or excitation-response cases, is provided. Damage diagnosis, including both the detection and identification subproblems, is tackled via scalar or vector vibration signals. The methods' effectiveness is assessed via repeated experiments under various damage scenarios, with each scenario corresponding to the loosening of one or more selected bolts. The results of the study confirm the 'global' damage detection capability and effectiveness of statistical time series methods for SHM.

  6. Removal Torque and Biofilm Accumulation at Two Dental Implant-Abutment Joints After Fatigue.

    Science.gov (United States)

    Pereira, Jorge; Morsch, Carolina S; Henriques, Bruno; Nascimento, Rubens M; Benfatti, Cesar Am; Silva, Filipe S; López-López, José; Souza, Júlio Cm

    2016-01-01

    The aim of this study was to evaluate the removal torque and in vitro biofilm penetration at Morse taper and hexagonal implant-abutment joints after fatigue tests. Sixty dental implants were divided into two groups: (1) Morse taper and (2) external hexagon implant-abutment systems. Fatigue tests on the implant-abutment assemblies were performed at a normal force (FN) of 50 N at 1.2 Hz for 500,000 cycles in growth medium containing human saliva for 72 hours. Removal torque mean values (n = 10) were measured after fatigue tests. Abutments were then immersed in 1% protease solution in order to detach the biofilms for optical density and colony-forming unit (CFU/cm²) analyses. Groups of implant-abutment assemblies (n = 8) were cross-sectioned at 90 degrees relative to the plane of the implant-abutment joints for the microgap measurement by field-emission guns scanning electron microscopy. Mean values of removal torque on abutments were significantly lower for both Morse taper (22.1 ± 0.5 μm) and external hexagon (21.1 ± 0.7 μm) abutments after fatigue tests than those recorded without fatigue tests (respectively, 24 ± 0.5 μm and 24.8 ± 0.6 μm) in biofilm medium for 72 hours (P = .04). Mean values of microgap size for the Morse taper joints were statistically signicantly lower without fatigue tests (1.7 ± 0.4 μm) than those recorded after fatigue tests (3.2 ± 0.8 μm). Also, mean values of microgap size for external hexagon joints free of fatigue were statistically signicantly lower (1.5 ± 0.4 μm) than those recorded after fatigue tests (8.1 ± 1.7 μm) (P joints were lower in comparison to those recorded at external hexagon implant-abutment joints after fatigue tests in a simulated oral environment for 72 hours.

  7. Evaluation of resilient abutment components on measured strain using dynamic loading conditions.

    Science.gov (United States)

    Morton, D; Stanford, C M; Aquilino, S A

    1998-07-01

    Factors that affect transmission of strain from prostheses to bone may affect the long-term success of loaded implants. Current in vitro models are theoretically predictive (finite element modeling) or facsimile (photoelastic) in nature. A more clinically relevant in vitro model for strain evaluation should be investigated. This study attempted: (1) to validate a human cadaver bone model for vitro measurement of cortical bone strain, and (2) to evaluate the effect on cortical strain measurements of a resilient plastic component incorporated within a titanium implant in response to variable dynamic loading. Two IMZ (Interpore International) abutment alternatives were used: the titanium Abutment Complete and the polyoxymethylene Intra-mobile Element. The model system consisted of two implants placed in unfixed human cadaver ulna bone to simulate an implant bound edentulous region. Four biaxial rosette strain gauges simultaneously recorded cortical bone strain immediately mesial and distal to each implant. During experimentation a simulated prosthetic framework supported by either titanium or polyoxymethylene abutments was dynamically loaded 6 min from the terminal abutment along a cantilever extension. Cyclic nominal peak loads were applied with a materials testing machine at 20-N intervals from 20 to 200 N at a crosshead speed of 5 mm/minute. The protocol allowed frequency of load application to vary. A Newtonian linear correlation (r2 > or = 0.98) between load application and strain output was determined for each gauge position except for the terminal gauge located opposite the cantilever. Cortical strains recorded were within reported physiologic ranges involved in bone modeling and remodeling. Further, the polyoxymethylene abutment components did not result in reduction of peak microstrain at any gauge position. The Intra-mobile Element abutments, however, did increase the time required to complete 10 loading cycles when compared with the titanium Abutment

  8. Comparative study of the pullout strength of the 2.4-mm AO locking screw, 2.0-mm AO cortical screw and Herbert screw in sawbones: a biomechanical study.

    Science.gov (United States)

    Kosiyatrakul, Arkaphat; Sompan, Soon; Luenam, Suriya

    2014-02-01

    Headless screw is a standard implant for an osteochondral fragment fixation. With a threaded design, the screw head can be buried under the articular cartilage to prevent a post-traumatic arthritis. However, the screw is expensive and maybe not available in the emergency situation. The 2.4-mm AO locking screw also has a threaded head which is able to advance underneath the cartilage. This has been usedfor fixation of the osteochondal fracture clinically. We compared the pullout strength of 2.4-mm AO locking screw with those ofHerbert screw and 2.0-mm AO cortical screw. The studies pemformed by using Instron 4502 to measure the pullout strength in 12 models for each type of the screw. The pullout strength of the 2.4-mm AO locking screw from a corticocancellous bone model was compared with the pullout strength of the Herbert screw from a cancellous bone model and the 2.0-mm AO cortical screw ifom the corticocancellous bone model. The differences in pullout strength between the 2.4-mm AO locking screw and the other two screws were determined by independent t-test. The pullout strength of the 2.4-mm AO locking screw, Herbert screw and 2.0-mm AO cortical screw were 143.49+46.18 N, 72.83 +/- 16.64 N, and 80.38 +/- 1.42 N, respectively. The pullout strength of2.4-mm AO locking screw was signi2ficantly higher than those ofHerbert screw and 2.0-mm AO cortical screw (pAO locking screw in the corticocancellous bone model had pullout strength higher than the Herbert screw in the cancellous bone model and the 2.0-mm AO cortical screw in corticocancellous bone model. The 2.4-mm AO locking screw may use instead of headless screw for intra-articular fixation in a specific situation, such as when the headless screw is unavailable.

  9. Evaluation of two styles of slotted, flat-head screws

    International Nuclear Information System (INIS)

    Reeves, C.A. Jr.; Johnson, W.B.

    1979-01-01

    A series of torque tests were performed to evaluate the relative merits of two different flat-head screws fabricated from a uranium--6% niobium alloy. The screws tested were machined with both normal, straight-through slots in the head and with slots having radiused bottoms. Test results indicate that both designs easily surpass the required 20-inch-pound-proof torque

  10. scaphoid dimensions and appropriate screw sizes in a kenyan ...

    African Journals Online (AJOL)

    dimensions will aid in identifying appropriate screw systems. Objective: The purpose of this study was to determine the dimensions of the scaphoid and its distal pole and relating this to commonly used screw systems. Methods: One hundred and four human scaphoids were studied and their dimensions determined. These.

  11. Biomechanical analysis of titanium fixation plates and screws in ...

    African Journals Online (AJOL)

    2015-08-10

    Aug 10, 2015 ... Materials and Methods: Three different three-dimensional finite element models of the mandible were developed to simulate the biomechanical responses of titanium plates and screws. The fracture lines were fixed with double 4-hole straight, 4-hole square, and 5-hole Y plates with monocortical screws.

  12. Torsion strenght of biodegradable and titanium screws: a comparison.

    NARCIS (Netherlands)

    Buijs, Gerrit J.; van der Houwen, Eduard B.; Stegenga, Boudewijn; Bos, Rudolf R.M.; Verkerke, Gijsbertus Jacob

    2007-01-01

    Purpose: To determine 1) the differences in maximum torque between 7 biodegradable and 2 titanium screw systems, and 2) the differences of maximum torque between “hand tight” and break of the biodegradable and the titanium osteofixation screw systems. Materials and Methods: Four oral and

  13. Electromagnetic Lead Screw for Potential Wave Energy Application

    DEFF Research Database (Denmark)

    Lu, Kaiyuan; Wu, Weimin

    2014-01-01

    This paper presents a new type electromagnetic lead screw (EMLS) intended for wave energy application. Similar to the mechanical lead screw, this electromagnetic version can transfer slow linear motion to high-rotational motion, offering gearing effects. Compared with the existing pure magnetic...

  14. Influence of surface modified dental implant abutments on connective tissue attachment: A systematic review.

    Science.gov (United States)

    Blázquez-Hinarejos, Mónica; Ayuso-Montero, Raúl; Jané-Salas, Enric; López-López, José

    2017-08-01

    Determine whether surface modified prosthetic abutments for dental implants influence connective tissue attachment to the implant-abutment system. A systematic review was conducted using the MEDLINE-PubMed database, with two independent reviewers filtering the titles and abstracts. Two reviewers assessed all potentially relevant articles. An assessment was carried out on the level of evidence of the research according to the guidelines of the Oxford Centre for Evidence-Based Medicine (OCEBM). After an initial search, 109 potentially relevant articles were found. After reading the titles and abstracts, 99 articles were excluded because the surface treatment was limited to the implant and not to the abutment, or because different materials were analysed instead of surface treatments; 28 were also duplicate articles. An additional 6 research studies were included that were of interest and were found by reading the references of the included articles. The studies included are: 7 in vitro studies, 5 experimental studies in animals, 2 clinical trials in humans and 2 clinical cases. Surface modification for prosthetic abutments on dental implants can achieve connective tissue attachment to the abutment; however, more studies should be conducted in humans to obtain more and better evidence of these results. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Evaluation of the marginal fit at implant-abutment interface by optical coherence tomography

    Science.gov (United States)

    Kikuchi, Keisuke; Akiba, Norihisa; Sadr, Alireza; Sumi, Yasunori; Tagami, Junji; Minakuchi, Shunsuke

    2014-05-01

    Vertical misfit of implant-abutment interface can affect the success of implant treatment; however, currently available modalities have limitations to detect these gaps. This study aimed to evaluate implant-abutment gaps in vitro using optical coherence tomography (OCT). Vertical misfit gaps sized 50, 100, 150, or 200 μm were created between external hexagonal implants and titanium abutments (Nobel Biocare, Göteborg, Sweden). A porcine gingival tissue slice, 0.5, 1.0, 1.5, or 2.0 mm in thickness, was placed on each implant-abutment interface. The gaps were evaluated by swept-source OCT at a center wavelength of 1330 nm (Panasonic Healthcare, Ehime, Japan) with beam angles of 90, 75 and 60 deg to the implant long-axis. The results suggested that while the measurements were precise, gap size and gingival thickness affected the sensitivity of detection. Gaps sized 100 μm and above could be detected with good accuracy under 0.5- or 1.0-mm-thick gingiva (GN). Around 70% of gaps sized 150 μm and above could be detected under 1.5-mm-thick GN. On the other hand, 80% of gaps under 2.0-mm-thick GN were not detected due to attenuation of near-infrared light through the soft tissue. OCT appeared as an effective tool for evaluating the misfit of implant-abutment under thin layers of soft tissue.

  16. Topography, microhardness, and precision of fit on ready-made zirconia abutment before/after sintering process.

    Science.gov (United States)

    Kanno, Taro; Milleding, Percy; Wennerberg, Ann

    2007-09-01

    Sintering porcelain on a ceramic abutment may change the microstructure and result in aging processes that influence the mechanical properties, internal strain, and the three-dimensional form of the abutment, thus causing a possible misfit between the abutment and the fixture. The aim was to investigate topography, microhardness, and precision of fit on yttrium-stabilized zirconia (Y-TZP) abutments before/after the sintering process. Ten Y-TZP abutment samples were ground to a shape used in the clinical situation and divided at random into two groups: before/after sintering. After the surface roughness was measured on all abutments, the abutments were connected to fixture replicas, embedded in resin, and cut in the longitudinal axis. Both sides of the cut samples were measured with respect to microhardness and minimum distance between fixture and abutment surface. t-Test, one-way analysis of variance, and Bonferroni multiple comparisons were used to investigate statistical significant differences. The surface roughness (S(a) and S(dr)) after sintering was significantly higher than before sintering. The total average values of microhardness after sintering were statistically lower than before sintering with a difference of 2%. The total distance between abutment/fixture before/after sintering demonstrated no statistically significant difference. Contact between abutment/fixture was most common at the top area of the fixture. A slight decrease of microhardness and contamination of porcelain particles immediately below the veneered part were found on the Y-TZP abutment after sintering. The sintering process did not affect the precision of fit.

  17. A comparative radiographic evaluation of the titanium and zirconium implant-abutment gap of three different implant connections

    Directory of Open Access Journals (Sweden)

    Majid Sahebi

    2016-07-01

    Full Text Available Background and Aims: In response to esthetic demand and use of zirconia abutments; detection of implant-abutment connection misfit is so important. The purpose of this study was to evaluate the sensitivity and specificity of radiographic images in the detection of abutment-implant connection misfit in zirconia and titanium abutments of three different implant connections. Materials and Methods: One regular implant fixture of Branemark, Noble active and Replace systems were mount in acrylic models. Two pieces titanium and zirconium abutments were attached to the implants, once with correct adaptation and once with 0.5 mm spacer. Digital radiographic images were taken of 12 created states with zero degree vertical and horizontal inclination and evaluated by 10 specialists in implant treatment in two different time penods. Data were analyzed using Kappa analysis. Results: Interclass Correlation Coefficients (ICC of the agreement of answers in the first and second times were 97.4 and 97.5, respectively (P<0/001. Sensitivity of detecting gap in all groups was acceptable (95-100% except titanium abutment in Noble active which was the lowest value (35%. Specificity of all groups were acceptable (80-95% except zirconia abutments in Noble active and Replace with 45% and 30% values, respectively, and titanium abutments in Branemark had the highest value (95%. Conclusion: The sensitivity of radiographic images in detection of abutment