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Sample records for narrow diameter implants

  1. Clinical outcome of narrow diameter implants inserted into allografts

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    Maurizio Franco

    2009-08-01

    Full Text Available OBJECTIVE: Narrow diameter implants (NDI (i.e. diameter <3.75 mm are a potential solution for specific clinical situations, such as reduced interradicular bone, thin alveolar crest and replacement of teeth with small cervical diameter. NDI have been available in clinical practice since the 1990s, but only few studies have analyzed their clinical outcome and no study have investigated NDI inserted in fresh-frozen bone (FFB grafts. Thus, a retrospective study on a series of NDI placed in homologue FFB was designed to evaluate their clinical outcome. MATERIAL AND METHODS: In the period between December 2003 and December 2006, 36 patients (22 females and 14 males, mean age 53 years with FFB grafts were selected and 94 different NDI were inserted. The mean follow-up was 25 months. To evaluate the effect of several host-, surgery-, and implant-related factors, marginal bone loss (MBL was considered an indicator of success rate (SCR. The Kaplan Meier algorithm and Cox regression were used. RESULTS: Only 5 out of 94 implants were lost (i.e. survival rate - SVR 95.7% and no differences were detected among the studied variables. On the contrary, the Cox regression showed that the graft site (i.e. maxilla reduced MBL. CONCLUSIONS: NDI inserted in FFB have a high SVR and SCR similar to those reported in previous studies on regular and NDI inserted in non-grafted jaws. Homologue FFB is a valuable material in the insertion of NDI.

  2. The Use of Narrow Diameter Implants in the Molar Area

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    M. Saad

    2016-01-01

    Full Text Available Implant rehabilitations in the posterior jaw are influenced by many factors such as the condition of the remaining teeth, the force factors related to the patient, the quality of the bone, the maintenance of the hygiene, the limited bone height, the type and extent of edentulism, and the nature of the opposing arch. The gold standard is to place a regular diameter implant (>3.7 mm or a wide one to replace every missing molar. Unfortunately, due to horizontal bone resorption, this option is not possible without lateral bone augmentation. In this situation, narrow diameter implant (NDI < 3.5 mm could be the alternative to lateral bone augmentation procedures. This paper presents a clinical study where NDIs were used for the replacement of missing molars. They were followed up to 11 years. Special considerations were observed and many parameters were evaluated. NDI could be used to replace missing molar in case of moderate horizontal bone resorption if strict guidelines are respected. Yet, future controlled prospective clinical trials are required to admit their use as scientific evidence.

  3. Replacement of a molar with two narrow-diameter dental implants

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    Rajeshwari Penmetsa

    2016-01-01

    Full Text Available Dental implants have demonstrated a high degree of success in the restorations of teeth in partially or completely edentulous patients. However, when the buccolingual width of the edentulous crest is insufficient for the placement of standard sized implants, the use of two or more smaller diameter implants should be considered to avoid the need for invasive reconstruction techniques such as grafting procedures. The present case report describes the replacement of a single mandibular first molar with two narrow-diameter implants, in a 41-year- old male patient. No postoperative complications were reported in the 3-year follow-up period. The placement of two narrow-diameter implants replacing a missing mandibular molar could eliminate the mesiodistal bending, double the support capacity in the buccolingual direction, and minimize stress on the implants.

  4. Clinical and radiographic evaluation of early loaded narrow-diameter implants

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    Maiorana, Carlo; King, Paul; Quaas, Sebastian

    2015-01-01

    OBJECTIVE: To evaluate the clinical reliability of narrow implants placed in a one-stage procedure and early loaded in the upper and lower incisor region. MATERIAL AND METHODS: This is a prospective, single-arm, multicenter study in which patients with missing natural dentition in upper lateral...... and lower incisor positions were enrolled. Eligible implants (OsseoSpeed™ TX 3.0S, DENTSPLY Implants) were of three different lengths and of 3.0 mm in diameter. One-stage surgery was performed and healing abutment connection took place. Placement of the permanent single crown took place after a 6-10 weeks...... healing period. Clinical and radiographic checks were performed at implant placement, loading, and at the 6, 12, 24, and 36 months follow-up visits. RESULTS: A total of 69 subjects with 97 implants have been included in this study. From surgery to 36 months follow-up, 5.6% of the implants showed bone loss...

  5. Application of a narrow-diameter implant in a limited space

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    Chia-Yun Tsai

    2010-06-01

    Full Text Available This report presents a case of inadequate space distribution after orthodontic treatment, when a narrow-diameter implant was placed in a limited mandibular anterior space (ridge and prosthetic. A 26-year-old female patient presented with a purulent discharge from the mandibular right posterior area. Radiographic and clinical evaluations revealed a four-unit bridge spanning teeth 42 to 43 and acute apical periodontitis with root resorption around tooth 42. After careful evaluation, tooth 42 was extracted, and orthodontic treatment was performed to align the posterior teeth and create a dimensionally appropriate space between teeth 41 and 43. A 3i MicroMiniplant with dimensions of 3.25 mm (diameter × 11.5 mm was implanted in the edentulous area of tooth 42 because of the small size of tooth 42. Autogenous bone particles were placed on the buccal crestal defect, and a healing abutment was attached. After an 8-month healing phase, a final impression was made and an all-ceramic crown was delivered. This case demonstrates that osseous sites with significant dimensional space limitations can be successfully utilized to receive and integrate a narrow-diameter implant that will satisfy esthetic, phonetic and functional requirements.

  6. Retrospective multicenter analysis of immediate provisionalization using one-piece narrow-diameter (3.0-mm) implants.

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    Sohn, Dong-Seok; Bae, Min-Su; Heo, Jeong-Uk; Park, Jun-Sub; Yea, Sun-Hae; Romanos, Georgios E

    2011-01-01

    The aim of this retrospective analysis was to report on the clinical outcome of immediate provisionalization using one-piece narrow-diameter implants. The dental records of patients who received narrow implants were reviewed. Narrow-diameter (3.0-mm) one-piece implants were used to support restorations of missing maxillary lateral incisors and mandibular incisors. All implants were placed in a one-stage procedure according to the protocol recommended by the manufacturer, with immediate placement of provisional restorations. Following an average healing period of 3 months in the mandible and 5 months in the maxilla, the definitive prostheses were fabricated. The survival rate of the implants was analyzed, and radiographic evaluation was performed. RESULTS. Thirty-six patients (20 men and 16 women), aged from 42 to 72 years (average age of 53 years), were treated with 62 one-piece narrow implants. A success rate of 100% was observed over a period up to 33 months (mean, 23 ± 4.3 months). Among these, 8 implants were placed in maxillary lateral incisor positions and 54 implants were placed in mandibular incisor areas. Forty-four implants supported fixed partial prostheses, and 18 implants supported single crowns. The majority of the implants were 15 mm in length. Mean marginal bone loss at the 12-month follow-up visit was 0.53 ± 0.37 mm (range, 0 to 1.4 mm). The results obtained in this retrospective analysis suggest that the one-piece narrow-diameter implant can predictably restore missing maxillary lateral incisors and mandibular incisor with narrow interdental spaces and labiolingual widths.

  7. Trends in techniques to avoid bone augmentation surgery: Application of short implants, narrow-diameter implants and guided surgery.

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    Pommer, Bernhard; Busenlechner, Dieter; Fürhauser, Rudolf; Watzek, Georg; Mailath-Pokorny, Georg; Haas, Robert

    2016-10-01

    Minimally invasive implantology using reduced implant dimensions as well as virtual treatment planning and CAD/CAM stereolithographic templates has gained popularity in recent years. The aim of the present investigation was to analyze prevailing trends in clinical utilization of these graftless therapeutic options. A total of 12.865 dental implants were placed in 5.365 patients at the Academy for Oral Implantology in Vienna, of which 5.5% were short (length short implants and guided surgery increased significantly in all subgroups. Narrow-diameter implants were most frequent in single-tooth gaps (24.1%), however, upward trends could only be observed in partially and completely edentulous patients. Short implants were predominantly used in the mandible (9.9% vs. 2.5%, P Short implants (most frequent in partial edentulism) and guided implant surgery (most frequent in complete edentulism) represent uprising and promising surgical approaches to avoid patient morbidity associated with bone graft surgery. Copyright © 2016. Published by Elsevier Ltd.

  8. Two Versus Three Narrow-Diameter Implants with Locator Attachments Supporting Mandibular Overdentures: A Two-Year Prospective Study

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    Ali M. El-Sheikh

    2012-01-01

    Full Text Available Purpose. To compare treatment outcome (survival rate, condition of hard and soft peri-implant tissues and prosthodontic maintenance requirements of two versus three narrow-diameter bone level implants with Locator attachments supporting mandibular overdentures. Materials and Methods. Twenty completely edentulous patients with atrophic mandibles were treated. Ten patients (Group A were treated with overdentures supported by two narrow (3.3-mm diameter implants (Straumann AG, Basel, Switzerland and ten patients (Group B were treated with overdentures supported by three narrow implants. Locator (Zest Anchors, USA attachments were used for prosthetic anchorage. Standardized clinical and radiographic parameters (survival rate, plaque index, calculus index, gingival index, bleeding index, probing depth and marginal bone loss were evaluated at the time of the completion of the prosthetic treatment (baseline and after 6, 12 and 24 months of functional loading. Prosthodontic maintenance requirements were also scored. Results. Only one implant was lost (Group B during the healing period. There were no significant differences with regards to any of the studied clinical and radiographic parameters between the two groups (>0.05. Few prosthetic complications were recorded. Conclusions. No need to insert more than two narrow-diameter bone level implants with Locator attachments in cases of atrophic mandible to support an overdenture, however, long-term prospective studies are required to support this notion.

  9. Clinical and radiographic evaluation of narrow- vs. regular-diameter dental implants: a 3-year follow-up. A retrospective study

    NARCIS (Netherlands)

    Zweers, J.; van Doornik, A.; Hogendorf, E.A.H.; Quirynen, M.; van der Weijden, G.A.

    2015-01-01

    Objectives Narrow-diameter implants (NDIs) are used in severely resorbed mandibles. The reduced implant diameter means a reduction in the total contact surface between the implant and bone. The question arises whether the implant can be sufficiently osseointegrated to withstand loading forces. If

  10. Evaluation of 316 narrow diameter implants followed for 5-10 years: a clinical and radiographic retrospective study.

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    Arisan, Volkan; Bölükbaşi, Nilüfer; Ersanli, Selim; Ozdemir, Tayfun

    2010-03-01

    Narrow diameter implants (NDIs; diameter >3.75 mm) are useful in replacement of missing incisor teeth and when the bucco-lingual width of the edentulous crest is insufficient. The present study evaluated the success and survival rates, peri-implant parameters, mechanical and prosthetic post-loading complications of NDIs followed over a 10-year period. Three hundred and sixteen NDIs were inserted into 139 patients and restored with 120 prostheses. Clinical and radiographic assessment data were collected during recall visits. Implant success (SC), cumulative survival rate (CSR), marginal bone loss (MBL), peri-implant conditions and prosthetic complications were assessed. Cox proportional hazards regression analysis, Kaplan-Meier survival curves with the log-rank test and life table analysis were used to evaluate the outcome of NDIs within comparable subgroups. MBL and peri-implant parameters measured annually were further analyzed. The mean follow-up time was 9.1 years (range: 60-124 months). Twelve implants were lost in the healing phase and two during function. The mean MBL in the maxilla and the mandible was 1.32 +/- 0.13 and 1.28 +/- 0.3 mm, respectively, after 10 years. SC and CSR were 91.4% and 92.3%, respectively, after 124 months. Smoking and posterior localization were associated with an increased risk of failure. Cement loosening (16.8%) was the most common prosthetic complication. No implants were fractured. NDIs can be used with confidence where a regular diameter implant is not suitable. MBL around NDIs occurred predominantly within 2 years of loading and was minimal thereafter. Further studies are required to clarify the possible risks associated with smoking and posterior placement.

  11. 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.

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    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

  12. Titanium-zirconium alloy narrow-diameter implants (Straumann Roxolid(®)) for the rehabilitation of horizontally deficient edentulous ridges: prospective study on 18 consecutive patients.

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    Chiapasco, M; Casentini, P; Zaniboni, M; Corsi, E; Anello, T

    2012-10-01

    (i) To evaluate the survival and success rates of the new Roxolid narrow diameter implant placed in horizontally deficient ridges; and (ii) to evaluate the incidence of prosthetic complications. In a 24-month period (2009-2010) 18 partially or totally edentulous patients received 51 Straumann Roxolid (13 tissue level, 38 bone level) implants. Prosthetic loading of implants was either immediate (four implants; one patient) or delayed (2-12 months after placement; 47 implants; 17 patients). The patients were rehabilitated with either fixed (16 patients; 45 implants) or removable (two patients; six implants) prostheses. All implants successfully achieved osseointegration and all patients completed the planned prosthetic rehabilitation. Peri-implant bone resorption values ranged from 0 to 1 mm at the end of the observation period (range: 3-19 months). Implant survival and success rates were therefore 100%. No prosthetic complications occurred and all implants are still in function; therefore the prosthesis success rate was 100%. Narrow diameter implants fabricated with the new titanium-zirconium alloy were demonstrated to be reliable in supporting both fixed and removable prosthetic rehabilitations in horizontally deficient ridges. Implant survival, peri-implant bone resorption, and prosthetic complication rates were consistent with those reported in the literature for standard diameter implants placed in non-deficient edentulous ridges. © 2011 John Wiley & Sons A/S.

  13. Clinical outcome of narrow-diameter (3.3-mm) locking-taper implants: a prospective study with 1 to 10 years of follow-up.

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    Mangano, Francesco; Shibli, Jamil A; Sammons, Rachel L; Veronesi, Giovanni; Piattelli, Adriano; Mangano, Carlo

    2014-01-01

    To evaluate the outcome of narrow-diameter (3.3-mm) locking-taper implants used in the rehabilitation of partially and fully edentulous patients over a 10-year period. Between January 2002 and December 2011, all patients referred to a private dental clinic for treatment with narrow-diameter implants were enrolled in this study. At each annual follow-up session, clinical and radiographic parameters were assessed; the outcome measurements were implant failure, peri-implant marginal bone loss (distance between the implant shoulder and the first visible bone-to-implant contact [DIB]), and biologic and technical complications. The cumulative survival rate (CSR) was assessed using the Kaplan-Meier survival estimator; Tarone-Ware and chi-square analyses were used to evaluate correlations between the study variables. The statistical analysis was performed at the patient- and implant-level. A total of 324 narrow-diameter implants were placed in 279 patients (159 men, 120 women; age: 25 to 73 years). Four implants failed, for an overall CSR of 98.5% (patient-based) and 98.7% (implant-based) at the 10-year follow-up. The survival rate did not differ significantly with respect to patients' sex, age, smoking or parafunctional habits, bone type, prosthetic restoration, or implant location, position, or length. Among the surviving implants, a mean DIB of 0.31 ± 0.23 mm, 0.45 ± 0.27 mm, and 0.69 ± 0.28 mm was observed at the 1-, 5-, and 10-year follow-up examinations, respectively. A few biologic (1.2%) and technical complications (7.5%) were reported. Within the limitations of this study, it can be concluded that narrow-diameter locking-taper implants represent a good treatment option for the prosthetic rehabilitation of partially and totally edentulous patients.

  14. Retrospective cohort clinical investigation of a dental implant with a narrow diameter and short length for the partial rehabilitation of extremely atrophic jaws.

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    Maló, Paulo S; de Araújo Nobre, Miguel A; Lopes, Armando V; Ferro, Ana S

    2017-01-01

    We investigated the short-term clinical outcomes of narrow-diameter short-length implants for the fixed-prosthetic partial rehabilitation of extremely resorbed jaws. Twenty-three patients requiring partial rehabilitations with narrow-platform short-length implants in any jaw were included in this study. In total, 30 implants 3.3 mm in diameter and 7 (n = 15 implants) or 8.5 (n = 15 implants) mm in length were inserted. The primary outcome measure was implant cumulative survival rate (CSR); the secondary outcome measures were marginal bone resorption at 1 and 3 years and the incidence of biologic and mechanical complications. Five patients (21.7%) with six implants (20%) were lost to follow-up. Two implants failed in two patients, yielding a CSR at 3 years of follow-up of 93.4%. The average (standard deviation) marginal bone resorption was 1.34 mm (0.95 mm) after the first year and 1.38 mm (0.78 mm) after the third year. Biologic complications occurred in three patients; mechanical complications occurred in three patients. Despite the limitations of the study, our findings show that the use of new narrow-diameter short-length implants for the rehabilitation of extremely atrophic regions is viable in the short-term, and can be considered a treatment alternative in extremely resorbed jaws.

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

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    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.

  16. Mini-implants and narrow diameter implants as mandibular overdenture retainers: A systematic review and meta-analysis of clinical and radiographic outcomes.

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    Marcello-Machado, R M; Faot, F; Schuster, A J; Nascimento, G G; Del Bel Cury, A A

    2018-02-01

    This study reviews the clinical and radiographic outcomes of Mini-implants (MI) and Narrow Diameter Implants (NDI) as mandibular overdenture (MO) retainers. Six databases were consulted for clinical studies that evaluated implants with diameter ≤3.5 mm. Data on the MI and NDI for survival and success rate and peri-implant bone loss and were collected and submitted to meta-analysis. Thirty-six studies were included, 24 reporting MI performance and 12 describing NDI results. The MI group comprised data from 1 cross-sectional clinical study, 3 retrospective longitudinal (RL) clinical studies, 13 prospective longitudinal (PL) clinical studies and 7 randomised clinical trials (RCT) with follow-up periods ranging from 1 day to 7 years. Eight studies used conventional loading, thirteen used immediate loading, two studies used both loading types, and one study did not report. The NDI group comprised data from 3 RL clinical studies, 6 PL clinical studies and 3 RCT with follow-up ranging from 6 months to 10 years. Ten studies used conventional loading, 1 study used immediate loading, and 1 study did not report. The average survival rates of MI and NDI studies were 98% and 98%, respectively, while the average success rates were 93% and 96%, respectively. The average peri-implant bone loss after 12, 24 and 36 months was 0.89, 1.18 and 1.02 mm for MI and 0.18, 0.12 and -0.32 mm for NDI. Both MI and NDI showed adequate clinical behaviour as overdenture retainers. The NDI showed a better long-term predictability to retain OM with most studies adopting conventional loading. © 2017 John Wiley & Sons Ltd.

  17. Narrow- and regular-diameter implants in the posterior region of the jaws to support single crowns: A 3-year split-mouth randomized clinical trial.

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    de Souza, André Barbisan; Sukekava, Flávia; Tolentino, Livia; César-Neto, João Batista; Garcez-Filho, João; Araújo, Mauricio G

    2018-01-01

    The objective of this 3-year split-mouth randomized controlled clinical study was to compare narrow-diameter implants (NDIs) to regular-diameter implants (RDIs) in the posterior region of the jaws (premolars and molars) in regards to (i) the marginal bone level (MBL) and (ii) implant and prosthesis survival and success rates. A total of 22 patients were included in the study. Each patient received at least one implant of each diameter (Ø3.3 and Ø4.1 mm), placed either in the maxilla or mandible to support single crowns. A total 44 implants (22 NDIs and 22 RDIs) were placed and included in the study. Twenty-one implants were placed in the premolar, whereas 23 were placed in molar areas. Radiographic evaluations to access the MBL were performed immediately after implant placement, 1 and 3 years after implant loading. Peri-implant clinical variables including probing pocket depth (PPD) and bleeding on probing (BoP) were obtained after crown delivery, 1 and 3 years after loading. Furthermore, the survival and success rates of the implants and prosthesis were also evaluated. Twenty patients were able to complete the study. There was no statistically significant difference regarding MBL between groups at implant placement (p = .084), 1-year (p = .794) and 3-year (p = .598) time intervals. The mean peri-implant bone loss at 3-year follow-up was -0.58 ± 0.39 mm (95% CI: -0.751 to -0.409) and -0.53 ± 0.46 mm (95% CI: -0.731 to -0.329) for NDIs and RDIs, respectively. BoP was present at 15% and 10% of NDIs and RDIs, respectively, at 3-year follow-up. PPD >5 mm was observed in 5% and 0% of the implants of NDIs and RDIs, respectively, at 3-year follow-up. At the 3-year examination, the implant success rates were in the NDIs and RDIs sites, respectively, 95% and 100%. The corresponding values for prosthesis success rates were 90% for NDIs and 95% for RDIs. The present study demonstrated that NDIs placed to support single crowns in the posterior region did

  18. Narrow implants (2.75 and 3.25 mm diameter) supporting a fixed splinted prostheses in posterior regions of mandible: one-year results from a prospective cohort study.

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    Grandi, Tommaso; Svezia, Luigi; Grandi, Giovanni

    2017-09-08

    Can multiple splinted narrow-diameter implants be used as definitive implants in patients with insufficient bone ridge thickness in posterior regions of the mandible? With this aim, we evaluated their outcomes in this set up to 1 year after loading. Forty-two patients with a mean age of 61.3 years old (range 49-73) in need of fixed prosthetic implant-supported rehabilitations in the posterior region of the mandible, presenting a thin alveolar crest, were selected. One hundred twenty-four narrow-diameter implants (2.75 and 3.25 mm diameter) were placed and splinted with a bridge. One implant for each missing tooth was requested to be inserted. Outcomes measured were implant survival, complications, and marginal bone level changes up to 1 year after loading. At the 12-month follow-up, three implants failed. Two 2.75 mm diameter implants and one 3.2 mm diameter implant failed. The implant survival rate was 97.6%. Peri-implant bone resorption was 0.20 mm (CI 95% 0.14: 0.26) after 6 months and 0.47 mm (CI 95% 0.29; 0.65) after 12 months of loading, not different between 2.75 and 3.25 mm diameter groups (p = 0.786). Of the 42 cases, three had an episode of peri-implant mucositis (7.1%). Within the limits of this study, preliminary short-term data (1 year post-loading) suggested that narrow-diameter implants (2.75 to 3.25 mm) can be successfully used as a minimally invasive alternative to horizontal bone augmentation in the posterior mandible. However, larger and longer follow-ups of 5 years or more are needed.

  19. Combined influence of implant diameter and alveolar ridge width on crestal bone stress: a quantitative approach.

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    Yu, Wonjae; Jang, Yoon-Je; Kyung, Hee-Moon

    2009-01-01

    To quantitatively evaluate the combined influence of implant diameter and alveolar ridge width on crestal bone stress. ITI solid-screw implants, 10 mm in length and 3.3, 4.1, and 4.8 mm in diameter, and the alveolar bone were modeled using axisymmetric finite elements. Four different alveolar ridge geometries were selected for each implant: 5-, 6-, 7-, and 8-mm-wide ridges for the 3.3-mm implants; 6-, 7-, 8-, and 9-mm-wide ridges for the 4.1-mm implants; and 7-, 8-, 9-, and 10-mm-wide ridges for the 4.8-mm implants. A nonaxial oblique load of 100 N was applied at 30 degrees to the implant axis. Regression analysis was used to avoid ambiguity when estimating the peak stress occurring at the coronal contact point between the implant and the crestal bone, ie, the singularity point. Peak stresses were dependent on both implant diameter and alveolar ridge width. Substantially lower stresses were recorded around the implants placed in narrower ridges. A regression analysis may be used to quantify the peak stress at the singularity point. An implant with a diameter that is at least half the ridge width is recommended to reduce the stress concentration in the crestal bone.

  20. Fracture strength and probability of survival of narrow and extra-narrow dental implants after fatigue testing: In vitro and in silico analysis.

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    Bordin, Dimorvan; Bergamo, Edmara T P; Fardin, Vinicius P; Coelho, Paulo G; Bonfante, Estevam A

    2017-07-01

    To assess the probability of survival (reliability) and failure modes of narrow implants with different diameters. For fatigue testing, 42 implants with the same macrogeometry and internal conical connection were divided, according to diameter, as follows: narrow (Ø3.3×10mm) and extra-narrow (Ø2.9×10mm) (21 per group). Identical abutments were torqued to the implants and standardized maxillary incisor crowns were cemented and subjected to step-stress accelerated life testing (SSALT) in water. The use-level probability Weibull curves, and reliability for a mission of 50,000 and 100,000 cycles at 50N, 100, 150 and 180N were calculated. For the finite element analysis (FEA), two virtual models, simulating the samples tested in fatigue, were constructed. Loading at 50N and 100N were applied 30° off-axis at the crown. The von-Mises stress was calculated for implant and abutment. The beta (β) values were: 0.67 for narrow and 1.32 for extra-narrow implants, indicating that failure rates did not increase with fatigue in the former, but more likely were associated with damage accumulation and wear-out failures in the latter. Both groups showed high reliability (up to 97.5%) at 50 and 100N. A decreased reliability was observed for both groups at 150 and 180N (ranging from 0 to 82.3%), but no significant difference was observed between groups. Failure predominantly involved abutment fracture for both groups. FEA at 50N-load, Ø3.3mm showed higher von-Mises stress for abutment (7.75%) and implant (2%) when compared to the Ø2.9mm. There was no significant difference between narrow and extra-narrow implants regarding probability of survival. The failure mode was similar for both groups, restricted to abutment fracture. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. The Effect of Implant Length and Diameter on the Primary Stability in Different Bone Types

    Directory of Open Access Journals (Sweden)

    Hamidreza Barikani

    2013-01-01

    Full Text Available Objective: The focus of this paper is to evaluate the influence of mechanical characteristics of the implant on primary stability in different bone types, based on resonance frequency analysis (RFA.Materials and Methods: A number of 60 Nobel Biocare Replace Select TiUnit Tapered implants of two different lengths (10 mm and 13 mm and three different widths as 3.4 mm (narrow platform (NP, 4.3 mm (regular platform (RP and 5 mm (wide platform (WP were placed into two different groups of bone blocks. Bone blocks were different in bone quality, but similar to bone types D1 and D3. Immediately, after implant placement, implant stability quotient (ISQ was measured using the Osstell mentor device.Results: ISQ values for implant placements in D1 bone were significantly higher than those for implants placed in D3 bone. In D1 bone, the implant length did not make any significant difference in primary stability; however, in D3 bone, the primary stability of the implant increased when longer implants were utilized. NP implants presented significantly lower ISQ values compared to the two wider implants.Conclusion: In cases of low bone quality, the optimum increase in the implant length and diameter should be taken into account to achieve higher primary stability.

  2. The effect of implant and abutment diameter on peri-implant bone stress: A three-dimensional finite element analysis

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    Helen Mary Abraham

    2016-01-01

    Full Text Available Introduction: Load transfer mechanisms from the implant to surrounding bone and failure of osseointegrated implants are affected by implant geometry and mechanical properties of the site of placement as well as crestal bone resorption. Estimation of such effects allows for a correct design of implant geometry to minimize crestal bone loss and implant failure. Objectives: To evaluate the effect of implant and abutment diameter on stress distribution in the peri-implant area. Materials and Methods: Three-dimensional finite element models created to replicate completely osseointegrated endosseous titanium implants and were used for the purpose of stress analysis. Two study groups that consisting of a regular platform (RP group and narrow platform (NP group were used with a standard bone density and loaded using the ANSYS Workbench software to calculate the von Mises and Principal (maximum tensile and minimum compressive stress. Results: The von Mises, compressive, and tensile stresses in the peri-implant bone were lower in the RP model compared to the NP model. Conclusion: RP model yielded a positive result with regard to lowering of peri-implant bone stress levels, in healthy as well as compromised bone qualities when compared to NP designs.

  3. Narrow- versus mini-implants at crestal and subcrestal bone levels. Experimental study in beagle dogs at three months.

    Science.gov (United States)

    Calvo-Guirado, José Luis; Pérez-Albacete, Carlos; Aguilar-Salvatierra, Antonio; de Val Maté-Sánchez, José E; Delgado-Ruiz, Rafael A; Abboud, Marcus; Velasco, Eugenio; Gómez-Moreno, Gerardo; Romanos, Georgios E

    2015-07-01

    The objective of this study was to evaluate the osseointegration and crestal bone loss (CBL) in two implant designs with different diameters (Mini Sky® and Narrow Sky®) implants, placed at different vertical levels at healed canine ridges. The second, third, and fourth mandibular premolars of six Beagle dogs were extracted bilaterally. After 2 months healing, four implants divided into two groups according to their diameters (i.e., Narrow Sky® and Mini Sky®) were placed in each hemi-mandible at the level of the bone crest or 2 mm subcrestally. The animals were euthanized at 12 weeks and undecalcified samples were processed for histology. Histomorphometric analysis was carried out to compare bone-to-implant contacts (BIC) and crestal bone loss (CBL). There were not significant differences in CBL between groups when the implants were placed at subcrestal bone level (p > 0.05), meanwhile the CBL was significantly higher for both groups when the implants were inserted at crestal level (p mini-implants. Subcrestal insertion of both implants favors crestal bone preservation but crestal insertion of both designs is associated with crestal bone loss The study shows that narrow implants protect peri-implant crestal bone.

  4. The effect of shape, length and diameter of implants on primary stability based on resonance frequency analysis

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    Hamidreza Barikani

    2014-01-01

    Full Text Available Background: The aim of this in vitro study was to evaluate the effect of shape, diameter and length of implants on their primary stability based on resonance frequency analysis. Materials and Methods: Replace select tapered and Branemark MK III implants were selected. Each of these two selected groups was divided into nine subgroups based on the implant length (IL (short, medium and long and the implant diameter (ID (narrow platform [NP], regular platform [RP] and wide platform [WP]. Five implants were assigned to each of the nine subgroups. Implants were placed in artificial bone blocks with bone quality similar to D3 bone. Immediately after the implant placement, its primary stability was measured using Osstell Mentor equipment. T-test and Tukey′s honest significant difference Post hoc were performed for data analysis. Statistical significance was defined at P < 0.05. Results: Replace select system showed significantly higher primary stability compared to the Branemark system, when using the short implants for all three diameters (P ≤ 0.004. However, in medium length implants there were no significant differences between the two implant systems (P ≥ 0.31. In long implants, only when the NP and RP implants were used, the Replace Select system showed significantly higher primary stability compared to the Branemark system (P = 0.000. In the replace select system, long implants had a significantly higher primary stability compared to medium and short length implants (P ≤ 0.003. In the NP and RP Branemark implants, short implants showed significantly lower primary stability compared to medium and long implants (P ≤ 0.002. However, in WP Branemark implants, primary stability increased significantly with increasing the IL from short to medium and from medium to long (P = 0.000. There were also significant differences between NP and the two other wider implants in both systems (P = 0.000. Conclusion: The use of tapered implants is

  5. The effect of shape, length and diameter of implants on primary stability based on resonance frequency analysis

    Science.gov (United States)

    Barikani, Hamidreza; Rashtak, Shadab; Akbari, Soolmaz; Fard, Mohammadjavad Kharrazi; Rokn, Amirreza

    2014-01-01

    Background: The aim of this in vitro study was to evaluate the effect of shape, diameter and length of implants on their primary stability based on resonance frequency analysis. Materials and Methods: Replace select tapered and Branemark MK III implants were selected. Each of these two selected groups was divided into nine subgroups based on the implant length (IL) (short, medium and long) and the implant diameter (ID) (narrow platform [NP], regular platform [RP] and wide platform [WP]). Five implants were assigned to each of the nine subgroups. Implants were placed in artificial bone blocks with bone quality similar to D3 bone. Immediately after the implant placement, its primary stability was measured using Osstell Mentor equipment. T-test and Tukey's honest significant difference Post hoc were performed for data analysis. Statistical significance was defined at P Branemark system, when using the short implants for all three diameters (P ≤ 0.004). However, in medium length implants there were no significant differences between the two implant systems (P ≥ 0.31). In long implants, only when the NP and RP implants were used, the Replace Select system showed significantly higher primary stability compared to the Branemark system (P = 0.000). In the replace select system, long implants had a significantly higher primary stability compared to medium and short length implants (P ≤ 0.003). In the NP and RP Branemark implants, short implants showed significantly lower primary stability compared to medium and long implants (P ≤ 0.002). However, in WP Branemark implants, primary stability increased significantly with increasing the IL from short to medium and from medium to long (P = 0.000). There were also significant differences between NP and the two other wider implants in both systems (P = 0.000). Conclusion: The use of tapered implants is recommended, especially, when the use of short implants is necessary. The use of RP implants is also preferred to WP

  6. The Impact of Force Transmission on Narrow-Body Dental Implants Made of Commercially Pure Titanium and Titanium Zirconia Alloy with a Conical Implant-Abutment Connection: An Experimental Pilot Study.

    Science.gov (United States)

    Nelson, Katja; Schmelzeisen, Rainer; Taylor, Thomas D; Zabler, Simon; Wiest, Wolfram; Fretwurst, Tobias

    2016-01-01

    The purpose of this study was to visualize the mode and impact of force transmission in narrowdiameter implants with different implant-abutment designs and material properties and to quantify the displacement of the abutment. Narrow-diameter implants from two manufacturers were examined: Astra 3.0-mm-diameter implants (Astra OsseoSpeed TX; n = 2) and Straumann Bone Level implants with a 3.3-mm diameter made of commercially pure titanium (cpTi) Gr. 4 (n = 2) and 3.3-mm TiZr-alloy (n = 2; Bone Level, Straumann) under incremental force application using synchrotron radiography (absorption and inline x-ray phase-contrast) and tomography. During loading (250 N), Astra 3.0 and Bone Level 3.3- mm implants showed a deformation of the outer implant shoulder of 61.75 to 95 μm independent of the implant body material; the inner implant diameter showed a deformation of 71.25 to 109.25 μm. A deformation of the implant shoulder persisted after the removal of the load (range, 42.75 to 104.5 μm). An angulated intrusion of the abutment (maximum, 140 μm) into the implant body during load application was demonstrated; this spatial displacement persisted after removal of the load. This study demonstrated a deformation of the implant shoulder and displacement of the abutment during load application in narrow-diameter implants.

  7. The success rate of narrow body implants used for supporting immediate provisional restorations: a pilot feasibility study.

    Science.gov (United States)

    Wang, Hom-Lay; Okayasu, Kozue; Fu, Jia-Hui; Hamerink, Howard A; Layher, Mary G; Rudek, Ivan Elimar

    2012-12-01

    Implants were first designed to be used in the reconstruction of edentulous mandibles. However, with the technological advancement, enormous changes were made to improve the implant design and surface characteristics leading to the wide use of implants in the replacement of missing teeth. During the transition from an edentulous span to a fixed prosthesis, narrow body implants (NBIs) have been proposed to enhance patient comfort and function. Therefore, this study was aimed at investigating the survival and success rates of NBIs used for supporting immediately nonfunctional loaded provisional fixed partial denture (PFPD). Either 2.2- or 2.4-mm-diameter dental implants were placed transmucosally into the edentulous ridges of 10 partially edentulous patients. PFPD of self-cured bis-acryl composite material were made using either a vacuform template chairside or a relined prefabricated PFPD. Occlusal adjustments were made to ensure that there was no functional loading on the provisional restorations before they were secured onto the transitional implants. At 1 year, the implant success and survival rates were 38.7% and 93.5%, respectively, with a mean percentage of bone loss of 9.46% (0%-40%) and a mean bone loss of 1.19 mm (range: 0-3.5 mm). With a favorable implant survival rate, the use of NBIs to support provisional restorations seemed to be a feasible treatment option. In addition, there is merit for research on the long-term use of NBIs-supported final prostheses.

  8. Analysis of the distribution of stress and deformation in single implant-supported prosthetic units in implants of different diameters

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    Francesco Salvatore MANNARINO

    Full Text Available Abstract Introduction When stress and strain levels in the bone-implant system exceed It's capacity, a mechanical fatigue occurs, resulting in collapse and loss of osseointegration. Objective Analyze biomechanical behavior in single implant-supported prosthesis with implants of different diameters in the posterior mandible. Material and method Three different finite element models of Cone-Morse implants with the same height were created, varying the diameter (3.3 mm, 4.1 mm and 4.8 mm. The mandibular first molar area was the location of the implant, with It´s component and overlying prosthetic crown. The jawbone was composed of cortical and cancellous bone. Refined mesh of 0.5 mm was created in the critical interfaces to be analyzed. The loading of the models was performed at the point of occlusal contact with an occlusal load of 400 N. Result Maximum stress and strain occurred in the cervical regions of the implants in all groups, either in the implants or in components as well as in the analysis of cortical bone. The greater the diameter, the lower the stress and strain found in the implant. The 3.3 mm group had the highest strain in peri-implant cortical bone, and the 4.1 mm group had the smallest deformation, significantly lower than in the 4.8 mm group. Conclusion Although the biggest implant diameter (4.8 mm appears to have lower values of stress and strain, the group of intermediate implant diameter (4.1 mm showed less deformation rate in the cortical peri-implant bone. Therefore it is concluded that the 4.1 mm implant platform presented a more biomechanically effective peri-implant bone maintenance.

  9. Effects of implant diameter and prosthesis retention system on the reliability of single crowns.

    Science.gov (United States)

    Bonfante, Estevam A; Almeida, Erika O; Lorenzoni, Fabio C; Coelho, Paulo G

    2015-01-01

    The probability of survival of implant-supported prostheses may be affected by the interplay between different implant diameters supporting screwed or cemented crowns. The purpose of this study was to investigate the effect of implant diameter and prosthesis retention system on the reliability and failure modes of single crowns. Internal-hexagon implants were divided into six groups (n = 21 each) according to implant diameter (3.3, 4.0, or 5.0 mm) and crown retention system (screwed or cemented). Abutments were torqued to the implants, and crowns were then fixed and subjected to step-stress accelerated life testing in water. Use-level probability Weibull curves and reliability for missions of 50,000 cycles at 100, 150, and 200 N were calculated. Failure analysis was performed. Cemented systems presented higher reliability than screwed ones, except between 3.3-mm-diameter cemented and screwed systems at a load of 100 or 150 N. Failure modes were restricted to the abutment screw and varied with implant diameter only in the cement-retained groups. Higher reliability was observed for cement-retained crowns and implants of larger diameter compared to screw-retained and smaller diameter. Failure modes differed between groups.

  10. Experimental investigation of commercial small diameter dental implants in porcine mandibular segments.

    Science.gov (United States)

    Hasan, Istabrak; Heinemann, Friedhelm; Schwegmann, Monika; Keilig, Ludger; Stark, Helmut; Bourauel, Christoph

    2017-02-01

    Small diameter (mini) dental implants have become more popular in recent years as alternatives to classical implant treatment in clinical cases with critical bony situations. However, an in-depth scientific analysis of the mechanical and biomechanical effects of small diameter implants has not yet been published. The aim of the present study was to investigate experimentally different commercial mini implants by measuring their displacements under immediate loading. Twelve commercially available mini implants were measured. Implants were inserted into porcine mandibular segments and loaded by means of a predefined displacement of 0.5 mm of the loading system. The implants were loaded at an angle of 30° to the implant long axis using the self-developed biomechanical hexapod measurement system. Implant displacements were registered. The experimental results were compared to the numerical ones from a previous study. Measured implant displacements were within the range of 39-194 μm. A large variation in the displacements was obtained among the different implant systems due to the different designs and thread profiles. Comparing experimental and numerical results, the displacements that were obtained numerically were within the range of 79-347 μm. The different commercial mini implants showed acceptable primary stability and could be loaded immediately after their insertion.

  11. Influence of simulated bone-implant contact and implant diameter on secondary stability: a resonance frequency in vitro study.

    Science.gov (United States)

    Veltri, Mario; González-Martín, Oscar; Belser, Urs C

    2014-08-01

    This study tested the hypothesis of no differences in resonance frequency for standardized amounts of simulated bone-implant contact around implants with different diameters. In addition, it was evaluated if resonance frequency is able to detect a difference between stable and rotation mobile ("spinning") implants. Implants with diameters of 3.3, 4.1 and 4.8 mm were placed in a purposely designed metal mould where liquid polyurethane resin was then poured to obtain a simulated bone-implant specimen. By regulating the mould, it was possible to create the following simulated bone-implant contact groups: 3.3 mm (198.6 mm(2)); 4.1 mm (198.8 mm(2)); 4.8 mm (200.2 mm(2)); 4.8 mm (231.7 mm(2)); 4.8 mm (294.7 mm(2)). Each group included 10 specimens. After resin setting, resonance frequency was measured. On the last group, measurements were repeated after establishing implant rotational mobility. One-way ANOVA tests with post hoc comparisons, a Pearson's correlation coefficient and a t-test for repeated measurements were used to evaluate statistically significant differences. Implants with different diameters but with the same amount of simulated osseointegration revealed no differences in resonance frequency. On the contrary, an increase of simulated bone-implant contact resulted in significantly higher resonance frequency. A clear direct linear correlation resulted between resonance frequency and simulated bone-implant contact. Furthermore, a significant difference resulted between resonance frequency measured before and after creation of rotational mobility. Within the conditions of this study, the secondary stability was correlated with the simulated bone-implant contact. In addition, resonance frequency was able to discern between stable and rotation mobile implants. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  12. Clinical Evaluation of Small Diameter Straumann Implants in Partially Edentulous Patients: A 5-Year Retrospective Study

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    S. OZER

    2011-06-01

    Full Text Available Objective: The aim of the present study was to retrospectively evaluate small-diameter (3.3 mm Straumann® dental implants placed in the maxilla or the mandible over a period of 5 years in function.Materials and Methods: Twenty- eight partially edentulous patients received a total of 48 implants over a 5-year period. After the standard healing period (3 to 6 months, the implants were restored with single-tooth prostheses or fixed partial dentures. All patients were followed according to a strict maintenance program with regular recalls. The cumulative survival rates of implants were analyzed and prosthetic complications were assessed.Results: After 5 years of function, one single 10-mm-long implant in the maxillary premolar region was lost because of recurrent peri-implant infection in a female patient. Two single 10-mm-long maxillary implants placed in the posterior region were lost due to body fracture. The cumulative 5-year survival rate of the implants was 93.75 %. The most common prosthetic complication was loosening of the occlusal screw.Conclusion: Within the limited observation period and the number of patients included in this study, it may be concluded that the use of small-diameter implants appears to be predictable if clinical guidelines are followed and appropriate prosthetic restorations are provided. However, it should be noted that fatigue fracture may occur.

  13. Clinical evaluation of small diameter straumann implants in partially edentulous patients: a 5-year retrospective study.

    Science.gov (United States)

    Yaltirik, M; Gökçen-Röhlig, B; Ozer, S; Evlioglu, G

    2011-01-01

    The aim of the present study was to retrospectively evaluate small-diameter (3.3 mm) Straumann® dental implants placed in the maxilla or the mandible over a period of 5 years in function. Twenty-eight partially edentulous patients received a total of 48 implants over a 5-year period. After the standard healing period (3 to 6 months), the implants were restored with single-tooth prostheses or fixed partial dentures. All patients were followed according to a strict maintenance program with regular recalls. The cumulative survival rates of implants were analyzed and prosthetic complications were assessed. After 5 years of function, one single 10-mm-long implant in the maxillary premolar region was lost because of recurrent peri-implant infection in a female patient. Two single 10-mm-long maxillary implants placed in the posterior region were lost due to body fracture. The cumulative 5-year survival rate of the implants was 93.75 %. The most common prosthetic complication was loosening of the occlusal screw. Within the limited observation period and the number of patients included in this study, it may be concluded that the use of small-diameter implants appears to be predictable if clinical guidelines are followed and appropriate prosthetic restorations are provided. However, it should be noted that fatigue fracture may occur.

  14. Immediate provisionalization in the esthetic zone: 1-year interim results from a prospective single-cohort multicenter study evaluating 3.0-mm-diameter tapered implants.

    Science.gov (United States)

    Kolinski, Martin; Hess, Pablo; Leziy, Sonia; Friberg, Bertil; Bellucci, Gionata; Trisciuoglio, Davide; Wagner, Wilfried; Moergel, Maximilian; Pozzi, Alessandro; Wiltfang, Jörg; Behrens, Eleonore; Zechner, Werner; Vasak, Christoph; Weigl, Paul

    2018-02-03

    The aim of this interim analysis of a 5-year prospective multicenter study is to evaluate clinical and radiological performance of immediately provisionalized 3.0-mm-diameter tapered implants. Patients needing implant rehabilitation of maxillary lateral incisors or mandibular lateral and central incisors were treated with 3.0-mm-diameter implants placed in extraction or healed sites and immediately provisionalized. Clinical and radiographic examinations were performed at implant insertion, 6 months thereafter, and are ongoing. Marginal bone levels and changes, complications, the papilla, plaque, and bleeding indices, and the pink esthetic score (PES) were evaluated at each follow-up visit. Of 112 enrolled patients, 77 patients (91 implants) met the inclusion criteria. Seventy-one patients with 82 implants completed the 1-year follow-up. Three implants failed yielding a CSR of 96.7%. All failures occurred within the first 3 months after implant insertion. Marginal bone level changes from insertion to 6 months was - 0.57 ± 1.30 mm (n = 75) and from insertion to 12 months - 0.25 ± 1.38 mm (n = 72). Fifteen non-serious complications were recorded. Papilla index score and PES improved at the 1-year follow-up. Plaque formation and bleeding-on-probing showed no statistically significant differences between the 6-month and the 1-year visit. This 1-year analysis demonstrated high survival, stable bone levels, and healthy soft tissue with 3.0-mm-diameter implants. Narrow diameter implants are a safe and predictable treatment option in patients with limited bone volume and/or limited interdental space and eligible for immediate loading protocols.

  15. MAP optimization as a predictor of cochlear implant outcomes in children with narrow internal auditory canal.

    Science.gov (United States)

    Lee, Youngmee; Jeong, Sung-Wook; Kim, Lee-Suk

    2012-11-01

    The purposes of this study were to investigate the auditory performance and MAP characteristics of implanted children with narrow internal auditory canal (IAC), and to examine the clinical usefulness of MAP optimization as a predictor of their cochlear implant (CI) outcomes by analyzing their auditory performance and habilitation methods in relation to MAP optimization. Eight children with narrow IAC who had used a CI over 3 years were included. We retrospectively examined their auditory performance and MAPs. Auditory performance was measured by the Categories of Auditory Performance (CAP) and monosyllabic word tests before and after implantation. The relationship between auditory performance and MAP parameters was explored, and their habilitation methods were analyzed. Mean CAP scores improved from .25 preoperatively to 3.5 3 years postoperatively. Mean scores for monosyllabic word tests improved from 0% preoperatively to 27.8% 3 years postoperatively. The children used MAPs with a wider pulse width than the default setting. Four children using optimal MAPs achieved open-set speech perception, so were trained in the oral approach. The other four using suboptimal MAPs because of non-auditory stimulation achieved no open-set speech perception, so were trained in the total communication approach. MAP optimization had a predictable value in determining the postoperative performance of children with narrow IAC who received a CI. The most suitable habilitation method can be determined early after implantation by identifying the presence of MAP optimization. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  16. Strain analysis of different diameter Morse taper implants under overloading compressive conditions

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    Carolina Guimarães CASTRO

    2015-01-01

    Full Text Available The aim of this study was to evaluate the amount of deformation from compression caused by different diameters of Morse taper implants and the residual deformation after load removal. Thirty Morse taper implants lacking external threads were divided into 3 groups (n = 10 according to their diameter as follows: 3.5 mm, 4.0 mm and 5.0 mm. Two-piece abutments were fixed into the implants, and the samples were subjected to compressive axial loading up to 1500 N of force. During the test, one strain gauge remained fixed to the cervical portion of each implant to measure the strain variation. The strain values were recorded at two different time points: at the maximum load (1500 N and 60 seconds after load removal. To calculate the strain at the implant/abutment interface, a mathematical formula was applied. Data were analyzed using a one-way Anova and Tukey’s test (α = 0.05. The 5.0 mm diameter implant showed a significantly lower strain (650.5 μS ± 170.0 than the 4.0 mm group (1170.2 μS ± 374.7 and the 3.5 mm group (1388.1 μS ± 326.6 (p < 0.001, regardless of the load presence. The strain values decreased by approximately 50% after removal of the load, regardless of the implant diameter. The 5.0 mm implant showed a significantly lower strain at the implant/abutment interface (943.4 μS ± 504.5 than the 4.0 mm group (1057.4 μS ± 681.3 and the 3.5 mm group (1159.6 μS ± 425.9 (p < 0.001. According to the results of this study, the diameter influenced the strain around the internal and external walls of the cervical region of Morse taper implants; all diameters demonstrated clinically acceptable values of strain.

  17. Influence of platform diameter in the reliability and failure mode of extra-short dental implants.

    Science.gov (United States)

    Bordin, Dimorvan; Bergamo, Edmara T P; Bonfante, Estevam A; Fardin, Vinicius P; Coelho, Paulo G

    2018-01-01

    To evaluate the influence of implant diameter in the reliability and failure mode of extra-short dental implants. Sixty-three extra-short implants (5mm-length) were allocated into three groups according to platform diameter: Ø4.0-mm, Ø5.0-mm, and Ø6.0-mm (21 per group). Identical abutments were torqued to the implants and standardized crowns cemented. Three samples of each group were subjected to single-load to failure (SLF) to allow the design of the step-stress profiles, and the remaining 18 were subjected to step-stress accelerated life-testing (SSALT) in water. The use level probability Weibull curves, and the reliability (probability of survival) for a mission of 100,000 cycles at 100MPa, 200MPa, and 300MPa were calculated. Failed samples were characterized in scanning electron microscopy for fractographic inspection. No significant difference was observed for reliability regarding implant diameter for all loading missions. At 100MPa load, all groups showed reliability higher than 99%. A significant decreased reliability was observed for all groups when 200 and 300MPa missions were simulated, regardless of implant diameter. At 300MPa load, the reliability was 0%, 0%, and 5.24%, for Ø4.0mm, Ø5.0mm, and Ø6.0mm, respectively. The mean beta (β) values were lower than 0.55 indicating that failures were most likely influenced by materials strength, rather than damage accumulation. The Ø6.0mm implant showed significantly higher characteristic stress (η = 1,100.91MPa) than Ø4.0mm (1,030.25MPa) and Ø5.0mm implant (η = 1,012.97MPa). Weibull modulus for Ø6.0-mm implant was m = 7.41, m = 14.65 for Ø4.0mm, and m = 11.64 for Ø5.0mm. The chief failure mode was abutment fracture in all groups. The implant diameter did not influence the reliability and failure mode of 5mm extra-short implants. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. 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

  19. Immediate Placement of Ultrawide-Diameter Implants in Molar Sockets: Description of a Recommended Technique.

    Science.gov (United States)

    Hattingh, André C; De Bruyn, Hugo; Ackermann, Andrew; Vandeweghe, Stefan

    Immediate implant placement is performed less frequently in molar extraction sockets than in single root sockets. This is mainly due to the tripodal anatomical configuration of molar roots, which is perceived as complex and therefore unsuitable. The mechanical burden of molar sites, combined with much larger socket dimensions, make it amenable to the use of ultrawide-diameter dental implants. This article describes a practical, sequenced technique that can be used predictably for immediate implant placement in maxillary and mandibular first molar sockets, using a dry skull model for clarification. This detailed description is based on the experience of more than 580 clinical cases over a 10-year period.

  20. Effect of implantoplasty on fracture resistance and surface roughness of standard diameter dental implants.

    Science.gov (United States)

    Costa-Berenguer, Xavier; García-García, Marta; Sánchez-Torres, Alba; Sanz-Alonso, Mariano; Figueiredo, Rui; Valmaseda-Castellón, Eduard

    2018-01-01

    To assess the effect of implantoplasty on the fracture resistance, surface roughness, and macroscopic morphology of standard diameter (4.1 mm) external connection dental implants. An in vitro study was conducted in 20 screw-shaped titanium dental implants with an external connection. In 10 implants, the threads and surface were removed and polished with high-speed burs (implantoplasty), while the remaining 10 implants were used as controls. The final implant dimensions were recorded. The newly polished surface quality was assessed by scanning electron microscopy (SEM) and by 3D surface roughness analysis using a confocal laser microscope. Finally, all the implants were subjected to a mechanical pressure resistance test. A descriptive analysis of the data was made. Also, Student's t tests were employed to detect differences regarding the compression tests. Implantoplasty was carried out for a mean time of 10 min and 48 s (standard deviation (SD) of 1 min 22 s). Macroscopically, the resulting surface had a smooth appearance, although small titanium shavings and silicon debris were present. The final surface roughness (S a values 0.1 ± 0.02 μm) was significantly lower than that of the original (0.75 ± 0.08 μm S a ) (p = .005). There was minimal reduction in the implant's inner body diameter (0.19 ± 0.03 mm), and no statistically significant differences were found between the test and control implants regarding the maximum resistance force (896 vs 880 N, respectively). Implantoplasty, although technically demanding and time-consuming, does not seem to significantly alter fracture resistance of standard diameter external connection implants. A smooth surface with S a values below 0.1 μm can be obtained through the use of silicon polishers. A larger sample is required to confirm that implantoplasty does not significantly affect the maximum resistance force of standard diameter external connection implants. © 2017 John Wiley & Sons A/S. Published

  1. Tuning the electronic properties by width and length modifications of narrow-diameter carbon nanotubes for nanomedicine

    KAUST Repository

    Poater, Albert

    2012-10-01

    The distinctive characteristics of nanoparticles, resulting from properties that arise at the nano-scale, underlie their potential applications in the biomedical sector. However, the very same characteristics also result in widespread concerns about the potentially toxic effects of nanoparticles. Given the large number of nanoparticles that are being developed for possible biomedical use, there is a need to develop rapid screening methods based on in silico methods. This study illustrates the application of conceptual Density Functional Theory (DFT) to some carbon nanotubes (CNTs) optimized by means of static DFT calculations. The computational efforts are focused on the geometry of a family of packed narrow-diameter carbon nanotubes (CNTs) formed by units from four to twelve carbons evaluating the strength of the C-C bonds by means of Mayer Bond Orders (MBO). Thus, width and length are geometrical features that might be used to tune the electronic properties of the CNTs. At infinite length, partial semi-conductor characteristics are expected. © 2012 Bentham Science Publishers.

  2. Small-diameter dental implants: An adjunct for retention, stability, and comfort for the edentulous patient

    Directory of Open Access Journals (Sweden)

    Antonio Scarano

    2012-10-01

    Full Text Available Aim: Studies have shown that mandibular implant overdentures significantly increase satisfaction and quality of life of edentulous elders. Improved chewing ability appears to have a positive impact on nutritional state. Materials and methods: Forty edentulous subjects received four permucosal mini-implants for overdentures in the interforamina region of the mandible. Almost all participants were still satisfied with their overdentures. Participant satisfaction concerning retention and stability of the mandibular overdenture was assessed. A micro invasive technique was adopted, without open flap and performed in one chirurgical step; this technique can be used also in the so-called “highrisk” patients (anticoagulant terapy, diabetes, etc. Results and conclusion: Results and conclusion The results suggest that a mandibular overdenture retained by 4 mini-implants may be the best treatment strategy for edentulous people with atrophic ridges. The use of mini-implants is in many cases a good clinical alternative to the use of larger diameter implants, in that they enable to reduce surgical time, bleeding, postoperative discomfort and healing time.

  3. Selection of optimal dental implant diameter and length in type IV bone: a three-dimensional finite element analysis.

    Science.gov (United States)

    Li, T; Kong, L; Wang, Y; Hu, K; Song, L; Liu, B; Li, D; Shao, J; Ding, Y

    2009-10-01

    This study aimed to create a 3D finite element model for continuous variation of implant diameter and length, thereby identifying their optimal range in type IV bone under biomechanical consideration. Implant diameter ranged from 3.0 to 5.0mm, and implant length ranged from 6.0 to 14.0mm. The results suggest that under axial load, the maximum Von Mises stresses in cortical and cancellous bones decrease by 50% and 27%, respectively; and under buccolingual load, by 52% and 60%, respectively. Under these two loads, the maximum displacements of implant-abutment complex decrease by 39% and 43%, respectively. These results indicate that in type IV bone, implant length is more crucial in reducing bone stress and enhancing the stability of implant-abutment complex than implant diameter. Biomechanically, implant diameter exceeding 4.0mm and implant length exceeding 9.0mm are the combination with optimal properties for a screwed implant in type IV bone.

  4. Influence of the Diameter of Dental Implants Replacing Single Molars: 3- to 6-Year Follow-Up.

    Science.gov (United States)

    Mendonça, Jose Alfredo; Senna, Plinio Mendes; Francischone, Carlos Eduardo; Francischone Junior, Carlos Eduardo; Sotto-Maior, Bruno Salles

    The aim of this study was to evaluate the influence of the implant diameter on marginal bone remodeling around dental implants replacing single molars after a follow-up period of 3 to 6 years. Patients who received dental implants with an external hexagon platform in healed sites to support a single metal-ceramic crown in the molar region were recalled to the office. The implantation sites and implant length information were recorded, and the implants were divided according to the implant diameter: regular (RP) or wide (WP). Each implant was assessed by digital periapical radiography, using a sensor holder for the paralleling technique. The marginal bone remodeling was determined as the distance from the implant platform to the first bone-to-implant contact, and the known implant length was used to calibrate the images in the computer software. The follow-up measurements were compared with those obtained from the radiograph taken at the time of prosthetic loading to determine the late bone remodeling. The independent t test was used to compare data. A total of 67 implants from 46 patients were evaluated with a mean follow-up period of 4.5 ± 1.0 years. The RP group comprised 36 implants from 29 patients (mean age: 58.3 ± 10.6 years), while 31 implants from 17 patients (mean age: 56.9 ± 11.5 years) were included in the WP group. The RP group presented lower survival rates (86.1%) than the WP group (100.0%). Similar marginal bone loss (P implants exhibited lower incidence failures, the bone levels were similar after the prosthetic loading around regular- and wide-diameter implants supporting single molar crowns.

  5. Evaluation of design parameters of dental implant shape, diameter and length on stress distribution: a finite element analysis.

    Science.gov (United States)

    Mohammed Ibrahim, M; Thulasingam, C; Nasser, K S G A; Balaji, V; Rajakumar, M; Rupkumar, P

    2011-09-01

    The aim was to evaluate the design parameters of dental implants shape, diameter and length on stress distribution by finite element analysis (FEA).The objectives of the study was to compare the influence of stress distribution in the implants of screw-vent tapered and parallel design by varying the implant diameter with a standard implant length. Six dental implant models have been simulated three-dimensionally. The influence of diameter and length on stress distribution was evaluated by Group I: for screw-vent tapered design (Zimmer Dental Implant Carlsbad, CA, USA) (1) Dental implant model with diameter 3.7 mm and length 13 mm. (2) Dental implant model with diameter 4.1 mm and length 13 mm. (3) Dental implant model with diameter 4.7 mm and length 13 mm. Group II: for parallel design (Zimmer Dental Implant Carlsbad, CA, USA) (4) Dental implant model with diameter 3.7 mm and length 13 mm. (5) Dental implant model with diameter 4.1 mm and length 13 mm. (6) Dental implant model with diameter 4.7 mm and length 13 mm. The 3-D model of the implant was created in the pro-e wildfire 4.0 software by giving various commands. This model was imported to the ANSYS software through IGES (initial graphic exchange specification) file for further analysis. All six models were loaded with a force of 17.1, 114.6 and 23.4 N in a lingual, an axial and disto-mesial direction respectively, simulating average masticatory force in a natural oblique direction, to analyze the stress distribution on these implants. The increase in implant diameter in Group I and Group II from 3.7 to 4.1 mm and from 4.1 to 4.7 mm with constant 13 mm length for screw-vent tapered and parallel design implant resulted in a reduction in maximum value of Von Mises stress in the bone surrounding the implant was statistically significant at 5% level done by student "t" test. The overall maximum value of Von Mises stress was decreased in parallel design implant diameter of 4.7 mm with constant

  6. Short-term objective and subjective evaluation of small-diameter implants used to support and retain mandibular prosthesis.

    Science.gov (United States)

    Brandt, Robert; Hollis, Scott; Ahuja, Swati; Adatrow, Pradeep; Balanoff, William

    2012-01-01

    The introduction of small-diameter implants has provided dentists the means of providing edentulous and partially edentulous patients with immediate functioning transitional prostheses while definitive restorations are being fabricated. The successful use of these small-diameter implants for temporary stabilization of prostheses has led many clinicians to explore the option of using them as a definitive alternative, especially as the technique requires minimal time and also is economical for the patients. To date, there has been no study with multiple patients looking at both the subjective and objective outcomes of these small-diameter implants. Twenty-seven edentulous patients were enrolled in this study, seven of them were smokers. One-hundred and eight small-diameter (2.0 mm, MDL) implants were surgically placed in 24 edentulous mandibles. All implants were immediately loaded. The patients filled out a screening questionnaire and four subsequent questionnaires to test their satisfaction with the altered prosthesis at 6, 12, 18 and 24 months. The survival of the implants was also noted. Smokers had an implant survival of 79%. Non-smokers had an implant survival of 100%. The results of the questionnaire indicated an overall satisfaction with the implant-supported prosthesis.

  7. Mandibular single-implant overdentures: preliminary results of a randomised-control trial on early loading with different implant diameters and attachment systems.

    Science.gov (United States)

    Alsabeeha, Nabeel H M; Payne, Alan G T; De Silva, Rohana K; Thomson, W Murray

    2011-03-01

    To determine surgical and prosthodontic outcomes of mandibular single-implant overdentures, opposing complete maxillary dentures, using a wide diameter implant and large ball attachment system compared with different regular diameter implants with standard attachment systems. Thirty-six edentulous participants (mean age 68 years, SD 9.2) were randomly assigned into three treatment groups (n=12). A single implant was placed in the mandibular midline of participants to support an overdenture using a 6-week loading protocol. The control group received Southern regular implants and standard ball attachments. One group received Southern 8-mm-wide implants and large ball attachments. Another group received Neoss regular implants and Locator attachments. Parametric and non-parametric tests of a statistical software package (SPSS) were used to determine between groups differences in marginal bone loss, implant stability, implant, and prosthodontic success (PImplant success after 1 year was 75% for Southern regular implant (control) group; and 100% for the Southern wide and Neoss regular implant groups (P=0.038). Mean marginal bone loss at 1 year was 0.19 mm (SD 0.39) without significant differences observed. Implant stability quotient (ISQ) at baseline was significantly lower for the Southern regular (control) group than the other two groups (P=0.001; P=0.009). At 1 year, no significant difference in implant stability was observed (mean ISQ 74.6, SD 6.1). The change in implant stability from baseline to 1 year was significant for the control group (P=0.025). Prosthodontic success was comparable between the groups but the maintenance (41 events overall, mean 1.2) was greater for the Locator and the standard ball attachments. Mandibular single-implant overdentures are a successful treatment option for older edentulous adults with early loading protocol using implants of different diameters and with different attachment systems. © 2010 John Wiley & Sons A/S.

  8. [Comparison of aortic annular diameter defined by different measurement mordalities before transcatheter aortic valve implantation].

    Science.gov (United States)

    Qi, R X; You, X D; Pu, Z X; Yang, Q; Huang, Z X; Zhou, L M; Huang, P T

    2017-05-24

    Objective: To compare aortic annular diameter measured by transthoracic echocardiography (TTE), transesophageal echocardiography (TEE), and multislice computed tomography (MSCT) in patients with severe aortic stenosis, and to evaluate the impact on selection of prosthetic valve type in transcatheter aortic valve implantation (TAVI). Methods: Clinical data of 138 patients with severe aortic stenosis referred for TAVI between January 2014 and June 2016 in our hospital were retrospectively analyzed.The difference of aortic annular diameter measured by TTE, TEE, and MSCT were compared.TTE was performed after TAVI to evaluate the accuracy of measurement before TAVI. Results: (1) Aortic annular diameter was (23.37±2.22) mm by TTE and (23.52±1.70) mm by TEE ( P =0.12). Pearson correlation analysis showed that aortic annular diameter measured by TTE was correlated to that measured by TEE ( r =0.87, P TTE and TTE (all P TTE and TEE measurements are smaller than that from MSCT.In the absence of a gold standard, selection of prosthetic valve type in TAVI procedure should rely on comprehensive considerations, which is of importance to get good clinical results for severe aortic stenosis patients underwent TAVI.

  9. Influence of Metal and Ceramic Abutments on the Stress Distribution Around Narrow Implants: A Photoelastic Stress Analysis.

    Science.gov (United States)

    Galvão, Gustavo Holtz; Grossi, João Almeida; Zielak, João César; Giovanini, Allan Fernando; Furuse, Adilson Yoshio; Gonzaga, Carla Castiglia

    2016-08-01

    This study aimed to compare, through photoelastic analysis, the distribution of stresses around narrow implants with external hexagon (EH) and Morse taper (MT) connections, when single crowns made with metal and ceramic abutments were used. Six photoelastic models were prepared, simulating the use of narrow EH and MT implants replacing a lateral incisor. These 2 groups received 3 different abutments: prefabricated metal abutments, customized metal abutments, and customized zirconia abutments. All crowns were identical and made with a leucite reinforced glass-ceramic. Vertical loads of 0 to 100 N were applied on the palatal surface of the crowns, and the photoelastic stress fringes developed in each model were captured in a high-definition video, and digital photographs were taken at 100 N. The abutment type and material influenced the stress distribution patterns around narrow implants with EH and MT connections. Stresses were generated mainly around the apical and lingual regions of the implants. For both connections, the prefabricated metal abutments presented better stress distribution around the implants when compared to customized metal and zirconia abutments because low stress levels were developed in smaller areas around the implants.

  10. Effect of mini-implant length and diameter on primary stability under loading with two force levels.

    Science.gov (United States)

    Chatzigianni, Athina; Keilig, Ludger; Reimann, Susanne; Eliades, Theodore; Bourauel, Christoph

    2011-08-01

    Mini-implants are widely utilized as anchorage units in orthodontic treatment. Nevertheless, there are factors that interfere with their clinical performance. The aim of this study was to examine the impact of length and diameter on the primary stability of two different types of orthodontic mini-implants loaded with two force levels. A total of 90 self-drilling mini-implants were inserted in bovine ribs in vitro, 62 of which were used in data analysis. The mini-implants were of two types, Aarhus (n=29) and Lomas (n=33), of two lengths (7 and 9 mm, n=26 and n=28, respectively), and of two diameters (1.5 and 2 mm, Lomas only, n=6 and n=8, respectively). A closed nickel-titanium (NiTi) coil spring was attached to each mini-implant. Half of the preparations were loaded with a low force of 0.5 N and the other half with a force of 2.5 N. Mini-implant deflections during force application were non-invasively registered using a three-dimensional (3D) laser-optical system. The results were analysed with analysis of variance for the effects of implant type, implant length, and force level, and with a t-test for the study of the effect of diameter in two different diameter variants of the same (Lomas) implant. In the low-force group, implant displacements were not statistically significant difference according to the investigated parameters. In the high-force group, the 9 mm long mini-implants displaced significantly less (10.5±7.5 μm) than the 7 mm long (22.3±11.3 μm, P<0.01) and the 2 mm wide significantly less (8.8±2.2 μm) than the 1.5 mm implants (21.9±1.5 μm, P<0.001). The force level at which significance occurred was 1 N. The rotation of the Lomas mini-implants in the form of tipping was significantly higher than that of the Aarhus mini-implants at all force levels. Implant length and diameter become statistically significant influencing parameters on implant stability only when a high force level is applied.

  11. Stress analysis in bone tissue around single implants with different diameters and veneering materials: a 3-D finite element study.

    Science.gov (United States)

    Santiago Junior, Joel Ferreira; Pellizzer, Eduardo Piza; Verri, Fellippo Ramos; de Carvalho, Paulo Sérgio Perri

    2013-12-01

    The aim of this study was to evaluate the stress distribution on bone tissue with a single prosthesis supported by implants of large and conventional diameter and presenting different veneering materials using the 3-D finite element method. Sixteen models were fabricated to reproduce a bone block with implants, using two diameters (3.75×10 mm and 5.00×10 mm), four different veneering materials (composite resin, acrylic resin, porcelain, and NiCr crown), and two loads (axial (200 N) and oblique (100 N)). For data analysis, the maximum principal stress and von Mises criterion were used. For the axial load, the cortical bone in all models did not exhibit significant differences, and the trabecular bone presented higher tensile stress with reduced implant diameter. For the oblique load, the cortical bone presented a significant increase in tensile stress on the same side as the loading for smaller implant diameters. The trabecular bone showed a similar but more discreet trend. There was no difference in bone tissue with different veneering materials. The veneering material did not influence the stress distribution in the supporting tissues of single implant-supported prostheses. The large-diameter implants improved the transference of occlusal loads to bone tissue and decreased stress mainly under oblique loads. Oblique loading was more detrimental to distribution stresses than axial loading. © 2013.

  12. Consecutive Case Series of Healed Single-Molar Sites Immediately Restored with Wide-Diameter Implants: A 1-Year Evaluation

    Directory of Open Access Journals (Sweden)

    Hadi Antoun

    2016-01-01

    Full Text Available Introduction. To evaluate outcomes of wide-diameter (6 mm implants immediately provisionalized with cement-retained single crowns in posterior molar sites. Materials and Methods. Forty-eight consecutive patients received a total of 53 moderately rough-surface, 6 mm diameter implants in healed sites. All implants were immediately provisionalized with a cement-retained provisional crown. Final prosthesis with cement-retained porcelain fused to metal crowns was delivered 3–6 months later. Patients were followed up for 1 year. Outcome measures were implant failures and success rate, complications, marginal bone levels, bone level changes, papilla index, bleeding on probing, and inflammation. Results. One patient was lost to follow-up. At one year, the implant survival and success rate were 98.1%. The mean marginal bone loss after 1 year was −0.17±1.84 mm. Ideal papilla score was recorded at 83.8% of the sites. More than 95.6% of the sites showed no bleeding or inflammation. No procedure-related or device-related adverse events were reported. Conclusion. Wide-diameter (6 mm implants can safely and successfully replace single posterior molars. Longer follow-up studies are necessary to evaluate the long-term success of these implants.

  13. Consecutive Case Series of Healed Single-Molar Sites Immediately Restored with Wide-Diameter Implants: A 1-Year Evaluation

    Science.gov (United States)

    Cherfane, Pierre; Sojod, Bouchra

    2016-01-01

    Introduction. To evaluate outcomes of wide-diameter (6 mm) implants immediately provisionalized with cement-retained single crowns in posterior molar sites. Materials and Methods. Forty-eight consecutive patients received a total of 53 moderately rough-surface, 6 mm diameter implants in healed sites. All implants were immediately provisionalized with a cement-retained provisional crown. Final prosthesis with cement-retained porcelain fused to metal crowns was delivered 3–6 months later. Patients were followed up for 1 year. Outcome measures were implant failures and success rate, complications, marginal bone levels, bone level changes, papilla index, bleeding on probing, and inflammation. Results. One patient was lost to follow-up. At one year, the implant survival and success rate were 98.1%. The mean marginal bone loss after 1 year was −0.17 ± 1.84 mm. Ideal papilla score was recorded at 83.8% of the sites. More than 95.6% of the sites showed no bleeding or inflammation. No procedure-related or device-related adverse events were reported. Conclusion. Wide-diameter (6 mm) implants can safely and successfully replace single posterior molars. Longer follow-up studies are necessary to evaluate the long-term success of these implants. PMID:27195008

  14. The influence of implant diameter and length on stress distribution of osseointegrated implants related to crestal bone geometry: a three-dimensional finite element analysis.

    Science.gov (United States)

    Baggi, Luigi; Cappelloni, Ilaria; Di Girolamo, Michele; Maceri, Franco; Vairo, Giuseppe

    2008-12-01

    Load transfer mechanisms and possible failure of osseointegrated implants are affected by implant shape, geometrical and mechanical properties of the site of placement, as well as crestal bone resorption. Suitable estimation of such effects allows for correct design of implant features. The purpose of this study was to analyze the influence of implant diameter and length on stress distribution and to analyze overload risk of clinically evidenced crestal bone loss at the implant neck in mandibular and maxillary molar periimplant regions. Stress-based performances of 5 commercially available implants (2 ITI, 2 Nobel Biocare, and 1 Ankylos implant; diameters of 3.3 mm to 4.5 mm, bone-implant interface lengths of 7.5 mm to 12 mm) were analyzed by linearly elastic 3-dimensional finite element simulations, under a static load (lateral component: 100 N; vertical intrusive component: 250 N). Numerical models of maxillary and mandibular molar bone segments were generated from computed tomography images, and local stress measures were introduced to allow for the assessment of bone overload risk. Different crestal bone geometries were also modelled. Type II bone quality was approximated, and complete osseous integration was assumed. Maximum stress areas were numerically located at the implant neck, and possible overloading could occur in compression in compact bone (due to lateral components of the occlusal load) and in tension at the interface between cortical and trabecular bone (due to vertical intrusive loading components). Stress values and concentration areas decreased for cortical bone when implant diameter increased, whereas more effective stress distributions for cancellous bone were experienced with increasing implant length. For implants with comparable diameter and length, compressive stress values at cortical bone were reduced when low crestal bone loss was considered. Finally, dissimilar stress-based performances were exhibited for mandibular and maxillary

  15. Immediate and delayed loading of two-piece reduced-diameter implants with locator-analog attachments in edentulous mandibles: One-year results from a randomized clinical trial examining clinical outcome and patient expectation.

    Science.gov (United States)

    Giannakopoulos, Nikolaos Nikitas; Ariaans, Kirsten; Eberhard, Lydia; Klotz, Anna-Luisa; Oh, Keunyoung; Kappel, Stefanie

    2017-08-01

    Prosthetic management of thin alveolar ridges in the edentulous mandibles of elderly patients, especially the time of loading, the number of implants needed, and patient expectations and perception, is a challenge in implant dentistry. Survival of conventionally and immediately loaded 2-piece reduced-diameter implants in the interforaminal region of the edentulous mandible supporting locator-analog attachments was evaluated. Prosthetic complications and peri-implant hygiene were also studied, and patient expectation and subjective evaluation of the treatment were documented. Twenty-five patients with adapted complete dentures received 4 reduced-diameter implants. All anterior implants were immediately loaded. Three months later, patients were allocated by randomization to 1 of 2 treatment groups: 2 locator-analog attachments on the anterior implants (Group A); or 4 locator-analog attachments (Group B). After another 3 months patient allocation was changed (crossover design) for the next 3 months. Questionnaires with Likert scales and numeric rating scales were used to assess patients' expectations and subjective overdenture-related variables, respectively. One implant was lost in the immediate-loading group. Survival was 98% and 100% for immediate and delayed loading, respectively. During 12-month observation, 8 complications required aftercare. At the beginning of treatment, patients' expectations were highly positive. Subjective assessment of overdenture-related variables 3 months after immediate loading of 2 implants revealed a statistically significant improvement for most of the variables studied; this was maintained 1 year later. In the subjective assessments, there were no statistically significant differences between Groups A and B. Immediate loading of reduced-diameter implants supporting locator-analog attachments resulted in high implant survival, few prosthetic complications, good oral hygiene, and improvement of subjective denture perception in the

  16. Temperature changes of one-piece implants during the setting of acrylic resin temporary crown. The effect of implant diameter. An in vitro study.

    Science.gov (United States)

    Slutzkey, S; Cohen, O; Lauritano, D; Moses, O; Ormianer, Z; Tal, H; Kolerman, R; Carinci, F; Matalon, S

    2017-01-01

    The purpose of this work is to evaluate changes in temperature of one-piece titanium implant surface during the setting of acrylic resin temporary crowns and to correlate thermal changes to implant diameter. Thirty-three one-piece implants (ARRP, Alpha-Biotec) were divided into 3 groups according to diameter size (G1=3 mm, G2=3.3 mm, G3=3.6 mm). Implants were mounted on an acrylic glass apparatus. Thermocouples were positioned at the most coronal thread. Lower incisor temporary polycarbonate crowns were filled with 80 μL of self-curing acrylic resin and positioned immediately on the implant abutment. Thermal changes of the implant surface were recorded continuously for 10 min. Data were statistically analyzed using one-way analysis of variance. The mean initial temperature (C0) of groups G1, G2 and G3 was similar (24.79±0.78ºC, 25.26±0.63ºC, 24.97±1.06ºC, respectively). The setting of the acrylic resin temporary crown resulted in a significant increase in the implant surface temperature of all groups. The mean thermal amplitude (ΔC) for groups G1, G2 and G3 were 6.79±1.02ºC, 6.61±0.94ºC, 6.65±1.26ºC, respectively. The mean time to maximum temperature (Tmax) for groups G1, G2 and G3 were 337.38±42.91 sec, 324.69±41.46 sec and 317.98±37.91 sec respectively (P>0.05). Direct application of auto-polymerizing resin to the titanium abutment of one-piece implants significantly increased the cervical implant surface temperature. Implant diameter did not influence the temperature changes.

  17. 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.

  18. Osseointegration of Implants Surface-Treated with Various Diameters of TiO2 Nano tubes in Rabbit

    International Nuclear Information System (INIS)

    Kang, Ch.G.; Park, Y.B.; Choi, H.; Lee, K.W.; Shim, J.S.; Oh, S.; Choi, S.H.

    2014-01-01

    The aim of this study was to evaluate the osseointegration of implants which were surface-treated with various diameters of TiO 2 nano tubes (30 nm, 70 nm, and 100 nm) in rabbit. Resorbable blast media (RBM) surfaced implants (Osstem, Busan, Korea) 3.5 mm in diameter and 8.5 mm in length were designated as the control group and the implants surface-treated with various diameters of nano tubes (30 nm, 70 nm, and 100 nm) with the same shapes were designated as the experimental groups. The implants were maintained unloaded for 4 and 12 weeks. After this period, the animals were sacrificed and micro-CT analysis, histomorphometric analysis (bone to implant contact (BIC), bone volume (BV)), and removal torque test were performed. Micro-CT analysis, histomorphometric analysis, and removal torque test results all showed the similar pattern, showing that 70 nm experimental group had the highest value at 4 weeks while 30 nm experimental group had the highest value at 12 weeks. Therefore, on the basis of the results above, it can be concluded that 30 nm and 70 nm TiO 2 nano tubes may have positive effects on osteogenesis and osseointegration depending on the healing time

  19. Resonance Raman and IR spectroscopy of aligned carbon nanotube arrays with extremely narrow diameters prepared with molecular catalysts on steel substrates.

    Science.gov (United States)

    Jain, Sagar Motilal; Cesano, Federico; Scarano, Domenica; Edvinsson, Tomas

    2017-11-22

    Carbon nanotubes (CNTs) are considered promising for a large range of emerging technologies ranging from advanced electronics to utilization as nanoreactors. Here we report a controlled facile synthesis of aligned carbon nanotubes with very small dimensions directly grown on steel grid substrates via two-step catalytic chemical vapor deposition (CCVD) of a molecular catalyst (ferrocene) with ethylene as the carbon source. The system is characterized by resonance Raman spectroscopy and the results show single walled carbon nanotube (SWCNT) arrays composed of 0.80 nm to 1.24 nm semiconducting CNTs, as analyzed using Kataura analysis, which is approaching the lowest diameters attainable for SWCNTs. The G + and G - mode splitting, G - line shapes and ring breathing modes (RBMs) are analyzed to characterize the CNTs. The approach results in close packed and vertically aligned SWCNT bundles formed into hair shapes, with some contribution from multiwall CNTs (MWCNTs). IR spectroscopy is utilized to characterize the edge/defect states that have the ability to form esters and ether bonds in the as-prepared CNTs. The stepwise deposition of the catalyst followed by the carbon source gives control over the formation of small diameter single walled carbon nanotubes (SWCNTs). The utilization of molecular catalysts for narrow diameter growth directly on steel grid substrates forms a promising approach for producing cost-effective CNT substrates for a plethora of sensing and catalytic applications.

  20. Effect of catheter diameter on left innominate vein in breast cancer patients after totally implantable venous access port placement.

    Science.gov (United States)

    Song, Myung Gyu; Seo, Tae-Seok; Kim, Yun Hwan; Cho, Sung Bum; Chung, Hwan Hoon; Lee, Seung Hwa; Jung, Euichul

    2018-03-01

    The effect of catheter diameter on left innominate vein stenosis in breast cancer patients after totally implantable venous access port placement. To evaluate the effect of catheter diameter on left innominate vein stenosis in breast cancer patients after placement of totally implantable venous access ports. Totally implantable venous access ports were placed via the left internal jugular vein in 241 women with right breast cancer from January 2010 to December 2014 (mean age, 51.5 years; range, 19-83 years). There were 67 totally implantable venous access ports with a 6.5F catheter and 142 totally implantable venous access ports with an 8F catheter. Medical records were retrospectively reviewed. The presence of significant left innominate vein stenosis and tip location of the catheter was evaluated on chest computed tomography images. Statistical analysis was performed. Left innominate vein stenosis developed in 1 (1.5%) and 13 (9.2%) patients after implantation with 6.5 and 8F catheters, respectively. Difference in the cumulative incidence of left innominate vein stenosis was statistically significant between the two groups (log rank test p-value: 0.002). In Cox regression analysis, the hazard ratio for left innominate vein stenosis was 20.766 ( p = 0.005) for an 8F catheter. The incidence of left innominate vein stenosis was higher after implantation of totally implantable venous access ports with 8F catheter rather than with 6.5F catheter. Considering that using 8F catheter versus 6.5F catheter has no advantage in terms of performance of the device, the results of our study suggest that ports with catheters >7F should be avoided.

  1. Clinical and Radiographic Evaluation of a Small-Diameter Dental Implant Used for the Restoration of Patients with Permanent Tooth Agenesis (Hypodontia) in the Maxillary Lateral Incisor and Mandibular Incisor Regions: A 36-Month Follow-Up.

    Science.gov (United States)

    King, Paul; Maiorana, Carlo; Luthardt, Ralph G; Sondell, Katarina; Øland, Jesper; Galindo-Moreno, Pablo; Nilsson, Peter

    2016-01-01

    For patients with narrow, single-tooth edentulous ridges as a result of permanent tooth agenesis (hypodontia) in the maxillary lateral and mandibular incisor regions, dental implant treatment may present a reliable and predictable restorative treatment solution. The aim of the present study was to evaluate the clinical reliability and outcome of small-diameter dental implants placed in a one-stage procedure with early loading replacing maxillary lateral or mandibular incisor teeth. Patients with hypodontia in the maxillary lateral incisor or mandibular incisor region analyzed in this report were selected from a larger prospective multicenter study. Small-diameter dental implants (AstraTech OsseoSpeed TX 3.0 S, Dentsply) of different lengths were placed using a one-stage surgical protocol with a 6- to 10-week healing period before loading. Probing pocket depth, bleeding on probing, and gingival zenith score were assessed after 6, 12, 24, and 36 months. Radiographic examination was assessed at 6, 12, and 36 months. In total, 38 patients were included in this analysis and 62 small-diameter implants were placed. The mean distance between adjacent teeth was 6.30 mm (SD: 1.36). All patients received a titanium transmucosal abutment and cement-retained ceramic crown after 6 to 10 weeks of healing. Two implants were lost during the healing period before loading, providing a total implant survival rate of 96.8%. No implant fractures were reported. Mean marginal bone level change from surgery to follow-up visits at 6, 12, and 36 months were 0.39 mm, 0.22 mm, and 0.23 mm, respectively. The condition of soft tissue was stable at all follow-up visits with clinically insignificant changes in probing depth, bleeding on probing, and gingival zenith score. This study evaluated the behavior over 36 months of AstraTech Osseospeed TX 3.0 S dental implants placed into narrow one-tooth defect edentulous ridges as a result of hypodontia. The data collected highlighted the stability of

  2. Changes in the fractal dimension, feret diameter, and lacunarity of mandibular alveolar bone during initial healing of dental implants.

    Science.gov (United States)

    Önem, Erinç; Baksı, B Güniz; Sogur, Elif

    2012-01-01

    To evaluate the combination of fractal dimension (FD), lacunarity, and Feret diameter (FeD) to quantitatively characterize structural changes of mandibular alveolar bone around dental implants during initial healing. Three standard-sized regions of interest (ROIs) (mesial and distal crest and apical area) around implants and three ROIs of the same size in the alveolar bone on the contralateral side were analyzed on digital panoramic images. FD was calculated using the box-counting method, and lacunarity was calculated using the FracLac plugin of Image J software. FeD was measured in the same ROIs. Comparisons of the groups were done with the Dunnett test. Forty-two implants in the posterior mandibles of 21 patients were used for FD measurements. A total of 189 ROIs was segmented into binary images. Mean FD values for mesial, distal, and apical ROIs around implants were 1.26, 1.36, and 1.4, respectively. The mean FD of alveolar bone around premolars/molars was 1.39 for all ROIs. The mean FeD for mesial, distal, and apical ROIs around implants was 7.63, 7.86, and 8.02, respectively, whereas it ranged between 7.88 and 8.13 for premolar teeth. Mean lacunarity values for mesial, distal, and apical ROIs around implants were 0.53, 0.51, and 0.48, respectively. Lacunarity values for ROIs around premolars ranged between 0.45 and 0.50. No significant differences were observed in FD, FeD, or lacunarity measurements between ROIs around implants and around teeth. The satisfactory healing of bone following implant placement may be monitored by calculating FD, lacunarity, and FeD using digital panoramic images. Although preliminary, these values may alert the practitioner to any implants with loss of stability.

  3. Biomechanical evaluation of one-piece and two-piece small-diameter dental implants: In-vitro experimental and three-dimensional finite element analyses.

    Science.gov (United States)

    Wu, Aaron Yu-Jen; Hsu, Jui-Ting; Chee, Winston; Lin, Yun-Te; Fuh, Lih-Jyh; Huang, Heng-Li

    2016-09-01

    Small-diameter dental implants are associated with a higher risk of implant failure. This study used both three-dimensional finite-element (FE) simulations and in-vitro experimental tests to analyze the stresses and strains in both the implant and the surrounding bone when using one-piece (NobelDirect) and two-piece (NobelReplace) small-diameter implants, with the aim of understanding the underlying biomechanical mechanisms. Six experimental artificial jawbone models and two FE models were prepared for one-piece and two-piece 3.5-mm diameter implants. Rosette strain gauges were used for in-vitro tests, with peak values of the principal bone strain recorded with a data acquisition system. Implant stability as quantified by Periotest values (PTV) were also recorded for both types of implants. Experimental data were analyzed statistically using Wilcoxon's rank-sum test. In FE simulations, the peak value and distribution of von-Mises stresses in the implant and bone were selected for evaluation. In in-vitro tests, the peak bone strain was 42% lower for two-piece implants than for one-piece implants. The PTV was slightly lower for one-piece implants (PTV = -6) than for two-piece implants (PTV = -5). In FE simulations, the stresses in the bone and implant were about 23% higher and 12% lower, respectively, for one-piece implants than those for two-piece implants. Due to the higher peri-implant bone stresses and strains, one-piece implants (NobelDirect) might be not suitable for use as small-diameter implants. Copyright © 2016. Published by Elsevier B.V.

  4. 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).

  5. Fracture of Reduced-Diameter Zirconia Dental Implants Following Repeated Insertion.

    Science.gov (United States)

    Karl, Matthias; Scherg, Stefan; Grobecker-Karl, Tanja

    Achievement of high insertion torque values indicating good primary stability is a goal during dental implant placement. The objective of this study was to evaluate whether or not two-piece implants made from zirconia ceramic may be damaged as a result of torque application. A total of 10 two-piece zirconia implants were repeatedly inserted into polyurethane foam material with increasing density and decreasing osteotomy size. The insertion torque applied was measured, and implants were checked for fractures by applying the fluorescent penetrant method. Weibull probability of failure was calculated based on the recorded insertion torque values. Catastrophic failures could be seen in five of the implants from two different batches at insertion torques ranging from 46.0 to 70.5 Ncm, while the remaining implants (all belonging to one batch) survived. Weibull probability of failure seems to be low at the manufacturer-recommended maximum insertion torque of 35 Ncm. Chipping fractures at the thread tips as well as tool marks were the only otherwise observed irregularities. While high insertion torques may be desirable for immediate loading protocols, zirconia implants may fracture when manufacturer-recommended insertion torques are exceeded. Evaluating bone quality prior to implant insertion may be useful.

  6. Wide diameter immediate post-extractive implants vs delayed placement of normal-diameter implants in preserved sockets in the molar region: 1-year post-loading outcome of a randomised controlled trial.

    Science.gov (United States)

    Checchi, Vittorio; Felice, Pietro; Zucchelli, Giovanni; Barausse, Carlo; Piattelli, Maurizio; Pistilli, Roberto; Grandi, Giovanni; Esposito, Marco

    To compare the effectiveness of 6.0 to 8.0 mm-wide diameter implants, placed immediately after tooth extraction, with conventional 4.0 or 5.0 mm diameter implants placed in a preserved socket after a 4-month period of healing in the molar region. Just after extraction of one or two molar teeth, and with no vertical loss of the buccal bone in relation to the palatal wall, 100 patients requiring immediate post-extractive implants were randomly allocated to immediate placement of one or two 6.0 to 8.0 mm-wide diameter implants (immediate group; 50 patients) or for socket preservation using a porcine bone substitute covered by a resorbable collagen barrier (delayed group; 50 patients), according to a parallel group design in one centre. Bone-to-implant gaps were filled with autogenous bone retrieved with a trephine drill used to prepare the implant sites for the immediate wide diameter post-extractive implants. Four months after socket preservation, one to two 4.0 or 5.0 mm-wide delayed implants were placed. Implants were loaded 4 months after placement with fixed provisional restorations in acrylic, and replaced after 4 months by fixed, definitive, metal-ceramic restorations. Patients were followed to 1 year after loading. Outcome measures were: implant failures, complications, aesthetics assessed using the pink esthetic score (PES), peri-implant marginal bone level changes, patient satisfaction, number of appointments and surgical interventions recorded, when possible, by blinded assessors. Three patients dropped out 1 year after loading from the immediate group vs six from the delayed group. Five implants out of 47 failed in the immediate group (10.6%) vs two out 44 (4.6%) in the delayed group, the difference being not statistically significant (difference in proportion = 6.0%, 95% CI: -8.8% to 20.8%, P = 0.436). In the immediate group 10 patients were affected by 10 complications, while in the delayed group four patients were affected by four complications. The

  7. Clinical evaluation of short and wide-diameter implants immediately placed into extraction sockets of posterior areas: a 2-year retrospective study.

    Science.gov (United States)

    Jiansheng, Huang; Dongying, Xuan; Xianfeng, Wang; Baoyi, Xie; Qiong, Liu; Jincai, Zhang

    2012-12-01

    The objective of the study was to determine the short-term success rate of short and wide single-tooth implants, immediately placed into extraction sockets of the posterior area. A retrospective cohort study design was used. A total of 145 subjects received 162 short and wide-diameter single-tooth implants between 2006 and 2009. A minimal 7-mm residual height and 9-mm ridge width was available in all the implant sites, and the attached gingivae were at least 2 mm wide. All implants were placed and restored with the single crown by one experienced operator. The data were analyzed with descriptive statistics. All implants were placed in molar areas. There were 20 Ankylos implants with a diameter 5.5 or 7 mm and a length of 8 mm and 142 hydroxyapatite-coated implants with a diameter 5 or 6 mm and a length of 5.7 to 8 mm. One of the 162 implants failed before prosthetic restoration, resulting in a survival rate of 99.4% after loading. Patients were followed for up to 56 months (mean = 24 months) after loading of implants. The radiographic and clinical data revealed well-maintained hard and soft tissues with acceptable short-term results. For residual ridges with minimal height but adequate width, the immediate placement of short and wide-diameter implants in fresh extraction sockets may offer a simple and predictable treatment alternative if implants are positioned appropriately after a thorough preoperative analysis.

  8. A retrospective study of the hearing results obtained after stapedotomy by the implantation of two Teflon pistons with a different diameter

    NARCIS (Netherlands)

    Grolman, W.; Tange, R. A.; de Bruijn, A. J.; Hart, A. A.; Schouwenburg, P. F.

    1997-01-01

    This study reports the evaluation of hearing results after implantation of a Teflon piston of a different diameter in cases of otosclerosis requiring stapedotomy. By random selection, a Teflon piston with a shaft diameter of 0.3 mm was inserted in 34 cases and a piston with a shaft diameter of 0.4

  9. Transcribing the Speech of Children with Cochlear Implants: Clinical Application of Narrow Phonetic Transcriptions

    Science.gov (United States)

    Teoh, Amy P.; Chin, Steven B.

    2009-01-01

    Purpose: The phonological systems of children with cochlear implants may include segment inventories that contain both target and nontarget speech sounds. These children may not consistently follow phonological rules of the target language. These issues present a challenge for the clinical speech-language pathologist who uses phonetic…

  10. Five-year follow-up of wide-diameter implants placed in fresh molar extraction sockets in the mandible: immediate versus delayed loading.

    Science.gov (United States)

    Prosper, Loris; Crespi, Roberto; Valenti, Edoardo; Capparé, Paolo; Gherlone, Enrico

    2010-01-01

    The aim of this study was to compare the long-term success rates of wide-diameter implants in the mandibular molar region placed immediately after extraction and loaded either immediately or after a 3-month healing period. In 71 patients, 120 implants were positioned immediately after tooth extraction; 60 implants (immediate loading group) were loaded immediately and 60 were loaded after 3 months (delayed loading group). Radiographic examinations were made at baseline and at 1, 2, 3, 4, and 5 years after implant placement. After 5 years, a survival rate of 96.67% was reported for all implants (failure rate, 3.33%). Four implants were lost, two from the immediate loading group and two from the delayed loading group. There were no patient dropouts in either group. Wide-diameter implants placed in fresh extraction sockets and loaded immediately or after a delay showed no significant clinical or radiographic differences after 5 years.

  11. Influence of different abutment diameter of implants on the peri-implant stress in the crestal bone: A three-dimensional finite element analysis--In vitro study.

    Science.gov (United States)

    Aradya, Anupama; Kumar, U Krishna; Chowdhary, Ramesh

    2016-01-01

    The study was designed to evaluate and compare stress distribution in transcortical section of bone with normal abutment and platform switched abutment under vertical and oblique forces in posterior mandible region. A three-dimensional finite element model was designed using ANSYS 13.0 software. The type of bone selection for the model was made of type II mandibular bone, having cortical bone thickness ranging from 0.595 mm to 1.515 mm with the crestal region measuring 1.5 mm surrounding dense trabecular bone. The implant will be modulated at 5 mm restorative platform and tapering down to 4.5 mm wide at the threads, 13 mm long with an abutment 3 mm in height. The models will be designed for two situations: (1) An implant with a 5 mm diameter abutment representing a standard platform in the posterior mandible region. (2) An implant with a 4.5 mm diameter abutment representing platform switching in the posterior mandible region. Force application was performed in both oblique and vertical conditions using 100 N as a representative masticatory force. For oblique loading, a force of 100 N was applied at 15° from the vertical axis. von Mises stress analysis was evaluated. The results of the study showed cortical stress in the conventional and platform switching model under oblique forces were 59.329 MPa and 39.952 MPa, respectively. Cortical stress in the conventional and platform switching model under vertical forces was 13.914 MPa and 12.793 MPa, respectively. Results from this study showed the platform switched abutment led to relative decrease in von Mises stress in transcortical section of bone compared to normal abutment under vertical and oblique forces in posterior mandible region.

  12. Clinical, esthetic, and radiographic evaluation of small-diameter (3.0-mm) implants supporting single crowns in the anterior region: a 3-year prospective study.

    Science.gov (United States)

    Pieri, Francesco; Siroli, Lucia; Forlivesi, Caterina; Corinaldesi, Giuseppe

    2014-01-01

    Fifty patients underwent single-tooth replacement in the maxillary and mandibular incisor area using two-piece 3.0-mm-diameter implants. Clinical and radiographic measurements of soft and hard tissue levels and esthetic parameters (pink esthetic score/white esthetic score [PES/WES]) were assessed at 3 years. No implant failed (success rate: 100%), and facial soft tissues and marginal bone levels remained stable throughout the study period. The mean total PES/WES was high (14.1 ± 1.75), and only one implant demonstrated an unfavorable esthetic outcome (PES/WES = 10). The use of 3.0-mm-diameter implants appears to be a viable treatment procedure in the medium term for single-tooth anterior restorations with limited dimensions.

  13. Clinical Outcome of a Wide-diameter Bone-anchored Hearing Implant and a Surgical Technique With Tissue Preservation

    DEFF Research Database (Denmark)

    Mowinckel, Marius S; Møller, Martin N; Wielandt, Kirsten N

    2016-01-01

    OBJECTIVE: To investigate the clinical outcome of a surgical technique with tissue preservation for a wide bone-anchored hearing implant concerning postoperative complications, skin reactions, implant loss, and implant stability. STUDY DESIGN: Consecutive, prospective case series. SETTING: Tertia...

  14. A new wide-diameter bone-anchored hearing implant-prospective 1-year data on complications, implant stability, and survival

    DEFF Research Database (Denmark)

    Foghsgaard, Søren; Caye-Thomasen, Per

    2014-01-01

    OBJECTIVE: To investigate a new wide bone-anchored hearing implant considering initial stability, stability over time, implant loss, and skin reaction. STUDY DESIGN: Consecutive, prospective case series. SETTING: Tertiary referral center. PATIENTS: Twenty adult patients were enrolled. All operati...

  15. A double-blind Randomized Controlled Trial (RCT) of Titanium-13Zirconium versus Titanium Grade IV small-diameter bone level implants in edentulous mandibles: results from a 1-year observation period

    NARCIS (Netherlands)

    Al-Nawas, B.; Brägger, U.; Meijer, H.J.A.; Naert, I.; Persson, R.; Perucchi, A.; Quirynen, M.; Raghoebar, G.M.; Reichert, T.E.; Romeo, E.; Santing, H.J.; Schimmel, M.; Storelli, S.; ten Bruggenkate, C.; Vandekerckhove, B.; Wagner, W.; Wismeijer, D.; Müller, F.

    2012-01-01

    Background: The use of endosseous dental implants has become common practice for the rehabilitation of edentulous patients, and a two-implant overdenture has been recommended as the standard of care. The use of small-diameter implants may extend treatment options and reduce the necessity for bone

  16. A Double-Blind Randomized Controlled Trial (RCT) of Titanium-13Zirconium versus Titanium Grade IV Small-Diameter Bone Level Implants in Edentulous Mandibles - Results from a 1-Year Observation Period

    NARCIS (Netherlands)

    Al-Nawas, Bilal; Bragger, Urs; Meijer, Henny J. A.; Naert, Ignace; Persson, Rigmor; Perucchi, Alessandro; Quirynen, Marc; Raghoebar, Gerry M.; Reichert, Torsten E.; Romeo, Eugenio; Santing, Hendrik J.; Schimmel, Martin; Storelli, Stefano; ten Bruggenkate, Christiaan; Vandekerckhove, Betty; Wagner, Wilfried; Wismeijer, Daniel; Mueller, Frauke; Meyer, H.J.A.

    2012-01-01

    Background: The use of endosseous dental implants has become common practice for the rehabilitation of edentulous patients, and a two-implant overdenture has been recommended as the standard of care. The use of small-diameter implants may extend treatment options and reduce the necessity for bone

  17. Magnet-Retained Two-Mini-Implant Overdenture: Clinical and Mechanical Consideration

    Directory of Open Access Journals (Sweden)

    Yuichi Ishida

    2016-10-01

    Full Text Available Two-implant overdentures have become the accepted treatment for restoring mandibular edentulism. The dimensions of regular implants sometimes limit their use, such as in the case of narrow ridges. Mini-implants with reduced diameters (less than 3.0 mm enable insertion into narrow ridges. A magnet-retained two-mini-implant overdenture system was developed and is described in this paper. Additionally, we describe a clinical mandibular procedure using the system and evaluate its biomechanical performance.

  18. Fine Adhesion Patterning and Aligned Nuclei Orientation of Mesenchymal Stem Cell on Narrow Line-Width of Silicone Rubber Implanted by Carbon Negative Ions

    Science.gov (United States)

    Sommani, Piyanuch; Tsuji, Hiroshi; Sato, Hiroko; Gotoh, Yasuhito; Ishikawa, Junzo; Takaoka, Gikan H.

    Fine cell-adhesion patterning and nuclei orientation control on silicone rubber were investigated by limiting line-width of carbon negative-ion implantation. The ions were implanted at 3×1015 ions/cm2 and 10 keV through masks of ridge-pattern and rectangle-pattern with various slit apertures of 0-40 μm in width. After 2 days culture, nuclei of rat mesenchymal stem cells were stained with fluorescent dye to evaluate the nuclei positions at each tip ridge-region and the relative angles between the major axis of ellipse-shape nuclei and the implanted line-region. Results showed the individual nucleus arrangement along the narrow line-widths of 3-12 μm and the gathered one on the wider line-width. Number of nuclei orientation in the angle range of 0°-10° increased to 79% on the line-width of 10 μm. As a result, the fine cell-adhesion patterning and nuclei orientation could be achieved by decreasing the implanted line-width to 10 μm.

  19. Recognition and Comprehension of "Narrow Focus" by Young Adults with Prelingual Hearing Loss Using Hearing Aids or Cochlear Implants

    Science.gov (United States)

    Segal, Osnat; Kishon-Rabin, Liat

    2017-01-01

    Purpose: The stressed word in a sentence (narrow focus [NF]) conveys information about the intent of the speaker and is therefore important for processing spoken language and in social interactions. The ability of participants with severe-to-profound prelingual hearing loss to comprehend NF has rarely been investigated. The purpose of this study…

  20. A double-blind randomized controlled trial (RCT) of Titanium-13Zirconium versus Titanium Grade IV small-diameter bone level implants in edentulous mandibles--results from a 1-year observation period.

    Science.gov (United States)

    Al-Nawas, Bilal; Brägger, Urs; Meijer, Henny J A; Naert, Ignace; Persson, Rigmor; Perucchi, Alessandro; Quirynen, Marc; Raghoebar, Gerry M; Reichert, Torsten E; Romeo, Eugenio; Santing, Hendrik J; Schimmel, Martin; Storelli, Stefano; ten Bruggenkate, Christiaan; Vandekerckhove, Betty; Wagner, Wilfried; Wismeijer, Daniel; Müller, Frauke

    2012-12-01

    The use of endosseous dental implants has become common practice for the rehabilitation of edentulous patients, and a two-implant overdenture has been recommended as the standard of care. The use of small-diameter implants may extend treatment options and reduce the necessity for bone augmentation. However, the mechanical strength of titanium is limited, so titanium alloys with greater tensile and fatigue strength may be preferable. This randomized, controlled, double-blind, multicenter study investigated in a split-mouth model whether small-diameter implants made from Titanium-13Zirconium alloy (TiZr, Roxolid™) perform at least as well as Titanium Grade IV implants. Patients with an edentulous mandible received one TiZr and one Ti Grade IV small-diameter bone level implant (3.3 mm, SLActive®) in the interforaminal region. The site distribution was randomized and double-blinded. Outcome measures included change in radiological peri-implant bone level from surgery to 12 months post-insertion (primary), implant survival, success, soft tissue conditions, and safety (secondary). Of 91 treated patients, 87 were available for the 12-month follow-up. Peri-implant bone level change (-0.3 ± 0.5 mm vs -0.3 ± 0.6 mm), plaque, and sulcus bleeding indices were not significantly different between TiZr and Ti Grade IV implants. Implant survival rates were 98.9 percent and 97.8 percent, success rates were 96.6 percent and 94.4 percent, respectively. Nineteen minor and no serious adverse events were related to the study devices. This study confirms that TiZr small-diameter bone level implants provide at least the same outcomes after 12 months as Ti Grade IV bone level implants. The improved mechanical properties of TiZr implants may extend implant therapy to more challenging clinical situations. © 2011 Wiley Periodicals, Inc.

  1. Performance improvement in narrow MuGFETs by gate work function and source/drain implant engineering

    Science.gov (United States)

    Ferain, I.; Duffy, R.; Collaert, N.; van Dal, M. J. H.; Pawlak, B. J.; O'Sullivan, B.; Witters, L.; Rooyackers, R.; Conard, T.; Popovici, M.; van Elshocht, S.; Kaiser, M.; Weemaes, R. G. R.; Swerts, J.; Jurczak, M.; Lander, R. J. P.; De Meyer, K.

    2009-07-01

    At short gate lengths, narrow multiple-gate FETs (MuGFETs) are known to offer superior short channel effect (SCE) control than their bulk Si counterpart [Doyle BS et al. High performance fully-depleted tri-gate CMOS transistors. IEEE Electron Dev Lett 2003;24(4):263-5, van Dal MJH et al. Highly manufacturable FinFETs with sub-10 nm fin width and high aspect ratio fabricated with immersion lithography. In: VLSI Symp Tech Dig; 2007. p. 110-1 [1,2

  2. Single post-extractive ultra-wide 7 mm-diameter implants versus implants placed in molar healed sites after socket preservation for molar replacement: 6-month post-loading results from a randomised controlled trial.

    Science.gov (United States)

    Tallarico, Marco; Xhanari, Erta; Pisano, Milena; De Riu, Giacomo; Tullio, Antonio; Meloni, Silvio Mario

    To test the hypothesis that there is no difference in clinical, radiographic and aesthetic outcomes positioning single post-extractive ultra-wide 7 mm-diameter implants or waiting 4 months to place implant, after molar extraction and the socket preservation procedure. Patients requiring one implant-supported single restoration to replace a failed tooth in the molar region of both maxilla and mandible were selected. Patients were randomised according to a parallel group design into two arms: implant installation in fresh extraction sockets augmented with corticocancellous heterologous bone and porcine derma (group A) or delayed implant installation 4 months after tooth extraction and socket preservation using the same materials (group B). Ultra-wide 7 mm-diameter implants were submerged for 4 months. Outcome measures were implant success and survival; complications; horizontal dimensional changes measured on cone beam computed tomography (CBCT) scans at three levels, localised 1, 2 and 3 mm below the most coronal aspect of the bone crest (level A, B and C); peri-implant marginal bone level changes; implant stability quotient (ISQ); and pink esthetic score (PES). Twelve patients were randomised to group A and 12 to group B. No patients dropped out. No implant failed or complications occurred up to 6-months post-loading. Six months after loading there was more horizontal alveolar bone reduction at immediate post-extractive implants, which was statistically significant. At level A was 1.78 mm ± 1.30 in group A, 0.45 mm ± 0.42 in group B, (difference 1.33 mm ± 1.39; 95% CI: 0.38 to 1.95; P = 0.003); at level B was 0.98 mm ± 1.13 in group A, 0.14 mm ± 0.22 in group B, (difference 0.84 mm ± 1.16; 95% CI: 0.24 to 1.07; P = 0.019); at level C was 0.55 mm ± 0.74 in group A, 0.03 mm ± 0.24 in group B, (difference 0.51 mm ± 0.76, 95% CI: 0.01 to 0.87; P = 0.032). One year after implant

  3. Narrow, duplicated internal auditory canal

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, T. [Servico de Neurorradiologia, Hospital Garcia de Orta, Avenida Torrado da Silva, 2801-951, Almada (Portugal); Shayestehfar, B. [Department of Radiology, UCLA Oliveview School of Medicine, Los Angeles, California (United States); Lufkin, R. [Department of Radiology, UCLA School of Medicine, Los Angeles, California (United States)

    2003-05-01

    A narrow internal auditory canal (IAC) constitutes a relative contraindication to cochlear implantation because it is associated with aplasia or hypoplasia of the vestibulocochlear nerve or its cochlear branch. We report an unusual case of a narrow, duplicated IAC, divided by a bony septum into a superior relatively large portion and an inferior stenotic portion, in which we could identify only the facial nerve. This case adds support to the association between a narrow IAC and aplasia or hypoplasia of the vestibulocochlear nerve. The normal facial nerve argues against the hypothesis that the narrow IAC is the result of a primary bony defect which inhibits the growth of the vestibulocochlear nerve. (orig.)

  4. Ridge expansion alone or in combination with guided bone regeneration to facilitate implant placement in narrow alveolar ridges: a retrospective study.

    Science.gov (United States)

    Tang, Yu-Long; Yuan, Jing; Song, Ying-Liang; Ma, Wei; Chao, Xie; Li, De-Hua

    2015-02-01

    To evaluate the long-term outcomes of ridge expansion technique in dealing with horizontal bony insufficiency of alveolar ridges for implant placement. During the period 2004-2009, 168 patients with width insufficiency of alveolar ridges were treated using the ridge expansion technique to obtain an improved bony base for implant placement. Depending on the severity of width insufficiency, the surgical procedures were classified into two groups: ridge expansion alone (Group 1) and ridge expansion in combination with guided bone regeneration (Group 2). After 4-6 months of unloaded healing, the implants were restored. The patients were followed up until 2013 with clinical and radiographic examinations. Among the 168 patients, 11 patients underwent a fracture of labial/buccal bony plate during surgery, which was corrected by changing the procedure into bone grafting, yielding a surgical failure rate of 6.5%. In the remaining 157 patients successfully treated by ridge expansion alone or in combination with GBR, 226 implants were simultaneously placed as planned. No implant failed over 2.8 years (6 months to 8 years) of follow-up, yielding a cumulative implant survival rate of 100% in each group. Six implants in Group 1 and 4 implants in Group 2, although osseointegrated and in function, did not fulfill success criteria: Cumulative implants' success rates were 93.2% in Group 1 and 95.6% in Group 2. The mean marginal bone losses during the first year in Group 1 and Group 2 were 0.69 and 0.43 mm, respectively, followed by an annual loss of ~ 0.06 and 0.07 mm, respectively, in the following years. No clinical parameter was abnormal. Twenty-two (10.4%) implants were exposed to peri-implant mucositis, whereas 19 (11.0%) implant-supported restorations were involved in prosthetic complications. The preliminary results of this retrospective study indicate that ridge expansion alone or in combination with GBR can be considered an effective and safe procedure for treatment of

  5. Relationship of implant stability and bone density derived from computerized tomography images.

    Science.gov (United States)

    Merheb, Joe; Vercruyssen, Marjolein; Coucke, Wim; Quirynen, Marc

    2018-02-01

    Implant stability is one of the most important factors influencing osseointegration. Using stereolithographical guides for maximizing precision, this study aimed at investigating the relationship between implant stability and bone density derived from computerized tomography analysis. One hundred ninety-five implants were placed in 48 patients using digitally designed stereolithographical surgical guides. Ninety-five implants were placed using a mucosa supported guide and 100 implants were placed using a bone supported guide. Implant stability was measured by means of resonance frequency analysis (RFA) and damping capacity assessment (Periotest, PTV). Bone density (Hounsfield units) was measured at different regions of interest (ROI) and cortex thickness was measured around each implant. Implant stability correlated significantly with the different ROI. The best correlation for RFA was obtained for the spongious bone ROI (r = .64) and PTV best correlated with the coronal cortex density (r = -.41). Shorter implants (9 mm) had a significantly lower primary stability than longer implants (11, 13, 15 mm). Primary stability was also significantly higher in 4 mm diameter implants than in 3.5 mm diameter implants. A formula for the prediction of primary stability based on the different variables investigated was developed. Bone density and cortex thickness have a significant influence on implant primary stability. Longer and wider implants reached higher primary stability than shorter and narrower implants. These correlations lose their significance after osseointegration has taken place. Implant stability can be predicted based on an preoperative analysis of bone characteristics. © 2017 Wiley Periodicals, Inc.

  6. Complete Edentulous Rehabilitation Using an Immediate Function Protocol and an Implant Design Featuring a Straight Body, Anodically Oxidized Surface, and Narrow Tip with Engaging Threads Extending to the Apex of the Implant: A 5-year Retrospective Clinical Study.

    Science.gov (United States)

    Maló, Paulo; de Araújo Nobre, Miguel; Lopes, Armando; Ferro, Ana; Gravito, Inês

    2016-01-01

    To report the 5-year outcome of NobelSpeedy design implants in immediate function fixed prosthetic rehabilitations. This retrospective clinical study included 46 consecutive patients (29 women and 17 men) with an average age of 55 years (range, 32 to 78 years) who were rehabilitated between 2003 and 2004 with full-arch restorations supported by dental implants in immediate function. The primary outcome measures were implant survival calculated based on implant function and using life tables. The secondary outcome measures were marginal bone levels measured at 3 and 5 years, and the incidence of mechanical and biologic complications. Five patients with 21 study implants dropped out (11%). One-hundred eighty-nine implants were inserted in the maxilla (n = 166) and mandible (n = 23). Five patients lost five implants, giving a cumulative survival rate of 97.3% at 5 years of follow-up. The average (SD) marginal bone levels were 1.45 mm (0.83 mm) and 1.72 mm (1.04 mm) at 5 years of follow-up. The incidence of mechanical complications in the provisional and definitive prostheses was registered in 14 and 6 patients, respectively: prosthetic screw loosening (n = 4 provisional prostheses, n = 3 definitive prostheses), abutment screw loosening (n = 5 provisional prostheses), fracture of the acrylic resin prostheses (n = 5 provisional prostheses, n = 1 definitive prosthesis), chipping of a ceramic crown (n = 1 definitive prosthesis), and fracture of a ceramic crown (n = 1 definitive prosthesis). The incidence of biologic complications (peri-implant pathology) was registered in 6 patients and 12 implants (7.1%). Within the limitations of this study, it is possible to conclude that implants of the NobelSpeedy type used in immediate function for support of fixed prosthetic full-arch rehabilitations are a valid option, with a high survival rate.

  7. Properties of axially loaded implant-abutment assemblies using digital holographic interferometry analysis.

    Science.gov (United States)

    Brozović, Juraj; Demoli, Nazif; Farkaš, Nina; Sušić, Mato; Alar, Zeljko; Gabrić Pandurić, Dragana

    2014-03-01

    The aim of this study was to (i) obtain the force-related interferometric patterns of loaded dental implant-abutment assemblies differing in diameter and brand using digital holographic interferometry (DHI) and (ii) determine the influence of implant diameter on the extent of load-induced implant deformation by quantifying and comparing the obtained interferometric data. Experiments included five implant brands (Ankylos, Astra Tech, blueSKY, MIS and Straumann), each represented by a narrow and a wide diameter implant connected to a corresponding abutment. A quasi-Fourier setup with a 25mW helium-neon laser was used for interferometric measurements in the cervical 5mm of the implants. Holograms were recorded in two conditions per measurement: a 10N preloaded and a measuring-force loaded assembly, resulting with an interferogram. This procedure was repeated throughout the whole process of incremental axial loading, from 20N to 120N. Each measurement series was repeated three times for each assembly, with complete dismantling of the implant-loading device in between. Additional software analyses calculated deformation data. Deformations were presented as mean values±standard deviations. Statistical analysis was performed using linear mixed effects modeling in R's lme4 package. Implants exhibited linear deformation patterns. The wide diameter group had lower mean deformation values than the narrow diameter group. The diameter significantly affected the deformation throughout loading sessions. This study gained in vitro implant performance data, compared the deformations in implant bodies and numerically stated the biomechanical benefits of wider diameter implants. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  8. Secondary implant stability outcome of immediate versus late placed variable-thread implants in the maxilla. A retrospective cohort study.

    Science.gov (United States)

    Grognard, Nicolas; Verleye, Gino; Mavreas, Dimitrios; Vande-Vannet, Bart

    2017-09-01

    The healing of xenograft augmentated intra-alveolar gaps following immediate implant placement (IMIP) after tooth extraction is likely to differ in time and density compared to the native bone part that directly contacts the implant. Secondary implant stability (SIS) data recorded 2-3 months following a late implant placement protocol (LIP) (n= 43) and 6-8 months following an immediate implant placement protocol (IMIP) (n=33) of variable-thread implants (Nobel Active™) in the maxilla were retrospectively collected from files of 63 patients (42 females, 21 males). Statistical analysis was performed using a generalized estimating equation model (GEE). Data split-up according to implant diameter (RP, Ø= 4.3mm) , narrow platform (NP, Ø= 3.5mm) was adopted. For NP implants, the mean ISQ (±SD) values were 70.84 (±4.86) in LIP group and 72.41 (±3.89) in the IMIP group. For RP implants, mean ISQ (±SD) values were 73.45 (±8.77) in the LIP group and 75.93 (±5.73) in the IMIP group. Significant effect of treatment modus in favour of the IMIP and gender in favour of males and implant position was noted ( p implant stability, RFA, Osstell Mentor, variable thread implants, Nobel Active, Bio-Oss, immediate implant placement, late implant placement, non-submerged healing, gap.

  9. Influence of irradiation (Co60) in pre-implant rabbits embryos: effect on blastocyst diameters and embryos smaller than 2 mm

    International Nuclear Information System (INIS)

    Approbato, Mario S.; Oliveira Moura, Katia K.V. de; Souza Florencio, Rodopiano de; Cunha Junior, Carlos; Garcia, Ricardo; Faria, Renato S.; Benedetti, Leonardo N.; Goulart, Flamarion B.

    1995-01-01

    We studied the effect of ionizing irradiation on 12 New Zealand rabbits (65 embryos), in three different times: at match time (zero hour), two days after and four days after, with two different irradiation doses, 5 c Gy and 10 c Gy. Six rabbits (36 blastocysts) were used as controls. The matching instant was the zero hour. Exactly six days after (± 60 minutes) the embryos of each rabbit was picked up by flushing the uterus with culture media. The embryos were fixed in methanol for 48 hours, and colored with acid Mayer hematoxylin. The following embryos parameters were studied: diameter growth; percentage of embryos smaller than 2 mm. We observed that only the irradiation time influenced the blastocysts diameter (no irradiation dose). There was no relation between percentage of embryos smaller than 2 mm and the irradiation. (author)

  10. Mini implants for definitive prosthodontic treatment: a systematic review.

    Science.gov (United States)

    Bidra, Avinash S; Almas, Khalid

    2013-03-01

    Mini implants are commonly used in orthodontics and for interim prosthodontic treatment, but evidence for their use in definitive prosthodontic treatment is not clear. This systematic review evaluated the mini-implant literature to analyze short-term (1 to 5 years), medium-term (5 to 10 years), and long-term (beyond 10 years) survival rates when used for definitive prosthodontic treatment. An electronic search of the English language literature for articles published between January 1974 and May 2012 was performed by using PubMed and Cochrane databases with predetermined inclusion criteria. Key terms included in the search were mini dental implants, narrow diameter implants, reduced diameter implants, small diameter implants, transitional implants, interim implants, and provisional implants. After a systematic filtering process, the selected articles were subjected to a detailed review, and the data collected were used to calculate the 1-year interval survival rate (ISR) and the cumulative survival rate (CSR). The electronic database search yielded 1807 titles. By scrutinizing the titles and abstracts with inclusion and exclusion criteria, the researchers identified 9 studies of mini implants for definitive prosthodontic treatment. Of the studies identified, 1 was a randomized controlled trial, 2 were prospective studies, and 6 were retrospective studies. The majority of mini implants were placed by using a flapless surgical technique in the mandibular anterior region to support an overdenture. The 1st year ISR was 94.7% and the CSR over a 9-year period, primarily attributed to data from 1 study, was 92.2%. Most implants were immediately loaded and almost all implant failures occurred during the first year after implant placement. For short-term survival, the first year ISR of 94.7% of mini dental implants appears encouraging, but the true 1-year survival rate is unknown, as the minimum follow-up period reported for several implants was less than a year

  11. Guided proliferation and bone-forming functionality on highly ordered large diameter TiO2 nanotube arrays.

    Science.gov (United States)

    Zhang, Ruopeng; Wu, Hongliu; Ni, Jiahua; Zhao, Changli; Chen, Yifan; Zheng, Chengjunyi; Zhang, Xiaonong

    2015-08-01

    The significantly enhanced osteoblast adhesion, proliferation and alkaline phosphatase (ALP) activity were observed on TiO2 nanotube surface in recent studies in which the scale of nanotube diameter was restricted under 100 nm. In this paper, a series of highly ordered TiO2 nanotube arrays with larger diameters ranging from 150 nm to 470 nm were fabricated via high voltage anodization. The behaviors of MC3T3-E1 cells in response to the diameter-controlled TiO2 nanotubes were investigated. A contrast between the trend of proliferation and the trend of cell elongation was observed. The highest cell elongation (nearly 10:1) and the lowest cell number were observed on the TiO2 nanotube arrays with 150 nm diameter. While, the lowest cell elongation and highest cell number were achieved on the TiO2 nanotube arrays with 470 nm diameter. Furthermore, the ALP activity peaked on the 150 nm diameter TiO2 nanotube arrays and decreased dramatically with the increase of nanotube diameter. Thus a narrow range of diameter (100-200 nm) that could induce the greatest bone-forming activity is determined. It is expected that more delicate design of orthopedic implant with regional abduction of cell proliferation or bone forming could be achieved by controlling the diameter of TiO2 nanotubes. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Cervical spinal canal narrowing in idiopathic syringomyelia

    Energy Technology Data Exchange (ETDEWEB)

    Struck, Aaron F. [Massachusetts General Hospital, Department of Neurology, Boston, MA (United States); Carr, Carrie M. [Mayo Clinic, Department of Radiology, Rochester, MN (United States); Shah, Vinil [University of California San Francisco, Department of Radiology, San Francisco, CA (United States); Hesselink, John R. [University of California San Diego, Department of Radiology, San Diego, CA (United States); Haughton, Victor M. [University of Wisconsin, Department of Radiology, Madison, WI (United States)

    2016-08-15

    The cervical spine in Chiari I patient with syringomyelia has significantly different anteroposterior diameters than it does in Chiari I patients without syringomyelia. We tested the hypothesis that patients with idiopathic syringomyelia (IS) also have abnormal cervical spinal canal diameters. The finding in both groups may relate to the pathogenesis of syringomyelia. Local institutional review boards approved this retrospective study. Patients with IS were compared to age-matched controls with normal sagittal spine MR. All subjects had T1-weighted spin-echo (500/20) and T2-weighted fast spin-echo (2000/90) sagittal cervical spine images at 1.5 T. Readers blinded to demographic data and study hypothesis measured anteroposterior diameters at each cervical level. The spinal canal diameters were compared with a Mann-Whitney U test. The overall difference was assessed with a Friedman test. Seventeen subjects were read by two reviewers to assess inter-rater reliability. Fifty IS patients with 50 age-matched controls were studied. IS subjects had one or more syrinxes varying from 1 to 19 spinal segments. Spinal canal diameters narrowed from C1 to C3 and then enlarged from C5 to C7 in both groups. Diameters from C2 to C4 were narrower in the IS group (p < 0.005) than in controls. The ratio of the C3 to the C7 diameters was also smaller (p = 0.004) in IS than controls. Collectively, the spinal canal diameters in the IS were significantly different from controls (Friedman test p < 0.0001). Patients with IS have abnormally narrow upper and mid cervical spinal canal diameters and greater positive tapering between C3 and C7. (orig.)

  13. Clinical evidence on titanium-zirconium dental implants: a systematic review and meta-analysis.

    Science.gov (United States)

    Altuna, P; Lucas-Taulé, E; Gargallo-Albiol, J; Figueras-Álvarez, O; Hernández-Alfaro, F; Nart, J

    2016-07-01

    The use of titanium implants is well documented and they have high survival and success rates. However, when used as reduced-diameter implants, the risk of fracture is increased. Narrow diameter implants (NDIs) of titanium-zirconium (Ti-Zr) alloy have recently been developed (Roxolid; Institut Straumann AG). Ti-Zr alloys (two highly biocompatible materials) demonstrate higher tensile strength than commercially pure titanium. The aim of this systematic review was to summarize the existing clinical evidence on dental NDIs made from Ti-Zr. A systematic literature search was performed using the Medline database to find relevant articles on clinical studies published in the English language up to December 2014. Nine clinical studies using Ti-Zr implants were identified. Overall, 607 patients received 922 implants. The mean marginal bone loss was 0.36±0.06mm after 1 year and 0.41±0.09mm after 2 years. The follow-up period ranged from 3 to 36 months. Mean survival and success rates were 98.4% and 97.8% at 1 year after implant placement and 97.7% and 97.3% at 2 years. Narrow diameter Ti-Zr dental implants show survival and success rates comparable to regular diameter titanium implants (>95%) in the short term. Long-term follow-up clinical data are needed to confirm the excellent clinical performance of these implants. Copyright © 2016 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  14. Horizontal osteotomy for reconstruction of the narrow edentulous mandible

    NARCIS (Netherlands)

    Raghoebar, GM; Batenburg, RHK; Meijer, HJA; Vissink, A

    The aim of this retrospective study was to evaluate the applicability of a horizontal osteotomy procedure for reconstruction of a narrow edentulous mandible in order to enable insertion of implants. In 7 edentulous patients a narrow inferior alveolar ridge was reconstructed with autogenous bone

  15. Bone Healing Around Dental Implants: Simplified vs Conventional Drilling Protocols at Speed of 400 rpm.

    Science.gov (United States)

    Gil, Luiz Fernando; Sarendranath, Alvin; Neiva, Rodrigo; Marão, Heloisa F; Tovar, Nick; Bonfante, Estevam A; Janal, Malvin N; Castellano, Arthur; Coelho, Paulo G

    This study evaluated whether simplified drilling protocols would provide comparable histologic and histomorphometric results to conventional drilling protocols at a low rotational speed. A total of 48 alumina-blasted and acid-etched Ti-6Al-4V implants with two diameters (3.75 and 4.2 mm, n = 24 per group) were bilaterally placed in the tibiae of 12 dogs, under a low-speed protocol (400 rpm). Within the same diameter group, half of the implants were inserted after a simplified drilling procedure (pilot drill + final diameter drill), and the other half were placed using the conventional drilling procedure. After 3 and 5 weeks, the animals were euthanized, and the retrieved bone-implant samples were subjected to nondecalcified histologic sectioning. Histomorphology, bone-to-implant contact (BIC), and bone area fraction occupancy (BAFO) analysis were performed. Histology showed that new bone was formed around implants, and inflammation or bone resorption was not evident for both groups. Histomorphometrically, when all independent variables were collapsed over drilling technique, no differences were detected for BIC and BAFO; when drilling technique was analyzed as a function of time, the conventional groups reached statistically higher BIC and BAFO at 3 weeks, but comparable values between techniques were observed at 5 weeks; 4.2-mm implants obtained statistically higher BAFO relative to 3.75-mm implants. Based on the present methodology, the conventional technique improved bone formation at 3 weeks, and narrower implants were associated with less bone formation.

  16. Guided proliferation and bone-forming functionality on highly ordered large diameter TiO{sub 2} nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ruopeng; Wu, Hongliu; Ni, Jiahua, E-mail: jiahua.ni@sjtu.edu.cn; Zhao, Changli; Chen, Yifan; Zheng, Chengjunyi; Zhang, Xiaonong, E-mail: xnzhang@sjtu.edu.cn

    2015-08-01

    The significantly enhanced osteoblast adhesion, proliferation and alkaline phosphatase (ALP) activity were observed on TiO{sub 2} nanotube surface in recent studies in which the scale of nanotube diameter was restricted under 100 nm. In this paper, a series of highly ordered TiO{sub 2} nanotube arrays with larger diameters ranging from 150 nm to 470 nm were fabricated via high voltage anodization. The behaviors of MC3T3-E1 cells in response to the diameter-controlled TiO{sub 2} nanotubes were investigated. A contrast between the trend of proliferation and the trend of cell elongation was observed. The highest cell elongation (nearly 10:1) and the lowest cell number were observed on the TiO{sub 2} nanotube arrays with 150 nm diameter. While, the lowest cell elongation and highest cell number were achieved on the TiO{sub 2} nanotube arrays with 470 nm diameter. Furthermore, the ALP activity peaked on the 150 nm diameter TiO{sub 2} nanotube arrays and decreased dramatically with the increase of nanotube diameter. Thus a narrow range of diameter (100–200 nm) that could induce the greatest bone-forming activity is determined. It is expected that more delicate design of orthopedic implant with regional abduction of cell proliferation or bone forming could be achieved by controlling the diameter of TiO{sub 2} nanotubes. - Highlights: • Improved anodization methods leading to more ordered large diameter TiO{sub 2} nanotubes • Significantly enhanced ALP activity was observed on 150 nm diameter TiO{sub 2} nanotubes. • The highest cell density was observed on 470 nm diameter TiO{sub 2} nanotube arrays. • Similar cell response was observed on the amorphous and anatase phased nanotube surface.

  17. Failure Diameter Resolution Study

    Energy Technology Data Exchange (ETDEWEB)

    Menikoff, Ralph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-12-19

    Previously the SURFplus reactive burn model was calibrated for the TATB based explosive PBX 9502. The calibration was based on fitting Pop plot data, the failure diameter and the limiting detonation speed, and curvature effect data for small curvature. The model failure diameter is determined utilizing 2-D simulations of an unconfined rate stick to find the minimum diameter for which a detonation wave propagates. Here we examine the effect of mesh resolution on an unconfined rate stick with a diameter (10mm) slightly greater than the measured failure diameter (8 to 9 mm).

  18. Jihadism, Narrow and Wide

    DEFF Research Database (Denmark)

    Sedgwick, Mark

    2015-01-01

    The term “jihadism” is popular, but difficult. It has narrow senses, which are generally valuable, and wide senses, which may be misleading. This article looks at the derivation and use of “jihadism” and of related terms, at definitions provided by a number of leading scholars, and at media usage....... It distinguishes two main groups of scholarly definitions, some careful and narrow, and some appearing to match loose media usage. However, it shows that even these scholarly definitions actually make important distinctions between jihadism and associated political and theological ideology. The article closes...

  19. Dental Implant Treatment with Computer-assisted Surgery for Bilateral Agenesis of Maxillary Lateral Incisors: A Case Report.

    Science.gov (United States)

    Sasaki, Hodaka; Hirano, Tomoki; Nomoto, Syuntaro; Nishii, Yasushi; Yajima, Yasutomo

    2018-01-01

    Here, we report a case of dental implant treatment involving computer-assisted surgery for bilateral agenesis of the maxillary lateral incisors. The patient was a 39-year-old woman with the chief complaint of functional and esthetic disturbance due to maxillary and mandibular malocclusion. The treatment plan comprised non-extraction comprehensive orthodontic treatment and prosthodontic treatment for space due to the absence of bilateral maxillary lateral incisors. A preliminary examination revealed that the mesiodistal spaces left by the absent bilateral maxillary lateral incisors were too narrow for implant placement (right, 5.49 mm; left, 5.51 mm). Additional orthodontic treatment increased these spaces to approximately 6 mm, the minimum required for implant placement if risk of damage to the adjacent teeth due to inaccuracies in directionality of drilling is to be avoided. For dental implant treatment with computer-assisted surgery, preoperative planning/simulation was performed using Simplant ® ver.12 software and a toothsupported surgical template fabricated using stereolithography. Two narrow-diameter implants were placed in a two-stage procedure. It was confirmed that there was sufficient distance between the implant fixtures and the roots of the adjacent teeth, together with no exposure of alveolar bone. Following a 4-month non-loading period, second-stage surgery and provisional restoration with a temporary screw-retained implant crown were performed. Cement-retained superstructures made of customized zirconia abutment and a zirconia-bonded ceramic crown were fitted as the final restoration. At 5 years after implant surgery, there were no complications, including inflammation of the peri-implant soft tissue and resorption of peri-implant bone. Computer-assisted implant surgery is useful in avoiding complications in bilateral agenesis of the maxillary lateral incisors when only a narrow mesiodistal space is available for implant placement.

  20. Correlates of Narrow Bracketing

    DEFF Research Database (Denmark)

    Koch, Alexander; Nafziger, Julia

    We examine whether different phenomena of narrow bracketing can be traced back to some common characteristic and whether and how different phenomena are related. We find that making dominated lottery choices or ignoring the endowment when making risky choices are related phenomena and are both as...

  1. Customized SmartPeg for measurement of resonance frequency of mini dental implants

    OpenAIRE

    Dhaliwal, Jagjit Singh; Albuquerque, Rubens F.; Fakhry, Ali; Kaur, Sukhbir; Feine, Jocelyne S.

    2017-01-01

    Background One-piece narrow diameter implants (NDIs) have been recommended as ?Single-tooth replacements in the anterior zones, single posterior, multiple-unit fixed dental prosthesis (FDP), edentulous jaws to be rehabilitated with FDP, and edentulous jaws rehabilitation with overdentures in situations with reduced mesiodistal space or reduced ridge width.? (ITI consensus 2013). Since NDIs can be immediately loaded, it is important to be able to carry out stability testing. We developed and v...

  2. Riesgo de fractura implantaria en relación con el diámetro y la plataforma del implante: estudio clínico y analítico de una serie de 33 casos

    Directory of Open Access Journals (Sweden)

    Celia Sánchez Acedo

    2013-03-01

    related to the implant and prosthetic rehabilitation used and we looked for statistical significant differences regarding prosthetic connection and the platform-diameter and implant body-diameter ratio in external hex implants (3.75mm implant body-diameter or wider compared to 3,4mm implants both with 4.1mm platform. Results: The 33 analyzed implant fractures occurred in a total of 23 patients, 13 fractures (8 patients occurred in implants placed outside our department and the remaining 20 (15 patients on the pool of 2.765 implants placed in our department of Oral Surgery. Within this group, we compared the frequency of implant fracture of the 3.4mm body-diameter implants to the 3.75mm or wider bodydiameter implants (both with 4.1mm diameter-platform finding significant differences between both groups (P=.02. No statistical difference was found when comparing internal vs external hex prosthetic connection (P=.7. Conclusions: Implant fracture is a rare complication. The incidence in our patient group was 0,72%. Risk of implant fracture is closely related to implant design, therefore existing a high risk in implants that have a large discrepancy between neck and implant body diameter, i.e. implant fracture occurs more frequently in narrow implants that have a wide platform. The type of prosthetic connection appears to be unrelated.

  3. Clinical and radiological investigations of mandibular overdentures supported by conventional or mini-dental implants: A 2-year prospective follow-up study.

    Science.gov (United States)

    Temizel, Sonay; Heinemann, Friedhelm; Dirk, Cornelius; Bourauel, Christoph; Hasan, Istabrak

    2017-02-01

    Conventional dental implants are not applicable in the mandibular interforaminal region if bone volume is limited. Mini-dental implants offer an alternative means of supporting mandibular overdentures in a narrow residual ridge, without additional surgery. The purpose of this nonrandomized clinical trial was to compare the ability of mini-dental implants with that of conventional dental implants in supporting mandibular overdentures during a 2-year clinical follow-up. Bone quality, bone resorption, implant stability, and oral health were assessed radiographically. A total of 32 participants with edentulism were included. Twenty-two participants (99 implants) received 4 to 5 mini-dental implants (diameter: 1.8-2.4 mm; length: 13-15 mm, study group), and 10 participants (35 implants) received 2 to 4 conventional dental implants (diameter: 3.3-3.7 mm; length: 11-13 mm, control group). The selection of the participants in the study or control group was based on the available bone volume in the mandible. The selection was not randomized. The density of cortical bone thickness was measured in Hounsfield units (HU) from computed tomography data, and patients were followed for 2 years. The participants were examined 3, 6, 12, and 24 months after surgery. Primary stability immediately after the insertion of dental implants (Periotest), secondary stability 6 months after implantation, modified plaque, bleeding on probing indices, and probing depth were measured and analyzed statistically (α=.05). The mean HU value 6 months after implantation in the participants who received mini-dental implants was significantly (P=.035) higher (1250 HU) than that in the participants who received conventional dental implants (1100 HU). The probing depths around the conventional dental implants (1.6 and 1.8 mm, respectively) were significantly higher than those around the mini-dental implants (1.3 and 1.2 mm, respectively) 12 and 24 months after surgery, respectively (Pdental implants were

  4. New stimulation method with the function of narrowing and moving the stimulated region for cochlear implants. Its evaluation by the animal experiment and the numerical analysis; Jinko naiji no tame no shigeki bui no seneika to ido kino wo motta shigeki hoshiki. Suchi kaiseki to dobutsu jikken ni yoru hyoka

    Energy Technology Data Exchange (ETDEWEB)

    Miyoshi, S.; Sakajiri, M.; Ifukube, T.; Matsushima, J. [Hokkaido University, Sapporo (Japan)

    1998-02-01

    The electrical stimulation of the auditory nerve can elicit auditory sensations in the subjects with sensorineural deafness. Each stimulating electrode of an electrode array of the multi-channel cochlear implants may stimulate a distinct neural population. However, a great deal of current spreads from each electrode throughout a lymph because of the high electrical conductivity of the lymph liquid. This phenomenon causes the transmitted information to be reduce due to channel interactions. Even if the number of electrodes is increased, the transmitted information will be limited because of current spread. We have proposed the Tripolar Electrode Stimulation Method (TESM) which may succeed in narrowing the stimulation region and continuously moving the stimulation site for the cochlear implants. We evaluate whether or not TESM works according to a theory which is based on the numerical analysis using the auditory nerve fiber model consisted of unmyelinated and myelinated segments. In this simulation, the neural site and the am of the excited fibers are compared with the compound action potentials which we obtained through animal experiments. As a result, based on the numerical analysis using this model, it is also proved that the anodal/cathodal threshold stimulation current ratio increases by decreasing unmyelinated segment between the inner hair cell and the habenula perforate. Also by comparing the result of the numerical analysis with that of the animal experiment, It is suggested that an effect of the unmyelinated segment is not significant. Based on their results mentioned above, we succeed in narrowing a Stimulation region by controlling the am of the currents emitted from the electrodes on both sides. Also we succeed in continuously moving a stimulation site by changing the ratio of the currents emitted from the electrodes on both sides. 11 refs., 14 figs., 1 tab.

  5. Damage and in-situ annealing during ion implantation

    International Nuclear Information System (INIS)

    Sadana, D.K.; Washburn, J.; Byrne, P.F.; Cheung, N.W.

    1982-11-01

    Formation of amorphous (α) layers in Si during ion implantation in the energy range 100 keV-11 MeV and temperature range liquid nitrogen (LN)-100 0 C has been investigated. Cross-sectional transmission electron microscopy (XTEM) shows that buried amorphous layers can be created for both room temperature (RT) and LN temperature implants, with a wider 100 percent amorphous region for the LN cooled case. The relative narrowing of the α layer during RT implantation is attributed to in-situ annealing. Implantation to the same fluence at temperatures above 100 0 C does not produce α layers. To further investigate in situ annealing effects, specimens already containing buried α layers were further irradiated with ion beams in the temperature range RT-400 0 C. It was found that isolated small α zones (less than or equal to 50 diameter) embedded in the crystalline matrix near the two α/c interfaces dissolved into the crystal but the thickness of the 100 percent α layer was not appreciably affected by further implantation at 200 0 C. A model for in situ annealing during implantation is presented

  6. Value of Combining Left Atrial Diameter and Amino-terminal Pro-brain Natriuretic Peptide to the CHA2DS2-VASc Score for Predicting Stroke and Death in Patients with Sick Sinus Syndrome after Pacemaker Implantation

    Directory of Open Access Journals (Sweden)

    Bin-Feng Mo

    2017-01-01

    Conclusions: CHA2DS2-VASc score is valuable for predicting stroke and death risk in patients with SSS after pacemaker implantation. The addition of LAD and NT-proBNP to the CHA2DS2-VASc score improved its predictive power for stroke and death, respectively, in this patient cohort. Future prospective studies are warranted to validate the benefit of adding LAD and NT-proBNP to the CHA2DS2-VASc score for predicting stroke and death risk in non-AF populations.

  7. Influences of internal tapered abutment designs on bone stresses around a dental implant: three-dimensional finite element method with statistical evaluation.

    Science.gov (United States)

    Chu, Chun-Ming; Huang, Heng-Li; Hsu, Jui-Ting; Fuh, Lih-Jyh

    2012-01-01

    The aim of this study is to determine the effects of various designs of internal tapered abutment joints on the stress induced in peri-implant crestal bone by using the three-dimensional finite element method and statistical analyses. Thirty-six models with various internal tapered abutment-implant interface designs including different abutment diameters (3.0, 3.5, and 4.0 mm), connection depths (4, 6, and 8 mm), and tapers (2°, 4°, 6°, and 8°) were constructed. A force of 170 N was applied to the top surface of the abutment either vertically or 45° obliquely. The maximum von Mises bone-stress values in the crestal bone surrounding the implant were statistically analyzed using analysis of variance. In addition, patterns of bone stress around the implant were examined. The results demonstrate that a smaller abutment diameter and a longer abutment connection significantly reduced the bone stresses (P implant interfaced connection was more parallel, bone stresses under vertical loading were less (P = 0.0002), whereas the abutment taper did not show significant effects on bone stresses under oblique loading (P = 0.83). Bone stresses were mainly influenced by the abutment diameter, followed by the abutment connection depth and the abutment taper. For an internal tapered abutment design, it was suggested that a narrower and deeper abutment-implant interface produced the biomechanical advantage of reducing the stress concentration in the crestal region around an implant.

  8. New dental implant selection criterion based on implant design

    OpenAIRE

    El-Anwar, Mohamed I.; El-Zawahry, Mohamed M.; Ibraheem, Eman M.; Nassani, Mohammad Zakaria; ElGabry, Hisham

    2017-01-01

    Objective: A comparative study between threaded and plain dental implant designs was performed to find out a new criterion for dental implant selection. Materials and Methods: Several dental implant designs with a systematic increase in diameter and length were positioned in a cylindrical-shaped bone section and analyzed using finite element method. Four loading types were tested on different dental implant designs; tension of 50 N, compression of 100 N, bending of 20 N, and torque of 2 Nm, t...

  9. Impact of stent diameter and length on in-stent restenosis after DES vs BMS implantation in patients needing large coronary stents-A clinical and health-economic evaluation

    DEFF Research Database (Denmark)

    Zbinden, Rainer; von Felten, Stefanie; Wein, Bastian

    2017-01-01

    AIMS: The British National Institute of Clinical Excellence (NICE) guidelines recommend to use drug-eluting stents (DES) instead of bare-metal stents (BMS) only in lesions >15 mm in length or in vessels 3 mm in diameter. We analyzed the impact of stent length and stent diameter on in......-stent restenosis (ISR) in the BASKET-PROVE study population and evaluated the cost-effectiveness of DES compared to BMS. METHODS/RESULTS: The BASKET-PROVE trial compared DES vs BMS in large coronary arteries (≥3 mm). We calculated incremental cost-effectiveness ratios (ICERs) and cost-effectiveness acceptability...... of 10 000 CHF per TLR avoided, DES had a high probability of being cost-effective. CONCLUSION: In the BASKET-PROVE study population, the strongest predictor of ISR is the use of a BMS, even in patients in need of stents ≥3.0 mm and ≤15 mm lesion length and DES were cost-effective. This should prompt...

  10. Simple, quick, and efficient implant placement jig

    Directory of Open Access Journals (Sweden)

    Nikhil Narayan Pai

    2015-01-01

    Full Text Available Implants have become an inherent part of everyday orthodontic practice, but unlike prosthodontic implants, their placement and insertion into narrow interradicular spaces for orthodontic purposes remain a tricky and challenging part to most clinicians. An innovative and clinically useful method has been described here for safe and easy insertion of mini-implants.

  11. Puente Verrazano-Narrows

    Directory of Open Access Journals (Sweden)

    Ammann, -

    1964-05-01

    Full Text Available This outstanding suspension bridge underwent a long process of preparation, and it has finally served to solve a most urgent and intense problem of communication between Brooking and Staten Island. This bridge represents an exceptional engineering achievement firstly because of the 1,298 m span between its two towers, and the two side spans of 370 m; secondly due to the vast amounts of materials involved in its construction. The suspended deck will have two directions of traffic, each consisting of six lanes, the two directions separated by a central division. The anchorage and foundations reach down to a depth of 50 m. The towers supporting the main suspension cables are 210 m high above the mean sea level. Their prefabricated external metal shell contain inside a complex system of thousands of metal cells. The deck hangs from four main suspension cables, each 90 cm in diameter. Hanger cables, each 55 cm in diameter, support the deck. The cable spinning over the main towers was a difficult and highly complicated operation. Details of this are given in the accompanying diagrams. Simultaneous with the construction of the bridge, the main access roads to it have been improved and altered, in order to chanalise the heavy traffic more effectively towards it. The whole project, including the construction of the bridge and alterations to the approaches, has amounted to a total cost of the order of 400 million dollars. The safety of the personnel working on this project has been very carefully studied. Ellaborate arrangements are being rigidly enforced for the protection of human lives. It is hoped that this huge project will be completed within the present year.Esta destacada obra, suspendida, realizada por la Triborough Bridge and Tunnel Authority, cuenta con una larga gestación que por fin culminó en una realidad y, con ella, a dar solución a una angustiosa situación que el tráfico rodado venía creando progresivamente con sus innumerables

  12. Breast Implants

    Science.gov (United States)

    ... Medical Procedures Implants and Prosthetics Breast Implants Breast Implants Share Tweet Linkedin Pin it More sharing options Linkedin Pin it Email Print Breast implants are medical devices that are implanted under the ...

  13. NUMERICAL ANALYSIS OF THE EFFECT OF IMPLANT GEOMETRY TO STRESS DISTRIBUTIONS OF DENTAL IMPLANT SYSTEM

    OpenAIRE

    topkaya, tolga; solmaz, murat yavuz; dündar, serkan; Eltas, Abubekir

    2015-01-01

    ABSTRACT Purpose: The success of dental implants is related to the quality, quantity of local bones, implant design and surgical technique. Implant diameter and length are accepted as key factors. Present work focuses to investigate the effect of titanium implant geometry to stress distributions in implant system.Materials and Methods: For this purpose three different implant models which are currently being used in clinical cases constructed by using ANSYS Workbench 12.1. The stress distribu...

  14. Retinal vessel diameters and risk of stroke: the Rotterdam Study

    NARCIS (Netherlands)

    Ikram, M. K.; de Jong, F. J.; Bos, M. J.; Vingerling, J. R.; Hofman, A.; Koudstaal, P. J.; de Jong, P. T. V. M.; Breteler, M. M. B.

    2006-01-01

    Retinal vessels may provide information on cerebral vascular pathology, because they share many features with cerebral vessels. A smaller ratio of the retinal arteriolar-to-venular diameters reportedly predicts the risk of stroke. It is unclear if this is due to arteriolar narrowing or venular

  15. Small diameter carbon nanopipettes

    Science.gov (United States)

    Singhal, Riju; Bhattacharyya, Sayan; Orynbayeva, Zulfiya; Vitol, Elina; Friedman, Gary; Gogotsi, Yury

    2010-01-01

    Nanoscale multifunctional carbon probes facilitate cellular studies due to their small size, which makes it possible to interrogate organelles within living cells in a minimally invasive fashion. However, connecting nanotubes to macroscopic devices and constructing an integrated system for the purpose of fluid and electrical signal transfer is challenging, as is often the case with nanoscale components. We describe a non-catalytic chemical vapor deposition based method for batch fabrication of integrated multifunctional carbon nanopipettes (CNPs) with tip diameters much smaller (10-30 nm) than previously reported (200 nm and above) and approaching those observed for multiwalled carbon nanotubes. This eliminates the need for complicated attachment/assembly of nanotubes into nanofluidic devices. Variable tip geometries and structures were obtained by controlled deposition of carbon inside and outside quartz pipettes. We have shown that the capillary length and gas flow rate have a marked effect on the carbon deposition. This gives us a flexible protocol, useful for growing carbon layers of different thicknesses at selective locations on a glass pipette to yield a large variety of cellular probes in bulk quantities. The CNPs possess an open channel for fluid transfer with the carbon deposited inside at 875 °C behaving like an amorphous semiconductor. Vacuum annealing of the CNP tips at temperatures up to 2000 °C yields graphitic carbon structures with an increase in conductivity of two orders of magnitude. Penetration of the integrated carbon nanoprobes into cells was shown to produce minimal Ca2+ signals, fast recovery of basal Ca2+ levels and no adverse activation of the cellular metabolism during interrogation times as long as 0.5-1 h.

  16. Lower lip numbness due to the mandibular canal narrowing after dental reimplantation: A case report

    Directory of Open Access Journals (Sweden)

    Nafiseh Shamloo

    2015-01-01

    Full Text Available Mandibular canal is the most important anatomical landmark in the body of mandible which always must be considered for implant surgery in posterior mandibular region. Damage to vessels and inferior alveolar nerve that passes through the mandibular canal can cause problems such as hemorrhage and neurosensory disturbances. Damage to the mandibular canal can occur during implant surgery. Depending on the severity of injuries, it would result in temporary or permanent neurosensory disturbances. We have reported a case that mandibular canal narrowing occurred following implant surgery and resulted in anesthetic and hypoesthetic areas in the lower lip. Patient had a history of implant surgery in the region of teeth numbered 30 and numbered 31. The inserted implant failed after 6 years, and reimplantation was done in this area, but due to lower lip numbness in the right side, the second implant was removed, and another implant was inserted in the region of the tooth numbered 32. After 2 years, right lower lip numbness was reported again by the patient. Cone beam computed tomography images showed canal narrowing in the region of the tooth numbered 31 where the second implant was inserted. It seems that the main cause for anesthesia and hypoesthesia in this patient is canal narrowing due to damage during implant replacement and removal.

  17. The DIAMET campaign

    Science.gov (United States)

    Vaughan, G.

    2012-04-01

    DIAMET (DIAbatic influences on Mesoscale structures in ExTratropical storms) is a joint project between the UK academic community and the Met Office. Its focus is on understanding and predicting mesoscale structures in synoptic-scale storms, and in particular on the role of diabatic processes in generating and maintaining them. Such structures include fronts, rain bands, secondary cyclones, sting jets etc, and are important because much of the extreme weather we experience (e.g. strong winds, heavy rain) comes from such regions. The project conducted two field campaigns in the autumn of 2011, from September 14 - 30 and November 24 - December 14, based around the FAAM BAe146 aircraft with support from ground-based radar and radiosonde measurements. Detailed modelling, mainly using the Met Office Unified model, supported the planning and interpretation of these campaigns. This presentation will give a brief overview of the campaigns. Both in September and November-December the weather regime was westerly, with a strong jet stream directed across the Atlantic. Three IOPs were conducted in September, to observe a convective band ahead of an upper-level trough, waves on a long trailing cold front, and a warm conveyor belt associated with a secondary cyclone. In November-December six IOPs were conducted, to observe frontal passages and high winds. This period was notable for a number of very strong windstorms passing across the north of the UK, and gave us an opportunity to examine bent-back warm fronts in the southern quadrant of these storms where the strongest winds are found. The case studies fell into two basic patterns. In the majority of cases, dropsonde legs at high level were used to obtain a cross-section of winds and thermodynamic structure (e.g. across a front), followed by in situ legs at lower levels (generally where the temperature was between 0 and -10°) to examine microphysical processes, especially ice multiplication and the extent of supercooled water

  18. Cervical spinal canal narrowing and cervical neurologi-cal injuries

    Directory of Open Access Journals (Sweden)

    ZHANG Ling

    2012-04-01

    Full Text Available 【Abstract】Cervical spinal canal narrowing can lead to injury of the spinal cord and neurological symptoms in-cluding neck pain, headache, weakness and parasthesisas. According to previous and recent clinical researches, we investigated the geometric parameters of normal cervical spinal canal including the sagittal and transverse diameters as well as Torg ratio. The mean sagittal diameter of cervical spinal canal at C 1 to C 7 ranges from 15.33 mm to 20.46 mm, the mean transverse diameter at the same levels ranges from 24.45 mm to 27.00 mm and the mean value of Torg ratio is 0.96. With respect to narrow cervical spinal canal, the following charaterstics are found: firstly, extension of the cervical spine results in statistically significant stenosis as compared with the flexed or neutral positions; secondly, females sustain cervical spinal canal narrowing more easily than males; finally, the consistent narrowest cervical canal level is at C 4 for all ethnicity, but there is a slight variation in the sagittal diameter of cervical spinal stenosis (≤14 mm in Whites, ≤ 12 mm in Japanese, ≤13.7 mm in Chinese. Narrow sagittal cervical canal diameter brings about an increased risk of neurological injuries in traumatic, degenerative and inflam-matory conditions and is related with extension of cervical spine, gender, as well as ethnicity. It is hoped that this re-view will be helpful in diagnosing spinal cord and neuro-logical injuries with the geometric parameters of cervical spine in the future. Key words: Spinal cord injuries; Spinal stenosis; Trauma, nervous system

  19. Penile Implants

    Science.gov (United States)

    ... the discussion with your doctor. Types of penile implants There are two main types of penile implants: ... might help reduce the risk of infection. Comparing implant types When choosing which type of penile implant ...

  20. Differences in mean fibre diameter and fibre diameter variance in ...

    African Journals Online (AJOL)

    sampled at five different body locations (Figure 1) at an age of 15 months. Samples were analysed by the Wool Testing. Bureaux, using an Optical Fibre Diameter Analyser which measured 4000 individual fibres in each sample. Apart from the mean, the variance of fibre diameter within samples was available. The statistical ...

  1. [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

  2. Wheel Diameter and Speedometer Reading

    Science.gov (United States)

    Murray, Clifton

    2010-01-01

    Most introductory physics students have seen vehicles with nonstandard wheel diameters; some may themselves drive "low-rider" cars or "big-wheel" pickup trucks. But how does changing wheel diameter affect speedometer readout for a given speed? Deriving the answer can be followed readily by students who have been introduced to rotation, and it…

  3. Why are mini-implants lost: the value of the implantation technique!

    Science.gov (United States)

    Romano, Fabio Lourenço; Consolaro, Alberto

    2015-01-01

    The use of mini-implants have made a major contribution to orthodontic treatment. Demand has aroused scientific curiosity about implant placement procedures and techniques. However, the reasons for instability have not yet been made totally clear. The aim of this article is to establish a relationship between implant placement technique and mini-implant success rates by means of examining the following hypotheses: 1) Sites of poor alveolar bone and little space between roots lead to inadequate implant placement; 2) Different sites require mini-implants of different sizes! Implant size should respect alveolar bone diameter; 3) Properly determining mini-implant placement site provides ease for implant placement and contributes to stability; 4) The more precise the lancing procedures, the better the implant placement technique; 5) Self-drilling does not mean higher pressures; 6) Knowing where implant placement should end decreases the risk of complications and mini-implant loss.

  4. Why are mini-implants lost: The value of the implantation technique!

    Science.gov (United States)

    Romano, Fabio Lourenço; Consolaro, Alberto

    2015-01-01

    The use of mini-implants have made a major contribution to orthodontic treatment. Demand has aroused scientific curiosity about implant placement procedures and techniques. However, the reasons for instability have not yet been made totally clear. The aim of this article is to establish a relationship between implant placement technique and mini-implant success rates by means of examining the following hypotheses: 1) Sites of poor alveolar bone and little space between roots lead to inadequate implant placement; 2) Different sites require mini-implants of different sizes! Implant size should respect alveolar bone diameter; 3) Properly determining mini-implant placement site provides ease for implant placement and contributes to stability; 4) The more precise the lancing procedures, the better the implant placement technique; 5) Self-drilling does not mean higher pressures; 6) Knowing where implant placement should end decreases the risk of complications and mini-implant loss. PMID:25741821

  5. Why are mini-implants lost: The value of the implantation technique!

    Directory of Open Access Journals (Sweden)

    Fabio Lourenço Romano

    2015-02-01

    Full Text Available The use of mini-implants have made a major contribution to orthodontic treatment. Demand has aroused scientific curiosity about implant placement procedures and techniques. However, the reasons for instability have not yet been made totally clear. The aim of this article is to establish a relationship between implant placement technique and mini-implant success rates by means of examining the following hypotheses: 1 Sites of poor alveolar bone and little space between roots lead to inadequate implant placement; 2 Different sites require mini-implants of different sizes! Implant size should respect alveolar bone diameter; 3 Properly determining mini-implant placement site provides ease for implant placement and contributes to stability; 4 The more precise the lancing procedures, the better the implant placement technique; 5 Self-drilling does not mean higher pressures; 6 Knowing where implant placement should end decreases the risk of complications and mini-implant loss.

  6. Diameter 2 properties and convexity

    Czech Academy of Sciences Publication Activity Database

    Abrahamsen, T. A.; Hájek, Petr Pavel; Nygaard, O.; Talponen, J.; Troyanski, S.

    2016-01-01

    Roč. 232, č. 3 (2016), s. 227-242 ISSN 0039-3223 R&D Projects: GA ČR GA16-07378S Institutional support: RVO:67985840 Keywords : diameter 2 property * midpoint locally uniformly rotund * Daugavet property Subject RIV: BA - General Mathematics Impact factor: 0.535, year: 2016 https://www.impan.pl/pl/wydawnictwa/czasopisma-i-serie-wydawnicze/studia- mathematica /all/232/3/91534/diameter-2-properties-and-convexity

  7. Influence of different implant materials on the primary stability of orthodontic mini-implants

    OpenAIRE

    Chin-Yun Pan; Szu-Ting Chou; Yu-Chuan Tseng; Yi-Hsin Yang; Chao-Yi Wu; Ting-Hsun Lan; Pao-Hsin Liu; Hong-Po Chang

    2012-01-01

    This study evaluates the influence of different implant materials on the primary stability of orthodontic mini-implants by measuring the resonance frequency. Twenty-five orthodontic mini-implants with a diameter of 2 mm were used. The first group contained stainless steel mini-implants with two different lengths (10 and 12 mm). The second group included titanium alloy mini-implants with two different lengths (10 and 12 mm) and stainless steel mini-implants 10 mm in length. The mini-implants w...

  8. New dental implant selection criterion based on implant design.

    Science.gov (United States)

    El-Anwar, Mohamed I; El-Zawahry, Mohamed M; Ibraheem, Eman M; Nassani, Mohammad Zakaria; ElGabry, Hisham

    2017-01-01

    A comparative study between threaded and plain dental implant designs was performed to find out a new criterion for dental implant selection. Several dental implant designs with a systematic increase in diameter and length were positioned in a cylindrical-shaped bone section and analyzed using finite element method. Four loading types were tested on different dental implant designs; tension of 50 N, compression of 100 N, bending of 20 N, and torque of 2 Nm, to derive design curves. Better stress distribution on both spongy and cortical bone was noted with an increase in dental implant diameter and length. With the increase in dental implant side area, a stress reduction in the surrounding bones was observed, where threaded dental implants showed better behavior over the plain ones. Increasing value of ratio between dental implant side area and its cross-sectional area reduces stresses transferred to cortical and spongy bones. The use of implants with higher ratio of side area to cross-section area, especially with weak jaw bone, is recommended.

  9. Crestal bone loss of standard implant versus platform switch implant design using minimal invasive technique

    OpenAIRE

    Karim M. Ahmed; Salah Abd Elfatah; Mohamed Abd El-Mageed Katamish

    2016-01-01

    The aim of the current study was to investigate the role of the type of abutment/implant connection on the marginal bone loss around dental implant. The present study was conducted on eleven patients, six males and five females with age range from 26 to 45 years. Twenty consecutive dental implants were inserted for implant – supported restoration in the maxillary premolar area. The diameter and length of dental implants of all subjects were the same in groups, 3.7 mm diameter and 11.5 mm leng...

  10. The Relationship amongst Intervertebral Disc Vertical Diameter, Lateral Foramen Diameter and Nerve Root Impingement in Lumbar Vertebra

    Directory of Open Access Journals (Sweden)

    Yusof MI

    2018-03-01

    Full Text Available Introduction: The vertical diameter of the foramen is dependent upon the vertical diameter of the corresponding intervertebral disc. A decrease in disc vertical diameter has direct anatomic consequences to the foraminal diameter and area available for the nerve root passing through it. This study is to establish the relationship amongst the intervertebral disc vertical diameter, lateral foramen diameters and nerve root compression in the lumbar vertebra. Materials and Methods: Measurements of the study parameters were performed using sagittal MRI images. The parameters studied were: intervertebral disc vertical diameter (DVD, foraminal vertical diameter (FVD, foraminal transverse diameter (FTD and nerve root diameter (NRD of both sides. The relationship between the measured parameters were then analyzed. Results: A total of 62 MRI images were available for this study. Statistical analysis showed moderate to strong correlation between DVD and FVD at all the lumbar levels except at left L23 and L5S1 and right L3L4 and L4L5. Correlation between DVD and FTD were not significant at all lumbar levels. Regression analysis showed that a decrease of 1mm of DVD was associated with 1.3, 1.7, 3.3, 3.3 and 1.3mm reduction of FVD at L1L2, L2L3, L3L4, L4L5 and L5S1 respectively. Conclusion: Reduction of DVD was associated with reduction of FVD. However, FVD was relatively wide for the nerve root even with complete loss of DVD. FTD was much narrower than the FVD making it more likely to cause nerve root compression at the exit foramina. These anatomical details should be given consideration in treating patients with lateral canal stenosis.

  11. Diameters of classes of smooth functions

    Science.gov (United States)

    Kudryavtsev, S. N.

    1995-08-01

    We describe the weak asymptotic behaviour of diameters of n-th order of the unit ball of W_p^l H^\\omega (I^d) in L_q(I^d), where I=(0,1), in dependence on n. Namely we consider the Kolmogorov diameter, the Gel'fand diameter, the linear diameter, the Aleksandrov diameter and the entropy diameter.

  12. Foam relaxation in fractures and narrow channels

    Science.gov (United States)

    Lai, Ching-Yao; Rallabandi, Bhargav; Perazzo, Antonio; Stone, Howard A.

    2017-11-01

    Various applications, from foam manufacturing to hydraulic fracturing with foams, involve pressure-driven flow of foams in narrow channels. We report a combined experimental and theoretical study of this problem accounting for the compressible nature of the foam. In particular, in our experiments the foam is initially compressed in one channel and then upon flow into a second channel the compressed foam relaxes as it moves. A plug flow is observed in the tube and the pressure at the entrance of the tube is higher than the exit. We measure the volume collected at the exit of the tube, V, as a function of injection flow rate, tube length and diameter. Two scaling behaviors for V as a function of time are observed depending on whether foam compression is important or not. Our work may relate to foam fracturing, which saves water usage in hydraulic fracturing, more efficient enhanced oil recovery via foam injection, and various materials manufacturing processes involving pressure-driven flow foams.

  13. Diameter sensitive effect in singlewalled carbon nanotubes upon acid treatment

    International Nuclear Information System (INIS)

    Costa, S.; Borowiak-Palen, E.

    2009-01-01

    Singlewalled carbon nanotubes (SWCNT) exhibit very unique properties. As an electronic system they undergo amphoteric doping effects (n-type and p-type) which can be reversed. These processes affect the optical and vibronic properties of the carbon nanotubes. The most common and widely used procedure which changes the properties of the SWCNT is acid treatment applied as a purification procedure. This effect has been widely studied but not fully understood so far. Here, we present a study, in which a diameter sensitive effect has been observed. Therefore, two kinds of SWCNT samples have been studied: (i) produced via chemical vapour deposition with a broad diameter distribution, and (ii) synthesised by the laser ablation technique which is commonly known to result in narrow diameter distribution bulk SWCNT samples. Resonance Raman spectroscopy, optical absorption spectroscopy, and Fourier transform middle-infrared spectroscopy have been applied for the characterisation of the samples.

  14. 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.

  15. Implant survival rate and marginal bone loss of 6-mm short implants: a 2-year clinical report.

    Science.gov (United States)

    Bratu, Emanuel; Chan, Hsun-Liang; Mihali, Sorin; Karancsi, Olimpiu; Bratu, Dana Cristina; Fu, Jia-Hui; Wang, Hom-Lay

    2014-01-01

    This study aimed to evaluate (1) the association between implant diameter and marginal bone loss (MBL) of short (6 mm) implants and (2) the survival rates of short implants. Thirty-three 6-mm implants were placed in the mandibles of 16 qualified patients. The selected sites had > 5 mm ridge width and implant sites required bone augmentation procedures. All implants were uncovered 3 months after placement, and all patients were rehabilitated with 2- or 3-unit implant-supported fixed partial dentures. Standardized periapical films were taken after 24 months of function. Radiographs were digitalized, and MBL was assessed. For all implants, the mean MBL was 0.17 mm at the point of uncovering. At the 2-year follow-up, all implants were immobile and functional. Implants with 4.2-mm diameters had significantly more MBL (1.95 mm) than wider implants (0.47 mm and 0.35 mm for 5.0-mm and 6.0-mm implants, respectively). This 2-year study illustrated that short implants are a viable option in selected clinical scenarios. Short implants with wider diameters are preferred because they have less marginal implant bone loss.

  16. Narrow gap electronegative capacitive discharges

    Energy Technology Data Exchange (ETDEWEB)

    Kawamura, E.; Lieberman, M. A.; Lichtenberg, A. J. [Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720 (United States)

    2013-10-15

    Narrow gap electronegative (EN) capacitive discharges are widely used in industry and have unique features not found in conventional discharges. In this paper, plasma parameters are determined over a range of decreasing gap length L from values for which an electropositive (EP) edge exists (2-region case) to smaller L-values for which the EN region connects directly to the sheath (1-region case). Parametric studies are performed at applied voltage V{sub rf}=500 V for pressures of 10, 25, 50, and 100 mTorr, and additionally at 50 mTorr for 1000 and 2000 V. Numerical results are given for a parallel plate oxygen discharge using a planar 1D3v (1 spatial dimension, 3 velocity components) particle-in-cell (PIC) code. New interesting phenomena are found for the case in which an EP edge does not exist. This 1-region case has not previously been investigated in detail, either numerically or analytically. In particular, attachment in the sheaths is important, and the central electron density n{sub e0} is depressed below the density n{sub esh} at the sheath edge. The sheath oscillations also extend into the EN core, creating an edge region lying within the sheath and not characterized by the standard diffusion in an EN plasma. An analytical model is developed using minimal inputs from the PIC results, and compared to the PIC results for a base case at V{sub rf}=500 V and 50 mTorr, showing good agreement. Selected comparisons are made at the other voltages and pressures. A self-consistent model is also developed and compared to the PIC results, giving reasonable agreement.

  17. Thin microelectrodes reduce GFAP expression in the implant site in rodent somatosensory cortex

    Science.gov (United States)

    Stice, Paula; Gilletti, Aaron; Panitch, Alyssa; Muthuswamy, Jit

    2007-06-01

    The objective of this study was to test the hypothesis that neural implants with reduced cross-sectional areas will have less glial scarring associated with implantation injury in long-term experiments. In this study, we implanted nine adult rats with two different implants of 12 µm (n = 6), and 25 µm (n = 6) diameters (cross-sectional areas of 68 µm2, 232 µm2 respectively) and the expression of glial fibrilliary acidic protein (GFAP) was assessed after 2 weeks and 4 weeks of implantation. In order to facilitate implantation, the 12 µm diameter implants were coated with poly-glycolic acid (PGA), a biodegradable polymer that degraded within minutes of implantation. In n = 3 animals, 25 µm diameter implants also coated with PGA were implanted and assessed for GFAP expression at the end of 4 weeks of implantation. Statistical analysis of the GFAP expression around the different implants demonstrated that after 2 weeks of implantation there is no statistically significant difference in GFAP expression between the 12 µm and the 25 µm diameter implants. However, after 4 weeks of implantation the implant site of 12 µm diameter implants exhibited a statistically significant reduction in GFAP expression when compared to the implant sites of the 25 µm diameter implants (both with and without the PGA coating). We conclude that in neural implants that are tethered to the skull, implant cross-sectional areas of 68 µm2 and smaller could lead to a reduced glial scarring under chronic conditions. Future studies with longer implant durations can confirm if this observation remains consistent beyond 4 weeks.

  18. Cochlear Implants

    Science.gov (United States)

    A cochlear implant is a small, complex electronic device that can help to provide a sense of sound. People who are ... of-hearing can get help from them. The implant consists of two parts. One part sits on ...

  19. Goserelin Implant

    Science.gov (United States)

    Goserelin implant is used in combination with radiation therapy and other medications to treat localized prostate cancer and is ... treatment of abnormal bleeding of the uterus. Goserelin implant is in a class of medications called gonadotropin- ...

  20. Ion implantation for semiconductors

    International Nuclear Information System (INIS)

    Grey-Morgan, T.

    1995-01-01

    configuration and remote handling options. Current implanter capacities are around 60 wafers/hr, each wafer being 150mm in diameter with a typical doping level of 3 x 10 15 cm -r 2

  1. Diameter Tuning of Single-Walled Carbon Nanotubes by Diffusion Plasma CVD

    Directory of Open Access Journals (Sweden)

    Toshiaki Kato

    2011-01-01

    Full Text Available We have realized a diameter tuning of single-walled carbon nanotubes (SWNTs by adjusting process gas pressures with plasma chemical vapor deposition (CVD. Detailed photoluminescence measurements reveal that the diameter distribution of SWNTs clearly shifts to a large-diameter region with an increase in the pressure during plasma CVD, which is also confirmed by Raman scattering spectroscopy. Based on the systematical investigation, it is found that the main diameter of SWNTs is determined by the pressure during the heating in an atmosphere of hydrogen and the diameter distribution is narrowed by adjusting the pressure during the plasma generation. Our results could contribute to an application of SWNTs to high-performance thin-film transistors, which requires the diameter-controlled semiconductor-rich SWNTs.

  2. Biomechanical Effects of Platform Switching in Two Different Implant Systems: A Three-Dimensional Finite Element Analysis

    Directory of Open Access Journals (Sweden)

    Mahasti Sahabi

    2013-01-01

    Full Text Available Aims: The purpose of this study was to determine the influence of platform switching on stress distribution of two different implant systems, using three-dimensional (3D finite element models.Methods: Six 3D finite element models were created to replicate two different implant systems with peri-implant bone tissue, in which six different implant-abutment configurations were represented: model XiVE-a: 3.8-mm-diameter implant and 3.8-mm-diameter abutment; model XiVE-b (platform-switching model: 4.5-mm-diameter implant and 3.8-mm-diameter abutment; model XiVE-c: 4.5-mm-diameter implant and 4.5-mm-diameter abutment; model 3i-a: 4.0-mm-diameter implant and 4.1-mm-diameter abutment; model 3i-b (platform-switching model: 5.0-mm-diameter implant and 4.1-mm-diameter abutment; model 3i-c: 5.0-mm-diameter implant and 5.0-mm-diameter abutment. Axial and oblique loads of 100 were applied to all models.Results: While the pattern of stress distribution was similar for both loading situations, oblique loading resulted in higher intensity and greater distribution of stress than axial loading in both cortical bone and abutment-implant interface. Stress distribution at peri-implant bone was almost identical with similar magnitudes for all six models. In both implant systems, platform switching models demonstrated lower maximum von Mises stress in cortical bone than conventional models. However, in both implant systems and under both loading situation, platform switching models showed higher stresses at the abutment-implant interface than conventional models.Conclusion: In both implant systems, platform switching design reduced the stress concentration in the crestal bone and shifted it towards the area of implant-abutment interface

  3. Prediction of bubble detachment diameter in flow boiling based on force analysis

    International Nuclear Information System (INIS)

    Chen Deqi; Pan Liangming; Ren Song

    2012-01-01

    Highlights: ► All the forces acting on the growing bubbles are taken into account in the model. ► The bubble contact diameter has significant effect on bubble detachment. ► Bubble growth force and surface tension are more significant in narrow channel. ► A good agreement between the predicted and the measured results is achieved. - Abstract: Bubble detachment diameter is one of the key parameters in the study of bubble dynamics and boiling heat transfer, and it is hard to be measured in a boiling system. In order to predict the bubble detachment diameter, a theoretical model is proposed based on forces analysis in this paper. All the forces acting on a bubble are taken into account to establish a model for different flow boiling configurations, including narrow and conventional channels, upward, downward and horizontal flows. A correlation of bubble contact circle diameter is adopted in this study, and it is found that the bubble contact circle diameter has significant effect on bubble detachment. A new correlation taking the bubble contact circle diameter into account for the evaluation of bubble growth force is proposed in this study, and it is found that the bubble growth force and surface tension force are more significant in narrow channel when comparing with that in conventional channel. A visual experiment was carried out in order to verify present model; and the experimental data from published literature are used also. A good agreement between predicted and measured results is achieved.

  4. Dental Implant Surgery

    Science.gov (United States)

    ... here to find out more. Dental Implant Surgery Dental Implant Surgery Dental implant surgery is, of course, surgery, ... here to find out more. Dental Implant Surgery Dental Implant Surgery Dental implant surgery is, of course, surgery, ...

  5. Short implants to support mandibular complete dentures - photoelastic analysis.

    Science.gov (United States)

    Pimentel, Marcele Jardim; Silva, Wander José da; Del Bel Cury, Altair Antoninha

    2017-02-23

    This study evaluated the stress behavior around short implants in edentulous atrophic mandibles. Six groups included implants with two diameters regular and wide (4 and 5 mm) and three lengths (5, 7 and 9 mm) as follows: Ci9 (9 x 4 mm), Ci7 (7 x 4 mm), Ci5 (5 x 4 mm), Wi9 (9 x 5 mm), Wi7 (7 x 5 mm) and Wi5 (5 x 5 mm). These groups were compared to the control group CG (11 x 4 mm). The analysis was performed with the photoelastic method (n = 6). Each model comprised 4 implants with the same length and diameter connected by a chromium-cobalt bar that simulates a fixed denture. A 0.15 kg force was applied at the end of the cantilever (15 mm), and the maximum shear stress was recorded around the distal and subsequent implants. The stress values were determined, and the quantitative data (Fringes®) were submitted to statistical analysis with one-way ANOVA and the Dunnett test (p implant length increased stress values with a significant difference (p implant diameter reduced the stress values without any differences found between short and long implants. Implants with 5 and 7 mm with regular diameter increased stress levels while short implants with larger diameters experienced similar stress to that of longer implants.

  6. Quantitative measurement of changes in retinal vessel diameter in ocular fundus images

    DEFF Research Database (Denmark)

    Pedersen, Lars; Grunkin, Michael; Ersbøll, Bjarne Kjær

    2000-01-01

    The change in diameter of retinal vessels as a function of increasing distance to the optic disc is believed to be indicative of the risk level of various vascular diseases such as generalised arteriosclerosis and Diabetes Mellitus. In particular, focal arteriolar narrowing (FAN) is considered re...

  7. Quantitative Measurement of Changes in Retinal Vessel Diameter in Ocular Fundus Images

    DEFF Research Database (Denmark)

    Pedersen, Lars; Grunkin, Michael; Ersbøll, Bjarne Kjær

    1999-01-01

    The Change in diameter of retinal vessels as a funcion of increasing distance to the optic disc is believed to be indicative of the risk level of various vascular diseases such as generalised arteriosclerosis and Diabetes Mellitus. In particular, Focal Arteriolar Narrowing (FAN) is considered...

  8. Surgical factors influencing mesiodistal implant angulation.

    Science.gov (United States)

    Payer, Michael; Kirmeier, Robert; Jakse, Norbert; Pertl, Christof; Wegscheider, Walther; Lorenzoni, Martin

    2008-03-01

    The aim of this experimental study was to identify relevant surgical parameters influencing the mesiodistal angular deviation of dental implants. Pilot drillings of 2 mm diameter were performed in bovine ribs with a parallelometer. The subsequent preparation of the implant socket was performed freehand. Utilizing six different implant systems, at least 80 drillings per system of different diameters were performed. The pilot drillings were marked with 2 mm steel pins and cephalometric radiographs were taken. The mesiodistal angle between the longitudinal implant axis and the marked pilot drillings was measured and evaluated by a blinded investigator. To evaluate the influence of the surgeons' experience, their drillings were compared with those of a group of unexperienced surgeons. Additionally, the influence of drilling speed and size of bur steps on drilling accuracy were evaluated. The difference between the lowest value of 0.91 degrees of mesiodistal angular deviation found for 3i implants and the highest of 1.36 degrees for Ankylos implants was of low statistical significance (P=0.065). Drillings of experienced surgeons showed less deviation compared with those of a beginners group (P<0.0001). Higher deviations were measured when a bur size was skipped. Drillings performed at high speed showed significantly higher deviations than those with fewer rewinds per minute. In order to achieve precise implant angulation, all bur diameters available should be used. Utilizing low drilling speeds results in less mesiodistal deviation. The surgeon's experience seems to be the most relevant factor in precise implant placement.

  9. Novel technique to accurately measure femoral diameter using a Thomas splint.

    Science.gov (United States)

    Liew, Ignatius; Qureshi, Mobeen; Joseph, Jibu; Bailey, Oliver

    2017-11-01

    During surgical management of femoral shaft fractures, difficulties arise when treating patients with narrow femoral diaphyseal canals, such as young patients and those with dysplastic femurs secondary to underlying pathology. Accurate pre-operative assessment of the femoral diaphyseal canal diameter would allow the surgeon to plan surgical technique and ensure appropriate equipment was available, such as narrow, unreamed or paediatric sized nails. When secured to the patient both longitudinal rods of the main Thomas Splint component lie parallel with the femoral shaft and horizontal to the radiographic x-ray plate. The diameter of these rods are 13mm (Adult and paediatric). Using the calibration tool, we calibrate the diameter of the Thomas Splint to 13mm, accurately measuring any further detail on that radiograph, such as the diaphyseal canal diameter. Accurate knowledge pre-operatively of radiographic measurements is highly valuable to the operating surgeon. This technique can accurately measure femoral canal diameter using the Thomas splint, negates the requirement for a calibration marker, is reproducible, easy to perform, and is indispensible when faced with a patient with a narrow femoral canal in a diaphyseal femoral fracture. (181 words). Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  10. SEX DETERMINATION FROM FEMORAL HEAD DIAMETERS IN ...

    African Journals Online (AJOL)

    hi-tech

    2000-03-01

    Mar 1, 2000 ... Request for reprints to: Dr. P S Igbigbi, Department of Anatomy, College of Medicine, Private Bag 360 Chichiri, Blantyre 3 Malawi. SEX DETERMINATION .... Figure 2. Bar chart showing the ranges of head diameters of male and female femurs. (RVD-Right vertical diameter; LVD-Left vertical diameter; RTD -.

  11. 7 CFR 51.2850 - Diameter.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Diameter. 51.2850 Section 51.2850 Agriculture... Diameter. Diameter means the greatest dimension measured at right angles to a straight line running from the stem to the root. ...

  12. 7 CFR 51.3211 - Diameter.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Diameter. 51.3211 Section 51.3211 Agriculture... Standards for Grades of Bermuda-Granex-Grano Type Onions Definitions § 51.3211 Diameter. Diameter means the greatest dimension of the onion at right angles to a line running from the stem to the root. Metric...

  13. Image distortion in narrow beam rotation radiography

    International Nuclear Information System (INIS)

    Welander, U.; Wickman, G.

    1978-01-01

    A general mathematical analysis of the image distortion in narrow beam rotation radiography has been performed. Distortion effects are often evident in panoramic images exposed in clinical practice. It is found that in spite of this general experience panoramic images, exposed with the aid of a rotating narrow beam, are reliable for ordinary clinical demands when the object morphology is to be assessed. This statement is valid provided that the object has been properly positioned at the exposure. (Auth.)

  14. Tribological properties of nitrogen implanted and boron implanted steels

    International Nuclear Information System (INIS)

    Kern, K.T.

    1996-01-01

    Samples of a steel with high chrome content was implanted separately with 75 keV nitrogen ions and with 75 keV boron ions. Implanted doses of each ion species were 2-, 4-, and 8 x 10 17 /cm 2 . Retained doses were measured using resonant non-Rutherford Backscattering Spectrometry. Tribological properties were determined using a pin-on-disk test with a 6-mm diameter ruby pin with a velocity of 0.94 m/min. Testing was done at 10% humidity with a load of 377 g. Wear rate and coefficient of friction were determined from these tests. While reduction in the wear rate for nitrogen implanted materials was observed, greater reduction (more than an order of magnitude) was observed for boron implanted materials. In addition, reduction in the coefficient of friction for high-dose boron implanted materials was observed. Nano-indentation revealed a hardened layer near the surface of the material. Results from grazing incidence x-ray diffraction suggest the formation of Fe 2 N and Fe 3 N in the nitrogen implanted materials and Fe 3 B in the boron implanted materials. Results from transmission electron microscopy will be presented

  15. Influence of different implant materials on the primary stability of orthodontic mini-implants.

    Science.gov (United States)

    Pan, Chin-Yun; Chou, Szu-Ting; Tseng, Yu-Chuan; Yang, Yi-Hsin; Wu, Chao-Yi; Lan, Ting-Hsun; Liu, Pao-Hsin; Chang, Hong-Po

    2012-12-01

    This study evaluates the influence of different implant materials on the primary stability of orthodontic mini-implants by measuring the resonance frequency. Twenty-five orthodontic mini-implants with a diameter of 2 mm were used. The first group contained stainless steel mini-implants with two different lengths (10 and 12 mm). The second group included titanium alloy mini-implants with two different lengths (10 and 12 mm) and stainless steel mini-implants 10 mm in length. The mini-implants were inserted into artificial bones with a 2-mm-thick cortical layer and 40 or 20 lb/ft(3) trabecular bone density at insertion depths of 2, 4, and 6 mm. The resonance frequency of the mini-implants in the artificial bone was detected with the Implomates(®) device. Data were analyzed by two-way analysis of variance followed by the Tukey honestly significant difference test (α = 0.05). Greater insertion depth resulted in higher resonance frequency, whereas longer mini-implants showed lower resonance frequency values. However, resonance frequency was not influenced by the implant materials titanium alloy or stainless steel. Therefore, the primary stability of a mini-implant is influenced by insertion depth and not by implant material. Insertion depth is extremely important for primary implant stability and is critical for treatment success. Copyright © 2012. Published by Elsevier B.V.

  16. Influence of different implant materials on the primary stability of orthodontic mini-implants

    Directory of Open Access Journals (Sweden)

    Chin-Yun Pan

    2012-12-01

    Full Text Available This study evaluates the influence of different implant materials on the primary stability of orthodontic mini-implants by measuring the resonance frequency. Twenty-five orthodontic mini-implants with a diameter of 2 mm were used. The first group contained stainless steel mini-implants with two different lengths (10 and 12 mm. The second group included titanium alloy mini-implants with two different lengths (10 and 12 mm and stainless steel mini-implants 10 mm in length. The mini-implants were inserted into artificial bones with a 2-mm-thick cortical layer and 40 or 20 lb/ft3 trabecular bone density at insertion depths of 2, 4, and 6 mm. The resonance frequency of the mini-implants in the artificial bone was detected with the Implomates® device. Data were analyzed by two-way analysis of variance followed by the Tukey honestly significant difference test (α = 0.05. Greater insertion depth resulted in higher resonance frequency, whereas longer mini-implants showed lower resonance frequency values. However, resonance frequency was not influenced by the implant materials titanium alloy or stainless steel. Therefore, the primary stability of a mini-implant is influenced by insertion depth and not by implant material. Insertion depth is extremely important for primary implant stability and is critical for treatment success.

  17. Finite Element Analysis of Bone Stress for Miniscrew Implant Proximal to Root Under Occlusal Force and Implant Loading.

    Science.gov (United States)

    Shan, Li-Hua; Guo, Na; Zhou, Guan-jun; Qie, Hui; Li, Chen-Xi; Lu, Lin

    2015-10-01

    Because of the narrow interradicular spaces and varying oral anatomies of individual patients, there is a very high risk of root proximity during the mini implants inserting. The authors hypothesized that normal occlusal loading and implant loading affected the stability of miniscrew implants placed in proximity or contact with the adjacent root. The authors implemented finite element analysis (FEA) to examine the effectiveness of root proximity and root contact. Stress distribution in the bone was assessed at different degrees of root proximity by generating 4 finite element models: the implant touches the root surface, the implant was embedded in the periodontal membrane, the implant touches the periodontal surface, and the implant touches nothing. Finite element analysis was then carried out with simulations of 2 loading conditions for each model: condition A, involving only tooth loading and condition B, involving both tooth and implant loading. Under loading condition A, the maximum stress on the bone for the implant touching the root was the distinctly higher than that for the other models. For loading condition B, peak stress areas for the implant touching the root were the area around the neck of the mini implant and the point of the mini implant touches the root. The results of this study suggest that normal occlusal loading and implant loading contribute to the instability of the mini implant when the mini implant touches the root.

  18. Flow characteristics of ice slurry in narrow tubes

    Energy Technology Data Exchange (ETDEWEB)

    Kumano, Hiroyuki; Hirata, Tetsuo; Shouji, Ryouta; Hagiwara, Yosuke [Department of Mechanical Systems Engineering, Shinshu University, 4-17-1, Wakasato, Nagano-shi, Nagano 380-8553 (Japan); Shirakawa, Michito [Toyota Motor Corporation, 1 Toyota-cho, Toyota, Aichi 471-8571 (Japan)

    2010-12-15

    Flow characteristics of ice slurry were experimentally investigated using narrow tubes. Reynolds number, the diameter of the tubes and the ice packing factor (IPF) were varied as the experimental parameters. Theoretical analysis was carried out using the experimental results. For laminar flow, it was found that the ratio of the coefficients of pipe friction increases with the IPF, and the rate of increase is high in the case of a low Reynolds number. For turbulent flow, the ratio of the coefficients of pipe friction was 1 for each condition in the case of a low IPF. The ratio of coefficients of pipe friction then decreased slightly at a particular IPF and increased with the IPF in the high-IPF region. In theoretical analysis, it was found that the flow characteristics of ice slurry can be treated as those of pseudoplastic fluid and clarified using the apparent Reynolds number. (author)

  19. Boron precipitates in ion implanted silicon

    International Nuclear Information System (INIS)

    Wu, W.K.; Washburn, J.

    1975-03-01

    Long rod-like defects are observed in ion implanted silicon when boron is present either as a prior dopant addition or as the implanted species. Results of recent work indicates that these defects have the characteristics of narrow extrinsic dipoles or elongated dislocation loops and that there are two different types along each of the six (110) directions. An annealing kinetics method has been used to identify the nature of these defects formed during post-implantation annealing in boron ion (100 keV) implanted silicon irradiated at room temperature to a dose of 2 x 10 14 /cm 2 . It is concluded that at least two different kinds of rod-like defects exist in boron ion implanted silicon. From the activation energy for shrinkage, it is also concluded that one type (anti A) is composed largely of boron atoms. (U.S.)

  20. Systemic alendronate treatment improves fixation of press-fit implants: a canine study using nonloaded implants

    DEFF Research Database (Denmark)

    Jensen, Thomas B; Bechtold, Joan E; Chen, Xinqian

    2007-01-01

    investigated the influence of oral alendronate treatment on early implant fixation in two implant interface settings representing sites of an implant that are in contact with surrounding bone, and other sites without intimate bone contact. One plasma-sprayed cylindrical titanium implant (6 mm diameter...... of alendronate treatment. Bone ongrowth (bone in contact with implant surface) was estimated using the linear intercept technique and shear strength was calculated as the slope on a load-displacement curve. For the press fit implants, alendronate treatment significantly increased bone ongrowth from 24% to 29......Bone resorption associated with local trauma occurring during insertion of joint prostheses is recognized as an early event. Being an osteoclastic inhibitor, alendronate is a potential candidate means to decrease early periprosthetic bone resorption and thereby improve implant fixation. We...

  1. Survival of dental implants placed in sites of previously failed implants.

    Science.gov (United States)

    Chrcanovic, Bruno R; Kisch, Jenö; Albrektsson, Tomas; Wennerberg, Ann

    2017-11-01

    To assess the survival of dental implants placed in sites of previously failed implants and to explore the possible factors that might affect the outcome of this reimplantation procedure. Patients that had failed dental implants, which were replaced with the same implant type at the same site, were included. Descriptive statistics were used to describe the patients and implants; survival analysis was also performed. The effect of systemic, environmental, and local factors on the survival of the reoperated implants was evaluated. 175 of 10,096 implants in 98 patients were replaced by another implant at the same location (159, 14, and 2 implants at second, third, and fourth surgeries, respectively). Newly replaced implants were generally of similar diameter but of shorter length compared to the previously placed fixtures. A statistically significant greater percentage of lost implants were placed in sites with low bone quantity. There was a statistically significant difference (P = 0.032) in the survival rates between implants that were inserted for the first time (94%) and implants that replaced the ones lost (73%). There was a statistically higher failure rate of the reoperated implants for patients taking antidepressants and antithrombotic agents. Dental implants replacing failed implants had lower survival rates than the rates reported for the previous attempts of implant placement. It is suggested that a site-specific negative effect may possibly be associated with this phenomenon, as well as the intake of antidepressants and antithrombotic agents. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  2. Highly Tunable Narrow Bandpass MEMS Filter

    KAUST Repository

    Hafiz, Md Abdullah Al

    2017-07-07

    We demonstrate a proof-of-concept highly tunable narrow bandpass filter based on electrothermally and electrostatically actuated microelectromechanical-system (MEMS) resonators. The device consists of two mechanically uncoupled clamped-clamped arch resonators, designed such that their resonance frequencies are independently tuned to obtain the desired narrow passband. Through the electrothermal and electrostatic actuation, the stiffness of the structures is highly tunable. We experimentally demonstrate significant percentage tuning (~125%) of the filter center frequency by varying the applied electrothermal voltages to the resonating structures, while maintaining a narrow passband of 550 ± 50 Hz, a stopband rejection of >17 dB, and a passband ripple ≤ 2.5 dB. An analytical model based on the Euler-Bernoulli beam theory is used to confirm the behavior of the filter, and the origin of the high tunability using electrothermal actuation is discussed.

  3. Implantation metallurgy

    International Nuclear Information System (INIS)

    Picraux, S.T.

    1975-01-01

    Important changes in the near-surface physical properties of metals were obtained by high-fluence ion implantation. Recently there have been an increasing number of studies of the behavior of implanted species with the aim of understanding the detailed physical processes that occur in an implanted metal layer. A key aspect of these implantation metallurgy studies has been the ability to form uniquely controlled systems in the near-surface regions of metals that can be studied with accurate depth resolution. Metallurgical parameters that may be difficult or impossible to obtain by other means can be measured. Also, parameters that depend on the implantation process, due to the athermal introduction of atoms and defects can be determined. Thus the dual objective of implantation metallurgy is to obtain information to improve understanding of the microscopic aspects of metallurgy and to understand how to form controlled new metallurgical systems. Examples of parameters studied include implanted impurity location, diffusion, enhanced diffusion, solubility, precipitation, and dissolution. (auth)

  4. Novel implant design for initial stability of dental implants inserted in fresh extraction sockets: a preliminary study.

    Science.gov (United States)

    Levin, Liran; Frankenthal, Shai; Zigdon, Hadar; Suzuki, Marcelo; Coelho, Paulo G

    2012-08-01

    To evaluate a novel implant design for immediate implantation. This implant presents a specially designed expanded diameter midcrestal "wing" thread, which is aimed to provide added bone contact for greater insertion torque and primary stability. Mandibular premolars were extracted in 2 mongrel dogs, and immediate dental implants were inserted into the fresh extraction sockets. Implants were evaluated for stability using a resonance frequency analysis device immediately after insertion and after 4 and 8 weeks. Removal torque of 1 randomly selected implant in each hemimandible was measured as well. At 8 weeks, the remaining 6 implants were processed histologically. Mean implant stability quotient at implant placement was 64.38 (5.03) and 74.5 (3.08) at 8 weeks. Average removal torque immediately after implant placement was 49.65 (20.3) N.cm and 98.33 (12.34) N.cm at 8 weeks. The mean bone-to-implant contact value at 8 weeks was 38.89% (7.65%). The examined implant with the expanded diameter midcrestal "wing" thread showed good results of resonance frequency analysis and removal torque during the initial healing phase, and as such, it might be used for immediate implantation and loading.

  5. A naturally narrow positive-parity Θ+

    International Nuclear Information System (INIS)

    Carlson, Carl E.; Carone, Christopher D.; Kwee, Herry J.; Nazaryan, Vahagn

    2004-01-01

    We present a consistent color-flavor-spin-orbital wave function for a positive-parity Θ + that naturally explains the observed narrowness of the state. The wave function is totally symmetric in its flavor-spin part and totally antisymmetric in its color-orbital part. If flavor-spin interactions dominate, this wave function renders the positive-parity Θ + lighter than its negative-parity counterpart. We consider decays of the Θ + and compute the overlap of this state with the kinematically allowed final states. Our results are numerically small. We note that dynamical correlations between quarks are not necessary to obtain narrow pentaquark widths

  6. Narrow-Bicliques: Cryptanalysis of Full IDEA

    DEFF Research Database (Denmark)

    Khovratovich, D.; Leurent, G.; Rechberger, C.

    2012-01-01

    improves time and data complexities over existing attacks. We consider the first 7.5 rounds of IDEA and demonstrate a variant of the approach that works with practical data complexity. The conceptual contribution is the narrow-bicliques technique: the recently introduced independent-biclique approach...... extended with ways to allow for a significantly reduced data complexity with everything else being equal. For this we use available degrees of freedom as known from hash cryptanalysis to narrow the relevant differential trails. Our cryptanalysis is of high computational complexity, and does not threaten...

  7. Electronically steerable ultrasound-driven long narrow air stream

    Science.gov (United States)

    Hasegawa, Keisuke; Qiu, Liwei; Noda, Akihito; Inoue, Seki; Shinoda, Hiroyuki

    2017-08-01

    Acoustic streaming, which is the unidirectional movement of a medium driven by its internal intense acoustic vibrations, has been known for more than a century. Despite the long history of research, there have been no scientific reports on the creation of long stretching steerable airflows in an open space, generated by ultrasound. Here, we demonstrated the creation of a narrow, straight flow in air to a distance of 400 mm from an ultrasound phased array emitting a Bessel beam. We also demonstrated that the direction of the flow could be controlled by appropriately tuning the wavefronts of the emission from the phased array. Unlike conventional airflows such as those generated by jets or fans, which decelerate and spread out as they travel farther, the flow that we created proceeded while being accelerated by the kinetic energy supplied from the ultrasound beam and keeping the diameter as small as the wavelength. A flow of 3 m/s with a 10 mm diameter extended for several hundreds of millimeters in a room that was large enough to be regarded as an open-boundary environment. These properties of the generated flow will enable fine and rapid control of three-dimensional airflow distributions.

  8. Generic Post-closure Safety Assessment for Disposal of Disused Sealed Radioactive Sources in Narrow Diameter Boreholes

    International Nuclear Information System (INIS)

    2017-10-01

    This publication, prepared in light of the IAEA Action Plan on Nuclear Safety developed after the accident at the Fukushima Daiichi nuclear power plant, addresses the management of large volumes of radioactive waste arising in a nuclear or radiological emergency, as part of overall emergency preparedness. The management of large volumes of waste will be one of many efforts to be dealt with to allow recovery of affected areas, to support return of evacuated or relocated populations and preparations for normal social and economic activities, and/or to mitigate additional environmental impacts. The publication is intended to be of use to national planners and policy makers, facility and programme managers, and other professionals responsible for developing and implementing national plans and strategies to manage radioactive waste arising from nuclear or radiological emergencies.

  9. Cochlear implant

    Science.gov (United States)

    ... made up of a microphone/receiver, a speech processor, and an antenna. This part of the implant ... ear. This sound is sent to a speech processor, which is most often connected to the microphone ...

  10. Influence of irradiation (Co{sub 6}0) in pre-implant rabbits embryos: effect on blastocyst diameters and embryos smaller than 2 mm; Influencia da radiacao ionizante (bomba de cobalto) em embrioes de coelha na fase de pre-implantacao: efeito no diametro das blastulas e embrioes com menos de 2mm

    Energy Technology Data Exchange (ETDEWEB)

    Approbato, Mario S.; Oliveira Moura, Katia K.V. de; Souza Florencio, Rodopiano de; Cunha Junior, Carlos; Garcia, Ricardo; Faria, Renato S.; Benedetti, Leonardo N.; Goulart, Flamarion B.

    1995-06-01

    We studied the effect of ionizing irradiation on 12 New Zealand rabbits (65 embryos), in three different times: at match time (zero hour), two days after and four days after, with two different irradiation doses, 5 c Gy and 10 c Gy. Six rabbits (36 blastocysts) were used as controls. The matching instant was the zero hour. Exactly six days after ({+-} 60 minutes) the embryos of each rabbit was picked up by flushing the uterus with culture media. The embryos were fixed in methanol for 48 hours, and colored with acid Mayer hematoxylin. The following embryos parameters were studied: diameter growth; percentage of embryos smaller than 2 mm. We observed that only the irradiation time influenced the blastocysts diameter (no irradiation dose). There was no relation between percentage of embryos smaller than 2 mm and the irradiation. (author). 11 refs., 2 figs.

  11. The narrow U(3. 1) state

    Energy Technology Data Exchange (ETDEWEB)

    Ono, S.; Furui, S.; Mitra, A.N.

    1988-09-01

    The auhtors show that the decay of a certain kind of the diquonium is severely restricted for various reasons. They conclude that the narrow U(3.1) is a good candidate for the diquonium (sq)/sub 6/ (q-barq-bar)/sub 6/sup -//.

  12. Undersea Laser Communication with Narrow Beams

    Science.gov (United States)

    2015-09-29

    Underwater Wireless Optical Communications ...Gbit/s underwater wireless optical communications using directly modulated 520 nm laser diode," Optics Express, vol. 23, no. 16, pp. 20743-20748, 2015. ... wireless communication with narrow optical beams. The undersea systems analysis herein is inspired by lessons learned in the last few

  13. Narrow linewidth pulsed optical parametric oscillator

    Indian Academy of Sciences (India)

    Abstract. Tunable narrow linewidth radiation by optical parametric oscillation has many applications, particularly in spectroscopic investigation. In this paper, different techniques such as injection seeding, use of spectral selecting element like grating, grat- ing and etalon in combination, grazing angle of incidence, entangled ...

  14. Narrow-headed garter snake (Thamnophis rufipunctatus)

    Science.gov (United States)

    Nowak, Erika M.

    2006-01-01

    The narrow-headed garter snake is a harmless, nonvenomous snake that is distinguished by its elongated, triangular-shaped head and the red or dark spots on its olive to tan body. Today, the narrow-headed garter snake is a species of special concern in the United States because of its decline over much of its historic range. Arizona's Oak Creek has historically contained the largest population of narrow-headed garter snakes in the United States. The U.S. Geological Survey (USGS) and the Arizona Game and Fish Department jointly funded research by USGS scientists in Oak Creek to shed light on the factors causing declining population numbers. The research resulted in better understanding of the snake's habitat needs, winter and summer range, and dietary habits. Based on the research findings, the U.S. Forest Service has developed recommendations that visitors and local residents can adopt to help slow the decline of the narrow-headed garter snake in Oak Creek.

  15. Threat but not arousal narrows attention: Evidence from pupil dilation and saccade control

    Directory of Open Access Journals (Sweden)

    Henk eVan Steenbergen

    2011-10-01

    Full Text Available It has been shown that negative affect causes attentional narrowing. According to Easterbrook’s (1959 influential hypothesis this effect is driven by the withdrawal motivation inherent to negative emotions and might be related to increases in arousal. We investigated whether valence-unspecific increases in physiological arousal, as measured by pupil dilation, could account for attentional narrowing effects in a cognitive control task. Following the presentation of a negative, positive, or neutral picture, participants performed a saccade task with a prosaccade versus an antisaccade instruction. The reaction time difference between pro- and antisaccades was used to index attentional selectivity, and while pupil diameter was used as an index of physiological arousal. Pupil dilation was observed for both negative and positive pictures, which indicates increased physiological arousal. However, increased attentional selectivity was only observed following negative pictures. Our data show that motivational intensity effects on attentional narrowing can occur independently of physiological arousal effects.

  16. Soft and Hard Tissue Changes around Tissue-Oriented Tulip-Design Implant Abutments: A 1-Year Randomized Prospective Clinical Trial.

    Science.gov (United States)

    Gutmacher, Zvi; Levi, Guy; Blumenfeld, Israel; Machtei, Eli E

    2015-10-01

    The advantages of platform switching using narrower abutments remain controversial. Many researchers suggest that platform switching can yield enhanced clinical results, while others remain skeptical. We hypothesize that the effectiveness of platform switching might be associated with the degree of reduction in size of the abutment. To radiographically and clinically examine a new abutment design created to move the implant-abutment interface farther medially. This was a prospective, randomized controlled clinical trial that included 27 patients (41 MIS Lance Plus® implants; MIS Implant Technologies, Karmiel, Israel). The patients' age ranged from 39 to 75 years. At the second stage of the surgery, the implants were randomly assigned to either the new platform switch Tulip abutment (TA) design or to the standard platform abutment (SA). Implant probing depth (IPD) and bleeding on probing (BOP) were recorded at baseline and after 12 months. Standardized periapical radiographs were taken (at baseline and at 12 months) and the marginal bone height measured. All implants were successfully integrated. The mean IPD at 1 year post-op was 2.91 mm for the SA group and 2.69 mm for the TA group (p > .05). Similarly, the BOP at 1 year was almost identical in both groups. The mean values of bone resorption at baseline were 0.98 ± 0.37 mm and 0.69 ± 0.20 for the TA and SA groups, respectively (p > .05). Bone loss (baseline to 12 months) was significantly greater in the SA group compared with the TA group. Use of the new TA, with its significantly downsized diameter, resulted in reduced bone loss at 1 year. Further research will be required to assess the long-term effect of this abutment on peri-implant health. © 2014 Wiley Periodicals, Inc.

  17. Customized SmartPeg for measurement of resonance frequency of mini dental implants.

    Science.gov (United States)

    Dhaliwal, Jagjit Singh; Albuquerque, Rubens F; Fakhry, Ali; Kaur, Sukhbir; Feine, Jocelyne S

    2017-12-01

    One-piece narrow diameter implants (NDIs) have been recommended as "Single-tooth replacements in the anterior zones, single posterior, multiple-unit fixed dental prosthesis (FDP), edentulous jaws to be rehabilitated with FDP, and edentulous jaws rehabilitation with overdentures in situations with reduced mesiodistal space or reduced ridge width." (ITI consensus 2013). Since NDIs can be immediately loaded, it is important to be able to carry out stability testing. We developed and validated a customized SmartPeg for this type of implant to measure the Implant Stability Quotient (ISQ). The ISQ of mini dental implants (MDIs) was measured and compared with the stability of standard and in a rabbit model. The aim of the study is to test the feasibility of a customized SmartPeg for resonance frequency measurement of single-piece mini dental implants and to compare primary stability of a standard and the mini dental implant (3M™ESPE™ MDI) in a rabbit model after 6 weeks of healing. Eight New Zealand white rabbits were used for the study. The protocol was approved by the McGill University Animal Ethics Review Board. Sixteen 3M™ESPE™ MDI and equal number of standard implants (Ankylos® Friadent, Dentsply) were inserted into the tibia/femur of the rabbits and compared. Each rabbit randomly received two 3M™ESPE™ MDI and two Ankylos® implants in each leg. ISQ values were measured with the help of an Osstell ISQ device using custom-made SmartPegs for the MDIs and implant-specific SmartPegs™ (Osstell) for the Ankylos®. Measurements were obtained both immediately following implant placement surgery and after a 6-week healing period. Each reading was taken thrice and their average compared using Wilcoxon matched pairs signed-rank tests. The median ISQ and interquartile range (IQR) values were 53.3 (8.3) at insertion and 60.5 (5.5) at 6 weeks for the 3M™ESPE™MDI and, respectively, 58.5 (4.75) and 65.5 (9.3) for the Ankylos® implant. These values also indicate

  18. [Clinical research of immediate restoration implant with mini-implants in edentulous space].

    Science.gov (United States)

    Huang, Jian-sheng; Zhao, Jian-jiang; Liu, Qiong; Liu, Tian-tao

    2010-08-01

    The purpose of this study was to investigate the clinical effective of immediate restoration with Osstem MS mini-implant in the edentulous space of 5-6 mm. The sample consisted of 36 consecutively treated partially edentulous patients who had a total of 36 Osstem MS mini-implants, which were 2.5 mm or 3.0 mm in diameter and placed in 5-6 mm gap. The chair-side-made or laboratory-made provisional crowns for implants were fabricated at the time of fixtures placed. The final restorations were fabricated with gold alloy-fused-porcelain crown 3 to 5 months later. During the mean 21.3 months (12-37 months) follow-up time since fixtures placement, all implants were examined clinically and radiologically. No implant failed before restoration. One implant led an adjacent tooth pulp necrosis after the implantation, but the natural tooth and implant were successfully retained by root canal therapy. 36 implants in 36 patients who were followed-up were successful and their aesthetic results were satisfactory. Immediate loaded implant with Osstem MS mini-implant has good clinical prosthetic effects in the edentulous space of 5-6 mm.

  19. Potential Bone to Implant Contact Area of Short Versus Standard Implants: An In Vitro Micro-Computed Tomography Analysis.

    Science.gov (United States)

    Quaranta, Alessandro; DʼIsidoro, Orlando; Bambini, Fabrizio; Putignano, Angelo

    2016-02-01

    To compare the available potential bone-implant contact (PBIC) area of standard and short dental implants by micro-computed tomography (μCT) assessment. Three short implants with different diameters (4.5 × 6 mm, 4.1 × 7 mm, and 4.1 × 6 mm) and 2 standard implants (3.5 × 10 mm and 3.3 × 9 mm) with diverse design and surface features were scanned with μCT. Cross-sectional images were obtained. Image data were manually processed to find the plane that corresponds to the most coronal contact point between the crestal bone and implant. The available PBIC was calculated for each sample. Later on, the cross-sectional slices were processed by a 3-dimensional (3D) software, and 3D images of each sample were used for descriptive analysis and display the microtopography and macrotopography. The wide-diameter short implant (4.5 × 6 mm) showed the higher PBIC (210.89 mm) value followed by the standard (178.07 mm and 185.37 mm) and short implants (130.70 mm and 110.70 mm). Wide-diameter short implants show a surface area comparable with standard implants. Micro-CT analysis is a promising technique to evaluate surface area in dental implants with different macrodesign, microdesign, and surface features.

  20. Dosimetry and monitoring of X-rays narrow beams produced by linear particle accelerator, for using in radiosurgery

    International Nuclear Information System (INIS)

    Campos, J.C.F.; Vizeu, D.M.

    1987-01-01

    The main characteristics of X-rays narrow beams dosimetry and monitoring are examined, aiming the introduction of this system in brain radiosurgery. The non-protocolize detectors are used, once that the detectors used in therapy by megavoltage were projected for dosimetry with an irradiation field above 40 mm diameter. (C.G.C.) [pt

  1. Analytical approximations for wide and narrow resonances

    International Nuclear Information System (INIS)

    Suster, Luis Carlos; Martinez, Aquilino Senra; Silva, Fernando Carvalho da

    2005-01-01

    This paper aims at developing analytical expressions for the adjoint neutron spectrum in the resonance energy region, taking into account both narrow and wide resonance approximations, in order to reduce the numerical computations involved. These analytical expressions, besides reducing computing time, are very simple from a mathematical point of view. The results obtained with this analytical formulation were compared to a reference solution obtained with a numerical method previously developed to solve the neutron balance adjoint equations. Narrow and wide resonances of U 238 were treated and the analytical procedure gave satisfactory results as compared with the reference solution, for the resonance energy range. The adjoint neutron spectrum is useful to determine the neutron resonance absorption, so that multigroup adjoint cross sections used by the adjoint diffusion equation can be obtained. (author)

  2. Analytical approximations for wide and narrow resonances

    Energy Technology Data Exchange (ETDEWEB)

    Suster, Luis Carlos; Martinez, Aquilino Senra; Silva, Fernando Carvalho da [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Programa de Engenharia Nuclear]. E-mail: aquilino@lmp.ufrj.br

    2005-07-01

    This paper aims at developing analytical expressions for the adjoint neutron spectrum in the resonance energy region, taking into account both narrow and wide resonance approximations, in order to reduce the numerical computations involved. These analytical expressions, besides reducing computing time, are very simple from a mathematical point of view. The results obtained with this analytical formulation were compared to a reference solution obtained with a numerical method previously developed to solve the neutron balance adjoint equations. Narrow and wide resonances of U{sup 238} were treated and the analytical procedure gave satisfactory results as compared with the reference solution, for the resonance energy range. The adjoint neutron spectrum is useful to determine the neutron resonance absorption, so that multigroup adjoint cross sections used by the adjoint diffusion equation can be obtained. (author)

  3. Implantable Cardioverter Defibrillator

    Science.gov (United States)

    ... To Health Topics / Implantable Cardioverter Defibrillators Implantable Cardioverter Defibrillators Also known as What Is an Implantable Cardioverter ... pacemakers and defibrillators. Comparison of an Implantable Cardioverter Defibrillator and a Pacemaker The image compares an ICD ...

  4. Breast reconstruction - implants

    Science.gov (United States)

    Breast implants surgery; Mastectomy - breast reconstruction with implants; Breast cancer - breast reconstruction with implants ... to close the skin flaps. Breast reconstruction with implants is usually done in two stages, or surgeries. ...

  5. Interfacially driven transport in narrow channels

    OpenAIRE

    Bacchin, Patrice

    2018-01-01

    When colloids flow in a narrow channel, the transport efficiency is controlled by the non-equilibrium interplay between colloid-wall interactions and hydrodynamics. In this paper, a general, unifying description of colloidal dispersion flow in a confined system is proposed. A momentum and mass balance founded framework implementing the colloid-interface interactions is introduced. The framework allows us to depict how interfacial forces drive the particles and the liquid flows. The interfacia...

  6. Experimental evidence of narrow non strange dibaryons

    International Nuclear Information System (INIS)

    Willis, N.; Tatischeff, B.; Comets, M.P.; Le Bornec, Y.; Bonin, B.; Lugol, J.C.; Mayer, B.; Terrien, Y.; Beurtey, R.; Boudard, A.; Durand, J.M.; Fassnacht, P.; Hibou, F.

    1987-01-01

    The authors discuss the structures observed with masses above the pion production threshold (M > 2.015 GeV). An extensive study of p( 3 He,d)X and 3 He(p,d)X reactions at different angles and energies has been performed at Saturne. Narrow structures were observed at the same mass position in missing mass spectra. 16 refs.; 3 figs

  7. Implant supported overdentures--the Copenhagen experience

    DEFF Research Database (Denmark)

    Gotfredsen, K

    1997-01-01

    and all but two of the implants were longer than 10 mm. For the implant supported overdentures two methods of attachment were used, a bar or a ball. RESULTS: One of 69 fixtures was lost during the 4-5 year observation period. The mean bone loss for all fixtures was less than 0.2 mm per year. Complications......OBJECTIVES: To evaluate the functional and biological effect of implant-supported overdenture treatment in the lower jaw. METHODS AND MATERIALS: Thirty-two patients were consecutively treated with Astra Tech implants in the lower jaw for retaining overdentures. All implants had a diameter of 3.5 mm...... included 15 fractures of the ball attachment and 26 episodes of looseness of the matrices holding the screw in place. Patient satisfaction with the treatment of the lower jaw was high although 7 patients found that control of the upper denture was poor following treatment. CONCLUSIONS: When the bone...

  8. Effective diameters and corresponding states of fluids

    Science.gov (United States)

    Del Río, Fernando

    Effective hard-sphere diameters of fluids with purely repulsive interactions are derived from a generalized corresponding-states principle of Leland, Rowlinson and coworkers. Various alternative definitions are discussed and related. Virial expansions of the effective diameters and their corresponding volumes are obtained and compared with results of perturbation theory. Applications are made to inverse-power potentials, the repulsive part of the Lennard-Jones potential and hard spherocylinders and dumbells.

  9. Appendiceal diameter: CT versus sonographic measurements

    Energy Technology Data Exchange (ETDEWEB)

    Orscheln, Emily S. [University of Cincinnati Medical Center, Department of Radiology, Cincinnati, OH (United States); Trout, Andrew T. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, Cincinnati, OH (United States)

    2016-03-15

    Ultrasound and CT are the dominant imaging modalities for assessment of suspected pediatric appendicitis, and the most commonly applied diagnostic criterion for both modalities is appendiceal diameter. The classically described cut-off diameter for the diagnosis of appendicitis is 6 mm when using either imaging modality. To demonstrate the fallacy of using the same cut-off diameter for both CT and US in the diagnosis of appendicitis. We conducted a retrospective review of patients younger than 18 years who underwent both US and CT of the appendix within 24 h. The shortest transverse dimension of the appendix was measured at the level of the proximal, mid and distal appendix on US and CT images. We compared mean absolute difference in appendiceal diameter between US and CT, using the paired t-test. We reviewed exams of 155 children (58.7% female) with a mean age of 11.3 ± 4.2 years; 38 of the children (24.5%) were diagnosed with appendicitis. The average time interval between US and CT was 7.0 ± 5.4 h. Mean appendiceal diameter measured by CT was significantly larger than that measured by US in cases without appendicitis (5.3 ± 1.0 mm vs. 4.7 ± 1.1 mm, P < 0.0001) and in cases with appendicitis (8.3 ± 2.2 mm vs. 7.0 ± 2.0 mm, P < 0.0001). Mean absolute diameter difference at any location along the appendix was 1.3-1.4 mm in normal appendices and 2 mm in cases of appendicitis. Measured appendiceal diameter differs between US and CT by 1-2 mm, calling into question use of the same diameter cut-off (6 mm) for both modalities for the diagnosis of appendicitis. (orig.)

  10. Electron correlations in narrow band systems

    International Nuclear Information System (INIS)

    Kishore, R.

    1983-01-01

    The effect of the electron correlations in narrow bands, such as d(f) bands in the transition (rare earth) metals and their compounds and the impurity bands in doped semiconductors is studied. The narrow band systems is described, by the Hubbard Hamiltonian. By proposing a local self-energy for the interacting electron, it is found that the results are exact in both atomic and band limits and reduce to the Hartree Fock results for U/Δ → 0, where U is the intra-atomic Coulomb interaction and Δ is the bandwidth of the noninteracting electrons. For the Lorentzian form of the density of states of the noninteracting electrons, this approximation turns out to be equivalent to the third Hubbard approximation. A simple argument, based on the mean free path obtained from the imaginary part of the self energy, shows how the electron correlations can give rise to a discontinous metal-nonmetal transition as proposed by Mott. The band narrowing and the existence of the satellite below the Fermi energy in Ni, found in photoemission experiments, can also be understood. (Author) [pt

  11. Pain Intensity and Its Objective Determinants Following Implant ...

    African Journals Online (AJOL)

    Objectives: The main goal of this study was to evaluate the relationship between postoperative pain and short-term implant survival. Objective parameters, such as implant-related factors (type, diameter, length) and the surgical approach were also assessed to correlate them with pain. Materials and Methods: This ...

  12. Evaluation of fracture torque resistance of orthodontic mini-implants.

    Science.gov (United States)

    Dalla Rosa, Fernando; Burmann, Paola Fp; Ruschel, Henrique C; Vargas, Ivana A; Kramer, Paulo F

    2016-12-01

    This study sought to assess the fracture torque resistance of mini-implants used for orthodontic anchorage. Five commercially available brands of mini-implants were used (SIN®, CONEXÃO®, NEODENT®, MORELLI®, andFORESTADENT®). Ten mini-implants of each diameter of each brand were tested, for a total 100 specimens. The mini-implants were subject to a static torsion test as described in ASTMstandard F543. Analysis of variance (ANOVA) with the Tukey multiple comparisons procedure was used to assess results. Overall, mean fracture strength ranged from 15.7 to 70.4 N·cm. Mini-implants with larger diameter exhibited higher peak torque values at fracture and higher yield strength, regardless of brand. In addition, significant differences across brands were observed when implants were stratified by diameter. In conclusion, larger mini-implant diameter is associated with increased fracture torque resistance. Additional information on peak torque values at fracture of different commercial brands of mini-implants may increase the success rate of this orthodontic anchorage modality. Sociedad Argentina de Investigación Odontológica.

  13. Bijective Diameters of Gene Tree Parsimony Costs.

    Science.gov (United States)

    Gorecki, Pawel; Eulenstein, Oliver

    2017-08-04

    Synthesizing median trees from a collection of gene trees under the biologically motivated gene tree parsimony (GTP) costs has provided credible species tree estimates. GTP costs are defined for each of the classic evolutionary processes. These costs count the minimum number of events necessary to reconcile the gene tree with the species tree where the leaf-genes are mapped to the leaf-species through a function called labeling. To better understand the synthesis of median trees under these costs there is an increased interest in analyzing their diameters. The diameters of a GTP cost between a gene tree and a species tree are the maximum values of this cost of one or both topologies of the trees involved. We are concerned about the diameters of the GTP costs under bijective labelings. While these diameters are linear time computable for the gene duplication and deep coalescence costs, this has been unknown for the classic gene duplication and loss, and for the loss cost. For the first time, we show how to compute these diameters and proof that this can be achieved in linear time, and thus, completing the computational time analysis for all of the bijective diameters under the GTP costs.

  14. One-year results of maxillary overdentures supported by 2 titanium-zirconium implants - implant survival rates and radiographic outcomes.

    Science.gov (United States)

    Zembic, Anja; Tahmaseb, Ali; Jung, Ronald E; Wismeijer, Daniel

    2017-07-01

    To assess implant survival rates and peri-implant bone loss of 2 titanium-zirconium implants supporting maxillary overdentures at 1 year of loading. Twenty maxillary edentulous patients (5 women and 15 men) being dissatisfied with their complete dentures were included. In total, 40 diameter-reduced titanium-zirconium implants were placed in the anterior maxilla. Local guided bone regeneration (GBR) was allowed if the treatment did not compromise implant stability. Following 3 to 5 months of healing, implant-supported overdentures were inserted on two ball anchors. Implants and overdentures were assessed at 1, 2, 4, and 8 weeks after implant insertion and 2, 4, and 12 months after insertion of overdentures (baseline). Standardized radiographs were taken at implant loading and 1 year. Implant survival rates and bone loss were the primary outcomes. Nineteen patients (1 dropout) with 38 implants were evaluated at a mean follow-up of 1.1 years (range 1.0-1.7 years). One implant failed resulting in an implant survival rate of 97.3%. There was a significant peri-implant bone loss of the implants at 1 year of function (mean, 0.7 mm, SD = 1.1 mm; median: 0.48 mm, IQR = 0.56 mm). There was a high 1-year implant survival rate for edentulous patients receiving 2 maxillary implants and ball anchors as overdenture support. However, several implants exhibited an increased amount of bone loss of more than 2 mm. Overdentures supported by 2 maxillary implants should thus be used with caution as minimally invasive treatment for specific patients encountering problems with their upper dentures until more long-term data is available. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  15. Biomechanical analysis and comparison of 12 dental implant systems using 3D finite element study.

    Science.gov (United States)

    Liang, Rui; Guo, Weihua; Qiao, Xiangchen; Wen, Hailin; Yu, Mei; Tang, Wei; Liu, Lei; Wei, Yongtao; Tian, Weidong

    2015-01-01

    Finite element analysis plays an important role in dental implant design. The objective of this study was to show the effect of the overall geometry of dental implants on their biomechanics after implantation. In this study, 12 dental implants, with the same length, diameter and screw design, were simulated from different implant systems. Numerical model of right mandibular incisor bone segment was generated from CT data. The von-Mises stress distributions and the total deformation distributions under vertical/lateral load were compared for each implant by scores ranking method. The implants with cylindrical shapes had highest scores. Results indicated that cylindrical shape represented better geometry over taper implant. This study is helpful in choosing the optimal dental implant for clinical application and also contributes to individual implant design. Our study could also provide reference for choice and modification of dental implant in any other insertion sites and bone qualities.

  16. Narrow nuclear resonance profiling of Al with subnanometric depth resolution

    International Nuclear Information System (INIS)

    Rosa, E.B.O. da; Krug, C.; Stedile, F.C.; Morais, J.; Baumvol, I.J.R.

    2002-01-01

    We report on the use of the narrow and isolated resonance at 404.9 keV in the cross-section curve of the 27 Al(p,γ) 28 Si nuclear reaction for profiling Al in ultrathin aluminum oxide films on Si. The samples were characterized as-deposited and after thermal annealing, so that Al transport could be studied. An estimated depth resolution of approximately 0.4 nm near the surface of the films could be obtained owing to: (i) the very small resonance width; (ii) the high stopping power of Al 2 O 3 for 404.9 keV protons; (iii) the high energy stability of the proton beam provided by the 500 kV HVEE ion implanter at Porto Alegre; and (iv) an apparent thickness magnification by a factor between 2.0 and 2.4 with the use of glancing incidence. This technique is compared to other methods for Al profiling like medium energy ion scattering and some sputtering-based techniques

  17. Basic surgical principles with ITI implants.

    Science.gov (United States)

    Buser, D; von Arx, T; ten Bruggenkate, C; Weingart, D

    2000-01-01

    The basic surgical principles governing the placement of ITI implants are based on research-oriented developments in harmony with evidence-based and outcome-oriented clinical procedures. In the past 15 years, the range of implant indications has been significantly widened, and partially edentulous patients clearly represent the majority of patients seeking treatment with dental implants today. An important aspect of the successful rehabilitation of patients with ITI implants is the careful selection of implant candidates with respect to systemic and local risk factors. These factors are presented based on current knowledge. Today, solid-screw implants in various screw dimensions and neck configurations comprise the ITI Dental Implant System. These different implant types are necessary to handle the full range of implant indications, in particular in partially edentulous patients. The main clinical factors are presented for the selection of the appropriate implant type, length and diameter. These implants are utilized both in a non-submerged and in a submerged approach. The main goal of surgical therapy is low trauma and the least demanding surgical procedure for patient and clinician to optimize the cost-effectiveness of implant therapy. Hence, a non-submerged approach is preferred in all sites without esthetic priority, such as in fully edentulous patients or in posterior sites of partially edentulous patients. These indications clearly represent the majority of implant patients. In esthetic sites, a submerged approach is utilized to satisfy the specific esthetic demands. The possibility to successfully utilize short implants (6 and 8 mm) and a reduced healing period of 3 months are further advantages of ITI implants due to favorable properties of the rough TPS surface. With the introduction of the microrough SLA surface, a reduction of the healing period to 6 weeks facilitates further progress towards simplification of implant therapy. In summary, the ITI Dental

  18. Pool Boiling CHF in Inclined Narrow Annuli

    International Nuclear Information System (INIS)

    Kang, Myeong Gie

    2010-01-01

    Pool boiling heat transfer has been studied extensively since it is frequently encountered in various heat transfer equipment. Recently, it has been widely investigated in nuclear power plants for application to the advanced light water reactors designs. Through the review on the published results it can be concluded that knowledge on the combined effects of the surface orientation and a confined space on pool boiling heat transfer is of great practical importance and also of great academic interest. Fujita et al. investigated pool boiling heat transfer, from boiling inception to the critical heat flux (CHF, q' CHF ), in a confined narrow space between heated and unheated parallel rectangular plates. They identified that both the confined space and the surface orientation changed heat transfer much. Kim and Suh changed the surface orientation angles of a downward heating rectangular channel having a narrow gap from the downward-facing position (180 .deg.) to the vertical position (90 .deg.). They observed that the CHF generally decreased as the inclination angle (θ ) increased. Yao and Chang studied pool boiling heat transfer in a confined heat transfer for vertical narrow annuli with closed bottoms. They observed that when the gap size ( s ) of the annulus was decreased the effect of space confinement to boiling heat transfer increased. The CHF was occurred at much lower value for the confined space comparing to the unconfined pool boiling. Pool boiling heat transfer in narrow horizontal annular crevices was studied by Hung and Yao. They concluded that the CHF decreased with decreasing gap size of the annuli and described the importance of the thin film evaporation to explain the lower CHF of narrow crevices. The effect of the inclination angle on the CHF on countercurrent boiling in an inclined uniformly heated tube with closed bottoms was also studied by Liu et al. They concluded that the CHF reduced with the inclination angle decrease. A study was carried out

  19. Factors Affecting the Survival Rate of Dental Implants: A Retrospective Study.

    Science.gov (United States)

    Raikar, Sonal; Talukdar, Pratim; Kumari, Sarala; Panda, Sangram Kumar; Oommen, Vinni Mary; Prasad, Arvind

    2017-01-01

    Dental implants have emerged as new treatment modality for the majority of patients and are expected to play a significant role in oral rehabilitation in the future. The present study was conducted to assess various factors affecting the survival rate of dental implants. The present retrospective study was conducted in the Department of Prosthodontics. In this study, 5200 patients with dental implants which were placed during June 2008-April 2015 were included. Exclusion criteria were patients with hormonal imbalance, patients with chronic infectious disease, patients receiving immunosuppressive therapy, pregnant women, drug and alcohol addicts, and patients with severe periodontal diseases. Parameters such as name, age, gender, length of implant, diameter of implant, location of implant, and bone quality were recorded. Data were tabulated and statistically evaluated with IBM SPSS Statistics for Windows, Version 20.0., IBM Corp., Armonk, NY, USA. Out of 5200 patients, 2800 were males and 2400 females. Maximum implants failures (55) were seen in age group above 60 years of age (males - 550, females -700). Age group implants. Age group 41-60 years (males - 1500, females - 1150) showed 45 failed implants. The difference was nonsignificant ( P = 0.21). Maximum implant failure was seen in implants with length >11.5 mm (40/700) followed by implants with implants failure (30/1000) was seen in implants with diameter implants with diameter >4.5 mm (16/1600) and implants with diameter 3.75-4.5 mm (50/2600). The Chi-square test showed significant results ( P implants failure, maxillary posterior revealed 2.2%, maxillary anterior showed 2.1%, and mandibular anterior showed 1% failure rate; this difference was significant ( P implant failure, Type II showed 1.95%, Type III showed 3%, and Type IV revealed 0.8% failure rate; this difference was significant ( P implant, diameter of implant, bone quality, and region of implant are factors determining the survival rate of implants

  20. Fracture strength of orthodontic mini-implants.

    Science.gov (United States)

    Assad-Loss, Tatiana Feres; Kitahara-Céia, Flávia Mitiko Fernandes; Silveira, Giordani Santos; Elias, Carlos Nelson; Mucha, José Nelson

    2017-01-01

    This study aimed at evaluating the design and dimensions of five different brands of orthodontic mini-implants, as well as their influence on torsional fracture strength. Fifty mini-implants were divided into five groups corresponding to different manufactures (DEN, RMO, CON, NEO, SIN). Twenty-five mini-implants were subjected to fracture test by torsion in the neck and the tip, through arbors attached to a Universal Mechanical Testing Machine. The other 25 mini-implants were subjected to insertion torque test into blocks of pork ribs using a torquimeter and contra-angle handpiece mounted in a surgical motor. The shape of the active tip of the mini-implants was evaluated under microscopy. The non-parametric Friedman test and Snedecor's F in analysis of variance (ANOVA) were used to evaluate the differences between groups. The fracture torque of the neck ranged from 23.45 N.cm (DEN) to 34.82 N.cm (SIN), and of the tip ranged from 9.35 N.cm (CON) to 24.36 N.cm (NEO). Insertion torque values ranged from 6.6 N.cm (RMO) to 10.2 N.cm (NEO). The characteristics that most influenced the results were outer diameter, inner diameter, the ratio between internal and external diameters, and the existence of milling in the apical region of the mini-implant. The fracture torques were different for both the neck and the tip of the five types evaluated. NEO and SIN mini-implants showed the highest resistance to fracture of the neck and tip. The fracture torques of both tip and neck were higher than the torque required to insert mini-implants.

  1. Fracture strength of orthodontic mini-implants

    Science.gov (United States)

    Assad-Loss, Tatiana Feres; Kitahara-Céia, Flávia Mitiko Fernandes; Silveira, Giordani Santos; Elias, Carlos Nelson; Mucha, José Nelson

    2017-01-01

    ABSTRACT Objective: This study aimed at evaluating the design and dimensions of five different brands of orthodontic mini-implants, as well as their influence on torsional fracture strength. Methods: Fifty mini-implants were divided into five groups corresponding to different manufactures (DEN, RMO, CON, NEO, SIN). Twenty-five mini-implants were subjected to fracture test by torsion in the neck and the tip, through arbors attached to a Universal Mechanical Testing Machine. The other 25 mini-implants were subjected to insertion torque test into blocks of pork ribs using a torquimeter and contra-angle handpiece mounted in a surgical motor. The shape of the active tip of the mini-implants was evaluated under microscopy. The non-parametric Friedman test and Snedecor’s F in analysis of variance (ANOVA) were used to evaluate the differences between groups. Results: The fracture torque of the neck ranged from 23.45 N.cm (DEN) to 34.82 N.cm (SIN), and of the tip ranged from 9.35 N.cm (CON) to 24.36 N.cm (NEO). Insertion torque values ranged from 6.6 N.cm (RMO) to 10.2 N.cm (NEO). The characteristics that most influenced the results were outer diameter, inner diameter, the ratio between internal and external diameters, and the existence of milling in the apical region of the mini-implant. Conclusions: The fracture torques were different for both the neck and the tip of the five types evaluated. NEO and SIN mini-implants showed the highest resistance to fracture of the neck and tip. The fracture torques of both tip and neck were higher than the torque required to insert mini-implants. PMID:28746487

  2. Cochlear Implants

    Science.gov (United States)

    ... For young children who are deaf or severely hard-of-hearing, using a cochlear implant while they are young exposes them to sounds during an optimal period to develop speech and language skills. Research has shown that when these children receive ...

  3. Comparison of urethral diameters for calculating the urethral dose after permanent prostate brachytherapy

    International Nuclear Information System (INIS)

    Tanaka, Osamu; Hayashi, Shinya; Matsuo, Masayuki; Nakano, Masahiro; Kubota, Yasuaki; Maeda, Sunaho; Ohtakara, Kazuhiro; Deguchi, Takashi; Hoshi, Hiroaki

    2007-01-01

    No studies have yet evaluated the effects of a dosimetric analysis for different urethral volumes. We therefore evaluated the effects of a dosimetric analysis to determine the different urethral volumes. This study was based on computed tomography/magnetic resonance imaging (CT/MRI) combined findings in 30 patients who had undergone prostate brachytherapy. Postimplant CT/MRI scans were performed 30 days after the implant. The urethra was contoured based on its diameter (8, 6, 4, 2, and 0 mm). The total urethral volume-in cubic centimeters [UrV150/200 (cc)] and percent (UrV150%/200%), of the urethra receiving 150% or 200% of the prescribed dose-and the doses (UrD90/30/5) in Grays to 90%, 30%, and 5% of the urethral volume were measured based on the urethral diameters. The UrV150 (cc) and UrD30 were statistically different between the of 8-, 6-, 4-, 2-, and 0-mm diameters, whereas the UrD5 was statistically different only between the 8-, 6-, and 4-mm diameters. Especially for UrD5, there was an approximately 40-Gy difference between the mean values for the 8- and 0-mm diameters. We recommend that the urethra should be contoured as a 4- to 6-mm diameter circle or one side of a triangle of 5-7 mm. By standardizing the urethral diameter, the urethral dose will be less affected by the total urethral volume. (author)

  4. Directed growth of diameter-tunable nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Ozturk, Birol; Talukdar, Ishan; Flanders, Bret N [Department of Physics, Oklahoma State University, 145 Physical Sciences II, Stillwater, OK 74078 (United States)

    2007-09-12

    This study characterizes a method for controlling the nanowire diameter in the directed electrochemical nanowire assembly technique, where alternating voltages applied to electrodes in simple salt solutions induce the crystallization of metallic wires. Dendritic solidification is identified as an important component of this technique. A characteristic of dendritic solidification is that the growth velocity and tip radius are anti-correlated. This relationship is exploited here to realize diameter-tunable nanowire growth. The experimental parameter that provides this control is {omega}, the frequency of the alternating voltage. Increasing {omega} effectively steepens the metal cation concentration gradient at the wire-solution interface, thereby increasing the growth velocity of the wire. For indium wires, increasing {omega} from 0.5 to 3.5 MHz increases their growth velocity from 11 to 78 {mu}m s{sup -1} and reduces their diameter from 770 to 114 nm. Gold wires exhibit diameter-tunability that ranges from 150 nm to 45 nm. Thus, it is possible to tune the wire diameter from the microscale down to the nanoscale. Moreover, this control is a consequence of non-stationary dendritic growth, which distinguishes this process from most previously studied examples of dendritic solidification.

  5. Narrow Linewidth Laser Cooling via Adiabatic Transfer

    Science.gov (United States)

    Bartolotta, John; Holland, Murray; Norcia, Matthew; Thompson, James; Cline, Julia

    2017-04-01

    We simulate and provide a theoretical framework for a new cooling method applicable to particles with narrow-linewidth optical transitions. The particles are adiabatically transferred to lower momentum states upon interaction with counter-propagating laser beams that are repeatedly swept over the transition frequency. A reduced reliance on spontaneous emission (compared to Doppler cooling) allows for larger slowing forces. Cooling via a 7.6 kHz dipole forbidden transition in Strontium-88 is simulated using one-dimensional quantum jump and c-number Langevin equation methods. This ``sweep cooling'' mechanism also shows promise for application to systems lacking closed cycling transitions, such as molecules.

  6. Critical unpairing currents in narrow niobium films

    International Nuclear Information System (INIS)

    Gershenzon, M.E.; Gubankov, V.N.

    1979-01-01

    Investigated are the dependences of critical currents of narrow ( with the width of W=0.5-15 μm) superconducting niobium films on temperature and a magnetic field. The proposed method of film production with the width of the 1μm order and with small edge inhomogeneities ((<=500 A) permitted to realize the Ginsburg-Landau unpairing currents in the wide range of temperatures. The correct comparison with the theory showed that the unpairing currents are observed if W(< or approximately) 2delta, where delta is the effective depth of the penetration of the perpendicular magnetic field

  7. Itinerant ferromagnetism in the narrow band limit

    CERN Document Server

    Liu, S H

    2000-01-01

    It is shown that in the narrow band, strong interaction limit the paramagnetic state of an itinerant ferromagnet is described by the disordered local moment state. As a result, the Curie temperature is orders of magnitude lower than what is expected from the large exchange splitting of the spin bands. An approximate analysis has also been carried out for the partially ordered state, and the result explains the temperature evolvement of the magnetic contributions to the resistivity and low-energy optical conductivity of CrO sub 2.

  8. Volume dips; spot price ranges narrow

    International Nuclear Information System (INIS)

    Anon.

    1994-01-01

    This article is the September 1994 uranium market summary. Volume in the spot concentrates market fell below 1 million lbs U3O8. In total, twelve deals took place compared to 28 deals in August. Of the twelve deals, three took place in the spot concentrates market, two took place in the medium and long-term market, three in the conversion market, and four in the enrichment market. Restricted prices weakened, but unrestricted prices firmed slightly. The enrichment price range narrowed a bit

  9. CLINICAL EVALUATION OF THE STABILITY OF IMPLANTS PLACED AT DIFFERENT SUPRACRESTAL LEVELS

    Directory of Open Access Journals (Sweden)

    B. Alper GÜLTEKIN

    2016-10-01

    Full Text Available Purpose: The aim of this study was to evaluate the stability during healing and before loading of implants placed at two different supracrestal levels according to their collar texture. Materials and Methods: This retrospective study included patients who received posterior implants with the same macro design. Implants with a machined collar were placed 0.3 mm above the crestal bone (M group, while those with a laser-microtextured collar were placed 1 mm above the crestal bone (L group. All implants healed in a single stage with healing abutments. Implant stability quotient (ISQ values were determined using resonance frequency analysis immediately after implant placement during surgery and after 1, 4, 8, and 12 weeks after surgery. Other evaluated factors for stability included the implant diameter and length and the site of placement (maxilla or mandible. Results: In total, 103 implants (47 L, 56 M were evaluated. The median ISQ values at baseline and 1 week after placement were significantly higher for the M group than for the L group (p=0.006 and p=0.031, respectively. There were no differences at the subsequent observation points. The ISQ value was higher for wide-diameter than regular diameter (p=0.001 and mandibular implants than maxillary implants (p=0.001 at 0-8. weeks; p=0.012 at 12 weeks at all observation points. When diameter data were neglected, the implant length did not influence the ISQ value at all observation points. Conclusion: Our results suggest that submerging implant more inside bone may only influence primary stability. Moreover, the implant diameter and site of placement influence primary and secondary stability before loading, whereas the implant length does not when its diameter is not accounted for.

  10. The Effects of Post Diameter on Stress Distribution in Maxillary Central Incisor, A Three Dimensional Finite Element Study

    Directory of Open Access Journals (Sweden)

    A. Monzavi

    2004-06-01

    Full Text Available Statement of Problem: Currently there are three recognized theories about the diameter of prepared dowel space in endodontically treated teeth. Diameter of the dowel is commonly contributed to the root fracture.Purpose: This study used a 3 dimensional (3D finite element method to predict stress distribution in endodontically treated central maxillary tooth with cast post and core with various post diameter according to three philosophies about post diameter (Conservational,Proportional, Preservational.Materials and Methods: In this study three 3D models of central maxillary incisors with different post diameter were created and depend on the size of post called narrow, medium and thick model with post diameter of 1.1mm, 1.7 mm and 2.6 mm of in (CEJrespectively. A load of 100 N was applied to cingulum fossa from lingual direction with 45-degree angle to long axis of tooth and maximum tensile, compressive and Von Misses stresses and their distribution in dentin and post was studied.Results: The post in narrow, medium and thick models produced a similar magnitude of tensile, compressive and Von Misses stresses in dentin. Stress distribution was also similar in all models. Peak stresses in dentin were slightly decreased when post diameter increased from narrow to thick model. In all models peak tensile stresses in dentin occurred in the coronally one third of the lingual surface of the root, whereas peak compressive stresseswere evident in the coronal one third of the facial surface of the root.Conclusion: There were not significant differences stress distribution pattern and magnitude in dentin between the three theories of post diameter.

  11. [Current dental implant design and its clinical importance].

    Science.gov (United States)

    Ye, Lin

    2017-02-01

    The development of clinical implant dentistry was intensively affected by dental implant design improvement and innovation, which brought about new concept, even milestone-like changes of clinical protocol. The current improvements of dental implant design and their clinical importance could be highlighted as followings: 1) The implant apical design influences the implant preliminary stability in immediate implant. The apical 3-5 mm design of implant makes implant stable in immediate implant, because this part would be screwed into alveolar bone through fresh socket, the other part of implant could not be tightly screwed in the socket because of smaller implant diameter. Implant apical form, screw design, self-taping of apical part would be essential for immediate implant. 2) The enough preliminary stability of implant makes immediate prosthesis possible. When osseointegration does not occur, the implant stability comes from a mechanical anchorage, which depends on implant form, screw thread and self-taping design. 3) Implant neck design may have influence for soft tissue recession in esthetic zone. The implant with large shoulder would not be selected for the esthetic area. The platform design may be more favorable in the area. 4) The connection design between implant and abutment is thought a very important structure in implant long-term stability. Moose taper and "tube in tube" were well documented structure design in 20-year clinical practice in Peking University. 5) In last 15 years, the plenty studies showed the platform design of implant had positive influence in implant marginal bone level. Whatever in single implant restoration or multi-implant prosthesis. 6) The digital technology makes clinical work more precise and high-tech. This would be a trend in implant dentistry. New generation of chair-side digital computer-aided design/computer-aided manufacturing makes immediate prosthesis without conventional impression possible. 7) New abutment design have

  12. Cluster headache or narrow angle glaucoma?

    Directory of Open Access Journals (Sweden)

    Prasad Palimar

    1991-01-01

    Full Text Available A 47 year old man with episodes of attacks of pain, redness and mild blurring of vision was investigated for narrow angle glaucoma in view of shallow anterior chambers and a cupped optic disc. The history was reviewed following a spontaneous attack in hospital, which had features other than acute glaucoma. A diagnosis of cluster headache was made on the basis of tests. Cluster headache has been defined as unilateral intense pain, involving the eye and head on one side, usually associated with flushing, nasal congestion and lacrimation; the attacks recurring one or more times daily and lasting 20 - 120 minutes. Such attacks commonly continue for weeks or months and are separated by an asymptomatic period of months to years. This episodic nature, together with unilaterality and tendency to occur at night, closely mimics narrow angle glaucoma. Further, if patients have shallow anterior chambers and disc cupping, the differentiation becomes more difficult yet critical. Resource to provocative tests is often the only answer as the following case report demonstrates.

  13. Narrow field electromagnetic sensor system and method

    International Nuclear Information System (INIS)

    McEwan, T.E.

    1996-01-01

    A narrow field electromagnetic sensor system and method of sensing a characteristic of an object provide the capability to realize a characteristic of an object such as density, thickness, or presence, for any desired coordinate position on the object. One application is imaging. The sensor can also be used as an obstruction detector or an electronic trip wire with a narrow field without the disadvantages of impaired performance when exposed to dirt, snow, rain, or sunlight. The sensor employs a transmitter for transmitting a sequence of electromagnetic signals in response to a transmit timing signal, a receiver for sampling only the initial direct RF path of the electromagnetic signal while excluding all other electromagnetic signals in response to a receive timing signal, and a signal processor for processing the sampled direct RF path electromagnetic signal and providing an indication of the characteristic of an object. Usually, the electromagnetic signal is a short RF burst and the obstruction must provide a substantially complete eclipse of the direct RF path. By employing time-of-flight techniques, a timing circuit controls the receiver to sample only the initial direct RF path of the electromagnetic signal while not sampling indirect path electromagnetic signals. The sensor system also incorporates circuitry for ultra-wideband spread spectrum operation that reduces interference to and from other RF services while allowing co-location of multiple electronic sensors without the need for frequency assignments. 12 figs

  14. Narrow field electromagnetic sensor system and method

    Science.gov (United States)

    McEwan, Thomas E.

    1996-01-01

    A narrow field electromagnetic sensor system and method of sensing a characteristic of an object provide the capability to realize a characteristic of an object such as density, thickness, or presence, for any desired coordinate position on the object. One application is imaging. The sensor can also be used as an obstruction detector or an electronic trip wire with a narrow field without the disadvantages of impaired performance when exposed to dirt, snow, rain, or sunlight. The sensor employs a transmitter for transmitting a sequence of electromagnetic signals in response to a transmit timing signal, a receiver for sampling only the initial direct RF path of the electromagnetic signal while excluding all other electromagnetic signals in response to a receive timing signal, and a signal processor for processing the sampled direct RF path electromagnetic signal and providing an indication of the characteristic of an object. Usually, the electromagnetic signal is a short RF burst and the obstruction must provide a substantially complete eclipse of the direct RF path. By employing time-of-flight techniques, a timing circuit controls the receiver to sample only the initial direct RF path of the electromagnetic signal while not sampling indirect path electromagnetic signals. The sensor system also incorporates circuitry for ultra-wideband spread spectrum operation that reduces interference to and from other RF services while allowing co-location of multiple electronic sensors without the need for frequency assignments.

  15. The biocompatibility of SLA-treated titanium implants

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyeongil [Restorative Dentistry, School of Dental Medicine, University at Buffalo, New York 14214 (United States); Choi, Seong-Ho [Department of Periodontology, Research Institiute for Periodontal Regeneration, College of Dentistry, Yonsei University, Seoul 120-752 (Korea, Republic of); Ryu, Jae-Jun [Department of Prosthodontics, College of Medicine, Korea University, Seoul 136-701 (Korea, Republic of); Koh, Seung-Yong; Park, Ju-Han [Dentium Co. Ltd, Suwon 443-270 (Korea, Republic of); Lee, In-Seop [Institute of Physics and Applied Physics, and Atomic-Scale Surface Science Research Center, Yonsei University, Seoul 120-749 (Korea, Republic of)], E-mail: inseop@yonsei.ac.kr

    2008-06-01

    The titanium implant surface was sandblasted with large grits and acid etched (SLA) to increase the implant surface for osseointegration. The topography of the titanium surface was investigated with scanning electron microscopy (SEM) and a profilometer. The SLA implant demonstrated uniform small micro pits (1-2 {mu}m in diameter). The values of average roughness (R{sub a}) and maximum height (R{sub t}) were 1.19 {mu}m and 10.53 {mu}m respectively after sandblasting and the acid-etching treatment. In the cell-surface interaction study, the human osteoblast cells grew well in vitro. The in vivo evaluation of the SLA implant placed in rabbit tibia showed good bone-to-implant contact (BIC) with a mean value of 29% in total length of the implant. In the short-term clinical study, SLA implants demonstrated good clinical performance, maintaining good crestal bone height.

  16. The biocompatibility of SLA-treated titanium implants

    International Nuclear Information System (INIS)

    Kim, Hyeongil; Choi, Seong-Ho; Ryu, Jae-Jun; Koh, Seung-Yong; Park, Ju-Han; Lee, In-Seop

    2008-01-01

    The titanium implant surface was sandblasted with large grits and acid etched (SLA) to increase the implant surface for osseointegration. The topography of the titanium surface was investigated with scanning electron microscopy (SEM) and a profilometer. The SLA implant demonstrated uniform small micro pits (1-2 μm in diameter). The values of average roughness (R a ) and maximum height (R t ) were 1.19 μm and 10.53 μm respectively after sandblasting and the acid-etching treatment. In the cell-surface interaction study, the human osteoblast cells grew well in vitro. The in vivo evaluation of the SLA implant placed in rabbit tibia showed good bone-to-implant contact (BIC) with a mean value of 29% in total length of the implant. In the short-term clinical study, SLA implants demonstrated good clinical performance, maintaining good crestal bone height

  17. Flow of Jeffrey Fluid through Narrow Tubes

    OpenAIRE

    Nallapu, Santhosh; Radhakrishnamacharya, G.

    2014-01-01

    The present paper deals with a two-fluid model for the flow of Jeffrey fluid in tubes of small diameters. It is assumed that the core region consists of Jeffrey fluid and Newtonian fluid in the peripheral region. Analytical expressions for velocity, effective viscosity, core hematocrit and mean hematocrit have been derived. The effects of various parameters, namely, Jeffrey parameter ({\\lambda}1), tube hematocrit (H0) and tube radius (a) on effective viscosity, core hematocrit and mean hemato...

  18. Impact of crestal and subcrestal implant placement in peri-implant bone: A prospective comparative study

    Science.gov (United States)

    Pellicer-Chover, Hilario; Peñarrocha-Diago, María; Peñarrocha-Oltra, David; Gomar-Vercher, Sonia; Agustín-Panadero, Rubén

    2016-01-01

    Background To assess the influence of the crestal or subcrestal placement of implants upon peri-implant bone loss over 12 months of follow-up. Material and Methods Twenty-six patients with a single hopeless tooth were recruited in the Oral Surgery Unit (Valencia University, Valencia, Spain). The patients were randomized into two treatment groups: group A (implants placed at crestal level) or group B (implants placed at subcrestal level). Control visits were conducted by a trained clinician at the time of implant placement and 12 months after loading. A previously established standard protocol was used to compile general data on all patients (sex and age, implant length and diameter, and brushing frequency). Implant success rate, peri-implant bone loss and the treatment of the exposed implant surface were studied. The level of statistical significance was defined as 5% (α=0.05). Results Twenty-three patients (8 males and 15 females, mean age 49.8±11.6 years, range 28-75 years) were included in the final data analyses, while three were excluded. All the included subjects were nonsmokers with a brushing frequency of up to twice a day in 85.7% of the cases. The 23 implants comprised 10 crestal implants and 13 subcrestal implants. After implant placement, the mean bone position with respect to the implant platform in group A was 0.0 mm versus 2.16±0.88 mm in group B. After 12 months of follow-up, the mean bone positions were -0.06±1.11 mm and 0.95±1.50 mm, respectively - this representing a bone loss of 0.06±1.11 mm in the case of the crestal implants and of 1.22±1.06 mm in the case of the subcrestal implants (p=0.014). Four crestal implants and 5 subcrestal implants presented peri-implant bone levels below the platform, leaving a mean exposed treated surface of 1.13 mm and 0.57 mm, respectively. The implant osseointegration success rate at 12 months was 100% in both groups. Conclusions Within the limitations of this study, bone loss was found to be greater in

  19. Height - Diameter predictive equations for Rubber (Hevea ...

    African Journals Online (AJOL)

    BUKOLA

    The importance of calibrating models on height-diameter relationship can never be over emphasized in predicting mean ... parameters that variously important in forest growth modeling and many sustainable forest management options(e.g., Van ..... Natural forest Ecosystem, southwest Nigeria. Research Journal of Forestry ...

  20. Liquid-vapor rectilinear diameter revisited

    Science.gov (United States)

    Garrabos, Y.; Lecoutre, C.; Marre, S.; Beysens, D.; Hahn, I.

    2018-02-01

    In the modern theory of critical phenomena, the liquid-vapor density diameter in simple fluids is generally expected to deviate from a rectilinear law approaching the critical point. However, by performing precise scannerlike optical measurements of the position of the SF6 liquid-vapor meniscus, in an approach much closer to criticality in temperature and density than earlier measurements, no deviation from a rectilinear diameter can be detected. The observed meniscus position from far (10 K ) to extremely close (1 mK ) to the critical temperature is analyzed using recent theoretical models to predict the complete scaling consequences of a fluid asymmetry. The temperature dependence of the meniscus position appears consistent with the law of rectilinear diameter. The apparent absence of the critical hook in SF6 therefore seemingly rules out the need for the pressure scaling field contribution in the complete scaling theoretical framework in this SF6 analysis. More generally, this work suggests a way to clarify the experimental ambiguities in the simple fluids for the near-critical singularities in the density diameter.

  1. Maximum Diameter of Impacting Liquid Droplets

    NARCIS (Netherlands)

    Laan, N.; de Bruin, K.G.; Bartolo, D.; Josserand, C.; Bonn, D.

    2014-01-01

    The maximum diameter a droplet that impacts on a surface will attain is the subject of controversy, notably for high-velocity impacts of low-viscosity liquids such as water or blood. We study the impact of droplets of simple liquids of different viscosities, and a shear-thinning complex fluid

  2. Photoacoustic determination of blood vessel diameter

    NARCIS (Netherlands)

    Kolkman, R.G.M.; Klaessens, John H.G.M.; Hondebrink, Erwin; Hopman, Jeroen C.W.; de Mul, F.F.M.; Steenbergen, Wiendelt; Thijssen, Johan M.; van Leeuwen, Ton

    2004-01-01

    A double-ring sensor was applied in photoacoustic tomographic imaging of artificial blood vessels as well as blood vessels in a rabbit ear. The peak-topeak time (τ pp) of the laser (1064 nm) induced pressure transient was used to estimate the axial vessel diameter. Comparison with the actual vessel

  3. Diameter preserving linear maps and isometries, II

    Indian Academy of Sciences (India)

    We study linear bijections of simplex spaces A ( S ) which preserve the diameter of the range, that is, the seminorm ϱ ( f ) = sup { | f ( x ) − f ( y ) | : x , y ∈ S } . Author Affiliations. Félix Cabello Sánchez1. Departamento de Matemáticas, Universidad de Extremadura, Avenida de Elvas 06071- Badajoz, Spain. Dates. Manuscript ...

  4. Short Implants: New Horizon in Implant Dentistry

    Science.gov (United States)

    Gulati, Manisha; Garg, Meenu; Pathak, Chetan

    2016-01-01

    The choice of implant length is an essential factor in deciding the survival rates of these implants and the overall success of the prosthesis. Placing an implant in the posterior part of the maxilla and mandible has always been very critical due to poor bone quality and quantity. Long implants can be placed in association with complex surgical procedures such as sinus lift and bone augmentation. These techniques are associated with higher cost, increased treatment time and greater morbidity. Hence, there is need for a less invasive treatment option in areas of poor bone quantity and quality. Data related to survival rates of short implants, their design and prosthetic considerations has been compiled and structured in this manuscript with emphasis on the indications, advantages of short implants and critical biomechanical factors to be taken into consideration when choosing to place them. Studies have shown that comparable success rates can be achieved with short implants as those with long implants by decreasing the lateral forces to the prosthesis, eliminating cantilevers, increasing implant surface area and improving implant to abutment connection. Short implants can be considered as an effective treatment alternative in resorbed ridges. Short implants can be considered as a viable treatment option in atrophic ridge cases in order to avoid complex surgical procedures required to place long implants. With improvement in the implant surface geometry and surface texture, there is an increase in the bone implant contact area which provides a good primary stability during osseo-integration. PMID:27790598

  5. Short Implants: New Horizon in Implant Dentistry.

    Science.gov (United States)

    Jain, Neha; Gulati, Manisha; Garg, Meenu; Pathak, Chetan

    2016-09-01

    The choice of implant length is an essential factor in deciding the survival rates of these implants and the overall success of the prosthesis. Placing an implant in the posterior part of the maxilla and mandible has always been very critical due to poor bone quality and quantity. Long implants can be placed in association with complex surgical procedures such as sinus lift and bone augmentation. These techniques are associated with higher cost, increased treatment time and greater morbidity. Hence, there is need for a less invasive treatment option in areas of poor bone quantity and quality. Data related to survival rates of short implants, their design and prosthetic considerations has been compiled and structured in this manuscript with emphasis on the indications, advantages of short implants and critical biomechanical factors to be taken into consideration when choosing to place them. Studies have shown that comparable success rates can be achieved with short implants as those with long implants by decreasing the lateral forces to the prosthesis, eliminating cantilevers, increasing implant surface area and improving implant to abutment connection. Short implants can be considered as an effective treatment alternative in resorbed ridges. Short implants can be considered as a viable treatment option in atrophic ridge cases in order to avoid complex surgical procedures required to place long implants. With improvement in the implant surface geometry and surface texture, there is an increase in the bone implant contact area which provides a good primary stability during osseo-integration.

  6. A staged approach of implant placement in immediate extraction sockets for preservation of peri-implant soft and hard tissue.

    Science.gov (United States)

    Vinnakota, Dileep Nag; Akula, Sreenivasa Rao; Krishna Reddy, V Vamsi; Sankar, V Vijay

    2014-03-01

    Esthetic zone restoration is a challenging aspect in implant dentistry because of two critical factors such as level of bone support and soft tissue dimensions. Preservation of healthy peri-implant tissues is of primary importance for ensuring better esthetics over an extended period. The aim of the present case-series was to evaluate a new staged approach of implant placement in immediate extraction sockets for preservation of peri-implant soft and hard tissues. Four subjects scheduled for extraction of teeth in the esthetic zone with neither a periapical nor periodontal infection and with thick tissue biotype were included. For all the subjects sand blasted, large grit, acid etched platform switched implant with a diameter 2 mm less than the diameter of extraction socket and a conical abutment-implant connection (Morse taper) were placed 2 mm below the crest of the socket, with almost 2 mm gap between the labial plate and the implant with shoulder placed palatally/lingually. The implants were loaded after 2 months healing period and followed for a period of 1-2 years. In all the four patients there was preservation of both hard and soft tissues around the implant with a good esthetic outcome in all the follow up visits. Integrating immediate placement with stable implant-abutment connection, platform switching concept and careful case selection, we can achieve a very good esthetic outcome.

  7. Effect of the number of implants on stress distribution of anterior implant-supported fixed prostheses combined with a removable partial denture: a finite element analysis.

    Directory of Open Access Journals (Sweden)

    Minoo Mahshid

    2014-06-01

    Full Text Available The main goal of this study was to evaluate differences in stress distribution relevant to the number of implants under an anterior bridge when combined with a removable partial denture in the posterior region.Four three-dimensional finite element models (3D FEM were designed from a mandible containing an implant-supported bridge extending between canines, and a bilateral distal extension removable partial denture. A nonrigid connection was selected as the attachment method between the partial denture and the anterior implant-supported fixed prosthesis; 2, 3, 4 and 5 implants supporting the bridge all with 10mm length and 3.8 mm diameter were assessed. With the aid of the finite element program ANSYS 8.0, the models were loaded and von Mises stresses were evaluated.In spongy bone, stress forces showed a decrease from 2 implants to 4 implants but showed an increase in the 5-implant model. Stresses on cortical bone of terminal implants were in similar range in the 2-, 3- and 4-implant models. While, in the 5-implant model the amount of stresses on terminal implants increased dramatically. The stresses on implants were nearly similar in all models, with the greatest amount on terminal implants.Within the limitations of this study, 2-, 3- and 4-implant models showed less stress on cortical and spongy bone in comparison with the 5-implant model. The stresses transferred to implants were nearly similar.

  8. Alternative approach for management of an electrical storm in Brugada syndrome:Importance of primary ablation within a narrow time window

    Directory of Open Access Journals (Sweden)

    Ahmed Karim Talib, MD, PhD

    2016-06-01

    Full Text Available Placement of an implantable cardioverter–defibrillator (ICD is the only powerful treatment modality for Brugada syndrome in patients presenting with ventricular fibrillation (VF. For those whose first presentation is an electrical storm, pharmacologic therapy is typically used to control VF followed by ICD implantation. We report an alternative approach whereby, before ICD implantation, emergency catheter ablation of the VF-triggering premature ventricular contraction (PVC resulted in long-term VF-free survival. The results suggest that, because VF triggers appear in a narrow time window, ablation of the culprit PVCs that initiate VF before the index PVCs subside is a reasonable alternative approach.

  9. Active Brownian motion in a narrow channel

    Science.gov (United States)

    Ao, X.; Ghosh, P. K.; Li, Y.; Schmid, G.; Hänggi, P.; Marchesoni, F.

    2014-12-01

    We review recent advances in rectification control of artificial microswimmers, also known as Janus particles, diffusing along narrow, periodically corrugated channels. The swimmer self-propulsion mechanism is modeled so as to incorporate a nonzero torque (propulsion chirality). We first summarize the effects of chirality on the autonomous current of microswimmers freely diffusing in channels of different geometries. In particular, left-right and upside-down asymmetric channels are shown to exhibit different transport properties. We then report new results on the dependence of the diffusivity of chiral microswimmers on the channel geometry and their own self-propulsion mechanism. The self-propulsion torque turns out to play a key role as a transport control parameter.

  10. Search for narrow four-baryon states

    International Nuclear Information System (INIS)

    Badelek, B.

    1981-01-01

    Highly excited (4.10 2 ) four-baryon resonances have been searched for in the missing-mass spectrum of the reaction π - + 4 He → π - + X at 5 GeV/c in the region of small four-momentum transfer (0.005 2 ), where one of the decay products of the X is either proton or deuteron or triton. No resonance signal is seen in the mass spectrum of X. Within our limited acceptance, the cross section for the production of a narrow (GAMMA approx. 20 MeV/c 2 ) four-baryon state with mass 4.9 GeV/c 2 is estimated to be smaller than approx. 100 nb. (orig.)

  11. Analysis of narrow effects in pp annihilations

    CERN Document Server

    Defoix, C

    1972-01-01

    The author describes briefly some methods of analysis that final states involving a number of like particles require. A first method consists of separating two competing channels to minimize the reflections due to the undesirable one. Later techniques of analysis lead to the isolation of the only channel of interest and circumvention of the problems of background and reflections due to irrelevant final states. Generally, all these processes are based on the presence of a narrow and identified resonance, for example the eta /sup 0/ or omega /sup 0/ ( to pi /sup +/ pi /sup -/ pi /sup 0/). To be efficient, it is necessary that the observed width of such a basic resonance not be increased too much by experimental errors. (6 refs).

  12. Sieving experiments and pore diameter: it's not a simple relationship.

    Science.gov (United States)

    Krauss, Daniel; Gillespie, Dirk

    2010-10-01

    The classic sieving experiment for estimating an ion channel's diameter with successively larger ions is re-examined. Using a very reduced model of a calcium channel, it is shown that sieving experiments measure a combination of three mechanisms: the cross-sectional area available to the sieving ions (the classic interpretation), the exclusion of the sieving ions from a pore crowded with amino acid side chains that protrude into the permeation pathway, and competitive selectivity of the sieving ions with other ions in the bath (even if those are present only at trace concentrations). The latter two can be called sieving-by-crowding because they stem from the excluded volume of the amino acids in the permeation pathway. The model shows that--to a first--order approximation-sieving experiments measure the available volume inside a selectivity filter, rather than the available cross-sectional area. The two are only the same if the narrow part of the pore does not have flexible amino acid side chains interacting directly with the permeant ions; this may be true of potassium channels, but not calcium, sodium, and other channels with "crowded" selectivity filters.

  13. Implantation, recoil implantation, and sputtering

    International Nuclear Information System (INIS)

    Kelly, R.

    1984-01-01

    Underlying ion-beam modification of surfaces is the more basic subject of particle-surface interaction. The ideas can be grouped into forward and backward features, i.e. those affecting the interior of the target and those leading to particle expulsion. Forward effects include the stopping of the incident particles and the deposition of energy, both governed by integral equations which are easily set up but difficult to solve. Closely related is recoil implantation where emphasis is placed not on the stopping of the incident particles but on their interaction with target atoms with resulting implantation of these atoms. Backward effects, all of which are denoted as sputtering, are in general either of collisional, thermal, electronic, or exfoliational origin. (Auth.)

  14. Effect of Dissolved gas on bubble behavior of subcooled boiling in narrow channel

    International Nuclear Information System (INIS)

    Li Shaodan; Tan Sichao; Xu Chao; Gao Puzhen; Xu Jianjun

    2013-01-01

    An experimental investigation was performed to study the effect of dissolved gas on bubble behavior in narrow rectangular channel under subcooled boiling condition. A high-speed digital video camera was applied to capture the dynamics of the bubble with or without dissolved gas in a narrow rectangular channel. It is found that the dissolved gas has great influence on bubble behavior in subcooled boiling condition. The dissolved gas slows down the rate of bubble growth and condensation and makes the variation of the bubble diameter present some oscillation characteristics. This phenomenon was discussed in the view of the vapor evaporation and condensation. The existence of the dissolved gas can facilitate the survival of the bubble and promote the aggregation of bubbles, and enhence heat transfer enhancement in some ways. (authors)

  15. An experimental study on critical heat flux in a hemispherical narrow gap

    International Nuclear Information System (INIS)

    Park, R.J.; Lee, S.J.; Kang, K.H.; Kim, J.H.; Kim, S.B.; Kim, H.D.; Jeong, J.H.

    2000-01-01

    An experimental study of CHFG (Critical Heat Flux in Gap) has been performed to investigate the inherent cooling mechanism using distilled water and Freon R-113 in hemispherical narrow gaps. As a separate effect test of the CHFG test, a CCFL (Counter Current Flow Limit) test has been also performed to confirm the mechanism of the CHF in narrow annular gaps with large diameter. The CHFG test results have shown that an increase in the gap thickness leads to an increase in critical power. The pressure effect on the critical power was found to be much milder than predictions by CHF correlations of other studies. In the CCFL experiment, the occurrence of CCFL was correlated with the Wallis parameter, which was assumed to correspond to the critical power in the CHFG experiment. The measured values of critical power in the CHFG tests are much lower than CCFL experimental data and the predictions made by empirical CHF correlations. (author)

  16. Predictors of excess cement and tissue response to fixed implant-supported dentures after cementation.

    Science.gov (United States)

    Korsch, Michael; Robra, Bernt-Peter; Walther, Winfried

    2015-01-01

    The cementation of fixed implant-supported restorations involves the risk of excess cement remaining in the peri-implant tissue that may cause a peri-implant tissue response with attachment loss. The aim was to study the peri-implant tissue response after cementation and to detect potential predictors of excess cement. Clinical complications after cementation in several index cases led to a recall of all patients treated with a special methacrylate cement (one hundred five patients with one hundred eighty-eight implants) and systematic reevaluation of 71 patients (68%) with one hundred twenty-six implants (67%). In all cases, suprastructures including abutments were removed, and findings were documented. Implant diameter was significantly associated with the frequency of excess cement. Implant location or system had no significant effect. Excess cement in turn was associated with bleeding on probing, suppuration, and peri-implant attachment loss. In the absence of excess cement 58.8% of implants had no peri-implant attachment loss versus 37.3% when excess cement was present. With increasing retention time of the methacrylate cement, more peri-implant attachment loss was detected. However, the latter association was not significant. Larger diameters are significantly associated with excess cement in peri-implant tissue. Consequences of excess cement may be increased bleeding on probing, suppuration, and possibly peri-implant attachment loss. © 2013 Wiley Periodicals, Inc.

  17. 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.

  18. Development, in vitro testing, and clinical use of a 3.5 mm-diameter zirconia abutment.

    Science.gov (United States)

    Grunder, Ueli; Spielmann, Hans-Peter; Snétivy, Daniel

    2010-01-01

    The use of small-diameter implants is indicated when small missing teeth have to be replaced, especially in esthetic zones. Nevertheless, the small diameter can pose a limiting factor with respect to what materials can be used for the final crown. In most cases, full-ceramic crowns in combination with a ceramic abutment are usually the material of choice for final reconstructions. To date, based on mechanical considerations, a 3.5 mm implant diameter has been a contraindication for using ceramic abutments. The authors describe here the development, in vitro testing, and clinical use of a zirconium abutment with a 3.5 mm diameter. The advantages of this small-diameter zirconia abutment include a minimum platform height that offers optimal prosthetic flexibility, and an accurate transfer of the implant position on to the master model. Furthermore, a precise rotational orientation for single-tooth restorations, optimal mechanical stability, and optimal fatigue resistance can be achieved. The microgap is minimized and protection against overload is afforded. In the reported case, high patient satisfaction was achieved due also to an esthetically pleasing final result.

  19. Coke from small-diameter tubes analyzed

    International Nuclear Information System (INIS)

    Albright, L.F.

    1988-01-01

    The mechanism for coke deposit formation and the nature of the coke itself can vary with the design of the ethylene furnace tube bank. In this article, coke deposits from furnaces with small-diameter pyrolysis tubes are examined. The samples were taken from four furnaces of identical design (Plant B). As in both the first and second installments of the series, the coke deposits were examined using a scanning electron microscope (SEM) and an energy dispersive X-ray analyzer (EDAX). The deposits from the small-diameter tubes are compared with the coke deposits from the furnace discussed in earlier articles. Analysis of the coke in both sets of samples are then used to offer recommendations for improved decoking procedures, operating procedures, better feed selection, and better selection of the metallurgy used in furnace tubes, to extend the operating time of the furnace tubes by reducing the amount and type of coke build up

  20. On finding minimum-diameter clique trees

    Energy Technology Data Exchange (ETDEWEB)

    Blair, J.R.S. (Tennessee Univ., Knoxville, TN (United States). Dept. of Computer Science); Peyton, B.W. (Oak Ridge National Lab., TN (United States))

    1991-08-01

    It is well-known that any chordal graph can be represented as a clique tree (acyclic hypergraph, join tree). Since some chordal graphs have many distinct clique tree representations, it is interesting to consider which one is most desirable under various circumstances. A clique tree of minimum diameter (or height) is sometimes a natural candidate when choosing clique trees to be processed in a parallel computing environment. This paper introduces a linear time algorithm for computing a minimum-diameter clique tree. The new algorithm is an analogue of the natural greedy algorithm for rooting an ordinary tree in order to minimize its height. It has potential application in the development of parallel algorithms for both knowledge-based systems and the solution of sparse linear systems of equations. 31 refs., 7 figs.

  1. Selective Growth of Single-, Double-, and Triple-Walled Carbon Nanotubes through Precise Control of Catalyst Diameter by Radiation-Heated Chemical Vapor Deposition

    Science.gov (United States)

    Taki, Yusuke; Shinohara, Kiyoaki; Kikuchi, Makiko; Tanaka, Akira

    2008-01-01

    Radiation-heated chemical vapor deposition (RHCVD) is a newly developed process which enables the maintenance of narrow catalyst diameter distributions until carbon nanotubes (CNTs) start growing and the synthesis of single-walled carbon nanotube (SWCNT), double-walled carbon nanotube (DWCNT), and triple-walled carbon nanotube (TWCNT) films by changing catalyst diameters. The proportions of specific walled CNTs/as-grown CNTs are as follows: SWCNT/CNT ratio of 100%, DWCNT/CNT ratio of 88% and TWCNT/CNT ratio of 76%. It is clarified that CNT diameter and the number of graphene walls of CNTs are proportional to catalyst diameter.

  2. Inhibited Bacterial Adhesion and Biofilm Formation on Quaternized Chitosan-Loaded Titania Nanotubes with Various Diameters

    Directory of Open Access Journals (Sweden)

    Wen-tao Lin

    2016-03-01

    Full Text Available Titania nanotube-based local drug delivery is an attractive strategy for combating implant-associated infection. In our previous study, we demonstrated that the gentamicin-loaded nanotubes could dramatically inhibit bacterial adhesion and biofilm formation on implant surfaces. Considering the overuse of antibiotics may lead to the evolution of antibiotic-resistant bacteria, we synthesized a new quaternized chitosan derivative (hydroxypropyltrimethyl ammonium chloride chitosan, HACC with a 27% degree of substitution (DS; referred to as 27% HACC that had a strong antibacterial activity and simultaneously good biocompatibility with osteogenic cells. Titania nanotubes with various diameters (80, 120, 160, and 200 nm and 200 nm length were loaded with 2 mg of HACC using a lyophilization method and vacuum drying. Two standard strain, methicillin-resistant Staphylococcus aureus (American Type Culture Collection 43300 and Staphylococcus epidermidis (American Type Culture Collection 35984, and two clinical isolates, S. aureus 376 and S. epidermidis 389, were selected to investigate the bacterial adhesion at 6 h and biofilm formation at 24, 48, and 72 h on the HACC-loaded nanotubes (NT-H using the spread plate method, confocal laser scanning microscopy (CLSM, and scanning electron microscopy (SEM. Smooth titanium (Smooth Ti was also investigated and compared. We found that NT-H could significantly inhibit bacterial adhesion and biofilm formation on its surface compared with Smooth Ti, and the NT-H with 160 nm and 200 nm diameters had stronger antibacterial activity because of the extended HACC release time of NT-H with larger diameters. Therefore, NT-H can significantly improve the antibacterial ability of orthopedic implants and provide a promising strategy to prevent implant-associated infections.

  3. Cochlear Implant

    Directory of Open Access Journals (Sweden)

    Mehrnaz Karimi

    1993-03-01

    Full Text Available People with profound hearing loss are not able to use some kinds of conventional amplifiers due to the nature of their loss. In these people, hearing sense is stimulated only when the auditory nerve is activated via electrical stimulation. This stimulation is possible through cochlear implant. In fact, for the deaf people who have good mental health and can not use surgical and medical treatment and also can not benefit from air and bone conduction hearing aids, this device is used if they have normal central auditory system. The basic parts of the device included: Microphone, speech processor, transmitter, stimulator and receiver, and electrode array.

  4. Cochlear Implant

    Directory of Open Access Journals (Sweden)

    Mehrnaz Karimi

    1992-04-01

    Full Text Available People with profound hearing loss are not able to use some kinds of conventional amplifiers due to the nature of their loss . In these people, hearing sense is stimulated only when the auditory nerve is activated via electrical stimulation. This stimulation is possible through cochlear implant. In fact, for the deaf people who have good mental health and can not use surgical and medical treatment and also can not benefit from air and bone conduction hearing aids, this device is used if they have normal central auditory system. The basic parts of the device included: Microphone, speech processor, transmitter, stimulator and receiver, and electrode array.

  5. Are short implants in the mandible safe?

    Directory of Open Access Journals (Sweden)

    Sergio Henrique Gonçalves Motta

    2009-10-01

    Full Text Available Objective: To analyze the importance of bioengineering and the improvement in surgical techniques demonstrated by the rates attained of the prevalence of successful placement of dental implants in the posterior region of the mandible, in D3 bone quality in patients between the ages of 52 and 60 years, with dentures fixed on 8.5 mm implants. Methods: The statistical data for this retrospective study were collected at the Post-Graduation Center of the Integrated Dentistry Center, Faculty of Sarandi / Academy of Dentistry - Rio de Janeiro, at the CLIVO clinic, from among a total of 2.294 implants placed in the mandible, in the period from 1999 to 2007. There was a total of 1.056 short implants, of a length shorter than or equal to 10 mm, among which 20 implants were randomly chosen and analyzed. Results: The data were treated statistically and comparison of these data was consubstantiated in constructive data analysis by means of Statistical Pattern Recognition Methods for each variable under study. A success rate of 85% was obtained, and the need to take certain care when indicating the use of short implants was verified. Conclusion: Bioengineering and the development of present day surgical techniques have optimized the use of short implants, with the aim of avoiding advanced surgeries. To compensate the smaller size, there are some factors that must be observed, such as: Bone quality, crown/implant ratio, number and diameter of implants, macroscopic and microscopic geometry of the implants, magnitude of mesial occlusal forces.

  6. Retinal vessel diameters decrease with macular ganglion cell layer thickness in autosomal dominant optic atrophy and in healthy subjects

    DEFF Research Database (Denmark)

    Rönnbäck, Cecilia; Grønskov, Karen; Larsen, Michael

    2014-01-01

    diameters (central retinal artery equivalent, CRAE, and central retinal vein equivalent, CRVE). Statistical analysis was corrected for age, gender, spherical equivalent refraction, axial length and mean arterial blood pressure (MABP) in a mixed model analysis. RESULTS: Retinal arteries and veins were...... ganglion cell-inner plexiform layer (GC-IPL) thickness (p = 0.0017 and p = 0.0057, respectively). CONCLUSION: Narrow retinal arteries and veins were associated not only with the severity of ADOA but with ganglion cell volume in patients with ADOA and in healthy subjects. This suggests that narrow vessels...

  7. Xylem Vessel Diameter Affects the Compartmentalization of the Vascular Pathogen Phaeomoniella chlamydospora in Grapevine

    Directory of Open Access Journals (Sweden)

    Jérôme Pouzoulet

    2017-08-01

    Full Text Available Fungal wilt diseases are a threat to global food safety. Previous studies in perennial crops showed that xylem vessel diameter affects disease susceptibility. We tested the hypothesis that xylem vessel diameter impacts occlusion processes and pathogen compartmentalization in Vitis vinifera L. We studied the interaction between four grape commercial cultivars with the vascular wilt pathogen Phaeomoniella chlamydospora. We used qPCR and wood necrotic lesion length to measure fungal colonization coupled with histological studies to assess differences in xylem morphology, pathogen compartmentalization, and fungal colonization strategy. We provided evidence that grape cultivar with wide xylem vessel diameter showed increased susceptibility to P. chlamydospora. The host response to pathogen included vessel occlusion with tyloses and gels, deposition of non-structural phenolic compounds and suberin in vessel walls and depletion of starch in parenchyma cells. Pathogen compartmentalization was less efficient in wide xylem vessels than in narrow diameter vessels. Large vessels displayed higher number of tyloses and gel pockets, which provided substrate for P. chlamydospora growth and routes to escape occluded vessels. We discuss in which capacity xylem vessel diameter is a key determinant of the compartmentalization process and in turn grape cultivar resistance to disease caused by P. chlamydospora.

  8. Incidence and impact of prosthesis-patient mismatch after transcatheter aortic valve implantation.

    Science.gov (United States)

    Bleiziffer, Sabine; Hettich, Ina; Hutter, Andrea; Wagner, Anke; Deutsch, Marcus-André; Piazza, Nicolo; Lange, Rüdiger

    2013-05-01

    The study aim was to investigate the incidence of patient-prosthesis mismatch (PPM) with new catheter valves, and its influence on the patients' clinical state. At present, few echocardiographic data are available on the incidence and impact of PPM with the CoreValve and Sapien prostheses for transcatheter aortic valve implantation (TAVI). The reliability of effective orifice area (EOA) measurements was assured by awaiting an interval of six months after TAVI. Of 256 survivors after TAVI, 149 complete echocardiographic data sets were available for the assessment of the indexed EOA (iEOA). In total, 106 CoreValve prostheses and 43 Sapien prostheses were implanted in this high-risk cohort (mean age 81 +/- 6 years, mean logistic EuroSCORE 20 +/- 13%). The overall incidence of PPM (iEOA body surface area were more likely to develop PPM (p = 0.001), while the prosthesis type, native annulus diameter, preoperative EOA, gender and prosthesis size had no influence. The mean aortic gradient was significantly higher in patients with PPM. A reduction in the left ventricular end-diastolic diameter was seen in all patients, without significant differences between groups. There were no differences in postoperative NYHA class or self-assessed health state between patients with or without PPM. PPM was common after TAVI in the presented cohort, presumably because the native calcium masses narrow the outflow area available for blood flow. As expected for low gradients, there was no impairment of left ventricular dimension regression or clinical state of the patients, even if severe PPM was present. Based on the presented data, it is assumed that PPM might be less relevant in TAVI patients.

  9. Neuroendoscopy via an Extremely Narrow Foramen of Monro: A Case Report.

    Science.gov (United States)

    Nagm, Alhusain; Ogiwara, Toshihiro; Goto, Tetsuya; Chiba, Akihiro; Hongo, Kazuhiro

    2017-01-01

    Herein, safe and reliable neuroendoscopic biopsy via an extremely narrow foramen of Monro (ENFM) for a non-hydrocephalic patient with hypothalamic and pineal region tumors was successfully applied. A 17-year-old boy presented with hypothalamic manifestations attributed to hypothalamic and pineal region tumors. Small ventricles were seen. Intraoperatively, to advance different diameter steerable fiberscopes via ENFM, the third ventricle was flushed to induce a moment increase in the intraventricular pressure with subsequent dilatation of FM. Postoperative course was uneventful. Histopathological studies revealed a yolk sac tumor. Adjuvant therapy was applied. Follow-up neuroimaging disclosed marvellous improvement of the condition. His symptoms gradually improved.

  10. Optical observations of the nearby galaxy IC342 with narrow band [SII] and Hα filters. I

    Directory of Open Access Journals (Sweden)

    Vučetić M.M.

    2013-01-01

    Full Text Available We present observations of a portion of the nearby spiral galaxy IC342 using narrow band [SII] and Hα filters. These observations were carried out in November 2011 with the 2m RCC telescope at Rozhen National Astronomical Observatory in Bulgaria. In this paper we report coordinates, diameters, Hα and [SII] fluxes for 203 HII regions detected in two fields of view in IC342 galaxy. The number of detected HII regions is 5 times higher than previously known in these two parts of the galaxy. [Projekat Ministarstva nauke Republike Srbije, br. 176005: Emission nebulae: structure and evolution

  11. Do implant length and width matter for short dental implants (<10 mm)? A meta-analysis of prospective studies.

    Science.gov (United States)

    Monje, Alberto; Fu, Jia-Hui; Chan, Hsun-Liang; Suarez, Fernando; Galindo-Moreno, Pablo; Catena, Andrés; Wang, Hom-Lay

    2013-12-01

    This meta-analysis of prospective clinical trials was conducted to determine the effects of dental implant length and width on implant survival rate of short (implants. An electronic search of the PubMed database for relevant studies published in English from November 1998 to March 2012 was performed. Selected studies were randomized clinical trials, human clinical trials, or prospective trials with a clear aim of investigating the success or survival rate of short (implants. Eight studies fulfilled the inclusion criteria and were subsequently analyzed. A total of 525 short (implants were analyzed, of which 253 were 3.5 mm in diameter (48.19%), 151 were 4.0 mm (28.76%), 90 were 4.1 mm (17.14%), 21 were 4.8 mm (4%), and 10 were 5.1 mm (1.9%). All implants included in this meta-analysis had a follow-up period of 12 to 72 months. The included studies reported on the survival rate and diameter of the implants. Six of the studies used "short implants" (7 to 9 mm), and the remaining were classified as "extra-short implants" (≤ 6 mm). Five-year estimated failure rates were 1.61% and 2.92%, respectively, for extra-short and short implants (z = -3.49, P implant, the higher the failure rate (estimated failure rate = 2.36%, 95% confidence interval = 1.07% to 5.23%). Neither implant length nor width seemed to significantly affect the survival rate of short implants (<10 mm). Nonetheless, further well-designed randomized clinical trials are needed to confirm these findings.

  12. Complications after cardiac implantable electronic device implantations

    DEFF Research Database (Denmark)

    Kirkfeldt, Rikke Esberg; Johansen, Jens Brock; Nohr, Ellen Aagaard

    2014-01-01

    Complications after cardiac implantable electronic device (CIED) treatment, including permanent pacemakers (PMs), cardiac resynchronization therapy devices with defibrillators (CRT-Ds) or without (CRT-Ps), and implantable cardioverter defibrillators (ICDs), are associated with increased patient...

  13. The feasibility of immediately loading dental implants in edentulous jaws

    Science.gov (United States)

    2016-01-01

    Purpose Immediate loading of dental implants has been proved to be feasible in partially edentulous jaws. The purpose of this retrospective investigation was to assess the feasibility of immediately loading dental implants in fully edentulous jaws. Methods A total of 24 patients aged between 53 and 89 years received a total of 154 implants in their edentulous maxillae or mandibles. Among the implants, 45 were set in fresh extracted sockets and 109 in consolidated alveolar bones. The implants were provisionally managed with chair-side made provisional resin bridges and exposed to immediate loading. Implants were followed up for 1–8 years, including radiographic imaging. Marginal bone levels were evaluated based on radiographic imaging. Results A total of 148 out of the 154 implants survived over the follow-up period of 1 to 8 years, giving a survival rate of 96%. The time or region of the implantation, the pre-implant augmentation, and the length and diameter of the implants had no statistically significant influence on the survival or the success rate. The marginal bone level remained stable with only minimal loss of 0.3 mm after 60 months of loading. Conclusions Within the limitations of this study, immediate loading is feasible for dental implants in edentulous jaws. PMID:27588213

  14. Thermal tuning On narrow linewidth fiber laser

    Science.gov (United States)

    Han, Peiqi; Liu, Tianshan; Gao, Xincun; Ren, Shiwei

    2010-10-01

    At present, people have been dedicated to high-speed and large-capacity optical fiber communication system. Studies have been shown that optical wavelength division multiplexing (WDM) technology is an effective means of communication to increase the channel capacity. Tunable lasers have very important applications in high-speed, largecapacity optical communications, and distributed sensing, it can provide narrow linewidth and tunable laser for highspeed optical communication. As the erbium-doped fiber amplifier has a large gain bandwidth, the erbium-doped fiber laser can be achieved lasing wavelength tunable by adding a tunable filter components, so tunable filter device is the key components in tunable fiber laser.At present, fiber laser wavelength is tuned by PZT, if thermal wavelength tuning is combined with PZT, a broader range of wavelength tuning is appearance . Erbium-doped fiber laser is used in the experiments,the main research is the physical characteristics of fiber grating temperature-dependent relationship and the fiber grating laser wavelength effects. It is found that the fiber laser wavelength changes continuously with temperature, tracking several temperature points observed the self-heterodyne spectrum and found that the changes in spectra of the 3dB bandwidth of less than 1kHz, and therefore the fiber laser with election-mode fiber Bragg grating shows excellent spectral properties and wavelength stability.

  15. Thermoelectricity in correlated narrow-gap semiconductors

    Science.gov (United States)

    Tomczak, Jan M.

    2018-05-01

    We review many-body effects, their microscopic origin, as well as their impact on thermoelectricity in correlated narrow-gap semiconductors. Members of this class—such as FeSi and FeSb2—display an unusual temperature dependence in various observables: insulating with large thermopowers at low temperatures, they turn bad metals at temperatures much smaller than the size of their gaps. This insulator-to-metal crossover is accompanied by spectral weight-transfers over large energies in the optical conductivity and by a gradual transition from activated to Curie–Weiss-like behaviour in the magnetic susceptibility. We show a retrospective of the understanding of these phenomena, discuss the relation to heavy-fermion Kondo insulators—such as Ce3Bi4Pt3 for which we present new results—and propose a general classification of paramagnetic insulators. From the latter, FeSi emerges as an orbital-selective Kondo insulator. Focussing on intermetallics such as silicides, antimonides, skutterudites, and Heusler compounds we showcase successes and challenges for the realistic simulation of transport properties in the presence of electronic correlations. Further, we explore new avenues in which electronic correlations may contribute to the improvement of thermoelectric performance.

  16. Narrow bandpass cryogenic filter for microwave measurements.

    Science.gov (United States)

    Ivanov, B I; Klimenko, D N; Sultanov, A N; Il'ichev, E; Meyer, H-G

    2013-05-01

    An ultra-wide stopband hairpin bandpass filter with integrated nonuniform transmission lines was designed and fabricated for highly sensitive measurements at cryogenic temperatures down to millikelvin and a frequency range of 10 Hz-10 GHz. The scattering matrices of the filter were characterized at T = 4.2 K. The filter provides a stopband from 10 Hz to 2.2 GHz and from 2.3 GHz to 10 GHz with more than 50 dB and 40 dB of amplitude suppression, respectively. The center frequency of the passband is f0 = 2.25 GHz with a bandwidth Δf = 80 MHz. The maximum insertion loss in the passband is 4 dB. The filter has a 50 Ω input and output impedance, SubMiniature version A connector termination, and significantly reduced form factor. The wide stopband frequency range and narrow passband in conjunction with small dimensions make the filter suitable to use it as a part of a high sensitive readout for superconducting quantum circuits, such as superconducting quantum bits and cryogenic parametric amplifiers.

  17. Nonlinear optical response in narrow graphene nanoribbons

    Science.gov (United States)

    Karimi, Farhad; Knezevic, Irena

    We present an iterative method to calculate the nonlinear optical response of armchair graphene nanoribbons (aGNRs) and zigzag graphene nanoribbons (zGNRs) while including the effects of dissipation. In contrast to methods that calculate the nonlinear response in the ballistic (dissipation-free) regime, here we obtain the nonlinear response of an electronic system to an external electromagnetic field while interacting with a dissipative environment (to second order). We use a self-consistent-field approach within a Markovian master-equation formalism (SCF-MMEF) coupled with full-wave electromagnetic equations, and we solve the master equation iteratively to obtain the higher-order response functions. We employ the SCF-MMEF to calculate the nonlinear conductance and susceptibility, as well as to calculate the dependence of the plasmon dispersion and plasmon propagation length on the intensity of the electromagnetic field in GNRs. The electron scattering mechanisms included in this work are scattering with intrinsic phonons, ionized impurities, surface optical phonons, and line-edge roughness. Unlike in wide GNRs, where ionized-impurity scattering dominates dissipation, in ultra-narrow nanoribbons on polar substrates optical-phonon scattering and ionized-impurity scattering are equally prominent. Support by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-SC0008712.

  18. Carrier Dynamics in Narrow Gap Ferromagnetic Semiconductors

    Science.gov (United States)

    Saha, D.; Pan, X.; Sanders, G. D.; Stanton, C. J.; Bhowmick, M.; Merritt, T.; Khodaparast, G. A.; Feeser, C.; Wessels, B. W.; McGill, S.

    2012-02-01

    Narrow gap ferromagnetic semiconductors are promising materials for spin photonic and spin transport devices because of their small effective masses, small energy gap, and high carrier mobility. We use time resolved differential transmission (TRDT) experiments to study carrier dynamics in ferromagnetic InMnAs and InMnSb. Electronic structure for InMnAs and InMnSb is calculated using an 8-band Pidgeon-Brown model generalized to include the effects of an external magnetic field. Our model includes the effects of the ferromagnetic Mn ions and their coupling to electrons and holes with or without an external magnetic field. Optical transitions are calculated from Fermi's Golden rule and interband transitions at a given pump or probe laser energy are identified. This allows us to understand a sign change seen in the TRDT. Our results show that 1) Phase-Space Filling, 2) Band Gap Renormalization and 3) Free Carrier Absorption all contribute to the TRDT and that the relative importance of these effects depends on the laser probe energy.

  19. [In hospital and mid-term outcome of patients with NIR stent implantation: multicenter ESPORT-NIR registry].

    Science.gov (United States)

    Iñiguez, A; García, E; Seabra, R; Bordes, P; Bethencourt, A; Rigla, J

    2001-05-01

    Despite improvements in the results and techniques of catheter-based revascularization, few studies have evaluated the clinical results of the application of new stent designs. We describe the in-hospital and mid-term outcome of patients undergoing a stent NIR implantation. At least 1 Stent NIR was implanted in 1.004 patients (1.136 lesions) recruited from 50 centers in an international, multicenter, prospective, registry (Spain and Portugal NIR stent registry). Inclusion criteria were objective coronary ischemia related to a severe de novo lesion or first restenosis in native vessels with a reference diameter >= 2.75 mm. The primary end-point was the incidence of major adverse cardiac events within the first 7 months of follow-up. The mean age of the patients was 60 years and 82% were male. Angioplasty was indicated due to unstable angina in 61% of the cases. Stent implantation was successfully achieved in 99.6%. Clinical success (angiographic success without in-hospital major events) was achieved in 98.6% of patients. The rate of angiographic restenosis (> 50% stenosis narrowing) was 16% (CI 95%; 11.7-21.2). The accumulated major cardiac adverse event rate at seven months of follow-up was 8.7%: death (0.9%), acute myocardial infarction (1.2%) and target lesion revascularization (6.6%). In the wide setting of the population included in the ESPORT-NIR registry, stent NIR implantation was a highly effective therapy with a good mid-term clinical and angiographic outcome.

  20. Fast and robust shape diameter function.

    Science.gov (United States)

    Chen, Shuangmin; Liu, Taijun; Shu, Zhenyu; Xin, Shiqing; He, Ying; Tu, Changhe

    2018-01-01

    The shape diameter function (SDF) is a scalar function defined on a closed manifold surface, measuring the neighborhood diameter of the object at each point. Due to its pose oblivious property, SDF is widely used in shape analysis, segmentation and retrieval. However, computing SDF is computationally expensive since one has to place an inverted cone at each point and then average the penetration distances for a number of rays inside the cone. Furthermore, the shape diameters are highly sensitive to local geometric features as well as the normal vectors, hence diminishing their applications to real-world meshes which often contain rich geometric details and/or various types of defects, such as noise and gaps. In order to increase the robustness of SDF and promote it to a wide range of 3D models, we define SDF by offsetting the input object a little bit. This seemingly minor change brings three significant benefits: First, it allows us to compute SDF in a robust manner since the offset surface is able to give reliable normal vectors. Second, it runs many times faster since at each point we only need to compute the penetration distance along a single direction, rather than tens of directions. Third, our method does not require watertight surfaces as the input-it supports both point clouds and meshes with noise and gaps. Extensive experimental results show that the offset-surface based SDF is robust to noise and insensitive to geometric details, and it also runs about 10 times faster than the existing method. We also exhibit its usefulness using two typical applications including shape retrieval and shape segmentation, and observe a significant improvement over the existing SDF.

  1. Transpedicular fixation for the espondilolistesis treatment, espondilolisis and channel lumbar narrow of the lumbosacral column

    International Nuclear Information System (INIS)

    Matta Javier Ernesto; Diaz, Cesar Jacobo; Gamba S, Cesar Enrique

    2002-01-01

    A descriptive, prospective study was designs with the objective of analyzing the experience with the technique of transpedicular fixation, for the treatment of degenerative espondilolistesis, espondilolisis and channel lumbar narrow. Eighty patients (42 men and 38 women) they were intervened between February of 1992 and February of 2002; the age average was of 46,3 years and the minimum pursuit of 7 months. The cases were tabulated according to the diagnostic, clinical presentation, previous interventions, descompressive procedures associated to the fixation, anatomical level of lesion, number of fixed vertebras, number of placed screws, type of bony implants and complications. In 33 patients (41,3%) it diagnose degenerative espondilolistesis, espondilolisis in 24 (30%), channel lumbar narrow in 20 (25%), displasic espondilolistesis in 2,5% and espondiloptosis in 1%. the clinical presentations more frequent were radicular and lumbar pain, with 33,8 each one; one carries out arthrodesis 15-S1 in 38 patients (47,5%) and 14 15 in 15 patients (18,7%). as complications we find deep infection in 7,5% of the cases, neurological deficit in 5%, rupture of duramadre 3,8%, false route of screws, bony failure and material rupture in 2,5% each one and seroma in 1,3%. Doesn't present seudoarthrosis. The transpedicular fixation is a sure technique for the treatment of the degenerative espondilolistesis, espondilolisis and channel lumbar narrow. With the transpedicular fixation the average of fixed vertebras is smaller than with the Harrington and Luque techniques, preserving in more degree the mobility to articulate. The association of the transpedicular fixation with arthrodesis and coalition by means of placement of autogenous implants diminishes the seudoarthrosis incidence

  2. 29 mm Diameter Target Test Report

    Energy Technology Data Exchange (ETDEWEB)

    Woloshun, Keith Albert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Olivas, Eric Richard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dale, Gregory E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Naranjo, Angela Carol [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Romero, Frank Patrick [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Chemerisov, Sergey [Argonne National Lab. (ANL), Argonne, IL (United States); Gromov, Roman [Argonne National Lab. (ANL), Argonne, IL (United States)

    2017-10-23

    After numerous delays, the test of the 29 mm diameter target was conducted on 8/18/2017. The complete target design report, dated 8/15/2016, is reproduced below for completeness. This describes in detail the 10 disk target with varying thickness disks. The report presents and discusses the test results. In brief summary, there appears to have been multiple instrumentation errors. Measured temperatures, pressures and IR camera window temperature measurement are all suspect. All tests were done at 35 MeV, with 171 μA current, or 6 kW of beam power.

  3. 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.

  4. Multivariate linear regression analysis to identify general factors for quantitative predictions of implant stability quotient values.

    Directory of Open Access Journals (Sweden)

    Hairong Huang

    Full Text Available This study identified potential general influencing factors for a mathematical prediction of implant stability quotient (ISQ values in clinical practice.We collected the ISQ values of 557 implants from 2 different brands (SICace and Osstem placed by 2 surgeons in 336 patients. Surgeon 1 placed 329 SICace implants, and surgeon 2 placed 113 SICace implants and 115 Osstem implants. ISQ measurements were taken at T1 (immediately after implant placement and T2 (before dental restoration. A multivariate linear regression model was used to analyze the influence of the following 11 candidate factors for stability prediction: sex, age, maxillary/mandibular location, bone type, immediate/delayed implantation, bone grafting, insertion torque, I-stage or II-stage healing pattern, implant diameter, implant length and T1-T2 time interval.The need for bone grafting as a predictor significantly influenced ISQ values in all three groups at T1 (weight coefficients ranging from -4 to -5. In contrast, implant diameter consistently influenced the ISQ values in all three groups at T2 (weight coefficients ranging from 3.4 to 4.2. Other factors, such as sex, age, I/II-stage implantation and bone type, did not significantly influence ISQ values at T2, and implant length did not significantly influence ISQ values at T1 or T2.These findings provide a rational basis for mathematical models to quantitatively predict the ISQ values of implants in clinical practice.

  5. Sagittal Abdominal Diameter: Application in Clinical Practice

    Directory of Open Access Journals (Sweden)

    Thaís Da Silva-Ferreira

    2014-05-01

    Full Text Available Excess visceral fat is associated with cardiovascular risk factors. Sagittal abdominal diameter (SAD has recently been highlighted as an indicator of abdominal obesity, and also may be useful in predicting cardiovascular risk. The purpose of the present study was to review the scientific literature on the use of SAD in adult nutritional assessment. A search was conducted for scientific articles in the following electronic databases: SciELO , MEDLINE (PubMed and Virtual Health Library. SAD is more associated with abdominal fat (especially visceral, and with different cardiovascular risk factors, such as, insulin resistance, blood pressure, and serum lipoproteins than the traditional methods of estimating adiposity, such as body mass index and waist-to-hip ratio. SAD can also be used in association with other anthropometric measures. There are still no cut-off limits established to classify SAD as yet. SAD can be an alternative measure to estimate visceral adiposity. However, the few studies on this diameter, and the lack of consensus on the anatomical site to measure SAD, are obstacles to establish cut-off limits to classify it.

  6. Aesthetic Shoulder Augmentation with Silicone Implants.

    Science.gov (United States)

    Chung, Yoon Jae; Jang, Hyun

    2014-02-01

    Men with narrower shoulders may appear less muscular than other men. Deltoid muscle underdevelopment or atrophy, a condition commonly linked to narrow shoulder issues, may be associated with congenital deformity, trauma, or neoplasm. For some people, regular exercise does not effectively develop the deltoid muscle region. Some people naturally have a smaller build than others. Even with developed deltoid muscles, these people still appear to be small. The authors have performed lateral shoulder augmentation with silicone implants for 4 years. Based on their experience, this procedure stands as a reliable solution for men with narrow shoulders. Lateral shoulder augmentation with silicone implants was developed and used for 81 patients between April 2009 and April 2013. None of the patients had shoulder deformities except for two patients (one patient with Poland's syndrome and one patient with Sprengel's deformity). The implants were placed through a horizontal axillary crease incision in a plane dissected between the deltoid fascia and muscle. All augmentation or correction procedures have been met with complete patient approval. Five patients had minor complications such as hematoma and implement displacement. However, all these complications were resolved to the satisfaction of the patients. When silicone implants are used to achieve purely aesthetic improvements, successful shoulder augmentation procedures are observed. This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors http://www.springer.com/00266 .

  7. Radiographic analysis of dental implant extensions using bone grafts on dogs.

    Science.gov (United States)

    Cardoso, Álida Lúcia; Lima, Cirilo Antônio de Paula; Montebello Filho, Agenor; Pereira, Adriano Alves

    2018-01-10

    Despite the wide use of dental implants they can bring inconveniences, as the moment one reaches osseointegration, these can no longer be extended. Therefore, if a problem occurs regarding its positioning, the options open are substitution or burial of the implant. With implant substitution, there exists the risk of local bone loss and/or future loss of the new implant. This study proposes a new device (implant extender) for extending the dental implant. The feasibility of this technique is verified through installing dental implant extensions onto the humerus bone of dogs with autogenous bone grafts. Implants of 3.3 mm in diameter by 6 mm in length and implant extensions with a 3.3 mm diameter and 2.2 mm length were installed onto humerus of 4 healthy dogs, using an autogenous bone graft in a block made from ilium. The biomechanical percussion tests were performed on the implant extensions and then the implant-extension sets were removed for radiographic analysis. In the biomechanical percussion, none of the extensions present clinical mobility. As for the x-rays, these were analyzed by 20 professionals, who concluded that there was a 100% success rate with bone formation around the implants, 74.1% for bone neoformation of the implant extensions, and 80.1% referring to the adaptation of the implant extension. Bone formation occurred in every installed dental implant. In most cases, there occurred bone neoformation of the extensions and adaptation of the extension/implant set, according to the x-ray analysis performed by the evaluators. An absence of clinical mobility in the extensions was also observed. Although the results were promising, these techniques still need to be researched in humans, as an alternative for reducing elongated prosthetic crowns or poorly installed implants, as well as the modification of the type of implants among other applications. © 2018 Wiley Periodicals, Inc.

  8. 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.

  9. 2D FEA of evaluation of micromovements and stresses at bone-implant interface in immediately loaded tapered implants in the posterior maxilla

    Directory of Open Access Journals (Sweden)

    Shrikar R Desai

    2013-01-01

    Full Text Available Aim: The aim of the study is to evaluate the influence implant length on stress distribution at bone implant interface in single immediately loaded implants when placed in D4 bone quality. Materials and Methods: A 2-dimensional finite element models were developed to simulate two types of implant designs, standard 3.75 mm-diameter tapered body implants of 6 and 10 mm lengths. The implants were placed in D4 bone quality with a cortical bone thickness of 0.5 mm. The implant design incorporated microthreads at the crestal part and the rest of the implant body incorporated Acme threads. The Acme thread form has a 29° thread angle with a thread height half of the pitch; the apex and valley are flat. A 100 N of force was applied vertically and in the oblique direction (at an angle of 45° to the long axis of the implants. The respective material properties were assigned. Micro-movements and stresses at the bone implant interface were evaluated. Results: The results of total deformation (micro-movement and Von mises stress were found to be lower for tapered long implant (10 mm than short implant (6 mm while using both vertical as well as oblique loading. Conclusion: Short implants can be successfully placed in poor bone quality under immediate loading protocol. The novel approach of the combination of microthreads at the crestal portion and acme threads for body portion of implant fixture gave promising results.

  10. Roentogenological study of antero-posterior diameter in developmental canal stenosis of cervical spine

    Energy Technology Data Exchange (ETDEWEB)

    Higo, Masaru

    1987-05-01

    Developmental canal stenosis of the cervical spine is an important underlying condition of cervical spondylotic myelopathy. However, the criteria of the degree of narrowing is different among investigators and their rationales are unclear. To clarify this point, the antero-posterior diameter of the cervical spinal canal was measured in groups of normal subjects, patients with neck-shoulder-arm syndrome and cervical spondylosis. The measured values were analyzed statistically. The antero-posterior diameter was the widest in normal individuals and the narrowest in patients with the cervical spondylotic myelopathy. The point of differentiation of developmental canal stenosis was determined as 14 mm for males and 13 mm for females using the mean +- 2SD of the values in normal subjects. Patients with values lower than this criteria comprised 82 % of those with the cervical spondylotic myelopathy. These patients could be further classified into those that also showed clear cervical spondylotic changes and those that did not.

  11. In situ observation of lubricant film formation in THR considering real conformity: The effect of diameter, clearance and material.

    Science.gov (United States)

    Nečas, D; Vrbka, M; Urban, F; Gallo, J; Křupka, I; Hartl, M

    2017-05-01

    The aim of the present study is to provide an analysis of protein film formation in hip joint replacements considering real conformity based on in situ observation of the contact zone. The main attention is focused on the effect of implant nominal diameter, diametric clearance and material. For this purpose, a pendulum hip joint simulator equipped with electromagnetic motors enabling to apply continuous swinging flexion-extension motion was employed. The experimental configuration consists of femoral component (CoCrMo, BIOLOX®forte, BIOLOX®delta) and acetabular cup from optical glass fabricated according to the dimensions of real cups. Two nominal diameters were studied, 28 and 36mm, respectively, while different diametric clearances were considered. Initially, a static test focused on the protein adsorption onto rubbing surfaces was performed with 36mm implants. It was found that the development of adsorbed layer is much more stable in the case of metal head, indicating that the adsorption forces are stronger compared to ceramic. A consequential swinging test revealed that the fundamental parameter influencing the protein film formation is diametric clearance. Independently of implant diameter, film was much thicker when a smaller clearance was considered. An increase of implant size from 28mm to 36mm did not cause a substantial difference in film formation; however, the total film thickness was higher for smaller implant. In terms of material, metal heads formed a thicker film, while this fact can be, among others, also attributed to clearance, which is more than two times higher in the case of ceramic implant. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Retrospective analysis of 56 edentulous dental arches restored with 344 single-stage implants using an immediate loading fixed provisional protocol: statistical predictors of implant failure.

    Science.gov (United States)

    Kinsel, Richard P; Liss, Mindy

    2007-01-01

    The purpose of this retrospective study was to evaluate the effects of implant dimensions, surface treatment, location in the dental arch, numbers of supporting implant abutments, surgical technique, and generally recognized risk factors on the survival of a series of single-stage Straumann dental implants placed into edentulous arches using an immediate loading protocol. Each patient received between 4 and 18 implants in one or both dental arches. Periapical radiographs were obtained over a 2- to 10-year follow-up period to evaluate crestal bone loss following insertion of the definitive metal-ceramic fixed prostheses. Univariate tests for failure rates as a function of age ( or = 60 years), gender, smoking, bone grafting, dental arch, surface type, anterior versus posterior, number of implants per arch, and surgical technique were made using Fisher exact tests. The Cochran-Armitage test for trend was used to evaluate the presence of a linear trend in failure rates regarding implant length and implant diameter. Logistic regression modeling was used to determine which, if any, of the aforementioned factors would predict patient and implant failure. A significance criterion of P = .05 was utilized. Data were collected for 344 single-stage implants placed into 56 edentulous arches (39 maxillae and 17 mandibles) of 43 patients and immediately loaded with a 1-piece provisional fixed prosthesis. A total of 16 implants failed to successfully integrate, for a survival rate of 95.3%. Increased rates of failure were associated with reduced implant length, placement in the posterior region of the jaw, increased implant diameter, and surface treatment. Implant length emerged as the sole significant predictor of implant failure. In this retrospective analysis of 56 consecutively treated edentulous arches with multiple single-stage dental implants loaded immediately, reduced implant length was the sole significant predictor of failure.

  13. Rehabilitations with immediate loading of one-piece implants stabilized with intraoral welding.

    Science.gov (United States)

    Pasqualini, M E; Lauritano, D; Rossi, F; Dal Carlo, L; Shulman, M; Meynardi, F; Colombo, D; Manenti, P; Comola, G; Zampetti, P

    2018-01-01

    The authors present an implant prosthesis procedure that uses screws on one-piece implants connected with a titanium pin at their abutment level and one supporter titanium bar in order to guarantee immediate stabilization. These can be implanted and fitted with customized temporary crowns in a single surgical procedure, restoring function and aesthetics and consenting recovery of the bone deficit with reduced healing times and limited patient discomfort. One-piece wide-diameter titanium screw implants with thread measurements of 2.1 and 2.6 mm (smaller diameter) up to diameter of 4.5 mm with one abutment of 2.0 and 2.5 mm respectively, were positioned and splinted by intraoral welding. One-piece titanium implants were used together with a pin (needle) titanium implant as supporting structure to achieve deep stabilization. The Scialom-like pin has a diameter of 1.2 mm and it is long enough to reach deep cortical bone that is “bicorticalism”. The One-piece implant is tightly connected to the needle implant by means of Mondani intra-oral welding technique. In severely atrophic anterior maxilla, the use of this method allows the immediate loading of a fixed resin prosthesis soon after surgery. These implants yielded satisfactory functional and aesthetic outcome in bone-deficient upper anterior sectors, without invasive regenerative procedures. The low invasiveness of this approach also consents rapid healing, reduced biological burden and greater patient benefit.

  14. Individual titanium zygomatic implant

    Science.gov (United States)

    Nekhoroshev, M. V.; Ryabov, K. N.; Avdeev, E. V.

    2018-03-01

    Custom individual implants for the reconstruction of craniofacial defects have gained importance due to better qualitative characteristics over their generic counterparts – plates, which should be bent according to patient needs. The Additive Manufacturing of individual implants allows reducing cost and improving quality of implants. In this paper, the authors describe design of zygomatic implant models based on computed tomography (CT) data. The fabrication of the implants will be carried out with 3D printing by selective laser melting machine SLM 280HL.

  15. Evaluation of retention of cemented laser-sintered crowns on unmodified straight narrow implant abutments.

    Science.gov (United States)

    Kilicarslan, Mehmet Ali; Ozkan, Pelin

    2013-01-01

    A common problem with cemented crowns is inadequate retention at the crown-abutment interface. The aim of this study was to compare the retention of new laser-sintered cobalt-chromium alloy crowns to the retention of cobalt-chromium alloy crowns fabricated with a traditional casting technique with and without an alloy primer. Twenty-four metallic crowns per casting technique were fabricated, and surface roughness values were recorded with a profilometer. Alloy primer was applied to half the specimens, and all crowns were luted with resin cement. After 24 hours, specimens were subjected to tensile force application with a universal testing machine. The effect of the cement amount was evaluated with an analytic balance. The results were compared using the Kruskal-Wallis multiple-comparison test. The Spearman correlation was used to determine correlations between crown retention and cement weight. The laser-sintered crowns (2.72 μm) were rougher than conventionally cast crowns. The mean load to failure values were as follows: 455.10 ± 192.69 Ncm for conventional crowns, 565.52 ± 112.87 Ncm for conventional crowns with alloy primer, 534.78 ± 130.15 Ncm for laser-sintered crowns, and 678.60 ± 212.83 Ncm for laser-sintered crowns with alloy primer. Laser-sintered crowns (10.10 ± 2.15 mg) showed a significant difference in terms of cement weight compared with cast crowns. In addition, negative correlations were found for retention and cement weight between all groups, except for the laser-sintered group without alloy primer. Retentive forces were significantly higher for laser-sintered crowns than for conventionally cast crowns. An increase in the surface roughness and the application of alloy primers led to an increase in the adhesive bonding of resin cements to metal alloys. It was concluded that a reduction in cement weight improved retention.

  16. Bone compaction enhances implant fixation in a canine gap model

    DEFF Research Database (Denmark)

    Kold, Søren Vedding; Rahbek, Ole; Toft, Marianne

    2005-01-01

    A new bone preparation technique, compaction, has increased fixation of implants inserted with exact-fit or press-fit to bone. Furthermore, a demonstrated spring-back effect of compacted bone might be of potential value in reducing the initial gaps that often exist between clinical inserted...... implants and bone. However, it is unknown whether the compression and breakage of trabeculae during the compaction procedure results in impaired gap-healing of compacted bone. Therefore, we compared compaction with conventional drilling in a canine gap model. Grit-blasted titanium implants (diameter 6 mm......) were bilaterally inserted into cavities initially expanded to 8 mm diameters in the proximal humeri. Each dog served as its own control; thus, one humerus had the implant cavity prepared with compaction, the other with drilling. Eight dogs were euthanized after 2 weeks, and 7 dogs after 4 weeks. Humeri...

  17. Submerged arc narrow gap welding of the steel DIN 20MnMoNi55

    International Nuclear Information System (INIS)

    Moraes, M.M.

    1987-01-01

    The methodology for submerged arc narrow gap welding for high thickness rolled steel DIN 20MnMoNi55 was developed, using din S3NiMo1 04 mm and 05 mm wires, and DIN 8B435 flux. For this purpose, submerged arc narrow gap welded joints with 50 mm and 120 mm thickness were made aiming the welding parameters optimization and the study of the influence of welding voltage, wire diameter and wire to groove face distance on the operational performance and on the welded joint quality, specially on the ISO-V impact toughness. These welded joints were checked by non-destructive mechanical and metallographic tests. Results were compared with those obtained by one 120 mm thickness submerged arc conventional gap welded joint, using the same base metal and consumables (05 mm wire). The analysis of the results shows that the increasing of the wire to groove face distance and the welding voltage increases the hardness and the ISO-V impact toughness of the weld metal. It shows that the reduction of the gap angle is the main cause for the obtained of a heat affected zone free from coarse grains, the reduction of the welding voltage, the increasing of the wire to groove face distance, and the grounding optimization also contribute for that. It was also concluded that the quality and the execution complexity level of a narrow gap welded joint are identical to a conventional gap welded joint. (author) [pt

  18. PARAMETERS OF NUCLEAR MAGNETIC RESONANCE IN PATIENTS WITH CONGENITAL NARROWING OF THE LUMBAR SPINAL CANAL

    Directory of Open Access Journals (Sweden)

    ELIU HAZAEL MORALES-RANGEL

    Full Text Available ABSTRACT Objective: To compare the morphological parameters of magnetic resonance in patients with congenital narrowing of the lumbar spinal canal with patients with low back pain. Methods: A descriptive, retrospective, observational study was conducted with measurements in the axial and sagittal magnetic resonance sections of the vertebral body and canal of the lumbar spine of 64 patients with diagnosis of low back pain, which were compared with resonance images taken from 31 Mexican patients with congenital narrowing of the lumbar spinal canal. Results: The results show that patients with congenital narrowing of the lumbar spinal canal in the axial sections have a difference in diameters, being L2<13.9 mm, L3<13.3 mm, L4<12.9 mm, L5<13.1 mm, compared with controls L2<20.5 mm, L3<20.5 mm, L4<19.3 mm, L5<18.1 mm with p = 0.000. Conclusions: We found different measurements in the Mexican population compared to those found by similar studies. With the parameters obtained, it would be possible to make the proper diagnosis, surgical planning, and treatment.

  19. Krypton ion implantation effect on selenium nanowires

    Science.gov (United States)

    Panchal, Suresh; Chauhan, R. P.

    2017-08-01

    Among the rapidly progressing interdisciplinary areas of physics, chemistry, material science etc. ion induced modifications of materials is one such evolving field. It has been realized in recent years that a material, in the form of an accelerated ion beam, embedded into a target specimen offers a most productive tool for transforming its properties in a controlled manner. In semiconductors particularly, where the transport behavior is determined by very small concentrations of certain impurities, implantation of ions may bring considerable changes. The present work is based on the study of the effect of krypton ion implantation on selenium nanowires. Selenium nanowires of diameter 80 nm were synthesized by template assisted electro deposition technique. Implantation of krypton ions was done at Inter University Accelerator Centre (IUAC), New Delhi, India. The effect of implantation on structural, electrical and optical properties of selenium nanowires was investigated. XRD analysis of pristine and implanted nanowires shows no shifting in the peak position but there is a variation in the relative intensity with fluence. UV-Visible spectroscopy shows the decrease in the optical band gap with fluence. PL spectra showed emission peak at higher wavelength. A substantial rise in the current was observed from I-V measurements, after implantation and with the increase in fluence. The increase in current conduction may be due to the increase in the current carriers.

  20. Influence of core diameter and length of polymer optical fiber on Brillouin scattering properties

    Science.gov (United States)

    Mizuno, Yosuke; Ishigure, Takaaki; Nakamura, Kentaro

    2012-02-01

    Brillouin scattering in perfluorinated graded-index polymer optical fibers (PFGI-POFs) is potentially useful in developing high-accuracy distributed temperature sensors with reduced strain sensitivity. In this study, we investigate, both experimentally and theoretically, the influence of the fiber core diameter and length on the Brillouin gain spectra (BGS) in PFGI-POFs. First, we show that smaller core diameter drastically enhances the Stokes power using PFGI-POFs with 62.5-μm and 120-μm core diameters, and discuss the Brillouin threshold power. Then, we demonstrate that the PFGI-POF length has little influence on the BGS when the length is longer than 50 m. We also predict that, at 1.55-μm wavelength, it is difficult to reduce the Brillouin threshold power of PFGI-POFs below that of long silica single-mode fibers even if their core diameter is sufficiently reduced to satisfy the single-mode condition. Finally, making use of the enhanced Stokes signal, we confirm the Brillouin linewidth narrowing effect.

  1. Implant stability and marginal bone level of microgrooved zirconia dental implants: A 3-month experimental study on dogs

    Directory of Open Access Journals (Sweden)

    Delgado-Ruíz Rafael Arcesio

    2014-01-01

    Full Text Available Background/Aim. The modification of implant surfaces could affect mechanical implant stability as well as dynamics and quality of peri-implant bone healing. The aim of this 3-month experimental study in dogs was to investigate implant stability, marginal bone levels and bone tissue response to zirconia dental implants with two laser-micro-grooved intraosseous surfaces in comparison with nongrooved sandblasted zirconia and sandblasted, high-temperature etched titanium implants. Methods. Implant surface characterization was performed using optical interferometric profilometry and energy dispersive X-ray spectroscopy. A total of 96 implants (4 mm in diameter and 10 mm in length were inserted randomly in both sides of the lower jaw of 12 Fox Hound dogs divided into groups of 24 each: the control (titanium, the group A (sandblasted zirconia, the group B (sandblasted zirconia plus microgrooved neck and the group C (sandblasted zirconia plus all microgrooved. All the implants were immediately loaded. Insertion torque, periotest values, radiographic crestal bone level and removal torque were recorded during the 3-month follow-up. Qualitative scanning electon micro-scope (SEM analysis of the bone-implant interfaces of each group was performed. Results. Insertion torque values were higher in the group C and control implants (p the control > the group B > the group A (p the control > the group B > the group A (p < 0.05. SEM showed that implant surfaces of the groups B and C had an extra bone growth inside the microgrooves that corresponded to the shape and direction of the microgrooves. Conclusion. The addition of micro-grooves to the entire intraosseous surface of zirconia dental implants enhances primary and secondary implant stability, promotes bone tissue ingrowth and preserves crestal bone levels.

  2. Rank Protein Immunolabeling during Bone-Implant Interface Healing Process

    OpenAIRE

    ?vila Souza, Francisley; Pereira Queiroz, Thallita; Rodrigues Luvizuto, Elo?; Nishioka, Renato Sussumu; Garcia-JR, Idelmo Rangel; de Carvalho, Paulo S?rgio Perri; Okamoto, Roberta

    2010-01-01

    The purpose of this paper was to evaluate the expression of RANK protein during bone-healing process around machined surface implants. Twenty male Wistar rats, 90 days old, after having had a 2?mm diameter and 6 mm long implant inserted in their right tibias, were evaluated at 7, 14, 21, and 42 days after healing. After obtaining the histological samples, slides were subjected to RANK immunostaining reaction. Results were quantitatively evaluated. Results. Immunolabeling analysis showed expre...

  3. Q2 anti Q2 states with relatively narrow widths

    International Nuclear Information System (INIS)

    Ono, Seiji.

    1978-09-01

    Using the mass formulas which correctly predict the mass of mesons and baryons the mass of diquark states is computed. From this mass spectrum the existance of the observed narrow baryonia and wide baryonia can be naturally understood. Other relatively narrow Q 2 anti Q 2 states are predicted to exist. (orig.) [de

  4. Prosthetic Rehabilitation of a Patient with Mandibular Resection Prosthesis Using Mini Dental Implants (MDIs) – Case Report

    OpenAIRE

    Vojvodić, Denis; Čelebić, Asja; Mehulić, Ketij; Žabarović, Domagoj

    2012-01-01

    Physical disfigurement and functional impairments associated with facial trauma are a challenge to a prosthodontist, because even novel sophisticated surgical reconstructive techniques fail to provide adequate support for dental resection prosthesis. Therefore, different endosseous implants are often used as prosthesis-supporting elements. Manufacturers of dental implants have recently presented mini dental implants (MDIs) with diameter of only 1.8–2.4 mm. These implants allow very suitable p...

  5. Complete Congenital Heart Block in a Neonatal Lupus Erythematosus Associated with Pulmonary Involvement without Pacemaker Implantation: A Case Report

    Directory of Open Access Journals (Sweden)

    Yazdan Ghandi

    2016-10-01

    Conclusion: This case report was conducted on a newborn with CCHB associated with pulmonary disorder. The newborn was intubated due to respiratory distress and did not need pacemaker implantation; however, after 8-month follow up, excellent outcomes were observed. It seems that atelectasis and mechanical ventilation can intolerance, and pacemaker implantation did not need in NLE with CCHB with narrowing QRS complex.

  6. Analysis of Peripapillary Retinal Vessel Diameter in Unilateral Normal-Tension Glaucoma

    Directory of Open Access Journals (Sweden)

    Yong Un Shin

    2017-01-01

    Full Text Available Purpose. This study sought to analyze peripapillary retinal vessel diameter and evaluate its correlation with retinal nerve fiber layer (RNFL thickness in patients with unilateral normal-tension glaucoma (NTG. Methods. This retrospective study included 37 patients with unilateral NTG and 40 healthy controls. The unilateral NTG patients were selected based on RNFL photography and unilateral visual field (VF defects from the Humphrey central 30-2 threshold test. The central retinal arteriolar equivalent (CRAE and central retinal venular equivalent (CRVE were measured and calculated using retinal photographs and a computer-assisted calculation program. The RNFL thickness was measured using spectral domain optical coherence tomography. Results. The mean CRAE and CRVE were significantly narrower in the glaucomatous and fellow eyes of the unilateral NTG patients than they were in the normal subjects (p<0.001. There was no significant correlation between CRAE/CRVE and RNFL thickness. There was only a significant correlation between VF severity and RNFL thickness in unilateral NTG eyes. Conclusions. Both NTG-affected eyes and NTG-fellow eyes in the unilateral NTG patients had narrower central retinal vessel diameters than did the eyes of normal subjects. Our results show that vascular factors may play a role in the NTG pathogenesis.

  7. The influence of crown-to-implant ratio on marginal bone levels around splinted short dental implants: A radiological and clincial short term analysis.

    Science.gov (United States)

    Hingsammer, Lukas; Watzek, Georg; Pommer, Bernhard

    2017-12-01

    The amount of marginal bone resorption around dental implants is considered to have a significant impact on implant stability as well as implant survival rates. The aim of this prospective study was to investigate the influence of prosthetic as well as patient specific factors on marginal bone loss around short dental implants. Seventy-six implants, which supported splinted crowns were included for investigation. All implants were from the same type and had an intraosseous length of 6.5 mm and a diameter of 4.0 mm. Twenty implants were additionally splinted onto longer ones. Measurements of marginal bone loss were performed at a mean of 12.38 months after prosthetic loading and the mean follow-up for clinical evaluation was 20.52 months. Overall two implant failures were recorded, revealing a survival rate of 97.3%. Marginal bone resorption around 72 short implants measured 0.71 mm (SD: 0.74 mm) and was found to have a strong correlation with calculated Crown-to-Implant ratio (r = .71; P implant surface area, location, position, bone quality, and insertion torque did not influence peri-implant bone loss after one year of loading. Within the limitations of the study, it is suggested that Crown-to-Implant ratios should not exceed 1.7 to avoid increased early marginal bone loss. © 2017 Wiley Periodicals, Inc.

  8. Productivity Improvement for the SHX--SEN's Single-Wafer High-Current Ion Implanter

    International Nuclear Information System (INIS)

    Ninomiya, Shiro; Ochi, Akihiro; Kimura, Yasuhiko; Yumiyama, Toshio; Kudo, Tetsuya; Kurose, Takeshi; Kariya, Hiroyuki; Tsukihara, Mitsukuni; Ishikawa, Koji; Ueno, Kazuyoshi

    2011-01-01

    Equipment productivity is a critical issue for device fabrication. For ion implantation, productivity is determined both by ion current at the wafer and by utilization efficiency of the ion beam. Such improvements not only result in higher fabrication efficiency but also reduce consumption of both electrical power and process gases. For high-current ion implanters, reduction of implant area is a key factor to increase efficiency. SEN has developed the SAVING system (Scanning Area Variation Implantation with Narrower Geometrical pattern) to address this opportunity. In this paper, three variations of the SAVING system are introduced along with discussion of their effects on fab productivity.

  9. Packing configuration performance for small stem diameters

    International Nuclear Information System (INIS)

    Aikin, J.A.; Spence, C.G.; Cumming, D.

    1997-01-01

    The extensive use of graphite packing and its excellent track record for large isolating valves in CANDU, Primary Heat Transfer (PHT) systems has resulted in an increased application of graphite packing on the conventional side. Many of these applications are in air operated valves (AOVs) where the packing sets are used on small stem diameters (<1 inch) with frequent short-cycling strokes (± 10% of full stroke). The direct application of the proven packing configurations for large isolated valves to control valve application has generated problems such as stiction, packing wear and, in isolated cases, stem stall. To address this issue, a test program was conducted at AECL, CRL by MED branch. The testing showed that by reconfiguring the packing sets and using PTFE wafers reductions in stem friction of 50% at ambient conditions, a 3 fold at hot conditions are achievable. The test program also demonstrated benefits gained in packing wear with different stem roughness finishes and the potential need to exercise small stems valves that see less than full stroke cycling. The paper describes the tests results and provides field support experience. (author)

  10. Association of lens vault with narrow angles among different ethnic groups.

    Science.gov (United States)

    Lee, Roland Y; Huang, Guofu; Cui, Qi N; He, Mingguang; Porco, Travis C; Lin, Shan C

    2012-06-01

    To compare lens vault between open-angle and narrow-angle eyes in African-, Caucasian-, Hispanic-, Chinese- and Filipino-Americans. In this prospective study, 436 patients with open angle and narrow angle based on the Shaffer gonioscopic grading classification underwent anterior-segment optical coherence tomography. The Zhongshan Angle Assessment Program was used to calculate lens vault. The narrow-angle group included 32 Chinese-Americans, 22 Filipino-Americans, 26 African-Americans, 24 Hispanic-Americans and 73 Caucasian-Americans. The open-angle group included 56 Chinese-Americans, 29 Filipino-Americans, 45 African-Americans, 27 Hispanic-Americans and 102 Caucasian-Americans. Linear mixed effect regression models, accounting for the use of both eyes and adjusting for age, sex, pupil diameter and spherical equivalent, were used to test for the ethnicity and angle coefficients. Tukey's multiple comparison test was used for pairwise comparisons among the open-angle racial groups. Significant difference in lens vault was found among the open-angle racial groups (P = 0.022). For the open-angle patients, mean values for the lens vault measurements were 265 ± 288 µm for Chinese-Americans, 431 ± 248 µm for Caucasian-Americans, 302 ± 213 µm for Filipino-Americans, 304 ± 263 µm for Hispanic-Americans and 200 ± 237 µm for African-Americans. Using Tukey's multiple comparison for pairwise comparisons among the open-angle racial groups, a significant difference was found between African-American and Caucasian-Americans groups (P values for the rest of the pairwise comparisons were not statistically significant. No significant difference was found among the narrow-angle racial groups (P = 0.14). Comparison between the open angle and narrow angle within each racial group revealed significant difference for all racial groups (P < 0.05). Among all the ethnicities included in this study, narrow-angle eyes have greater lens vault compared to open

  11. Long-term biocompatibility of implanted polymer-based intrafascicular electrodes

    DEFF Research Database (Denmark)

    Lawrence, Stephen M; Larsen, Jytte Overgaard; Horch, Kenneth W

    2002-01-01

    -term groups. Implantation of polyLIFEs had no significant effect on fiber counts, nerve-fiber diameter, or myelin thickness. A slight increase in connective tissue in the vicinity of the implant site was evident in the long-term group, including a thin but dense capsule immediately surrounding the implanted......Polymer-based longitudinal intrafascicular electrodes (polyLIFEs) were chronically implanted into the sciatic nerve of white New Zealand rabbits (n=8) for a period of 6 months (hereafter referred to as the long-term group). The impact of the implantation procedure, as observed 6 months post surgery......, was evaluated in a sham-treated control group (n=9). The contralateral sciatic nerve served as the control for each animal. Nerve-fiber counts, fiber diameters, and myelin thickness were estimated at the level of the implant site, 1.5 cm proximally, and 1.5 cm distally for both nerves in sham-treated and long...

  12. The Effect of Simplifying Dental Implant Drilling Sequence on Osseointegration: An Experimental Study in Dogs

    Directory of Open Access Journals (Sweden)

    Gabriela Giro

    2013-01-01

    Full Text Available Objectives. To test the hypothesis that there would be no differences in osseointegration by reducing the number of drills for site preparation relative to conventional drilling sequence. Methods. Seventy-two implants were bilaterally placed in the tibia of 18 beagle dogs and remained for 1, 3, and 5 weeks. Thirty-six implants were 3.75 mm in diameter and the other 36 were 4.2 mm. Half of the implants of each diameter were placed under a simplified technique (pilot drill + final diameter drill and the other half were placed under conventional drilling where multiple drills of increasing diameter were utilized. After euthanisation, the bone-implant samples were processed and referred to histological analysis. Bone-to-implant contact (BIC and bone-area-fraction occupancy (BAFO were assessed. Statistical analyses were performed by GLM ANOVA at 95% level of significance considering implant diameter, time in vivo, and drilling procedure as independent variables and BIC and BAFO as the dependent variables. Results. Both techniques led to implant integration. No differences in BIC and BAFO were observed between drilling procedures as time elapsed in vivo. Conclusions. The simplified drilling protocol presented comparable osseointegration outcomes to the conventional protocol, which proved the initial hypothesis.

  13. Breast Implants: Saline vs. Silicone

    Science.gov (United States)

    ... differ in material and consistency, however. Saline breast implants Saline implants are filled with sterile salt water. ... of any age for breast reconstruction. Silicone breast implants Silicone implants are pre-filled with silicone gel — ...

  14. [Biomaterials in cochlear implants].

    Science.gov (United States)

    Stöver, T; Lenarz, T

    2009-05-01

    Cochlear implants (CI) represent the "gold standard" for the treatment of congenitally deaf children and postlingually deafened adults. Thus, cochlear implantation is a success story of new bionic prosthesis development. Owing to routine application of cochlear implants in adults but also in very young children (below the age of one), high demands are placed on the implants. This is especially true for biocompatibility aspects of surface materials of implant parts which are in contact with the human body. In addition, there are various mechanical requirements which certain components of the implants must fulfil, such as flexibility of the electrode array and mechanical resistance of the implant housing. Due to the close contact of the implant to the middle ear mucosa and because the electrode array is positioned in the perilymphatic space via cochleostomy, there is a potential risk of bacterial transferral along the electrode array into the cochlea. Various requirements that have to be fulfilled by cochlear implants, such as biocompatibility, electrode micromechanics, and although a very high level of technical standards has been carried out there is still demand for the improvement of implants as well as of the materials used for manufacturing, ultimately leading to increased implant performance. General considerations of material aspects related to cochlear implants as well as potential future perspectives of implant development will be discussed.

  15. Application of uniform design to improve dental implant system.

    Science.gov (United States)

    Cheng, Yung-Chang; Lin, Deng-Huei; Jiang, Cho-Pei

    2015-01-01

    This paper introduces the application of uniform experimental design to improve dental implant systems subjected to dynamic loads. The dynamic micromotion of the Zimmer dental implant system is calculated and illustrated by explicit dynamic finite element analysis. Endogenous and exogenous factors influence the success rate of dental implant systems. Endogenous factors include: bone density, cortical bone thickness and osseointegration. Exogenous factors include: thread pitch, thread depth, diameter of implant neck and body size. A dental implant system with a crest module was selected to simulate micromotion distribution and stress behavior under dynamic loads using conventional and proposed methods. Finally, the design which caused minimum micromotion was chosen as the optimal design model. The micromotion of the improved model is 36.42 μm, with an improvement is 15.34% as compared to the original model.

  16. Effects of Ultraviolet Photofunctionalization on Bone Augmentation and Integration Capabilities of Titanium Mesh and Implants.

    Science.gov (United States)

    Hirota, Makoto; Ikeda, Takayuki; Tabuchi, Masako; Ozawa, Tomomichi; Tohnai, Iwai; Ogawa, Takahiro

    Ultraviolet (UV)-mediated photofunctionalization has earned considerable attention for the enhancement of the biologic capabilities of titanium. The effects of photofunctionalization on bone augmentation and gap closure were examined using titanium implants and mesh in a rat femur model. An acid-etched titanium implant (4-mm length, 1-mm diameter) was placed in the gluteal tuberosity that resembles a knife-edge-like edentulous ridge. The lower half of the implant was located in a 2-mm-diameter defect created in the bone without cortical bone support; the upper half was exposed and covered with a titanium mesh to provide augmentation space. After 12 and 24 days of healing, specimens were subjected to microcomputed tomography (micro-CT)- and histology-based bone morphometry in three zones of analysis: augmentation, cortical bone-implant gap, and bone marrow. A biomechanical push-in test was performed to examine the strength of bone-implant integration. Photofunctionalization was performed by treating titanium implants and mesh with UV light for 12 minutes. Photofunctionalized titanium mesh and implants were hydrophilic, whereas untreated controls were hydrophobic. Bone volume was significantly greater in photofunctionalized implants and mesh than in untreated implants in all zones on days 12 and 24. Bone-to-implant contact of photofunctionalized implants was greater than that of untreated implants, not just in the bone marrow but also in the gap and augmented zones. The strength of osseointegration was three times greater for photofunctionalized implants than for untreated implants. Use of photofunctionalized titanium mesh and implants effectively enhanced vertical bone augmentation, cortical bone-implant gap closure, and osseointegration without innate bone support.

  17. Mockup Small-Diameter Air Distribution System

    Energy Technology Data Exchange (ETDEWEB)

    A. Poerschke and A. Rudd

    2016-05-01

    This report investigates the feasibility of using a home-run manifold small-diameter duct system to provide space conditioning air to individual thermal zones in a low-load home. This compact layout allows duct systems to be brought easily within conditioned space via interior partition walls. Centrally locating the air hander unit in the house significantly reduces duct lengths. The plenum box is designed so that each connected duct receives an equal amount of airflow, regardless of the duct position on the box. Furthermore, within a reasonable set of length restrictions, each duct continues to receive similar airflow. The design method uses an additive approach to reach the total needed zonal airflow. Once the cubic feet per minute needed to satisfy the thermal load of a zone has been determined, the total number of duct runs to a zone can be calculated by dividing the required airflow by the standard airflow from each duct. The additive approach greatly simplifies the design effort and reduces the potential for duct design mistakes to be made. Measured results indicate that this plenum design can satisfy the heating load. However, the total airflow falls short of satisfying the cooling load in a hypothetical building. Static pressure inside the plenum box of 51.5 Pa limited the total airflow of the attached mini-split heat pump blower, thus limiting the total thermal capacity. Fan energy consumption is kept to 0.16 to 0.22 watt/CFM by using short duct runs and smooth duct material.

  18. Validation of the contralateral side as reference for selecting radial head implant sizes

    NARCIS (Netherlands)

    ten Berg, Paul W. L.; Dobbe, Johannes G. G.; van Wolfswinkel, Gerhard; Strackee, Simon D.; Streekstra, Geert J.

    2016-01-01

    In arthroplasty of comminuted radial head fractures, the contralateral radial head diameter can be used as reference for implant selection. However, potential bilateral asymmetry may result in a mismatch of the implant with the native bone. Therefore, our purpose was to evaluate anatomical

  19. Body diameters in 3 - 6 years old children from Plovdiv

    Directory of Open Access Journals (Sweden)

    Tineshev Slavi

    2013-01-01

    Full Text Available The purpose of the research is to analyze the body diameters in 3-6 year old children. The biacromial diameters were taken as well as the two chest diameters, the bicristal and bitrohanterial diameters in 316 children (157 boys and 159 girls 3, 4, 5 and 6 years of age attending kindergarten in Plovdiv. The analysis shows that all diameters, with the exception of the bitrohanterial have higher values in boys. The absolute year's increment of the diameters is greater in girls. The growth velocity of the researched features is greatest at the age of 3-4 and 4-5, decreasing at different rates for the different features at the age of 5-6. The only exception is the sagittal chest diameter in both sexes and the bitrohanterial diameters in girls.

  20. New innovative method relating guided surgery to dental implant placement.

    Science.gov (United States)

    Fauroux, M-A; De Boutray, M; Malthiéry, E; Torres, J-H

    2018-02-20

    Companies selling dental implant guided systems mostly offer similar surgical guides. The purpose of this paper is to present an innovative-guided surgery system which originality lies in its guidance device, and to report the author's experience in using this system for dental implant surgery. Two parallel tubes on either side of the drilling axis guide the successive drills and the implant placement. As a result of the lateral guidance, there is no friction of the drills on the surgical guide, which would damage it or contaminate the drilling hole with particles torn out from the guide. No radiological guide is needed during the radiographic examination stage. No successive diameter reduction tubes are requested. This guide can be used for all brands of implants. In our experience, 67 implants (31 titanium and 36 zircon implants) were placed in 35 patients with guided surgery system. Multiple clinical cases were treated with this system: 'one-stage' or a 'two-stage' surgical protocol, with flap and flapless surgical techniques, and with delayed or immediate loading. Clinical cases treated revealed good implant placement with planning. The widely open design of this guide allows irrigation and practitioner's sight control under conditions comparable to those of operations performed without surgical guide. This dental implant guided system appears to be a significant advance in the field of implant surgical guides. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

  1. 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.

  2. Morse taper dental implants and platform switching: The new paradigm in oral implantology

    OpenAIRE

    Macedo, Jos? Paulo; Pereira, Jorge; Vahey, Brendan R.; Henriques, Bruno; Benfatti, Cesar A. M.; Magini, Ricardo S.; L?pez-L?pez, Jos?; Souza, J?lio C. M.

    2016-01-01

    The aim of this study was to conduct a literature review on the potential benefits with the use of Morse taper dental implant connections associated with small diameter platform switching abutments. A Medline bibliographical search (from 1961 to 2014) was carried out. The following search items were explored: ?Bone loss and platform switching,? ?bone loss and implant-abutment joint,? ?bone resorption and platform switching,? ?bone resorption and implant-abutment joint,? ?Morse taper and platf...

  3. Comparison between inflammation-related markers in peri-implant crevicular fluid and clinical parameters during osseointegration in edentulous jaws

    DEFF Research Database (Denmark)

    Bielemann, Amália Machado; Marcello-Machado, Raissa Micaella; Manzolli Leite, Fabio Renato

    2017-01-01

    concentrations increased gradually over time, showing the highest concentrations at the 12th week (p implants failed at different periods. Conclusion While the clinical measurements presented differences between the evaluation periods, these were not indicative of early dental implant......Objectives The aim of this study is to improve the understanding of interleukin mechanisms during osseointegration to enhance the monitoring of implant failure and success. Clinical parameters, implant stability, and cytokine levels in peri-implant crevicular fluid (PICF) during early bone healing...... after implant placement were investigated. Material and methods Sixty narrow implants were placed in mandible anterior region of 30 edentulous patients (67.23 ± 7.66 years). Bone type, insertion torque, and primary stability were registered during surgery. Clinical measurements of peri-implant health...

  4. Implantable cardioverter-defibrillator

    Science.gov (United States)

    ... medlineplus.gov/ency/article/007370.htm Implantable cardioverter-defibrillator To use the sharing features on this page, please enable JavaScript. An implantable cardioverter-defibrillator (ICD) is a device that detects any life- ...

  5. Implantable cardioverter defibrillator - discharge

    Science.gov (United States)

    ... medlineplus.gov/ency/patientinstructions/000108.htm Implantable cardioverter defibrillator - discharge To use the sharing features on this page, please enable JavaScript. An implantable cardioverter-defibrillator (ICD) is a device that detects a life- ...

  6. About Implantable Contraception

    Science.gov (United States)

    ... a tube was inserted, and get a new contraceptive implant on schedule or switch to another method ... STDs. Possible Side Effects Young women who get contraceptive implants might notice such side effects as: irregular ...

  7. Urinary incontinence - collagen implants

    Science.gov (United States)

    ... gov/ency/article/007373.htm Urinary incontinence - injectable implant To use the sharing features on this page, please enable JavaScript. Injectable implants are injections of material into the urethra to ...

  8. Risk indicators for Peri-implantitis. A cross-sectional study with 916 implants.

    Science.gov (United States)

    Dalago, Haline Renata; Schuldt Filho, Guenther; Rodrigues, Mônica Abreu Pessoa; Renvert, Stefan; Bianchini, Marco Aurélio

    2017-02-01

    The aim of this study was to identify systemic and local risk indicators associated with peri-implantitis. One hundred eighty-three patients treated with 916 osseointegrated titanium implants, in function for at least 1 year, were included in the present study. The implants were installed at the Foundation for Scientific and Technological Development of Dentistry (FUNDECTO) - University of Sao Paulo (USP) - from 1998 to 2012. Factors related to patient's systemic conditions (heart disorders, hypertension, smoking habits, alcoholism, liver disorders, hepatitis, gastrointestinal disease, diabetes mellitus I and II, hyperthyroidism or hypothyroidism, radiation therapy, chemotherapy, menopause, osteoporosis, active periodontal disease, history of periodontal disease and bruxism), implant's characteristics (location, diameter, length, connection, shape, and antagonist), and clinical parameters (wear facets, periodontal status on the adjacent tooth, plaque accumulation on the adjacent tooth, modified plaque index, sulcus bleeding index, probing depth, bleeding on probing, width of keratinized tissue and marginal recession). An increased risk of 2.2 times for history of periodontal disease (PD), 3.6 times for cemented restorations compared to screw-retained prostheses, 2.4 times when wear facets were displayed on the prosthetic crown and 16.1 times for total rehabilitations when compared to single rehabilitations were found. Logistic regression analysis did not show any association between the implant's characteristics and peri-implantitis. A history of periodontal disease, cemented prostheses, presences of wear facets on the prosthetic crown and full mouth rehabilitations were identified as risk indicators for peri-implantitis. Implants' characteristics were not related to the presence of peri-implantitis. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  9. Lumbar Vertebral Canal Diameters in Adult Ugandan Skeletons ...

    African Journals Online (AJOL)

    The midsagittal, transverse diameters of the lumbar vertebral canal and the anteroposterior diameter of the inferior vertebral notch were measured using an electronic digital caliper. Collected data was analyzed using SPSS 12.0 computer program. Results and discussion: In both sexes, the midsagittal diameter of the canal ...

  10. Aortic Root Diameter and Longitudinal Blood Pressure Tracking

    OpenAIRE

    Ingelsson, Erik; Pencina, Michael J.; Levy, Daniel; Aragam, Jayashri; Mitchell, Gary F.; Benjamin, Emelia J.; Vasan, Ramachandran S.

    2008-01-01

    Proximal aortic diameter, including aortic root (AoR) diameter, has been inversely related to pulse pressure (PP) in cross-sectional studies. So, investigators have hypothesized that a smaller AoR diameter may increase risk of developing hypertension. Prospective studies are lacking to test this hypothesis.

  11. Moessbauer spectroscopy of implanted sources

    International Nuclear Information System (INIS)

    Niesen, L.

    1983-01-01

    A review is given of the field of Moessbauer spectroscopy of ion-implanted sources. After an introduction to the various aspects of the ion-implantation method, the following topics are treated: final site selection of implanted impurities; trapping of defects at implanted ions; on-line implantation; implantation in metals, semiconductors and insulators. (Auth.)

  12. Implantable electronic medical devices

    CERN Document Server

    Fitzpatrick, Dennis

    2014-01-01

    Implantable Electronic Medical Devices provides a thorough review of the application of implantable devices, illustrating the techniques currently being used together with overviews of the latest commercially available medical devices. This book provides an overview of the design of medical devices and is a reference on existing medical devices. The book groups devices with similar functionality into distinct chapters, looking at the latest design ideas and techniques in each area, including retinal implants, glucose biosensors, cochlear implants, pacemakers, electrical stimulation t

  13. COCHLEAR IMPLANTATION: MY EXPERIENCE

    OpenAIRE

    Shankar

    2015-01-01

    Cochlear implant is a small, surgically implanted complex electronic device that can help to provide a sense of sound to a person with severe to profound sensorineural hearing loss. This type of hearing loss, typically involves damage to hair cells in the cochlea, as a result sound cannot reach the auditory nerve which usually receives information from hair cells. A cochlear implant skips the damaged hair cells and to stimulate the auditory nerve directly. An implant does not rest...

  14. Correlation of Fractal Dimension Values with Implant Insertion Torque and Resonance Frequency Values at Implant Recipient Sites.

    Science.gov (United States)

    Suer, Berkay Tolga; Yaman, Zekai; Buyuksarac, Bora

    2016-01-01

    Fractal analysis is a mathematical method used to describe the internal architecture of complex structures such as trabecular bone. Fractal analysis of panoramic radiographs of implant recipient sites could help to predict the quality of the bone prior to implant placement. This study investigated the correlations between the fractal dimension values obtained from panoramic radiographs and the insertion torque and resonance frequency values of mandibular implants. Thirty patients who received a total of 55 implants of the same brand, diameter, and length in the mandibular premolar and molar regions were included in the study. The same surgical procedures were applied to each patient, and the insertion torque and resonance frequency values were recorded for each implant at the time of placement. The radiographic fractal dimensions of the alveolar bone in the implant recipient area were calculated from preoperative panoramic radiographs using a box-counting algorithm. The insertion torque and resonance frequency values were compared with the fractal dimension values using the Spearman test. All implants were successful, and none were lost during the follow-up period. Linear correlations were observed between the fractal dimension and resonance frequency, between the fractal dimension and insertion torque, and between resonance frequency and insertion torque. These results suggest that the noninvasive measurement of the fractal dimension from panoramic radiographs might help to predict the bone quality, and thus the primary stability of dental implants, before implant surgery.

  15. The Effect of Crown-to-Implant Ratio on the Clinical Performance of Extra-Short Locking-Taper Implants.

    Science.gov (United States)

    Mangano, Francesco; Frezzato, Irene; Frezzato, Alberto; Veronesi, Giovanni; Mortellaro, Carmen; Mangano, Carlo

    2016-05-01

    The aim of the present prospective 5-year study was to evaluate the influence of crown-to-implant ratio (C/I ratio) on the survival, peri-implant marginal bone loss, and complications of extra-short (6.5 mm) locking-taper implants placed in the posterior areas of the jaw. Over a 2-year period, all patients presenting with partial edentulism associated with vertical defects of the posterior alveolar ridges and sufficient bone volume to place extra-short (6.5 mm length × 5 mm diameter) implants were considered for inclusion in this study. Fifty-one patients (22 men, 29 women; aged between 40 and 75 years) were included in this study. Sixty-eight extra-short, locking-taper implants were placed to support 49 single crowns and 9 fixed partial dentures. The C/I ratio was implants and ≥2 for 17 implants. All patients underwent the 5-year clinical examination. Two implants failed. Failure proportion was 2% in the C/Ishort, locking-taper implants may be successfully used in the posterior areas of the jaw.

  16. Numerical simulation of two-phase slug flow with liquid carryover in different diameter ratio T-junction

    Science.gov (United States)

    Pao, W.; Hon, L.; Saieed, A.; Ban, S.

    2017-10-01

    A smaller diameter conduit pointing at 12 o’clock position is typically hot-tapped to a horizontal laying production header in offshore platform to tap produced gas for downstream process train. This geometric feature is commonly known as T-junction. The nature of multiphase fluid splitting at the T-junction is a major operational challenge due to unpredictable production environment. Often, excessive liquid carryover occurs in the T-junction, leading to complete platform trip and halt production. This is because the downstream process train is not designed to handle excessive liquid. The objective of this research is to quantify the effect of different diameter ratio on phase separation efficiency in T-junction. The liquid carryover is modelled as two-phase air-water flow using Eulerian Mixture Model coupled with Volume of Fluid Method to mimic the slug flow in the main pipe. The focus in this paper is 0.0254 m (1 inch) diameter horizontal main arm and vertical branch arm with diameter ratio of 1.0, 0.5 and 0.3. The present research narrowed the investigation to only slug flow regime using Baker’s map as reference. The investigation found that, contrary to common believe, smaller diameter ratio T-junction perform worse than larger diameter ratio T-junction.

  17. Imaging of 1.0-mm-diameter radiopaque markers with megavoltage X-rays: an improved online imaging system

    International Nuclear Information System (INIS)

    Pang, G.; Beachey, D.J.; O'Brien, P.F.; Rowlands, J.A.

    2002-01-01

    Purpose: To improve an online portal imaging system such that implanted cylindrical gold markers of small diameter (no more than 1.0 mm) can be visualized. These small markers would make the implantation procedure much less traumatic for the patient than the large markers (1.6 mm in diameter), which are usually used today to monitor prostate interfraction motion during radiation therapy. Methods and Materials: Several changes have been made to a mirror-video based online imaging system to improve image quality. First, the conventional camera tube was replaced by an avalanche-multiplication-based video tube. This new camera tube has very high gain at the target such that the camera noise, which is one of the main causes of image degradation of online portal imaging systems, was overcome and effectively eliminated. Second, the conventional linear-accelerator (linac) target was replaced with a low atomic number (low-Z) target such that more diagnostic X-rays are present in the megavoltage X-ray beam. Third, the copper plate buildup layer for the phosphor screen was replaced by a thin plastic layer for detection of the diagnostic X-ray components in the beam generated by the low-Z target. Results: Radiopaque fiducial gold markers of different sizes, i.e., 1.0 mm (diameter) x 5 mm (length) and 0.8 mm (diameter) x 3 mm (length), embedded in an Alderson Rando phantom, can be clearly seen on the images acquired with our improved system. These markers could not be seen on images obtained with any commercial system available in our clinic. Conclusion: This work demonstrates the visibility of small-diameter radiopaque markers with an improved online portal imaging system. These markers can be easily implanted into the prostate and used to monitor the interfraction motion of the prostate

  18. What's in a name? Expiratory tracheal narrowing in adults explained

    International Nuclear Information System (INIS)

    Leong, P.; Bardin, P.G.; Lau, K.K.

    2013-01-01

    Tracheomalacia, tracheobronchomalacia, and excessive dynamic airway collapse are all terms used to describe tracheal narrowing in expiration. The first two describe luminal reduction from cartilage softening and the latter refers to luminal reduction from exaggerated posterior membrane movement. Expiratory tracheal narrowing is a frequent occurrence that can cause symptoms of airway obstruction, such as dyspnoea, wheeze, and exercise intolerance. The accurate diagnosis and quantification of expiratory tracheal narrowing has important aetiological, therapeutic, and prognostic implications. The reference standard for diagnosis has traditionally been bronchoscopy; however, this method has significant limitations. Expiratory tracheal disorders are readily detected by four-dimensional dynamic volume multidetector computed tomography (4D-CT), an emerging, non-invasive method that will potentially enable detection and quantification of these conditions. This review discusses the morphological forms of expiratory tracheal narrowing and demonstrates the utility of 4D-CT in the diagnosis, quantification, and treatment of these important conditions

  19. Vascular narrowing in pulmonary arterial hypertension is heterogeneous: rethinking resistance

    NARCIS (Netherlands)

    Rol, N.; Timmer, E.M.; Faes, T.J.; Noordegraaf, A.V.; Grunberg, K.; Bogaard, H.J.; Westerhof, N.

    2017-01-01

    In idiopathic pulmonary arterial hypertension (PAH), increased pulmonary vascular resistance is associated with structural narrowing of small (resistance) vessels and increased vascular tone. Current information on pulmonary vascular remodeling is mostly limited to averaged increases in wall

  20. Single frequency narrow linewidth 2 micron laser, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA needs narrow linewidth lasers in the 1.5 or 2 micron wavelength regime for coherent Lidar applications. The laser should be tunable by several nm and frequency...

  1. Subglottic cysts and asymmetrical subglottic narrowing on neck radiograph

    International Nuclear Information System (INIS)

    Holinger, L.D.; Torium, D.M.; Anandappa, E.C.

    1988-01-01

    The congenital subglottic hemangioma typically appears as an asymmetric subglottic narrowing or mass on frontal neck radiograph. Therefore, soft tissue neck radiography has been advocated as a definitive non-operative approach for diagnosing these lesions. However, we have noted similar asymmetric subglottic narrowing in patients with acquired subglottic cysts. These retention cysts occur following long-term intubation in the neonate. The mechanism probably involves subglottic fibrosis which obstructs glands with subsequent cyst formation. Acquired subglottic cysts typically appear as an asymmetric narrowing on frontal or lateral soft tissue neck radiographs. These lesions may produce airway compromise but are effectively treated by forceps or laser removal. Acquired subglottic cysts must be included in the differential diagnosis of asymmetric subglottic narrowing. The definitive diagnosis is made by direct laryngoscopy, not soft tissue neck radiograph. (orig.)

  2. Integrating narrow therapeutic index drug formulations in transplantation

    NARCIS (Netherlands)

    A. Johnston (Andrew); L. Schick (Liz); T. van Gelder (Teun)

    2012-01-01

    textabstractThere is considerable debate regarding generic drug substitution in solid organ transplant recipients, and various European transplant associations and societies have expressed caution about the potential adverse consequences from uncontrolled switching between the different narrow

  3. Narrow-Band Bandpass Filter for Wireless Communication System

    Science.gov (United States)

    Kishor, Jugul; Kanaujia, Binod K.; Dwari, Santanu; Ashwani, Kumar

    2017-07-01

    This paper presents the design of a compact narrow-band bandpass filter using the cylindrical dielectric resonator (CDR) coupled with a microstrip line. The TE11δ mode of the dielectric resonator is used to obtain the narrow passband performance while, spurious mode suppression can be improved by etching the slot on the ground plane of the filter due to mode separation with the desired mode. Presented narrow bandpass filter performances are: center frequency 6.15 GHz, fractional bandwidth 0.7 %, and insertion loss (IL) 0.16 dB. To validate the above concept a second order narrow-band bandpass filter is designed, fabricated and measured. There is good agreement between simulated and measured results.

  4. NARROW READING IN AN EXTENSIVE READING COURSE: LEXICALLY-BASED

    Directory of Open Access Journals (Sweden)

    Siusana Kweldju

    2016-02-01

    Full Text Available One shot case study was conducted in one semester to undergraduate English majors who were preparing themselves to become English teachers at high school level. This study was to find out whether or not students had positive attitudes towards narrow reading, how high narrow reading helped them improve their English proficiency, and what problems students might have with narrow reading. Four questionnaires were completed during the case study to discover how students felt and thought about the course and how the course improved their English. It was found out that narrow reading not only improved students' language proficiency but also helped students develop their general knowledge, the love of reading and the appreciation on literary work.

  5. Stress Distribution on Short Implants at Maxillary Posterior Alveolar Bone Model With Different Bone-to-Implant Contact Ratio: Finite Element Analysis.

    Science.gov (United States)

    Yazicioglu, Duygu; Bayram, Burak; Oguz, Yener; Cinar, Duygu; Uckan, Sina

    2016-02-01

    The aim of this study was to evaluate the stress distribution of the short dental implants and bone-to-implant contact ratios in the posterior maxilla using 3-dimensional (3D) finite element models. Two different 3D maxillary posterior bone segments were modeled. Group 1 was composed of a bone segment consisting of cortical bone and type IV cancellous bone with 100% bone-to-implant contact. Group 2 was composed of a bone segment consisting of cortical bone and type IV cancellous bone including spherical bone design and homogenous tubular hollow spaced structures with 30% spherical porosities and 70% bone-to-implant contact ratio. Four-millimeter-diameter and 5-mm-height dental implants were assumed to be osseointegrated and placed at the center of the segments. Lateral occlusal bite force (300 N) was applied at a 25° inclination to the implants long axis. The maximum von Mises stresses in cortical and cancellous bones and implant-abutment complex were calculated. The von Mises stress values on the implants and the cancellous bone around the implants of the 70% bone-to-implant contact group were almost 3 times higher compared with the values of the 100% bone-to-implant contact group. For clinical reality, use of the 70% model for finite element analysis simulation of the posterior maxilla region better represents real alveolar bone and the increased stress and strain distributions evaluated on the cortical and cancellous bone around the dental implants.

  6. Influence of Implant Design (Cylindrical and Conical) in the Load Transfer Surrounding Long (13mm) and Short (7mm) Length Implants: A Photoelastic Analysis.

    Science.gov (United States)

    Gehrke, Sergio Alexandre; Frugis, Victor Lourenço; Shibli, Jamil Awad; Fernandez, Maria Piedad Ramirez; Sánchez de Val, José Eduardo Maté; Girardo, José Luis Calvo; Taschieri, Silvio; Corbella, Stefano

    2016-01-01

    This study compared the influence of implant design (cylindrical and conical) in the load transfer on bone surrounding 13mm and 7mm length implants under simulated occlusal loading, using photoelastic analysis. Dental implants of 4mm diameter were divided into four groups, which varied in length and design: Group 1- standard (13 mm) cylindrical implant; Group 2 - standard conical implant; Group 3 - short (7 mm) cylindrical implant, and Group 4 - short conical implant. After the inclusion of the implant models in a photoelastic resin, they were subjected to a static load of 100 N. The lengths of the fringes that were generated were measured in three portions since the implants body: crestal, central and apical portion, parallel to the implant long axis. Furthermore, the entire extension area of dissipation of force was measured. Data were analyzed by one-way ANOVA (α = 0.05). Lower stress was observed at the crestal bone in groups 2 and 4, while the stress levels in groups 1 and 3 were higher with significant differences compared to the other groups (pimplant length under axial loading condition, but changed in relation to the implant design with respect to the concentration of the fringes, which corresponded to the load distribution, with even more dissipation by conical implants.

  7. Peri-implant biomechanical responses to standard, short-wide, and double mini implants replacing missing molar supporting hybrid ceramic or full-metal crowns under axial and off-axial loading: an in vitro study.

    Science.gov (United States)

    Elfadaly, Lamiaa Said; Khairallah, Lamiaa Sayed; Al Agroudy, Mona Atteya

    2017-12-01

    The aim of this study was to evaluate the biomechanical response of the peri-implant bone to standard, short-wide, and double mini implants replacing missing molar supporting either hybrid ceramic crowns (Lava Ultimate restorative) or full-metal crowns under two different loading conditions (axial and off-axial loading) using strain gauge analysis. Three single-molar implant designs, (1) single, 3.8-mm (regular) diameter implant, (2) single, 5.8-mm (wide) diameter implant, and (3) two 2.5-mm diameter (double) implants connected through a single-molar crown, were embedded in epoxy resin by the aid of a surveyor to ensure their parallelism. Each implant supported full-metal crowns made of Ni-Cr alloy and hybrid ceramic with standardized dimensions. Epoxy resin casts were prepared to receive 4 strain gauges around each implant design, on the buccal, lingual, mesial, and distal surfaces. Results were analyzed statistically. Results showed that implant design has statistically significant effect on peri-implant microstrains, where the standard implant showed the highest mean microstrain values followed by double mini implants, while the short-wide implant showed the lowest mean microstrain values. Concerning the superstructure material, implants supporting Lava Ultimate crowns had statistically significant higher mean microstrain values than those supporting full-metal crowns. Concerning the load direction, off-axial loading caused uneven distribution of load with statistically significant higher microstrain values on the site of off-axial loading (distal surface) than the axial loading. Implant design, superstructure material, and load direction significantly affect peri-implant microstrains.

  8. Current status on narrow N anti N states

    International Nuclear Information System (INIS)

    Chung, S.U.

    1979-09-01

    An attempt is made to summarize the experimental status of narrow B anti B states as of mid-1979. In particular, concentration is placed on the current experimental situations and prospects regarding three serious contenders for the so-called baryonium states. Theoretical concepts of baryoniums, narrow N anti N states known as S(1935), anti pp(2020), and anti pp(2204), and some forthcoming results, and problems of the above three resonances are discussed. 31 references

  9. Analysis of implanted silicon dopant profiles

    Energy Technology Data Exchange (ETDEWEB)

    Prosa, T.J., E-mail: ty.prosa@ametek.com [Cameca Instruments Inc., Madison, WI 53711 (United States); Olson, D.; Geiser, B.; Larson, D.J. [Cameca Instruments Inc., Madison, WI 53711 (United States); Henry, K.; Steel, E. [National Institute of Standards and Technology, Gaithersburg, MD 20899 (United States)

    2013-09-15

    Atom probe tomography implant dose measurements are reported for National Institute of Standards and Technology Standard Reference Material 2134 (arsenic implant). Efforts were taken to manufacture specimens with limited variation in size and shape to minimize variation in physical reconstruction parameters. A tip profile reconstruction was utilized where measurements of tip profile, post-analysis specimen radius and sphere-to-cone radius ratio were required as inputs into the reconstruction process. A variation of 4% is observed in the dose measurement under these conditions. Various considerations necessary to narrow the observed variation in measured dose, toward the limit imposed by counting statistics, are discussed. - Highlights: ► Multiple APT measurements were made on a NIST standard reference implant material. ► Accuracy and precision of APT was assessed on implant dose measurements. ► Dose standard deviations of ∼2% (∼2× counting statistics limit) were achieved. ► SEM exposure was found to affect the ability to successfully analyze these specimens.

  10. Measurement of capsular contracture: the conventional breast implant and the Pittsburgh implant.

    Science.gov (United States)

    Cherup, L L; Antaki, J F; Liang, M D; Hamas, R S

    1989-12-01

    At present, there is no accurate, reliable method of experimentally measuring capsular contracture. This study had four goals: (1) to define the parameters of capsular contracture employing principles of biomechanics of soft tissues, (2) to develop laboratory techniques to measure the parameters, (3) to design an implant that mechanically impedes the process of encapsulation, and, (4) to test this implant against a conventional one. We have developed a breast implant (the Pittsburgh implant) with an altered surface topography. Its silicone shell is punctuated by projections 1 mm in height and 1 mm in diameter. Two techniques were devised to measure contracture. The first involved measuring the force deformation along a coronal axis. The second involved measuring hydrostatic pressures within the implant resulting from the injection of known quantities of saline. Measurements were performed in vivo on 36 animals. By both force and pressure measurements, the Pittsburgh implant showed less capsular contracture (p = 0.12 and 0.012, respectively). Histology revealed that the prototype surface alters the linear arrangement of myofibroblasts and redirects the laminar collagen into a waveform pattern. We conclude from this experimental study that an altered surface topography may serve as a means of rendering a capsule less mechanically effective. We feel that the proposed methods can be used in the laboratory to characterize the extent of capsular contracture.

  11. Effects of temperature and perch diameter on arboreal locomotion in the snake Elaphe guttata.

    Science.gov (United States)

    Gerald, Gary W; Mackey, Mark J; Claussen, Dennis L

    2008-03-01

    Arboreality is widespread in multiple lineages of snakes and these habitats are important for foraging, escaping predators, and thermoregulation for many species. However, very little is known about factors influencing the arboreal locomotor abilities of snakes. Arboreal performance was assessed in a semi-arboreal snake (Elaphe guttata) using an artificial perch apparatus. Locomotor velocity, body posture, and balance was measured during movement on three perch diameters (3, 6, 10-cm) at three temperatures (10, 20, 30 degrees C). Velocities attained by E. guttata on perches are much slower than those of terrestrial lateral undulation and swimming and somewhat slower than concertina velocities recorded in other species across the same experimental temperatures. At higher temperatures, faster speeds were associated with a more elongated posture. At lower temperatures, snakes displayed a more looped body posture, but still fell more often than at higher temperatures. Our results suggest that temperature has a large influence on both balance and movement by snakes on perches. Although there were no differences in velocities resulting from perch diameter, snakes fell more often from thicker perches. This differs from arboreal velocities attained by limbed vertebrates, which decrease with decreasing perch diameter, suggesting that snakes have a size-relative advantage over limbed animals, such as lizards, when traversing a network of narrow branches. Future studies investigating arboreal locomotion among snakes that vary both phylogenetically and morphologically are needed to assess the potential benefits of limblessness in complex, three-dimensional environments.

  12. Origami Wheel Transformer: A Variable-Diameter Wheel Drive Robot Using an Origami Structure.

    Science.gov (United States)

    Lee, Dae-Young; Kim, Sa-Reum; Kim, Ji-Suk; Park, Jae-Jun; Cho, Kyu-Jin

    2017-06-01

    A wheel drive mechanism is simple, stable, and efficient, but its mobility in unstructured terrain is seriously limited. Using a deformable wheel is one of the ways to increase the mobility of a wheel drive robot. By changing the radius of its wheels, the robot becomes able to pass over not only high steps but also narrow gaps. In this article, we propose a novel design for a variable-diameter wheel using an origami-based soft robotics design approach. By simply folding a patterned sheet into a wheel shape, a variable-diameter wheel was built without requiring lots of mechanical parts and a complex assembly process. The wheel's diameter can change from 30 to 68 mm, and it is light in weight at about 9.7 g. Although composed of soft materials (fabrics and films), the wheel can bear more than 400 times its weight. The robot was able to change the wheel's radius in response to terrain conditions, allowing it to pass over a 50-mm gap when the wheel is shrunk and a 50-mm step when the wheel is enlarged.

  13. In Vitro Evaluation of the Primary Stability of Short and Conventional Implants.

    Science.gov (United States)

    de Oliveira, Guilherme José Pimentel Lopes; Barros-Filho, Luiz Antônio Borelli; Barros, Luiz Antônio Borelli; Queiroz, Thalita Pereira; Marcantonio, Elcio

    2016-12-01

    The objective of this study was to evaluate the primary stability of short and conventional dental implants with different platform types at different site densities in vitro. One hundred twenty implants were placed in polyurethane blocks that simulate different bone densities (bone types I and IV). The implants were divided into 10 groups, with 12 implants each according to the type of prosthetic connections (external hexagon, EH; morse taper, MT) and size of the implants (conventional: 4 × 10 mm; short: 5 × 5, 5.5 × 5, 5 × 6, and 5.5 × 6 mm). Insertion torque and resonance frequency analyses were performed to evaluate the primary stability. The Kruskal-Wallis test complemented by Dunn's test and the Mann-Whitney test were used for statistical analysis. These tests were applied at the confidence level of 95% (P implants installed in blocks with density type IV exhibited reduced insertion torque compared with implants placed in blocks with density type I. Short implants with EH exhibited increased insertion torque compared with short implants with MT in blocks with bone density type I. In general, implants installed in blocks with density type I exhibited greater primary stability. The short implants with EH with a 5.5-mm diameter and the short implants with MT with a 5-mm diameter exhibited reduced primary stability. No differences between short and conventional implants were noted. Short implants have primary stability and insertion torque at least equivalent to conventional implants irrespective of the platform type and density of the site.

  14. Diagnostic Imaging for Implants

    Directory of Open Access Journals (Sweden)

    Sanjay M Mallya

    2004-01-01

    Full Text Available Dental implants are a popular modality for permanent tooth replacement. The key to successful implant placement, its subsequent osseointegration and the final prosthetic rehabilitation is proper preoperative assessment. Diagnostic imaging plays an important role in the pre- and post-surgical evaluation process. Imaging is used to evaluate suitability of implant sites, aid in selection of appropriate implants, and finally evaluate implant placement and osseointegration. This article reviews the role of diagnostic imaging in the various phases and the advantages and limitations of the numerous imaging modalities.

  15. The quantitative evaluation of intracranial pressure by optic nerve sheath diameter/eye diameter CT measurement.

    Science.gov (United States)

    Bekerman, Inessa; Sigal, Tal; Kimiagar, Itzhak; Ben Ely, Anna; Vaiman, Michael

    2016-12-01

    The changes of the optic nerve sheath diameter (ONSD) have been used to assess changes of the intracranial pressure for 20 years. The aim of this research was to further quantify the technique of measuring the ONSD for this purpose. Retrospective study of computed tomographic (CT) data of 1766 adult patients with intracranial hypotension (n=134) or hypertension (n=1632) were analyzed. The eyeball transverse diameter (ETD) and ONSD were obtained bilaterally, and the ONSD/ETD ratio was calculated. The ratio was used to calculate the normal ONSD for patients and to estimate the intracranial pressure of the patients before and after the onset of the pathology. Correlation analysis was performed with invasively measured intracranial pressure, the presence or absence of papilledema, sex, and age. In hypotension cases, the ONSD by CT was 3.4±0.7 mm (P=.03 against normative 4.4±0.8 mm). In cases with hypertension, the diameter was 6.9±1.3 (P=.02, with a cutoff value ˃5.5 mm). The ONSD/ETD ratio was 0.29±0.04 against 0.19±0.02 in healthy adults (P=.01). The ONSD and the ONSD/ETD ratio can indicate low intracranial pressure, but quantification is impossible at intracranial pressure less than 13 mm Hg. In elevated intracranial pressure, the ONSD and the ratio provide readings that correspond to readings in millimeters of mercury. The ONSD method, reinforced with additional calculations, may help to indicate a raised intracranial pressure, evaluate its severity quantitatively, and establish quantitative goals for treatment of intracranial hypertension, but the limitations of the method are to be taken into account. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Validation of system codes RELAP5 and SPECTRA for natural convection boiling in narrow channels

    Energy Technology Data Exchange (ETDEWEB)

    Stempniewicz, M.M., E-mail: stempniewicz@nrg.eu; Slootman, M.L.F.; Wiersema, H.T.

    2016-10-15

    Highlights: • Computer codes RELAP5/Mod3.3 and SPECTRA 3.61 validated for boiling in narrow channels. • Validated codes can be used for LOCA analyses in research reactors. • Code validation based on natural convection boiling in narrow channels experiments. - Abstract: Safety analyses of LOCA scenarios in nuclear power plants are performed with so called thermal–hydraulic system codes, such as RELAP5. Such codes are validated for typical fuel geometries applied in nuclear power plants. The question considered by this article is if the codes can be applied for LOCA analyses in research reactors, in particular exceeding CHF in very narrow channels. In order to answer this question, validation calculations were performed with two thermal–hydraulic system codes: RELAP and SPECTRA. The validation was based on natural convection boiling in narrow channels experiments, performed by Prof. Monde et al. in the years 1990–2000. In total 42 vertical tube and annulus experiments were simulated with both codes. A good agreement of the calculated values with the measured data was observed. The main conclusions are: • The computer codes RELAP5/Mod 3.3 (US NRC version) and SPECTRA 3.61 have been validated for natural convection boiling in narrow channels using experiments of Monde. The dimensions applied in the experiments were performed for a range that covers the values observed in typical research reactors. Therefore it is concluded that both codes are validated and can be used for LOCA analyses in research reactors, including natural convection boiling. The applicability range of the present validation is: hydraulic diameters of 1.1 ⩽ D{sub hyd} ⩽ 9.0 mm, heated lengths of 0.1 ⩽ L ⩽ 1.0 m, pressures of 0.10 ⩽ P ⩽ 0.99 MPa. In most calculations the burnout was predicted to occur at lower power than that observed in the experiments. In several cases the burnout was observed at higher power. The overprediction was not larger than 16% in RELAP and 15% in

  17. [Total cervical disk replacement--implant-specific approaches: keel implant (Prodisc-C intervertebral disk prosthesis)].

    Science.gov (United States)

    Korge, Andreas; Siepe, Christoph J; Heider, Franziska; Mayer, H Michael

    2010-11-01

    Dynamic intervertebral support of the cervical spine via an anterolateral approach using a modular artificial disk prosthesis with end-plate fixation by central keel fixation. Cervical median or mediolateral disk herniations, symptomatic cervical disk disease (SCDD) with anterior osseous, ligamentous and/or discogenic narrowing of the spinal canal. Cervical fractures, tumors, osteoporosis, arthrogenic neck pain, severe facet degeneration, increased segmental instability, ossification of posterior longitudinal ligament (OPLL), severe osteopenia, acute and chronic systemic, spinal or local infections, systemic and metabolic diseases, known implant allergy, pregnancy, severe adiposity (body mass index > 36 kg/m2), reduced patient compliance, alcohol abuse, drug abuse and dependency. Exposure of the anterior cervical spine using the minimally invasive anterolateral approach. Intervertebral fixation of retainer screws. Intervertebral diskectomy. Segmental distraction with vertebral body retainer and vertebral distractor. Removal of end-plate cartilage. Microscopically assisted decompression of spinal canal. Insertion of trial implant to determine appropriate implant size, height and position. After biplanar image intensifier control, drilling for keel preparation using drill guide and drill bit, keel-cut cleaner to remove bone material from the keel cut, radiologic control of depth of the keel cut using the corresponding position gauge. Implantation of original implant under lateral image intensifier control. Removal of implant inserter. Functional postoperative care and mobilization without external support, brace not used routinely, soft brace possible for 14 days due to postoperative pain syndromes. Implantation of 100 cervical Prodisc-C disk prostheses in 78 patients (average age 48 years) at a single center. Clinical and radiologic follow-up 24 months postoperatively. Significant improvement based on visual analog scale and Neck Disability Index. Radiologic

  18. Submillimeter Diameter Poly(Vinyl Alcohol) Vascular Graft Patency in Rabbit Model

    Science.gov (United States)

    Cutiongco, Marie F. A.; Kukumberg, Marek; Peneyra, Jonnathan L.; Yeo, Matthew S.; Yao, Jia Y.; Rufaihah, Abdul Jalil; Le Visage, Catherine; Ho, Jackie Pei; Yim, Evelyn K. F.

    2016-01-01

    Microvascular surgery is becoming a prevalent surgical practice. Replantation, hand reconstruction, orthopedic, and free tissue transfer procedures all rely on microvascular surgery for the repair of venous and arterial defects at the millimeter and submillimeter levels. Often, a vascular graft is required for the procedure as a means to bridge the gap between native arteries. While autologous vessels are desired for their bioactivity and non-thrombogenicity, the tedious harvest process, lack of availability, and caliber or mechanical mismatch contribute to graft failure. Thus, there is a need for an off-the-shelf artificial vascular graft that has low thrombogenic properties and mechanical properties matching those of submillimeter vessels. Poly(vinyl alcohol) hydrogel (PVA) has excellent prospects as a vascular graft due to its bioinertness, low thrombogenicity, high water content, and tunable mechanical properties. Here, we fabricated PVA grafts with submillimeter diameter and mechanical properties that closely approximated those of the rabbit femoral artery. In vitro platelet adhesion and microparticle release assay verified the low thrombogenicity of PVA. A stringent proof-of-concept in vivo test was performed by implanting PVA grafts in rabbit femoral artery with multilevel arterial occlusion. Laser Doppler measurements indicated the improved perfusion of the distal limb after implantation with PVA grafts. Moreover, ultrasound Doppler and angiography verified that the submillimeter diameter PVA vascular grafts remained patent for 2 weeks without the aid of anticoagulant or antithrombotics. Endothelial cells were observed in the luminal surface of one patent PVA graft. The advantageous non-thrombogenic and tunable mechanical properties of PVA that are retained even in the submillimeter diameter dimensions support the application of this biomaterial for vascular replacement in microvascular surgery. PMID:27376059

  19. Diameter of the lymphoid follicles in the vermiform appendix of Bangladeshi cadaver.

    Science.gov (United States)

    Rahman, M A; Parash, T H; Banu, L A

    2014-04-01

    Appendicitis is the most common clinical condition of the appendix. Many cases of acute appendicitis result from obstruction of the lumen of the appendix by lymphoid hyperplasia. The vermiform appendix is a worm-like, closed-ended, narrow, small tubular structure, projecting from posteromedial wall of cecum. It is an integral part of the Gut Associated Lymphoid Tissue (GALT) system. The lymphoid follicles of the vermiform appendix vary in respect to their number, diameter and location in different ages. This study was done to measure and establish the normal diameter with age related variation of the lymphoid follicles of vermiform appendix in Bangladeshi population. This descriptive cross sectional study was carried out in the Department of Anatomy, Sir Salimullah Medical College, Dhaka, from January 2008 to June 2009. Sixty (60) postmortem vermiform appendices of different age groups of Bangladeshi cadavers. For studying the diameter of lymphoid follicles in the vermiform appendix in relation to age, the collected samples were divided into five groups namely Group-A between age ranges 0-20 years, Group-B between age ranges 21-30 years, Group-C between age ranges 31-40 years, Group-D 41-50 years and Group-E age above 50 years. From each age group, six (6) fresh samples were selected for histological study. From each vermiform appendix three slides were prepared each from its base, middle part and near the tip and were stained with routine H & E stain. The normal diameter of the follicles of the vermiform appendix ranged from 0.40 mm to 0.66 mm. The highest average group diameter was 0.62±1.10mm in Group-A and the lowest value was 0.45±2.73mm in Group-E. It was obvious that the diameter decreased gradually with advancing age. The average normal diameter of the lymphoid follicles per histological section of vermiform appendix reduced with advancing age and showed a significant negative correlation with age (pvermiform appendix reduced significantly with advancing

  20. Imaging spectrophotometry of ionized gas in NGC 1068. I - Kinematics of the narrow-line region

    Science.gov (United States)

    Cecil, Gerald; Bland, Jonathan; Tully, R. Brent

    1990-01-01

    The kinematics of collisionally excited forbidden N II 6548, 6583 across the inner 1 arcmin diameter of the nearby Seyfert galaxy NGC 1068 is mapped using an imaging Fabry-Perot interferometer and low-noise CCD. The stack of monochromatic images, which spatially resolved the high-velocity gas, was analyzed for kinematic and photometric content. Profiles agree well with previous long-slit work, and their complete spatial coverage makes it possible to constrain the gas volume distribution. It is found that the narrow-line region is distributed in a thick center-darkened, line-emitting cylinder that envelopes the collimated radio jet. Three distinct kinematic subsystems, of which the cylinder is composed, are discussed in detail. Detailed behavior of the emission-line profiles, at the few points in the NE quadrant with simple kinematics, argues that the ionized gas develops a significant component of motion perpendicular to the jet axis.

  1. Analysis of Gear Wheel-shaft Joint Characterized by Comparable Pitch Diameter and Mounting Diameter

    Directory of Open Access Journals (Sweden)

    J. Ryś

    2003-01-01

    Full Text Available This paper presents the design procedure for a gear wheel-shaft direct frictional joint. The small difference between the operating pitch diameter of the gear and the mounting diameter of the frictional joint is the key feature of the connection. The contact surface of the frictional joint must be placed outside the bottom land of the gear, and the geometry of the joint is limited to the specific type of solutions.The strength analysis is based on the relation between the torque and statistical load intensity of the gear transmission. Several dimensionless parameters are introduced to simplify the calculations. Stress-strain verifying analysis with respect to combined loading, the condition of appropriate load-carrying capacity of the frictional joint and the fatigue strength of the shaft are applied to obtain the relations between the dimensions of the joint and other parameters. The final engineering solution may then be suggested. The approach is illustrated by a numerical example.The proposed procedure can be useful in design projects for small, high-powered modern reducers and new-generation geared motors, in particular when manufactured in various series of types.

  2. A CHF Model in Narrow Gaps under Saturated Boiling

    International Nuclear Information System (INIS)

    Park, Suki; Kim, Hyeonil; Park, Cheol

    2014-01-01

    Many researchers have paid a great attention to the CHF in narrow gaps due to enormous industrial applications. Especially, a great number of researches on the CHF have been carried out in relation to nuclear safety issues such as in-vessel retention for nuclear power plants during a severe accident. Analytical studies to predict the CHF in narrow gaps have been also reported. Yu et al. (2012) developed an analytical model to predict the CHF on downward facing and inclined heaters based on the model of Kandlikar et al. (2001) for an upward facing heater. A new theoretical model is developed to predict the CHF in narrow gaps under saturated pool boiling. This model is applicable when one side of coolant channels or both sides are heated including the effects of heater orientation. The present model is compared with the experimental CHF data obtained in narrow gaps. A new analytical CHF model is proposed to predict CHF for narrow gaps under saturated pool boiling. This model can be applied to one-side or two-sides heating surface and also consider the effects of heater orientation on CHF. The present model is compared with the experimental data obtained in narrow gaps with one heater. The comparisons indicate that the present model shows a good agreement with the experimental CHF data in the horizontal annular tubes. However, it generally under-predicts the experimental data in the narrow rectangular gaps except the data obtained in the gap thickness of 10 mm and the horizontal downward facing heater

  3. LUGOL'S IODINE CHROMOENDOSCOPY VERSUS NARROW BAND IMAGE ENHANCED ENDOSCOPY FOR THE DETECTION OF ESOPHAGEAL CANCER IN PATIENTS WITH STENOSIS SECONDARY TO CAUSTIC/CORROSIVE AGENT INGESTION.

    Science.gov (United States)

    Pennachi, Caterina Maria Pia Simoni; Moura, Diogo Turiani Hourneaux de; Amorim, Renato Bastos Pimenta; Guedes, Hugo Gonçalo; Kumbhari, Vivek; Moura, Eduardo Guimarães Hourneaux de

    2017-01-01

    The diagnosis of corrosion cancer should be suspected in patients with corrosive ingestion if after a latent period of negligible symptoms there is development of dysphagia, or poor response to dilatation, or if respiratory symptoms develop in an otherwise stable patient of esophageal stenosis. Narrow Band Imaging detects superficial squamous cell carcinoma more frequently than white-light imaging, and has significantly higher sensitivity and accuracy compared with white-light. To determinate the clinical applicability of Narrow Band Imaging versus Lugol´s solution chromendoscopy for detection of early esophageal cancer in patients with caustic/corrosive agent stenosis. Thirty-eight patients, aged between 28-84 were enrolled and examined by both Narrow Band Imaging and Lugol´s solution chromendoscopy. A 4.9mm diameter endoscope was used facilitating examination of a stenotic area without dilation. Narrow Band Imaging was performed and any lesion detected was marked for later biopsy. Then, Lugol´s solution chromoendoscopy was performed and biopsies were taken at suspicious areas. Patients who had abnormal findings at the routine, Narrow Band Imaging or Lugol´s solution chromoscopy exam had their stenotic ring biopsied. We detected nine suspicious lesions with Narrow Band Imaging and 14 with Lugol´s solution chromendoscopy. The sensitivity and specificity of the Narrow Band Imaging was 100% and 80.6%, and with Lugol´s chromoscopy 100% and 66.67%, respectively. Five (13%) suspicious lesions were detected both with Narrow Band Imaging and Lugol's chromoscopy, two (40%) of these lesions were confirmed carcinoma on histopathological examination. Narrow Band Imaging is an applicable option to detect and evaluate cancer in patients with caustic /corrosive stenosis compared to the Lugol´s solution chromoscopy.

  4. The application of mini-implants for orthodontic anchorage.

    Science.gov (United States)

    Tseng, Y-C; Hsieh, C-H; Chen, C-H; Shen, Y-S; Huang, I-Y; Chen, C-M

    2006-08-01

    The aim of this study was to explore the use of mini-implants for skeletal anchorage, and to assess their stability and the causes of failure. Forty-five mini-implants were used in orthodontic treatment. The diameter of the implants was 2mm, and their lengths were 8, 10, 12 and 14mm. The drill procedure was directly through the cortical bone without any incision or flap operation. Two weeks later, a force of 100-200g was applied by an elastometric chain or NiTi coil spring. Risk factors for the failure of mini-implants were examined statistically using the Chi-square or Fisher exact test as applicable. The average placement time of a mini-implant was about 10-15min. Four mini-implants loosened after orthodontic force loading. The overall success rate was 91.1%. The location of the implant was the significant factor related to failure. In conclusion, the mini-implants are easy to insert for skeletal anchorage and could be successful in the control of tooth movement.

  5. Trapping of deuterium in krypton-implanted nickel

    International Nuclear Information System (INIS)

    Frank, R.C.; McManus, S.P.; Rehn, L.E.; Baldo, P.

    1986-01-01

    Krypton ions with energy 600 keV were implanted in nickel to fluences of 2 x 10 16 cm -2 under three different conditions. Deuterium was subsequently introduced into the implanted regions by electrolysis at room temperature. After the diffusible deuterium was permitted to escape, the 2 H( 3 He, 1 H) 4 He nuclear reaction was used to analyze for the trapped deuterium during an isochronal annealing program. The region implanted at 100 0 C with no higher temperature anneal had the largest number of traps; the region implanted at 100 0 C and annealed for 100 min at 500 0 C had considerably less; the region implanted at 500 0 C had the least. Electron diffraction patterns confirmed the existence of solid crystalline krypton in all three regions. Transmission electron microscope studies revealed precipitates with an average diameter of 8 nm in the region implanted at 500 0 C. The two regions implanted at 100 0 C contained smaller precipitates. Trap binding enthalpies were obtained by math modeling. In addition to the traps with binding enthalpy of 0.55 eV reported earlier by other investigators for helium implanted in nickel, a smaller number of traps with binding enthalpies up to 0.83 eV were also found. The trapping of deuterium by various types of imperfections, including the solid krypton precipitates, is discussed

  6. Construction of tissue-engineered small-diameter vascular grafts in fibrin scaffolds in 30 days.

    Science.gov (United States)

    Gui, Liqiong; Boyle, Michael J; Kamin, Yishai M; Huang, Angela H; Starcher, Barry C; Miller, Cheryl A; Vishnevetsky, Michael J; Niklason, Laura E

    2014-05-01

    Tissue-engineered small-diameter vascular grafts have been developed as a promising alternative to native veins or arteries for replacement therapy. However, there is still a crucial need to improve the current approaches to render the tissue-engineered blood vessels more favorable for clinical applications. A completely biological blood vessel (3-mm inner diameter) was constructed by culturing a 50:50 mixture of bovine smooth muscle cells (SMCs) with neonatal human dermal fibroblasts in fibrin gels. After 30 days of culture under pulsatile stretching, the engineered blood vessels demonstrated an average burst pressure of 913.3±150.1 mmHg (n=6), a suture retention (53.3±15.4 g) that is suitable for implantation, and a compliance (3.1%±2.5% per 100 mmHg) that is comparable to native vessels. These engineered grafts contained circumferentially aligned collagen fibers, microfibrils and elastic fibers, and differentiated SMCs, mimicking a native artery. These promising mechanical and biochemical properties were achieved in a very short culture time of 30 days, suggesting the potential of co-culturing SMCs with fibroblasts in fibrin gels to generate functional small-diameter vascular grafts for vascular reconstruction surgery.

  7. Observation of diameter dependent carrier distribution in nanowire-based transistors

    Science.gov (United States)

    Schulze, A.; Hantschel, T.; Eyben, P.; Verhulst, A. S.; Rooyackers, R.; Vandooren, A.; Mody, J.; Nazir, A.; Leonelli, D.; Vandervorst, W.

    2011-05-01

    The successful implementation of nanowire (NW) based field-effect transistors (FET) critically depends on quantitative information about the carrier distribution inside such devices. Therefore, we have developed a method based on high-vacuum scanning spreading resistance microscopy (HV-SSRM) which allows two-dimensional (2D) quantitative carrier profiling of fully integrated silicon NW-based tunnel-FETs (TFETs) with 2 nm spatial resolution. The key elements of our characterization procedure are optimized NW cleaving and polishing steps, the use of in-house fabricated ultra-sharp diamond tips, measurements in high vacuum and a dedicated quantification procedure accounting for the Schottky-like tip-sample contact affected by surface states. In the case of the implanted TFET source regions we find a strong NW diameter dependence of conformality, junction abruptness and gate overlap, quantitatively in agreement with process simulations. In contrast, the arsenic doped drain regions reveal an unexpected NW diameter dependent dopant deactivation. The observed lower drain doping for smaller diameters is reflected in the device characteristics by lower TFET off-currents, as measured experimentally and confirmed by device simulations.

  8. Large-diameter metal-on-metal total hip arthroplasties: a page in orthopedic history?

    Science.gov (United States)

    Singh, Gurpal; Meyer, Heiko; Ruetschi, Marcel; Chamaon, Kathrin; Feuerstein, Bernd; Lohmann, Christoph H

    2013-11-01

    Large-diameter metal-on-metal (MoM) bearings evolved from the success of hip resurfacing. These implants were used in revision surgery in cases with well-fixed acetabular cups but loose or failed femoral stems, to avoid cup revision. Early data showed low rates of dislocation and potentially low wear profiles due to better fluid film lubrication. The risk of impingement was also thought to be low due to the increased head-neck ratio. Subsequently large-diameter MoM heads gained popularity in primary hip replacement. Recent data has emerged on the unacceptably high revision rates among patients with large-diameter MoM total hip arthroplasties (THAs), high blood levels of metal ions, and adverse tissue reactions. The head-neck (cone-taper) modular interface probably represents the weak link in large metal heads that have been used on conventional tapers. Increased torque of the large head, micromotion, and instability at the cone-taper interface, synergistic interactions between corrosion and wear, edge loading, low clearance, and psoas impingement are the likely causes for early failure of these prostheses. Copyright © 2013 Wiley Periodicals, Inc.

  9. Heat transfer augmentation for high heat flux removal in rib-roughened narrow channels

    International Nuclear Information System (INIS)

    Islam, M.S.; Hino, Ryutaro; Haga, Katsuhiro; Sudo, Yukio; Monde, Masanori.

    1997-03-01

    Heat transfer augmentation in narrow rectangular channels in a target system is a very important method to remove high heat flux up to 12 MW/m 2 generated at target plates of a high-intensity proton accelerator of 1.5 GeV and 1 mA with a proton beam power of 1.5 MW. In this report, heat transfer coefficients and friction factors in narrow rectangular channels with one-sided rib-roughened surface were evaluated for fully developed flows in the range of the Reynolds number from 6,000 to 1,00,000; the rib pitch-to-height ratios (p/k) were 10,20 and 30; the rib height-to-equivalent diameter ratios (k/De) were 0.025, 0.03 and 0.1 by means of previous existing experimental correlations. The rib-roughened surface augmented heat transfer coefficients approximately 4 times higher than the smooth surface at Re=10,000, p/k=10 and k/De=0.1; friction factors increase around 22 times higher. In this case, higher heat flux up to 12 MW/m 2 could be removed from the rib-roughened surface without flow boiling which induces flow instability; but pressure drop reaches about 1.8 MPa. Correlations obtained by air-flow experiments have showed lower heat transfer performance with the water-flow conditions. The experimental apparatus was proposed for further investigation on heat transfer augmentation in very narrow channels under water-flow conditions. This report presents the evaluation results and an outline of the test apparatus. (author)

  10. Silver nanoparticle formation in thin oxide layer on silicon by silver-negative-ion implantation for Coulomb blockade at room temperature

    International Nuclear Information System (INIS)

    Tsuji, Hiroshi; Arai, Nobutoshi; Matsumoto, Takuya; Ueno, Kazuya; Gotoh, Yasuhito; Adachi, Kouichiro; Kotaki, Hiroshi; Ishikawa, Junzo

    2004-01-01

    Formation of silver nanoparticles formed by silver negative-ion implantation in a thin SiO 2 layer and its I-V characteristics were investigated for development single electron devices. In order to obtain effective Coulomb blockade phenomenon at room temperature, the isolated metal nanoparticles should be in very small size and be formed in a thin insulator layer such as gate oxide on the silicon substrate. Therefore, conditions of a fine particles size, high particle density and narrow distribution should be controlled at their formation without any electrical breakdown of the thin insulator layer. We have used a negative-ion implantation technique with an advantage of 'charge-up free' for insulators, with which no breakdown of thin oxide layer on Si was obtained. In the I-V characteristics with Au electrode, the current steps were observed with a voltage interval of about 0.12 V. From the step voltage the corresponded capacitance was calculated to be 0.7 aF. In one nanoparticle system, this value of capacitance could be given by a nanoparticle of about 3 nm in diameter. This consideration is consistent to the measured particle size in the cross-sectional TEM observation. Therefore, the observed I-V characteristics with steps are considered to be Coulomb staircase by the Ag nanoparticles

  11. Synthesis and characterization of mesoporous ZnS with narrow size distribution of small pores

    Science.gov (United States)

    Nistor, L. C.; Mateescu, C. D.; Birjega, R.; Nistor, S. V.

    2008-08-01

    Pure, nanocrystalline cubic ZnS forming a stable mesoporous structure was synthesized at room temperature by a non-toxic surfactant-assisted liquid liquid reaction, in the 9.5 10.5 pH range of values. The appearance of an X-ray diffraction (XRD) peak in the region of very small angles (˜ 2°) reveals the presence of a porous material with a narrow pore size distribution, but with an irregular arrangement of the pores, a so-called worm hole or sponge-like material. The analysis of the wide angle XRD diffractograms shows the building blocks to be ZnS nanocrystals with cubic structure and average diameter of 2 nm. Transmission electron microscopy (TEM) investigations confirm the XRD results; ZnS crystallites of 2.5 nm with cubic (blende) structure are the building blocks of the pore walls with pore sizes from 1.9 to 2.5 nm, and a broader size distribution for samples with smaller pores. Textural measurements (N2 adsorption desorption isotherms) confirm the presence of mesoporous ZnS with a narrow range of small pore sizes. The relatively lower surface area of around 100 m2/g is attributed to some remaining organic molecules, which are filling the smallest pores. Their presence, confirmed by IR spectroscopy, seems to be responsible for the high stability of the resulting mesoporous ZnS as well.

  12. Posterior partially edentulous jaws, planning a rehabilitation with dental implants

    Science.gov (United States)

    Monteiro, Douglas R; Silva, Emily V F; Pellizzer, Eduardo P; Filho, Osvaldo Magro; Goiato, Marcelo C

    2015-01-01

    AIM: To discuss important characteristics of the use of dental implants in posterior quadrants and the rehabilitation planning. METHODS: An electronic search of English articles was conducted on MEDLINE (PubMed) from 1990 up to the period of March 2014. The key terms were dental implants and posterior jaws, dental implants/treatment planning and posterior maxilla, and dental implants/treatment planning and posterior mandible. No exclusion criteria were used for the initial search. Clinical trials, randomized and non randomized studies, classical and comparative studies, multicenter studies, in vitro and in vivo studies, case reports, longitudinal studies and reviews of the literature were included in this review. RESULTS: One hundred and fifty-two articles met the inclusion criteria of treatment planning of dental implants in posterior jaw and were read in their entirety. The selected articles were categorized with respect to their context on space for restoration, anatomic considerations (bone quantity and density), radiographic techniques, implant selection (number, position, diameter and surface), tilted and pterygoid implants, short implants, occlusal considerations, and success rates of implants placed in the posterior region. The results derived from the review process were described under several different topic headings to give readers a clear overview of the literature. In general, it was observed that the use of dental implants in posterior region requires a careful treatment plan. It is important that the practitioner has knowledge about the theme to evaluate the treatment parameters. CONCLUSION: The use of implants to restore the posterior arch presents many challenges and requires a detailed treatment planning. PMID:25610852

  13. Fracture resistance of bovine incisors restored with different glass fiber posts: effect of the diameter of fiber post.

    Science.gov (United States)

    Zogheib, Lucas Villaça; Vasconcellos, Luis Gustavo Oliveira; Salvia, Ana Carolina Rodrigues Danzi; Balducci, Ivan; Pagani, Clovis; Bottino, Marco Antonio; Valandro, Luiz Felipe

    2012-01-01

    Compare the effect of three post designs on the fracture resistance and failure modes of composite core - fiber post - crownless tooth sets. Ninety bovine incisors were selected and divided into nine groups of 10 specimens. The teeth were assigned to three groups based on the post design: Cylindrical, tapered, and double-tapered. Each group was subdivided into three subgroups in accordance with the diameter of the post: Small (No.1), medium (No.2), and large (No.3). The Panavia F system was used for post cementation. The specimens were mounted in acrylic resin blocks with a layer of silicone rubber covering the roots. A universal testing machine compressively loaded the specimens from the palatal side at a crosshead speed of 1 mm/min and at an angle of 135Ί to the long axis of the teeth, until failure occurred. The failure mode was determined by a stereomicroscope inspection of all the specimens. Data were analyzed by one-way ANOVA and the Tukey test (P < 0.05). The fracture resistance was affected by the type of post (P < 0.0001). A narrower diameter for all of the post systems allowed for higher resistance. The main failure mode in the large cylindrical group was catastrophic fractures, while the main failures in the other eight groups were favorable. Narrower diameter posts showed higher fracture resistance. The dominant failure pattern was repairable fracture, except for those with large cylindrical groups.

  14. Drilling dimension effects in early stages of osseointegration and implant stability in a canine model

    Science.gov (United States)

    Baires-Campos, Felipe-Eduardo; Jimbo, Ryo; Fonseca-Oliveira, Maiolino-Thomaz; Moura, Camila; Zanetta-Barbosa, Darceny; Coelho, Paulo-Guilherme

    2015-01-01

    Background This study histologically evaluated two implant designs: a classic thread design versus another specifically designed for healing chamber formation placed with two drilling protocols. Material and Methods Forty dental implants (4.1 mm diameter) with two different macrogeometries were inserted in the tibia of 10 Beagle dogs, and maximum insertion torque was recorded. Drilling techniques were: until 3.75 mm (regular-group); and until 4.0 mm diameter (overdrilling-group) for both implant designs. At 2 and 4 weeks, samples were retrieved and processed for histomorphometric analysis. For torque and BIC (bone-to-implant contact) and BAFO (bone area fraction occupied), a general-linear model was employed including instrumentation technique and time in vivo as independent. Results The insertion torque recorded for each implant design and drilling group significantly decreased as a function of increasing drilling diameter for both implant designs (pimplant designs for each drilling technique (p>0.18). A significant increase in BIC was observed from 2 to 4 weeks for both implants placed with the overdrilling technique (p0.32). Conclusions Despite the differences between implant designs and drilling technique an intramembranous-like healing mode with newly formed woven bone prevailed. Key words: Histomorphometry, biomechanical, in vivo, initial stability, insertion torque, osseointegration. PMID:25858087

  15. A randomized controlled clinical trial of two types of tapered implants on immediate loading in the posterior maxilla and mandible.

    Science.gov (United States)

    Kim, Young-Kyun; Lee, Jong-Ho; Lee, Ji-Young; Yi, Yang-Jin

    2013-01-01

    The aim of this study was to compare clinical outcomes and stability following immediate loading of two types of tapered implants in the partially edentulous posterior maxilla and mandible. A randomized controlled trial with 1 year of follow-up was performed on participants missing two consecutive teeth in a posterior quadrant with tapered implants with a hybrid textured surface. Group 1 received Osstem TSIII HA implants, and group 2 received Zimmer TSV implants. Group 1 implants were 4.5 or 5.0 mm in diameter, and group 2 implants were 4.7 mm in diameter; all implants were 10 mm long. Subjects received provisional restorations within 48 hours. Definitive restorations were provided 3 months (mandible) or 6 months (maxilla) later. Outcome measures were survival and success rates, marginal bone level change, implant stability quotient, and peri-implant soft tissue indices. Fifty participants completed the trial (group 1: 52 implants in 26 patients; group 2: 48 implants in 24 patients). The success rates were similar--98.1% in group 1 and 97.9% in group 2--at 12 months after immediate loading, but marginal bone loss was significantly different according to the implant design. Implant stability increased significantly in both arches. There were no significant differences in soft tissue indices between implant systems. If high primary stability is acquired, tapered implants with hybrid textured surfaces are predictable for immediate loading in the posterior maxilla and mandible. In spite of the influence of implant design on marginal bone loss, all tapered implants showed successful clinical outcomes and stability in immediate loading.

  16. Atom-bond connectivity index and diameter of graphs

    Directory of Open Access Journals (Sweden)

    Lin WU

    2016-12-01

    Full Text Available For further study of the numerous nice properties of topological indices in physical and chemical fields, it is worth considering the relation between a degree-based index and a distance-based index. With the fact that diameter is an invariant based on distance, the relations between atom-bond connectivity index, diameter in trees and unicyclic graphs are studied. Based on relative lemma, the relation between atom-bond connectivity index and diameter in tree and unicyclic graphs is investigated, then the sharp lower bounds of the difference of index and diameter are given.

  17. Does Physical Fitness Buffer the Relationship between Psychosocial Stress, Retinal Vessel Diameters, and Blood Pressure among Primary Schoolchildren?

    Science.gov (United States)

    Gerber, Markus; Endes, Katharina; Herrmann, Christian; Colledge, Flora; Brand, Serge; Donath, Lars; Faude, Oliver; Pühse, Uwe; Hanssen, Henner; Zahner, Lukas

    2016-01-01

    Background . Strong evidence exists showing that psychosocial stress plays an important part in the development of cardiovascular diseases. Because physical inactivity is associated with less favourable retinal vessel diameter and blood pressure profiles, this study explores whether physical fitness is able to buffer the negative effects of psychosocial stress on retinal vessel diameters and blood pressure in young children. Methods . 325 primary schoolchildren (51% girls, M age = 7.28 years) took part in this cross-sectional research project. Retinal arteriolar diameters, retinal venular diameters, arteriolar to venular ratio, and systolic and diastolic blood pressure were assessed in all children. Interactions terms between physical fitness (performance in the 20 m shuttle run test) and four indicators of psychosocial stress (parental reports of critical life events, family, peer and school stress) were tested in a series of hierarchical regression analyses. Results . Critical life events and family, peer, and school-related stress were only weakly associated with retinal vessel diameters and blood pressure. No support was found for a stress-buffering effect of physical fitness. Conclusion . More research is needed with different age groups to find out if and from what age physical fitness can protect against arteriolar vessel narrowing and the occurrence of other cardiovascular disease risk factors.

  18. Multilayer Photonic Crystal for Spectral Narrowing of Emission

    Directory of Open Access Journals (Sweden)

    Zhanfang LIU

    2017-08-01

    Full Text Available Multilayer colloidal crystal has been prepared by the layer-by-layer deposition of silica microspheres on a glass slide. Each layer is a slab consisting of a fcc close-packed colloidal arrays. By properly choosing the sizes of spheres, the whole spectral feature of multilayer colloidal crystal can be tuned. Here, we engineered a multilayer superlattice structure with an effective passband between two stop bands. This gives a strong narrowing effect on emission spectrum. With the stop bands at the shortwave and longwave edges of emission spectrum, the passband in the central wavelength region can be regarded as a strong decrease of suppression effect and enhancement of a narrow wavelength region of emission. The spectral narrowing modification effect of suitably engineered colloidal crystals shows up their importance in potential application as optical filters and lasing devices.DOI: http://dx.doi.org/10.5755/j01.ms.23.3.16320

  19. CT demonstration of pharyngeal narrowing in adult obstructive sleep apnea

    Energy Technology Data Exchange (ETDEWEB)

    Bohlman, M.E. (Johns Hopkins Univ. School of Medicine, Baltimore, MD); Haponik, E.F.; Smith, P.L.; Allen, R.P.; Bleecker, E.R.; Goldman, S.M.

    1983-03-01

    Sleep apnea is a major cause of daytime hypersomnolence. Among the proposed etiologies, focal obstruction of the airways at the level of the pharynx has been suggested but not proven. Using computed tomography, the cross-sectional area of the airway can be readily assessed. Thirty-three adults with clinically proven sleep apnea and 12 normal adults underwent systematic computed tomography of the neck. Significant airway narrowing was demonstrated in all the patients with obstructive sleep apnea, whereas no such narrowing was seen in the controls. In 11, the narrowing was at a single level, whereas in 22 patients two or more levels were affected. This study has shown that a structurally abnormal airway may serve as an anatomic substrate for the development of sleep apnea. On the basis of this evidence, uvulopalatopharyngoplasty has been performed in two patients with relief of symptoms in one.

  20. CT demonstration of pharyngeal narrowing in adult obstructive sleep apnea

    International Nuclear Information System (INIS)

    Bohlman, M.E.; Haponik, E.F.; Smith, P.L.; Allen, R.P.; Bleecker, E.R.; Goldman, S.M.

    1983-01-01

    Sleep apnea is a major cause of daytime hypersomnolence. Among the proposed etiologies, focal obstruction of the airways at the level of the pharynx has been suggested but not proven. Using computed tomography, the cross-sectional area of the airway can be readily assessed. Thirty-three adults with clinically proven sleep apnea and 12 normal adults underwent systematic computed tomography of the neck. Significant airway narrowing was demonstrated in all the patients with obstructive sleep apnea, whereas no such narrowing was seen in the controls. In 11, the narrowing was at a single level, whereas in 22 patients two or more levels were affected. This study has shown that a structurally abnormal airway may serve as an anatomic substrate for the development of sleep apnea. On the basis of this evidence, uvulopalatopharyngoplasty has been performed in two patients with relief of symptoms in one

  1. Short Dental Implants Retaining Two-Implant Mandibular Overdentures in Very Old, Dependent Patients: Radiologic and Clinical Observation Up to 5 Years.

    Science.gov (United States)

    Maniewicz, Sabrina; Buser, Ramona; Duvernay, Elena; Vazquez, Lydia; Loup, Angelica; Perneger, Thomas V; Schimmel, Martin; Müller, Frauke

    To describe the survival rate and peri-implant bone loss in very old patients dependent for their activities of daily living (ADL), treated with mandibular two-implant overdentures (IODs) in the context of a previously reported randomized controlled trial. A total of 19 patients received two interforaminal Straumann implants (Regular Neck, 4.1 mm diameter, 8 mm length) that were subsequently loaded with Locator attachments, transforming their preexisting inferior conventional denture into an IOD. The primary outcome measures were implant survival rate and radiographically assessed peri-implant bone loss. Secondary outcome measures included peri-implant probing depth and Plaque Index scores, as well as implant mobility. Nutritional state (body mass index and blood markers) and cognitive state (Mini-Mental State Examination) were also analyzed. The patient cohort comprised eight men and 11 women with a mean age of 85.7 ± 6.6 years. The implant survival rate up to 5 years was 94.7%, with one early and one late implant failure. The mean loss of peri-implant bone height was 0.17 mm per year (95% confidence interval: 0.09 to 0.24; P implant probing depth and Plaque Index scores were low and stable during the first 2 years, and thereafter increased continuously. Correlation analysis suggests that a reduced cognitive function and nutritional state are not a particular risk factor for accelerated peri-implant bone loss. The high implant survival and acceptable peri-implant health suggest that neither age nor dependency for the ADLs is a contraindication for the placement of implants. Nevertheless, close monitoring of the patients concerning a potential further functional decline precluding denture management and performing oral hygiene measures is advised.

  2. Epidemiology of Implant Mortality Disparity Among Intraoral Positions and Prosthesis Types.

    Science.gov (United States)

    Choi, Yong-Geun; Eckert, Steven E; Kang, Kyung Lhi; Shin, Sang-Wan; Kim, Young-Kyun

    To examine the disparity of single-crown implant failure with a similar loss of the splinted prosthesis in differing anatomical locations while controlling for other demographic and clinical variables that may confound the relationship between prosthesis types and implant loss. A multicenter retrospective cohort study was designed to include patients treated with dental implants from 2003 to 2014. The variables included age, sex, systemic disease, bone graft, implant placement date, position of dental implant, length of dental implant, diameter of dental implant, loading time, type of prosthesis, type of opposing occlusion, latest check date, and survival or loss of the dental implant. The demographic and clinical variables' influence on the survival of dental implants was estimated by the Kaplan-Meier method. The position and diameter were adjusted for the accurate estimation of the relationship between the prosthesis type and survival of the dental implant with the Cox proportional hazard method. A total of 1,151 dental implants from 403 patients were ascertained. After adjusting for the confounding effect of position and diameter, single-crown prostheses were 38.1 (95% CI: 15.1-118) times more likely to be lost than the connected-type prostheses. For single-crown implants, the waiting time for osseointegration before loading was the highest for the maxillary molar position and the lowest for the mandibular molar position (P < .0001), while the most frequent implant loss occurred in the maxillary anterior area, and the second frequent area was the maxillary molar position; the lowest occurrence of implant loss was for the mandibular molar position. This disparity was statistically significant (P = .0271). Despite the high survival rates of endosseous implants as a whole, since the variation of implant loss was observed among the different anatomical positions for single-crown implants, special attention has to be given to the maxillary anterior and maxillary

  3. Lossless backward second-harmonic generation of extremely narrow subdiffractive beams in two-dimensional photonic crystals

    International Nuclear Information System (INIS)

    Nistor, C.; Cojocaru, C.; Trull, J.; Karle, T. J.; Raj, R.; Raineri, F.; Staliunas, K.

    2010-01-01

    We report efficient second harmonic generation using extremely narrow beams (with diameter of the order of the wavelength) that propagate in the self-collimation (or nondiffractive) regime in a two-dimensional photonic crystal. We design and numerically test an AlGaAs photonic crystal membrane, where both fundamental and generated second harmonic beams propagate without diffraction and without out-of-plane losses. The characteristics of the generated second harmonic that is mainly propagating in the backward direction and the conversion efficiency of the proposed scheme are obtained by nonlinear finite-difference time-domain numerical simulations.

  4. Effect of Recycling Protocol on Mechanical Strength of Used Mini-Implants

    OpenAIRE

    Estelita, Sérgio; Janson, Guilherme; Chiqueto, Kelly; Ferreira, Eduardo Silveira

    2014-01-01

    Purpose. This study evaluated the influence of recycling process on the torsional strength of mini-implants. Materials and Methods. Two hundred mini-implants were divided into 4 groups with 50 screws equally distributed in five diameters (1.3 to 1.7 mm): control group (CG): unused mini-implants, G1: mini-implants inserted in pig iliac bone and removed, G2: same protocol of group 1 followed by sonication for cleaning and autoclave sterilization, and G3: same insertion protocol of group 1 follo...

  5. Preparation of polyamide microcapsules having narrow size distributions.

    Science.gov (United States)

    Muramatsu, N; Shiga, K; Kondo, T

    1994-01-01

    A novel emulsification technique which employs microporous glass membranes was adopted to prepare polyamide microcapsules of narrow size distribution. This technique proved to be simple and quite efficient for getting fairly uniform sizes of dispersed liquid droplets. Polyamide microcapsules prepared by using this technique were found not completely monodisperse, but far more satisfactory than those by any conventional mechanical methods in view of their narrow size distribution. This method also seems promising to get various sizes of the capsules by selecting the pore size of the glass membranes.

  6. Narrow-width mechanism of a=5 Ξ-state

    International Nuclear Information System (INIS)

    Kumagai-Fuse, I.; Akaishi, Y.

    1995-04-01

    Narrow-width mechanism of ≡ 5 H is discussed by calculating conversion widths to all its possible decay channels. Since the conversion processes have small reaction Q values, the three- and four- body decays are strongly suppressed owing to small phase volumes available. Decay widths to the two-body channels are significantly reduced by the distortion of emitted-particle waves. This mechanism brings about a narrow width of ≡ 5 H. The total width is estimated to be 0.87 MeV, in which the largest contribution comes from the decay into the Λ 4 H * +Λ channel. (author)

  7. The exchange narrowing of T1 in solid helium-3

    International Nuclear Information System (INIS)

    Matsumoto, Kazuyuki; Abe, Takayuki; Izuyama, Takeo.

    1989-01-01

    The exchange narrowing of the nuclear magnetic relaxation time T 1 of bcc 3 He is investigated. it is found that multiple exchange models with two and three parameters may explain the T 1 data observed in the region 0.2 m = 24.2 cm 3 /mol. We investigate further the narrowing in hcp 3 He. Based on the multiple exchange model with the exchange parameters J 1 , J 1 ', J 2 , and K sq , we obtain a theoretical expression for T 1 . (author)

  8. Investigation of the relations between screw diameter and pilot hole diameter with withdrawal resistance in LVL for establishing regression model

    Directory of Open Access Journals (Sweden)

    mossayeb dalvand

    2018-02-01

    Full Text Available In this study, variation in screw diameter and corresponding pilot hole, and relationship between these variables with withdrawal resistance for establishing multiple linear regression model was investigated. In this investigation 9-ply LVL was made of poplar (Populus deltoids. LVL was produced with polyvinyl acetate adhesive. Test specimens were prepared from LVL produced with dimensions of 7.5 * 7.5 cm. Dimension of pilot hole embedded in specimens at 4 levels (50, 60, 70 and 80 present of nominal screw diameter. The test Specimens were studied with nominal screw diameter 4.2, 5, 6 and 7mm were produced. Withdrawal resistance of screw was tested from surface and, edge and cross-sections. Results have shown that withdrawal resistance from edge (perpendicular to grain was more than withdrawal resistance from face and cross-section (parallel to grain. Also the results have shown that withdrawal resistance of different screw diameter decreased with increase of pilot hole diameter, but withdrawal resistance increased with increase of screw diameter itself. The highest withdrawal resistance was obtained from screw 7 mm in diameters and predrilled hole diameter 50% of screw diameter. The lowest withdrawal resistance was observed from screw 4.2 mm in diameter and predrilled hole diameter 80% of screw diameter. Finally multiple linear regression models ys= 3.055+.411X1-3.358X2, ye║=2.6361.694X1+.089X2 and ye┴= 2.334+.509X1-2.901X2 were obtained to predict of withdrawal resistance for face, cross-section and edge respectively.

  9. HA-Coated Implant

    DEFF Research Database (Denmark)

    Daugaard, Henrik; Søballe, Kjeld; Bechtold, Joan E

    2014-01-01

    The goal of osseointegration of orthopedic and dental implants is the rapid achievement of a mechanically stable and long lasting fixation between living bone and the implant surface. In total joint replacements of cementless designs, coatings of calcium phosphates were introduced as a means...... of improving the fixation of implants. Of these, hydroxyapatite (HA) is the most widely used and most extensively investigated. HA is highly osseoconductive, and the positive effect is well documented in both basic and long-term clinical research [1–6]. This chapter describes experimental and clinical studies...... evaluating bone-implant fixation with HA coatings....

  10. Ion implantation technology

    CERN Document Server

    Downey, DF; Jones, KS; Ryding, G

    1993-01-01

    Ion implantation technology has made a major contribution to the dramatic advances in integrated circuit technology since the early 1970's. The ever-present need for accurate models in ion implanted species will become absolutely vital in the future due to shrinking feature sizes. Successful wide application of ion implantation, as well as exploitation of newly identified opportunities, will require the development of comprehensive implant models. The 141 papers (including 24 invited papers) in this volume address the most recent developments in this field. New structures and possible approach

  11. Isotachophoresis system having larger-diameter channels flowing into channels with reduced diameter and with selectable counter-flow

    Energy Technology Data Exchange (ETDEWEB)

    Mariella, Jr., Raymond P.

    2018-03-06

    An isotachophoresis system for separating a sample containing particles into discrete packets including a flow channel, the flow channel having a large diameter section and a small diameter section; a negative electrode operably connected to the flow channel; a positive electrode operably connected to the flow channel; a leading carrier fluid in the flow channel; a trailing carrier fluid in the flow channel; and a control for separating the particles in the sample into discrete packets using the leading carrier fluid, the trailing carrier fluid, the large diameter section, and the small diameter section.

  12. Influence of implant number, length, and tilting degree on stress distribution in atrophic maxilla: a finite element study.

    Science.gov (United States)

    Gümrükçü, Zeynep; Korkmaz, Yavuz Tolga

    2017-11-09

    This study aims to evaluate the stress values, created in peri-implant region as a consequence of loading on fixed hybrid dentures that was planned with different implant numbers, lengths, or tilting angulations. Thirteen three-dimensional (3D) finite element analysis models were generated with four, five, or seven implants (group A, B, and C). Except the distal implants, all implants were modeled at 4.1 mm (diameter) and 11.5 mm (length) in size. Distal implants were configured to be in five different lengths (6, 8, 11.5, 13, and 16 mm) and three different implant inclination degrees (0°, 30°, and 45°). A 150-N load was applied vertically on prosthesis. Released stresses were evaluated comparatively. The lowest von Mises stress values were found in group C, in the 11.5-mm implant model. Tilting the distal implants 30° caused higher stress values. In 45°-tilting implant models, lower stress values were recorded according to the 30°-tilting models. The ideal implant number is seven for an edentulous maxilla. Tilting the implants causes higher stress values. A 45° inclination of implant causes lower stress values according to the 30° models due to a shorter cantilever. The ideal implant length is 11.5 mm.

  13. Clinical Parameters and Crestal Bone Loss in Internal Versus External Hex Implants at One Year after Loading

    Directory of Open Access Journals (Sweden)

    HamidReza Arab

    2015-09-01

    Full Text Available Introduction: The survival of an implant system is affected by the choice of antirotational design, which can include an external or internal hex. Implant success also is affected by the maintenance of the crestal bone around implants. The aim of present study was to evaluate the crestal bone loss and clinical parameters related to bone loss in patients loaded with an external or internal hex 3i implant (3i Implant Innovation, Palm Beach Gardens, FL, USA. The evaluations were performed one year after loading. Materials and Methods: A total of 39 implants (23 external hex, 16 internal hex were placed randomly in 23 patients (10 male, 13 female by a submerged approach. None of patients had compromised conditions or parafunctional habits. At placement and at one year after loading, periapical radiographs were taken via the parallel method from the implant sites. Results: Crestal bone loss was -0.712±0.831 mm in implants with an internal hex connection and -0.139±0.505 mm in implants with an external hex connection (P≤0.05. No correlation was found between crestal bone loss and parameters such as age, gender, jaw, implant location (anterior, premolar, or molar, implant diameter, or implant length. Conclusions: Crestal bone loss was greater in patients with internal hex 3i implants than in those with external implants. Similar results in other clinical factors were found between the groups.

  14. Slowing single-stranded DNA translocation through a solid-state nanopore by decreasing the nanopore diameter.

    Science.gov (United States)

    Akahori, Rena; Haga, Takanobu; Hatano, Toshiyuki; Yanagi, Itaru; Ohura, Takeshi; Hamamura, Hirotaka; Iwasaki, Tomio; Yokoi, Takahide; Anazawa, Takashi

    2014-07-11

    To slow the translocation of single-stranded DNA (ssDNA) through a solid-state nanopore, a nanopore was narrowed, and the effect of the narrowing on the DNA translocation speed was investigated. In order to accurately measure the speed, long (5.3 kb) ssDNA (namely, ss-poly(dA)) with uniform length (±0.4 kb) was synthesized. The diameters of nanopores fabricated by a transmission electron microscope were controlled by atomic-layer deposition. Reducing the nanopore diameter from 4.5 to 2.3 nm slowed down the translocation of ssDNA by more than 16 times (to 0.18 μs base(-1)) when 300 mV was applied across the nanopore. It is speculated that the interaction between the nanopore and the ssDNA dominates the translocation speed. Unexpectedly, the translocation speed of ssDNA through the 4.5 nm nanopore is more than two orders of magnitude higher than that of double-stranded DNA (dsDNA) through a nanopore of almost the same size. The cause of such a faster translocation of ssDNA can be explained by the weaker drag force inside the nanopore. Moreover, the measured translocation speeds of ssDNA and dsDNA agree well with those calculated by molecular-dynamics (MD) simulation. The MD simulation predicted that reducing the nanopore diameter to almost the same as that of ssDNA (i.e. 1.4 nm) decreases the translocation speed (to 1.4 μs base(-1)). Narrowing the nanopore is thus an effective approach for accomplishing nanopore DNA sequencing.

  15. Sex Dimorphism of the Heart Diameters and Cardiothoracic Ratios ...

    African Journals Online (AJOL)

    Objective: To determine gender associated differences in the cardiothoracic ratio (CTR) and heart diameters in a normal Nigerian population. Subject and Method: The normal heart diameters and cardiothoracic ratios were measured from posteroanterior (PA) chest radiographs of healthy 510 male and 508 female ...

  16. Generalized height-diameter models for Populus tremula L. stands

    African Journals Online (AJOL)

    USER

    2010-07-12

    Jul 12, 2010 ... Using permanent sample plot data, selected tree height and diameter functions were evaluated for their predictive abilities for Populus tremula stands in Turkey. Two sets of models were evaluated. The first set included five models for estimating height as a function of individual tree diameter; the second set.

  17. Mean particle diameters : From statistical definition to physical understanding

    NARCIS (Netherlands)

    Alderliesten, M.

    2008-01-01

    Mean particle diameters are important for the science of particulate systems. This thesis deals with a definition system for these mean diameters, called Moment-Ratio (M-R) definition system, and provides a general statistical and physical basis. Also, the current DIN/ISO definition system is

  18. Growth process and diameter structure of Pinus tabulaeformis forest ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-10-19

    Oct 19, 2009 ... Using stem analysis method, the biomass, growing process and diameter structure of 21-year shady and sunny slope Pinus tabulaeformis forest were investigated in hilly loess-gully region. Results showed that there were distinct difference in the indexes, tree height, diameter at breast height (DBH).

  19. Mean Normal Portal Vein Diameter Using Sonography among ...

    African Journals Online (AJOL)

    BACKGROUND: Mean portal vein diameter is considered as the best indicator for portal hypertension. However, the cutoff point differs from study to study (above 10-15 mm) despite the existence of normal mean portal vein diameter between 10-15 mm in different settings.This implies the existence of limited evidence on ...

  20. Growth process and diameter structure of Pinus tabulaeformis forest ...

    African Journals Online (AJOL)

    Using stem analysis method, the biomass, growing process and diameter structure of 21-year shady and sunny slope Pinus tabulaeformis forest were investigated in hilly loess-gully region. Results showed that there were distinct difference in the indexes, tree height, diameter at breast height (DBH) and timber volume ...

  1. Relationships between stem diameter at breast height (DBH), tree ...

    African Journals Online (AJOL)

    Trees show considerable variation and flexibility in their size of crowns, height and stem diameter at breast height (dbh). Dbh has been used as predictor variables in diameter and height growth equations. Relationships between dbh, tree height, crown length, crown height and crown ratio of Vitellaria paradoxa were ...

  2. Generalized height-diameter models for Populus tremula L. stands ...

    African Journals Online (AJOL)

    On average, by including stand level attributes, root mean square values were reduced by 21 cm. In the second set, the best results were obtained by the Schnute's function. In this function, dominant diameter and dominant height independent variables in addition to tree diameter were found significant at 0.01 significant ...

  3. Relationships between diameter and height of trees in natural ...

    African Journals Online (AJOL)

    Relationships between diameter and height of trees in natural tropical forest in Tanzania. Wilson A Mugasha, Ole M Bollandsås, Tron Eid. Abstract. The relationship between tree height (h) and tree diameter at breast height (dbh) is an important element describing forest stands. In addition, h often is a required variable in ...

  4. Influence of high intensity ultrasound with different probe diameter ...

    African Journals Online (AJOL)

    The main goal of this research is to analyze the influence of ultrasonic probe diameters (7 and 10 mm) of high-intensity ultrasound with constant frequency (30 kHz) on the degree of homogenization (variance) of cow milk. Influence of different probe diameters on the physical properties of cow milk was also tested. Changes ...

  5. The ankylos endosseous dental implant: assessment of stability up to 18 months with the Periotest.

    Science.gov (United States)

    Morris, H F; Winkler, S; Ochi, S

    2000-01-01

    Osseointegration is an ongoing histometric process that may vary during clinical function. The implant must be stable at uncovering, which reflects the status of bone-implant interface. The physiology of bone healing associated with endosseous implants suggests that this process occurs between 8 and 12 months, and Periotest values (PTVs) tend to reflect changes in the stability of the bone-implant interface. Stability generally increases gradually from the time of uncovering to an optimal PTV that occurs at a point close to 12 months. This stable interface must remain intact for long-term clinical survival. Rapid development of this optimal PTV is highly desirable in order to prevent premature overloading of the bone-implant interface. The Ankylos implant is a new screw-type implant design in which the thread pitch and length vary to maximize trabecular bone contact. The purpose of this report is to evaluate to 18 months the stability (PTVs) of this implant design. More than 457 implants were placed and followed for a period of 18 months by the multicentered, multidisciplinary Ankylos Implant Clinical Research Group (AICRG). Implant stability (PTVs) was assessed using the Periotest at abutment connection and at 3, 6, 9, 12, and 18 months after uncovering. The Periotest values for all implants rapidly reached an optimal status between uncovering (-3.1 PTVs) and 3 months (-3.4 PTVs). This rapid increase in stability has not previously been reported for other implant designs. The mandibular arch was more negative (-3.8 PTVs) at uncovering as compared with the PTVs for the maxillary arch (-1.7 PTVs). Negative PTVs were recorded (1) as length and diameter increased, (2) as bone density increased, (3) in certain jaw regions, (4) as the number of implants/case increased, and (5) for implants stabile at placement. The Ankylos screw implant design produced rapid stabilization 3 months after uncovering.

  6. Retrospective analysis of survival rates and marginal bone loss on short implants in the mandible.

    Science.gov (United States)

    Draenert, Florian G; Sagheb, Keyvan; Baumgardt, Katharina; Kämmerer, Peer W

    2012-09-01

    Short implants have become an interesting alternative to bone augmentation in dental implantology. Design of shorter implants and longer surveillance times are a current research issue. The goal of this study was to show the survival rates of short implants below 9 mm in the partly edentulous mandibular premolar and molar regions with fixed prosthetics. Marginal vertical and 2D bone loss was evaluated additionally. Different implant designs are orientationally evaluated. A total of 247 dental implants with fixed prosthetics (crowns and bridges) in the premolar and molar region of the mandible were evaluated; 47 implants were 9 mm or shorter. Patient data were evaluated to acquire implant survival rates, implant diameter, gender and age. Panoramic X-rays were analysed for marginal bone loss. Average surveillance time was 1327 days. Cumulative survival rate (CSR) of short implants was 98% (1 implants lost) compared to 94% in the longer implants group without significance. Thirty-five of the short implants were Astratech (0 losses) and 12 were Camlog Screw Line Promote Plus (1 loss). Early vertical and two-dimensional marginal bone loss was not significantly different in short and regular length implant group with an average of 0.6 mm and 0.7 mm(2) in short implants over the observation period. Within the limitations of this study, we conclude that short implants with a length of 9 mm or less have equal survival rates compared with longer implants over the observation period of 1-3 years. © 2011 John Wiley & Sons A/S.

  7. The prevalence of cervical myelopathy among subjects with narrow cervical spinal canal in a population-based magnetic resonance imaging study: the Wakayama Spine Study.

    Science.gov (United States)

    Nagata, Keiji; Yoshimura, Noriko; Hashizume, Hiroshi; Muraki, Shigeyuki; Ishimoto, Yuyu; Yamada, Hiroshi; Takiguchi, Noboru; Nakagawa, Yukihiro; Minamide, Akihito; Oka, Hiroyuki; Kawaguchi, Hiroshi; Nakamura, Kozo; Akune, Toru; Yoshida, Munehito

    2014-12-01

    A narrow cervical spinal canal (CSC) is a well-known risk factor for cervical myelopathy (CM). However, no epidemiologic data of the CSC based on a population-based cohort are available. The purpose of the study was to investigate the age-related differences in CSC diameters on plain radiographs and to examine the associated magnetic resonance imaging (MRI) abnormalities including cervical cord compression and increased signal intensity (ISI) as well as the clinical CM with the narrow CSC. This was a cross-sectional study. Data were obtained from the baseline survey of the Wakayama Spine Study that was performed from 2008 to 2010 in a western part of Japan. Finally, a total of 959 subjects (319 men and 640 women; mean age, 66.4 years) were included. The outcome measures included in the study were the CSC diameter at C5 level on plain radiographs, cervical cord compression and ISI on sagittal T2-weighted MRI, and physical signs related to CM (eg, the Hoffmann reflex, hyperreflexia of the patellar tendon, the Babinski reflex, sensory and motor function, and bowel/bladder symptoms). The age-related differences of CSC diameters in men and women were investigated by descriptive statistics. The prevalence of MRI abnormalities and clinical CM was compared among the groups divided by the CSC diameter (less than 13, 13-15, and 15 mm or more). In addition, a logistic regression analysis was performed to determine the association of the CSC diameter with cervical cord compression/clinical CM after overall adjustment for age, sex, and body mass index. The CSC diameter was narrower with increasing age in both men and women. The prevalence of cervical cord compression, ISI, and the clinical CM was significantly higher in the narrower CSC group. The prevalence of cervical cord compression, ISI, and CM among subjects with CSC diameter less than 13 mm was 38.0%, 5.4%, and 10.1%, respectively. In the logistic model, the CSC diameter was a significant predictive factor for the

  8. Dental Implant Thread Design and the Consequences on Long-Term Marginal Bone Loss.

    Science.gov (United States)

    Ormianer, Zeev; Matalon, Shlomo; Block, Jonathan; Kohen, Jerry

    2016-08-01

    The aim of this study was to present the implant macrostructure effect on marginal bone loss using 3 dental implant thread designs with differences in thread pitch, lead, and helix angle. All implants used were sourced from the same company and had the same microstructured surface. This is a nonrandomized, retrospective, double-blind study. Data were collected by an independent Tel Aviv University group from a general practitioner's private practice patient records. In total, 1361 implants met the inclusion criteria representing the 3 types of implants macrostructure. Overall survival rate was 96.3% with 50 implants failing (3.7%) out of a total of 1361 implants. Survival rates for the 3 groups were: group A 96.6%, group B 95.9%, and in group C 100%. Average bone loss for groups A, B, and C were 2.02 (±1.70) mm, 2.10 (±1.73) mm, and 1.90 (±1.40) mm, respectively. Pairwise comparisons revealed that less bone loss occurred in group A compared with group B (P = 0.036). Favorable long-term bone loss results were found in implants with a larger pitch, deeper apical threads, and a narrower implant core. One-piece V-thread design implants demonstrated 100% survival rate.

  9. Intraocular lens implantation in microphthalmic patients.

    Science.gov (United States)

    Sinskey, R M; Amin, P; Stoppel, J

    1992-09-01

    Microphthalmos is a developmental disorder of the eye consisting of a smaller than normal eye. This disorder can present as an isolated condition or associated with other systemic alterations. It is not uncommon for patients with microphthalmos to have congenital cataracts along with other ocular and systemic abnormalities. This paper reports the experience with 11 microphthalmic eyes of seven patients who had primary or secondary intraocular lens (IOL) implantation over a six-year period from 1985 to 1991. In all cases the IOL had a 13.5 mm or 14.0 mm overall diameter and a 6.0 mm or 6.5 mm optic. It was difficult to obtain documentation of objective visual improvement in many of these cases because of the associated nystagmus. However, all patients reported subjective improvements. These results suggest that with proper technique and lens selection microphthalmic patients should be considered for IOL implantation with relative safety and success.

  10. Orthodontic Implants: Concepts for the Orthodontic Practitioner

    Directory of Open Access Journals (Sweden)

    Carlos Nelson Elias

    2012-01-01

    Full Text Available Orthodontic implants have become a reliable method in orthodontic practice for providing temporary additional anchorage. These devices are useful to control skeletal anchorage in less compliant patients or in cases where absolute anchorage is necessary. There are a great number of advantages in this new approach which include easy insertion, decreased patient discomfort, low price, immediate loading, reduced diameter, versatility in the forces to be used, ease of cleaning, and ease of removal. However, a proper management of the screws by the practitioner is necessary in order to increase the success rate of the technique. The purpose of this paper is to update practitioners on the current concepts of orthodontic implants and orthodontic mechanics.

  11. Mini-Implants, Mega Solutions: A Case Series.

    Science.gov (United States)

    Kumari, Pooja; Verma, Mahesh; Sainia, Vikrant; Gupta, Ankur; Gupta, Rekha; Gill, Shubhra

    2016-12-01

    Dental implants have evolved as a standard of care for replacement of missing teeth. Though this treatment modality promises a high level of patient satisfaction and success, it cannot be performed in all cases. Apart from medically compromised patients, implant use is also restricted whenever there is limited available bone volume at the edentulous site. An example includes the mandibular incisor, the maxillary lateral incisor region, and other sites with reduced interdental spacing and atrophic edentulous maxillary and mandibular ridges. Bone volume at some of these sites can be increased by suitable augmentation procedure for placement of a regular diameter implant (3.75 to 4.2 mm). But many a times such procedure cannot be undertaken either due to financial constraint, risk of subjecting the patient to additional surgical procedure, added time factor, or guarded prognosis of the grafted site. In such cases, mini-implants can be used. In this case series, mini-implants (2.5 to 3 mm) were used to replace teeth in all mouth quadrants and to retain a mandibular overdenture in a compromised case. The implants served well at all the sites with minimal bone loss and a high level of patient satisfaction. Mini-implants hold the potential to serve as an alternate to regular diameter implants in certain situations. Preferably they should be used in multiples to retain fixed dental prostheses and might serve as an efficient, low-cost solution for retaining overdentures in selected cases. © 2015 by the American College of Prosthodontists.

  12. The effect of platform switching on stress distribution in implants and periimplant bone studied by nonlinear finite element analysis.

    Science.gov (United States)

    Liu, Siyu; Tang, Chunbo; Yu, Jinhua; Dai, Wenyong; Bao, Yidong; Hu, Dan

    2014-11-01

    It is unknown whether dental implant systems with a platform-switched configuration have better periimplant bone stress distribution and lead to less periimplant bone level changes. The purpose of this study was to quantitatively investigate interfacial stress and stress distribution in implant bone in 2 implant abutment designs (platform-switched design and conventional diameter matching) by using a nonlinear finite element analysis method. A finite element simulation study was applied to 2 commercially available dental implant systems: the Ankylos implant system with a reduced-diameter abutment (platform-switched implant) and the Anthogyr implant system with an abutment of the same diameter (regular platform implant). These 2 dental implant systems were positioned in a bone block, which was constructed based on a cross-sectional image of a human mandible in the molar region. In simulation, a single vertical load of 50 N, 100 N, or 150 N and horizontal loads of 50 N and 100 N were applied to the occlusal surface of the abutment. The finite element analysis found that the Ankylos implant system has a higher maximum von Mises stress in the implant abutment connection section and a lower maximum von Mises stress in the periimplant bone. The opposite results were found in the Anthogyr implant system. Lower stress levels in the periimplant bone with a more uniform stress distribution were found for the Ankylos implant system with a platform-switched configuration. Although relatively higher stress was found in the abutment, premature implant failure is not anticipated because of the high strength of titanium alloy. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  13. Effective implantation of light emitting centers by plasma immersion ion implantation and focused ion beam methods into nanosized diamond

    International Nuclear Information System (INIS)

    Himics, L.; Tóth, S.; Veres, M.; Tóth, A.; Koós, M.

    2015-01-01

    Highlights: • Characteristics of nitrogen implantation of nanodiamond using two low ion energy ion implantation methods were compared. • Formation of complex nitrogen-related defect centers was promoted by subsequent helium implantation and heat treatments. • Depth profiles of the implanted ions and the generated vacancies were determined using SRIM calculations. • The presence of nitrogen impurity was demonstrated by Fourier-transform infrared spectroscopic measurements. • A new nitrogen related band was detected in the photoluminescence spectrum of the implanted samples that was attributed to the N3 color center in nanodiamond. - Abstract: Two different implantation techniques, plasma immersion ion implantation and focused ion beam, were used to introduce nitrogen ions into detonation nanodiamond crystals with the aim to create nitrogen-vacancy related optically active centers of light emission in near UV region. Previously samples were subjected to a defect creation process by helium irradiation in both cases. Heat treatments at different temperatures (750 °C, 450 °C) were applied in order to initiate the formation of nitrogen-vacancy related complex centers and to decrease the sp 2 carbon content formed under different treatments. As a result, a relatively narrow and intensive emission band with fine structure at 2.98, 2.83 and 2.71 eV photon energies was observed in the light emission spectrum. It was assigned to the N3 complex defect center. The formation of this defect center can be expected by taking into account the relatively high dose of implanted nitrogen ions and the overlapped depth distribution of vacancies and nitrogen. The calculated depth profiles distribution for both implanted nitrogen and helium by SRIM simulation support this expectation

  14. Diameter of common bile duct: what are the predicting factors?

    Directory of Open Access Journals (Sweden)

    Atoosa Adibi

    2007-07-01

    Full Text Available

    BACKGROUND: This was a study to determine the correlation between the common bile duct (CBD diameter and demographic data, fasting, and the history of opium addiction.
    METHODS: This was a cross-sectional study on 375 patients (>16 years old including 219 females and 156 males. They had no evident hepatobiliary or pancreatic disease and underwent abdominopelvic ultrasonography for measurement of their CBD diameter. Ultrasound (US was performed to measure CBD diameter at the porta hepatis (proximal part and behind the head of the pancreas (distal part. Correlation coefficients for the association between CBD diameter and predictive factors were calculated. t-test was applied to compare the means between the groups.
    RESULTS: The mean CBD diameter (1 standard deviation, in proximal and distal parts were 3.64 mm (±1.2 and 3.72 mm (±1.2, respectively. The CBD diameters (proximal and distal were significantly (P<0.05 correlated with age (r = 0.55 and 0.54, respectively, BMI (r = 0.25 and 0.27, respectively and portal vein diameter (r = 0.24 and 0.22, respectively. Distal diameter of CBD was significantly larger in opium addicts (5.66 ± 2.65 in comparison with non addicts (3.68 ± 1.17, P = 0.04.
    CONCLUSIONS: CBD diameter associates with age, BMI, portal vein diameter and opium addiction. CBD dilatation, if it can not be explained by age, opium usage or large BMI, should be evaluated further to rule out obstruction.
    KEY WORDS: Common bile duct, predicting factors, ultrasonography.

  15. Relation of Coronary Artery Diameters With Cardiorespiratory Fitness.

    Science.gov (United States)

    Ho, John S; Cannaday, John J; FitzGerald, Shannon J; Leonard, David; Finley, Carrie E; Wade, Wendy A; Reinhardt, Dale B; Ellis, Joe R; Barlow, Carolyn E; Haskell, William L; Defina, Laura F; Gibbons, Larry W; Cooper, Kenneth H

    2018-02-06

    Cardiorespiratory fitness is associated with reduced cardiovascular morbidity and mortality when adjusted for traditional risk factors. Mechanisms by which fitness reduces risk have been studied but remain incompletely understood. We hypothesize that higher fitness is associated with larger coronary artery diameters independent of its effect on traditional risk factors. Two independent measurements of the proximal diameters of the left main, left anterior descending, left circumflex, and right coronary arteries were obtained from gated multidetector computed tomography scans in 500 men from the Cooper Center Longitudinal Study (CCLS). Men with coronary artery calcium scores ≥10 were excluded. Fitness was measured with a maximal exercise treadmill test and reported by quintiles and as a function of METs. We then evaluated the relation between coronary artery diameters and fitness using mixed effect regression models. Higher fitness was associated with larger coronary artery diameters after adjustment for body surface area, smoking status, low-density lipoprotein and high-density lipoprotein cholesterol, resting systolic blood pressure, and serum glucose. When examined continuously, each MET increase in fitness was associated with a mean 0.03 ± 0.01 mm larger diameter of the left main, a 0.04 ± 0.01 mm larger diameter of the left anterior descending, a 0.05 ± 0.01 mm larger diameter of the left circumflex, and a 0.07 ± 0.01 mm larger diameter of the right coronary artery (p = 0.002). This correlation between fitness and coronary artery diameters was most prominent for fitness levels above 10 METs. In conclusion, higher fitness is associated with larger coronary artery diameters. Copyright © 2018 Elsevier Inc. All rights reserved.

  16. Survival rate of short and long dental implants in chilean population.

    Directory of Open Access Journals (Sweden)

    Gisaku Kuramochi

    2012-12-01

    Full Text Available The use of short dental implants is often related with lower survival rates than the larger ones. However recent studies have reported dissimilar results. Aim of this study is to evaluate survival of long and short implants over a period of 12 years. Methods: Survival study of a retrospective cohort in a sample of 78 consecutively treated edentulous individuals each ones with long and short implants between 1997 and 2009, following the Branemark protocol, 548 implants were inserted (Branemark System, 396 long (>10mm with a diameter of 3.75 to 4.0mm and 152 short implants (<8.5mm with a diameter of 3.75 to 4.0mm. In 377 implants, the surface was machined and oxidized at 171. Data analysis was performed with SPSS 15.0 software. And p<0.05 was considered significant. Results: The survival rate for short implants was 77%, while for long implants was 94.9%. And the comparison between them by means the Mantel & Cox test was significant. Conclusions: Apparently implant length is related to survival. Prospective studies should focus on identifying risk factors for failure of osseointegration.

  17. Morse taper dental implants and platform switching: The new paradigm in oral implantology.

    Science.gov (United States)

    Macedo, José Paulo; Pereira, Jorge; Vahey, Brendan R; Henriques, Bruno; Benfatti, Cesar A M; Magini, Ricardo S; López-López, José; Souza, Júlio C M

    2016-01-01

    The aim of this study was to conduct a literature review on the potential benefits with the use of Morse taper dental implant connections associated with small diameter platform switching abutments. A Medline bibliographical search (from 1961 to 2014) was carried out. The following search items were explored: "Bone loss and platform switching," "bone loss and implant-abutment joint," "bone resorption and platform switching," "bone resorption and implant-abutment joint," "Morse taper and platform switching." "Morse taper and implant-abutment joint," Morse taper and bone resorption," "crestal bone remodeling and implant-abutment joint," "crestal bone remodeling and platform switching." The selection criteria used for the article were: meta-analysis; randomized controlled trials; prospective cohort studies; as well as reviews written in English, Portuguese, or Spanish languages. Within the 287 studies identified, 81 relevant and recent studies were selected. Results indicated a reduced occurrence of peri-implantitis and bone loss at the abutment/implant level associated with Morse taper implants and a reduced-diameter platform switching abutment. Extrapolation of data from previous studies indicates that Morse taper connections associated with platform switching have shown less inflammation and possible bone loss with the peri-implant soft tissues. However, more long-term studies are needed to confirm these trends.

  18. Antimicrobial coatings for implant surfaces

    OpenAIRE

    Brunetto, Priscilla S.; Fromm, Katharina M.

    2008-01-01

    Body-foreign materials are used more and more frequently in our lives: joint implants (hips, knees, fingers, etc.), catheters, pacemakers, dental and aesthetic implants, etc. The increasing numbers of patients requiring such implants also raises the absolute numbers of implant-related infections. Thus, it is known that body-foreign materials are prone to bacterial adhesion and subsequent biofilm formation, either via bacterial debris on implant materials, infections during implantation or, la...

  19. Predicting soil nitrogen content using narrow-band indices from ...

    African Journals Online (AJOL)

    Optimal fertiliser applications for sustainable forest stand productivity management, whilst protecting the environment, is vital. This study estimated soil nitrogen content using leaf-level narrow-band vegetation indices derived from a hand-held 350–2 500 nm spectroradiometer. Leaf-level spectral data were collected and ...

  20. Reduced dosages of atrazine and narrow rows can provide ...

    African Journals Online (AJOL)

    hope&shola

    2010-11-08

    Nov 8, 2010 ... of reduced herbicide dosages and narrow rows to achieve adequate weed control and optimise on yields in smallholder farming systems. Key words: Row spacing, reduced atrazine dosages, weed density, weed biomass, maize yield. INTRODUCTION. Inadequate weed control is one of the major causes of.

  1. Japanese VLBI Network Observations of a Gamma-Ray Narrow ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... We made simultaneous single-dish and VLBI observations of a gamma-ray narrow-line Seyfert 1 (NLS1) galaxy 1H 0323+342. We found significant flux variation at 8 GHz on a ... Institute for Cosmic Ray Research, The University of Tokyo, Chiba 277-8582, Japan. The Institute of Space and Astronautical ...

  2. A "Narrowing of Inquiry" in American Moral Psychology and Education

    Science.gov (United States)

    Richardson, Michael J.; Slife, Brent D.

    2013-01-01

    We explore the possibility that a priori philosophical commitments continue to result in a narrowing of inquiry in moral psychology and education where theistic worldviews are concerned. Drawing from the theories of Edward L. Thorndike and John Dewey, we examine naturalistic philosophical commitments that influenced the study of moral psychology…

  3. Note: Folded optical system for narrow forward looking probe

    International Nuclear Information System (INIS)

    Hou, Hsuan-Chao; Hah, Dooyoung; Kim, Jeonghwan; Feldman, M.

    2014-01-01

    An optical system is described in which a laser beam makes three passes through a single graded index lens, forming a focus along the optic axis. It has important applications in endoscopic probes, where the forward looking characteristic permits the avoidance of obstacles and the narrow structure makes it minimally invasive

  4. Career Attainment among Healthcare Executives: Is the Gender Gap Narrowing?

    Science.gov (United States)

    Branin, Joan Julia

    2009-01-01

    Health care occupations are expected to be among the fastest growing professions in the next ten years. With such incredible growth expected in employment and wages, and with women's participation in the industry remaining strong, are women in the health care industry, particularly those in health care administration, experiencing a narrowing of…

  5. Measurements of Narrow Mg II Associated Absorption Doublets with ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... The measurement of the variations of absorption lines over time is a good method to study the physical conditions of absorbers. In this paper, we measure the variations of the line strength of 36 narrow Mg II2796, 2803 associated absorption doublets, which are imprinted on 31 quasar spectra with two ...

  6. World Food Resources and Population: The Narrowing Margin.

    Science.gov (United States)

    Brown, Lester R.

    1981-01-01

    This bulletin examines the narrowing margin between global food production and population growth. Between 1950 and 1971, world grain production nearly doubled and per capita production increased 31 percent. During the 1970s, gains in output barely kept pace with population growth, consumption per person declined in sub-Saharan Africa and parts of…

  7. Synthesis of iron oxide nanoparticles of narrow size distribution on ...

    Indian Academy of Sciences (India)

    WINTEC

    Interaction between iron (II) sulfate and template has been carried out in aqueous phase, followed by the selective and controlled removal of the template to achieve narrow distribution of ... templates like aluminium oxide, carbon nanotubes, sur- factants, polymer fibres and egg shell membranes have been employed.

  8. Harmonic Generation and Linewidth Narrowing in Seeded FELs

    CERN Document Server

    Giannessi, Luca

    2004-01-01

    The process of harmonic generation in a seeded single pass Free Electron Laser are studied in the time/frequency domain. The linewidth narrowing of the fundamental harmonic is correlated to the amplitude of the input seed. The spectral evolution of the harmonics is studied within a self consistent time dependent model.

  9. Qualification of submerged-arc narrow strip cladding process

    International Nuclear Information System (INIS)

    Ayres, P.S.; Gottschling, J.D.; Jeffers, G.K.

    1975-08-01

    An unique narrow strip cladding process for use on both plate and forging material for nuclear components was developed. The qualification testing of this low-heat input process for cladding nuclear components, including those of SA508 Class 2 material is described. The theory that explains the acceptable results of these tests is also given. (auth)

  10. Qualification of submerged-arc narrow strip cladding process

    International Nuclear Information System (INIS)

    Ayres, P.S.; Gottschling, J.D.; Jeffers, G.K.

    1976-03-01

    Babcock and Wilcox has developed an unique narrow strip cladding process for use on both plate and forging material for nuclear components. The qualification testing of this low-heat input process for cladding nuclear components is described, including those of SA508 Class 2 material. The theory that explains the acceptable results of these tests is also given

  11. Extrinsic stretching narrowing and anterior indentation of the rectosigmoid junction

    International Nuclear Information System (INIS)

    Schulman, A.; Fataar, S.

    1979-01-01

    Thirty-five cases of extrinsic narrowing or anterior indentation of the rectosigmoid junction (RSJ) have been studied. The RSJ lies directly behind the pouch of Douglas which is a favoured site for peritoneal metastasis, abscess and endometriosis. Any space-occupying lesion of sufficient size at this site will indent the anterior aspects of the RSJ. Causes include distension or tumour of the ileum or sigmoid colon, gross ascites (when the patient is erect), and tumours below the pelvic peritonium, such as gynaecological neoplasm and internal iliac artery aneurysm. When a desmoplastic metastasis in the pouch of Douglas infiltrates the outer layers of the RSJ, the fibrosis produces an eccentric shortening on its anterior aspect, which in turn causes a pleating of the mucosa with the folds radiating towards the shortened area. This is also seen with primary pelvic carcinomas directly adherent to the rectum, endometriosis with repeated bleeding and increasing eccentric, submucosal fibrosis, and chronic abscess in the pouch of Douglas. Not all extrinsic narrowing of the RSJ are pathological. One case of anterior indentation followed operation for rectal prolapse. Ten additional cases showed narrowing due to a technical artefact air-distended colon rising into the upper abdomen to cause stretching at the RSJ. As with ascites, this narrowing due to 'high-rise sigmoid' disappeared when the patients became recumbent and the colonic air redistributed. (author)

  12. Motion tracking in narrow spaces: a structured light approach

    DEFF Research Database (Denmark)

    Olesen, Oline Vinter; Paulsen, Rasmus; Højgaard, Liselotte

    2010-01-01

    point clouds are matched to a reference surface using a robust iterative closest point algorithm. A main challenge is the narrow geometry requiring a compact structured light system and an oblique angle of observation. The system is validated using a mannequin head mounted on a rotary stage. We compare...

  13. Free-Molecular Gas Flow in Narrow (Nanoscale) Channel

    Czech Academy of Sciences Publication Activity Database

    Levdansky, V.V.; Roldugin, V.I.; Žďanov, V.M.; Ždímal, Vladimír

    2014-01-01

    Roč. 87, č. 4 (2014), s. 802-814 ISSN 1062-0125 Grant - others:BRFFI(BY) T12P-018; RFBR(RU) 12-08-90009 Institutional support: RVO:67985858 Keywords : narrow channels * free-molecular gas flow * surface diffusion Subject RIV: CF - Physical ; Theoretical Chemistry

  14. Narrow-band filters for the lightning imager

    Science.gov (United States)

    Piegari, Angela; Di Sarcina, Ilaria; Grilli, Maria Luisa; Menchini, Francesca; Scaglione, Salvatore; Sytchkova, Anna; Zola, Danilo; Cuevas, Leticia P.

    2017-11-01

    The study of lightning phenomena will be carried out by a dedicated instrument, the lightning imager, that will make use of narrow-band transmission filters for separating the Oxygen emission lines in the clouds, from the background signal. The design, manufacturing and testing of these optical filters will be described here.

  15. Moving beyond Idealistically Narrow Discourses in Citizenship Education

    Science.gov (United States)

    Fischman, Gustavo E.; Haas, Eric

    2014-01-01

    The main goal of this article is to provide conceptual guidelines to move the pedagogical debate in the field of citizenship education beyond idealistically narrow models. We begin by providing an overview of key shortcomings presented in most citizenship education programs, specifically in the United States of America. The second section presents…

  16. Age and growth of narrow-barred Spanish mackerel ...

    African Journals Online (AJOL)

    The narrow-barred Spanish mackerel Scomberomorus commerson is one of the most important linefish species caught in KwaZulu-Natal and southern Mozambique waters, forming the basis of important commercial, artisanal and recreational fisheries. A total of 439 S. commerson were sampled along the east coast of ...

  17. Learning English Vocabulary by Hyperglossing and Narrow Reading: Readlang

    Science.gov (United States)

    Kiliçkaya, Ferit

    2017-01-01

    Hyperglossing -textual and/or pictorial representations of lexical items is found to be aiding the development of decoding, and narrow reading is a useful strategy for L2 reading pedagogy. Although the research on glossing provides mixed findings regarding the benefits, it is also acknowledged that glossing improves especially incidental…

  18. Modeling of air flow through a narrow crack

    International Nuclear Information System (INIS)

    Trojek, T.; Cechak, T.; Moucka, L.; Fronka, A.

    2004-01-01

    Radon transport in dwellings is governed to a significant extent by pressure differences and properties of transport pathways. A model of air flow through narrow cracks was created in order to facilitate prediction of air velocity and air flow. Theoretical calculations, based on numerical solution of a system of differential equations, were compared with measurements carried out on a window crack. (P.A.)

  19. Electrical conductivity enhancement of polyethersulfone (PES) by ion implantation

    International Nuclear Information System (INIS)

    Bridwell, L.B.; Giedd, R.E.; Wang Yongqiang; Mohite, S.S.; Jahnke, T.; Brown, I.M.

    1991-01-01

    Amorphous polyethersulfone (PES) films have been implanted with a variety of ions (He, B, C, N and As) at a bombarding energy of 50 keV in the dose range 10 16 -10 17 ions/cm 2 . Surface resistance as a function of dose indicates a saturation effect with a significant difference between He and the other ions used. ESR line shapes in the He implanted samples changed from a mixed Gaussian/Lorentzian to a pure Lorentzian and narrowed with increasing dose. Temperature dependent resistivity indicates an electron hopping mechanism for conduction. Infrared results indicate cross-linking or self-cyclization occurred for all implanted ions with further destruction in the case of As. (orig.)

  20. The preoperative imaging evaluation for cochlear implantation

    International Nuclear Information System (INIS)

    Liu Zhonglin; Wang Zhenchang; Fu Lin; Li Yong; Xian Junfang; Yang Bentao; Lan Baosen; Li Yongxin; Zheng Jun; Song Yan; Liu Bo; Chen Xueqing; He Haili

    2006-01-01

    Objective: To analyze CT and MRI findings of temporal bone and to evaluate preoperative diagnostic value for cochlear implantation. Methods: One hundred and sixty candidates for cochlear implantation were examined with axial CT scan, 64 of them also with coronal CT scan, and 119 patients with MRI. Results: All of 320 ears were well-aerated, and 206 ears had mastoid cavities extended posteriorly to the sigmoid sinus. The length from posterior-lateral tympanic wall to the outer cortex was (2.34±0.42) mm (left side) and (2.25±0.40) mm (right side) (U=1.887, P 1 and T 2 signal on MRI. The congenital malformations of inner ear occurred in 67 ears, including complete dysplasia in 1 ear, cochlear hypodysplasia in 6 ears, Mondini deformation in 5 ears, enlarged vestibular aqueduct in 40 ears, dysplastic semicircular canal and the vestibulae in 10 ears, and narrowing of internal auditory canal in 5 ears. Conclusion: Preoperative imaging examinations can provide critical information to ensure successful cochlear' implantation. (authors)

  1. Electromechanical impedance method to assess dental implant stability

    Science.gov (United States)

    Tabrizi, Aydin; Rizzo, Piervincenzo; Ochs, Mark W.

    2012-11-01

    The stability of a dental implant is a prerequisite for supporting a load-bearing prosthesis and establishment of a functional bone-implant system. Reliable and noninvasive methods able to assess the bone interface of dental and orthopedic implants (osseointegration) are increasingly demanded for clinical diagnosis and direct prognosis. In this paper, we propose the electromechanical impedance method as a novel approach for the assessment of dental implant stability. Nobel Biocare® implants with a size of 4.3 mm diameter ×13 mm length were placed inside bovine bones that were then immersed in a solution of nitric acid to allow material degradation. The degradation simulated the inverse process of bone healing. The implant-bone systems were monitored by bonding a piezoceramic transducer (PZT) to the implants’ abutment and measuring the admittance of the PZT over time. It was found that the PZT’s admittance and the statistical features associated with its analysis are sensitive to the degradation of the bones and can be correlated to the loss of calcium measured by means of the atomic absorption spectroscopy method. The present study shows promising results and may pave the road towards an innovative approach for the noninvasive monitoring of dental implant stability and integrity.

  2. A Systematic Review of Outcomes Following Immediate Molar Implant Placement Based on Recently Published Studies.

    Science.gov (United States)

    Ketabi, Mohammad; Deporter, Douglas; Atenafu, Eshetu G

    2016-12-01

    Immediate implant placement in molar extraction sites has become a treatment option for experienced clinicians. The aim of this study was to provide a systematic review and meta-analysis of outcomes from recent clinical studies with immediate molar implants. A systematic review was undertaken of relevant literature published from November 2008 to May 2015. Data collected included implant survival rates after at least 1 year in function, cumulative crestal bone loss, and implant location (maxilla vs mandible) and diameter. Implant diameters were grouped as "wide" (4-6 mm) or "ultra-wide" (>6-9 mm). Survival and bone loss with 95% CIs were calculated using a random effects model. Meta-analysis techniques were used to compare survival rates and cumulative mean bone loss between immediate and delayed placement implants. Survival rates also were computed and compared between wide and ultra-wide implants using chi-square testing. The quality of each study was assessed using established criteria. The literature search provided 15 papers published between November 2008 and May 2015 that satisfied the inclusion criteria. Data on survival were found for a total of 768 immediate molar implants inserted in 757 patients. Meta-analysis of these data showed an implant survival rate of 98% with no difference between maxilla and mandible. Five studies included delayed molar implants as controls, and no significant differences were detected. A significant difference (p = .048) was found in relation to implant diameter with implant failures being higher (3.67 vs 1.45%) for ultra-wide (>6-9 mm) versus wide (4-6 mm) implants. The majority of the 15 studies were determined to be either "average" (prospective case series) or "fair" (retrospective) in quality. While there are still no published reports from double-blind, randomized, controlled (best quality) clinical trials of immediate molar implant placement, high survival rates have been reported. The present data, however

  3. Percutaneous and skeletal biocarbon implants

    Science.gov (United States)

    Mooney, V.

    1977-01-01

    Review of carbon implants developed by NASA discussed four different types of implants and subsequent improvements. Improvements could be of specific interest to rehabilitation centers and similar organizations.

  4. Comparison of proton and phosphorous ion implantation-induced intermixing of InAs/InP quantum dots

    International Nuclear Information System (INIS)

    Barik, S; Tan, H H; Jagadish, C

    2007-01-01

    We report and compare proton and phosphorous ion implantation-induced intermixing of InAs/InP quantum dots (QDs). After ion implantation at 20-300 deg. C, the QDs are rapid thermally annealed at 850 deg. C for 30 s. Proton implantation induces less energy shift than P ion implantation for a given concentration of atomic displacements due to the more efficient dynamic annealing of the defects created by protons. The implantation-induced energy shift reaches a maximum value of about 260 meV for a dose of 5 x 10 12 ions cm -2 in the P ion implanted QDs, which also show narrower PL linewidths compared to the proton implanted QDs. We also report the effects of an InGaAs top cap layer on the ion implantation-induced QD intermixing and show that defect production and annihilation processes evolve differently in InGaAs and InP layers and vary with the implantation temperature. When the implantation is performed at higher temperatures, the energy shift of the P ion implanted QDs capped with an InP layer increases due to the reduction in larger defect cluster formation at higher temperatures, while the energy shift of the proton implanted QDs decreases due to increased dynamic annealing irrespective of their cap layers

  5. Galaxy properties from J-PAS narrow-band photometry

    Science.gov (United States)

    Mejía-Narváez, A.; Bruzual, G.; Magris, C. G.; Alcaniz, J. S.; Benítez, N.; Carneiro, S.; Cenarro, A. J.; Cristóbal-Hornillos, D.; Dupke, R.; Ederoclite, A.; Marín-Franch, A.; de Oliveira, C. Mendes; Moles, M.; Sodre, L.; Taylor, K.; Varela, J.; Ramió, H. Vázquez

    2017-11-01

    We study the consistency of the physical properties of galaxies retrieved from spectral energy distribution (SED) fitting as a function of spectral resolution and signal-to-noise ratio (SNR). Using a selection of physically motivated star formation histories, we set up a control sample of mock galaxy spectra representing observations of the local Universe in high-resolution spectroscopy, and in 56 narrow-band and 5 broad-band photometry. We fit the SEDs at these spectral resolutions and compute their corresponding stellar mass, the mass- and luminosity-weighted age and metallicity, and the dust extinction. We study the biases, correlations and degeneracies affecting the retrieved parameters and explore the role of the spectral resolution and the SNR in regulating these degeneracies. We find that narrow-band photometry and spectroscopy yield similar trends in the physical properties derived, the former being considerably more precise. Using a galaxy sample from the Sloan Digital Sky Survey (SDSS), we compare more realistically the results obtained from high-resolution and narrow-band SEDs (synthesized from the same SDSS spectra) following the same spectral fitting procedures. We use results from the literature as a benchmark to our spectroscopic estimates and show that the prior probability distribution functions, commonly adopted in parametric methods, may introduce biases not accounted for in a Bayesian framework. We conclude that narrow-band photometry yields the same trend in the age-metallicity relation in the literature, provided it is affected by the same biases as spectroscopy, albeit the precision achieved with the latter is generally twice as large as with the narrow-band, at SNR values typical of the different kinds of data.

  6. Comparison of the size of artificial aortic valve with ring diameter by echocardiography

    Directory of Open Access Journals (Sweden)

    Rangbarnegad II

    1997-07-01

    Full Text Available In recent socio-economic state it is not possible to have different sets of prosthetic cardiac valves available in the operating room before open-heart surgery for valvular replacement. In this study the diameter of the aortic valve ring measured in 2-D echocardiography was compared with the size of the aortic prosthetic valves implanted for the patients with aortic valvular disease. The purpose was to find a logical correlation to help the surgeons to order the correct size of aortic prosthetic valve in advance of surgery. 26 patients with aortic valve disease were studied from 1972 till 1974 who underwent aortic valve replacement surgery. Now, it is possible to predict the accurate size of aortic mechanical valve prosthesis before surgery

  7. Effects of implant tilting and the loading direction on the displacement and micromotion of immediately loaded implants: an in vitro experiment and finite element analysis.

    Science.gov (United States)

    Sugiura, Tsutomu; Yamamoto, Kazuhiko; Horita, Satoshi; Murakami, Kazuhiro; Tsutsumi, Sadami; Kirita, Tadaaki

    2017-08-01

    The purpose of this study was to investigate the effects of implant tilting and the loading direction on the displacement and micromotion (relative displacement between the implant and bone) of immediately loaded implants by in vitro experiments and finite element analysis (FEA). Six artificial bone blocks were prepared. Six screw-type implants with a length of 10 mm and diameter of 4.3 mm were placed, with 3 positioned axially and 3 tilted. The tilted implants were 30° distally inclined to the axial implants. Vertical and mesiodistal oblique (45° angle) loads of 200 N were applied to the top of the abutment, and the abutment displacement was recorded. Nonlinear finite element models simulating the in vitro experiment were constructed, and the abutment displacement and micromotion were calculated. The data on the abutment displacement from in vitro experiments and FEA were compared, and the validity of the finite element model was evaluated. The abutment displacement was greater under oblique loading than under axial loading and greater for the tilted implants than for the axial implants. The in vitro and FEA results showed satisfactory consistency. The maximum micromotion was 2.8- to 4.1-fold higher under oblique loading than under vertical loading. The maximum micromotion values in the axial and tilted implants were very close under vertical loading. However, in the tilted implant model, the maximum micromotion was 38.7% less than in the axial implant model under oblique loading. The relationship between abutment displacement and micromotion varied according to the loading direction (vertical or oblique) as well as the implant insertion angle (axial or tilted). Tilted implants may have a lower maximum extent of micromotion than axial implants under mesiodistal oblique loading. The maximum micromotion values were strongly influenced by the loading direction. The maximum micromotion values did not reflect the abutment displacement values.

  8. Effects of implant tilting and the loading direction on the displacement and micromotion of immediately loaded implants: an in vitro experiment and finite element analysis

    Science.gov (United States)

    2017-01-01

    Purpose The purpose of this study was to investigate the effects of implant tilting and the loading direction on the displacement and micromotion (relative displacement between the implant and bone) of immediately loaded implants by in vitro experiments and finite element analysis (FEA). Methods Six artificial bone blocks were prepared. Six screw-type implants with a length of 10 mm and diameter of 4.3 mm were placed, with 3 positioned axially and 3 tilted. The tilted implants were 30° distally inclined to the axial implants. Vertical and mesiodistal oblique (45° angle) loads of 200 N were applied to the top of the abutment, and the abutment displacement was recorded. Nonlinear finite element models simulating the in vitro experiment were constructed, and the abutment displacement and micromotion were calculated. The data on the abutment displacement from in vitro experiments and FEA were compared, and the validity of the finite element model was evaluated. Results The abutment displacement was greater under oblique loading than under axial loading and greater for the tilted implants than for the axial implants. The in vitro and FEA results showed satisfactory consistency. The maximum micromotion was 2.8- to 4.1-fold higher under oblique loading than under vertical loading. The maximum micromotion values in the axial and tilted implants were very close under vertical loading. However, in the tilted implant model, the maximum micromotion was 38.7% less than in the axial implant model under oblique loading. The relationship between abutment displacement and micromotion varied according to the loading direction (vertical or oblique) as well as the implant insertion angle (axial or tilted). Conclusions Tilted implants may have a lower maximum extent of micromotion than axial implants under mesiodistal oblique loading. The maximum micromotion values were strongly influenced by the loading direction. The maximum micromotion values did not reflect the abutment

  9. Influence of spacing on the survival, frequency of diameter classes and height/diameter ratio in Eucalyptus urophylla. [In Portuguese

    Energy Technology Data Exchange (ETDEWEB)

    Brandi, R.M.; Couto, L.; Neto, F. de P.

    1977-01-01

    Survival of hybrid (unspecified parentage) E. urophylla in Minas Gerais after 93 months ranged from 47.1% at a spacing of 2 x 2 m to 60.5% at 3 x 4 m. Close spacing gave the largest number of trees per unit area, but with smaller average diameter Height/diameter ratio was not influenced by spacing.

  10. 3D finite element analysis of immediate loading of single wide versus double implants for replacing mandibular molar

    Directory of Open Access Journals (Sweden)

    Shrikar R Desai

    2013-01-01

    Full Text Available Purpose: The purpose of this finite element study was to compare the stresses, strains, and displacements of double versus single implant in immediate loading for replacing mandibular molar. Materials and Methods: Two 3D FEM (finite element method models were made to simulate implant designs. The first model used 5-mm-wide diameter implant to support a single molar crown. The second model used 3.75-3.75 double implant design. Anisotropic properties were assigned to bone model. Each model was analyzed with single force magnitude (100 N in vertical axis. Results: This FEM study suggested that micromotion can be controlled better for double implants compared to single wide-diameter implants. The Von Mises stress for double implant showed 74.44% stress reduction compared to that of 5-mm implant. The Von Mises elastic strain was reduced by 61% for double implant compared to 5-mm implant. Conclusion: Within the limitations of the study, when the mesiodistal space for artificial tooth is more than 12.5 mm, under immediate loading, the double implant support should be considered.

  11. 3D finite element analysis of immediate loading of single wide versus double implants for replacing mandibular molar

    Science.gov (United States)

    Desai, Shrikar R.; Karthikeyan, I.; Gaddale, Reetika

    2013-01-01

    Purpose: The purpose of this finite element study was to compare the stresses, strains, and displacements of double versus single implant in immediate loading for replacing mandibular molar. Materials and Methods: Two 3D FEM (finite element method) models were made to simulate implant designs. The first model used 5-mm-wide diameter implant to support a single molar crown. The second model used 3.75-3.75 double implant design. Anisotropic properties were assigned to bone model. Each model was analyzed with single force magnitude (100 N) in vertical axis. Results: This FEM study suggested that micromotion can be controlled better for double implants compared to single wide-diameter implants. The Von Mises stress for double implant showed 74.44% stress reduction compared to that of 5-mm implant. The Von Mises elastic strain was reduced by 61% for double implant compared to 5-mm implant. Conclusion: Within the limitations of the study, when the mesiodistal space for artificial tooth is more than 12.5 mm, under immediate loading, the double implant support should be considered. PMID:24554890

  12. Peri-Implant Diseases

    Science.gov (United States)

    ... Dentists about How Often They Floss Their Teeth Oral Hygiene Habits and Hypertension Risk Alcohol Consumption and Gum ... peri-implant disease include previous periodontal disease diagnosis, poor ... tooth. With a proper oral health routine, your dental implant can last a ...

  13. Biocompatible implant surface treatments

    Directory of Open Access Journals (Sweden)

    Bikash Pattanaik

    2012-01-01

    Limitation of this study is that we tried to give a broader overview related to implant surface treatments. It does not give any conclusion regarding the best biocompatible implant surface treatment investigated till date. Unfortunately, the eventually selected studies were too heterogeneous for inference of data.

  14. Ion implantation into diamond

    International Nuclear Information System (INIS)

    Sato, Susumu

    1994-01-01

    The graphitization and the change to amorphous state of diamond surface layer by ion implantation and its characteristics are reported. In the diamond surface, into which more than 10 16 ions/cm 2 was implanted, the diamond crystals are broken, and the structure changes to other carbon structure such as amorphous state or graphite. Accompanying this change of structure, the electric conductivity of the implanted layer shows two discontinuous values due to high resistance and low resistance. This control of structure can be done by the temperature of the base during the ion implantation into diamond. Also it is referred to that by the base temperature during implantation, the mutual change of the structure between amorphous state and graphite can be controlled. The change of the electric resistance and the optical characteristics by the ion implantation into diamond surface, the structural analysis by Raman spectroscopy, and the control of the structure of the implanted layer by the base temperature during implantation are reported. (K.I.)

  15. HA-Coated Implant

    DEFF Research Database (Denmark)

    Daugaard, Henrik; Søballe, Kjeld; Bechtold, Joan E

    2014-01-01

    The goal of osseointegration of orthopedic and dental implants is the rapid achievement of a mechanically stable and long lasting fixation between living bone and the implant surface. In total joint replacements of cementless designs, coatings of calcium phosphates were introduced as a means...

  16. Dynamic ion implantation

    International Nuclear Information System (INIS)

    Oppenheim, I.F.C.

    1988-01-01

    The Dynamic Ion Implantation Technique consists of ion implantation of a film during the film-deposition process. This technique was investigated theoretically and experimentally with ions whose incident energy is of the order of a few times 100 keV. It was found to be a viable alternative low-temperature method for the preparation of thick zirconium nitride films (∼1 μm) with good mechanical properties. Theoretical modeling of the processes involved during dynamic ion implantation lead to analytical expressions for the ions' depth-profile distributions. Numerical evaluations of these equations indicated that the depth distributions of dynamically implanted ions are in general more uniform than those predicted by the model for ions implanted by more conventional techniques. Mechanical properties of stoichiometric RF sputter-deposited zirconium nitride films post implanted with krypton and rubidium ions were investigated. Scratch-adhesion critical load and Vickers microhardness of samples implanted with doses varying from 1 x 10 15 to 5 x 10 16 ions/cm 2 and energies ranging from 300 to 500 keV were studied. In general, best mechanical properties were observed for 300- keV krypton implantations

  17. "COCHLEAR IMPLANTATION IN PATIENTS WITH INNER EAR MALFORMATIONS"

    Directory of Open Access Journals (Sweden)

    P. Borghei S. Abdi

    2004-08-01

    Full Text Available Performing cochlear implantation in patients with inner ear malformation has always been a matter of dispute. This study was designed to analyze the operative findings,complications, and postoperative performance of patients with inner ear anomalies who underwent cochlear implantation. Six patients with inner ear malformations underwent implantation in our academic tertiary referral center from 1997 to 2002. The average follow-up period was 27 months. Malformations included one incomplete partition, one common cavity, one narrow internal acoustic canal (IAC in a patient with Riley-Day syndrome and 3 cases of large vestibular aqueduct. All received multi-channel implants either Nucleus 22 or Clarion device. Facial nerve was anomalous in 2 cases. CSF gusher occurred in 4 patients, which was controlled with packing the cochleostomy site. In all cases, the full length of electrode array was inserted, except one with Mondini's dysplasia where insertion failed in the first operation and was referred to another center for a successful surgery on the opposite ear. No other surgical complications were encountered. In 4 cases, all the 22 electrodes could be activated. All patients showed improved hearing performance after implantation. Four showed open-set speech recognition. The one with narrow IAC showed improved awareness to environmental sounds. In the other case (common cavity, the perception tests could not be performed because of very young age. Cochlear implantation in patients with inner ear malformations is a successful way of rehabilitation, although complications should be expected and auditory responses may be highly variable and relatively moderate.

  18. Bacterial biofilm on successful and failed orthodontic mini-implants--a scanning electron microscopy study.

    Science.gov (United States)

    Ferreira, Nayra Oliveira; Andrucioli, Marcela Cristina Damião; Nelson-Filho, Paulo; Zanella, Eduardo Pereira; Consolaro, Alberto; Romano, Fábio Lourenço; Matsumoto, Mírian Aiko Nakane

    2015-12-01

    Mini-implants have been extensively used in Orthodontics as temporary bone anchorage devices. However, early failure of mini-implants due to mobility might occur and the colonization of their surfaces by pathogenic bacteria has been referred to as one of the contributing factors. In this study, scanning electron microscopy (SEM) was used to assess the presence of microorganisms adhered to the surface of mini-implants that failed due to loss of stability. Twelve self-drilling titanium mini-implants (1.6 mm diameter × 9.0 mm long) were collected from 12 patients undergoing orthodontic treatment-7 successful and 5 failed mini-implants. The mean time of permanence in the mouth was 15.8 and 2.4 months for successful and failed mini-implants, respectively. The devices were placed in the maxilla and/or mandible and removed by the same surgeon and were processed for SEM analysis of the presence of microorganisms on their surfaces (head, transmucosal profile, and body). Extensive bacterial colonization on mini-implant head and transmucosal profile was observed in all successful and failed mini-implants. None of the failed mini-implants exhibited bacteria on its body and only one mini-implant belonging to the successful (stable) group exhibited bacteria on its body. The results did not suggest a relationship between failure and presence of bacterial colonies on mini-implant surfaces. © 2015 Wiley Periodicals, Inc.

  19. A retrospective study on related factors affecting the survival rate of dental implants

    Science.gov (United States)

    Kang, Jeong-Kyung; Lee, Ki; Lee, Yong-Sang; Park, Pil-Kyoo

    2011-01-01

    PURPOSE The aim of this retrospective study is to analyze the relationship between local factors and survival rate of dental implant which had been installed and restored in Seoul Veterans Hospital dental center for past 10 years. And when the relationship is found out, it could be helpful to predict the prognosis of dental implants. MATERIALS AND METHODS A retrospective study of patients receiving root-shaped screw-type dental implants placed from January 2000 to December 2009 was conducted. 6385 implants were placed in 3755 patients. The following data were collected from the dental records and radiographs: patient's age, gender, implant type and surface, length, diameter, location of implant placement, bone quality, prosthesis type. The correlations between these data and survival rate were analyzed. Statistical analysis was performed with the use of Kaplan-Meier analysis, Chi-square test and odds ratio. RESULTS In all, 6385 implants were placed in 3755 patients (3120 male, 635 female; mean age 65 ± 10.58 years). 108 implants failed and the cumulative survival rate was 96.33%. There were significant differences in age, implant type and surface, length, location and prosthesis type (P.05). CONCLUSION Related factors such as age, implant type, length, location and prosthesis type had a significant effect on the implant survival. PMID:22259704

  20. Augmentation of localized defects of the anterior maxillary ridge with autogenous bone before insertion of implants

    NARCIS (Netherlands)

    Raghoebar, GM; Batenburg, RHK; Vissink, A; Reintsema, H

    1996-01-01

    Purpose: This study evaluated the applicability of intraorally harvested autogenous bone grafts for the augmentation of the narrow maxillary alveolar ridge to enable insertion of implants for single tooth replacement. Materials and Methods: Local defects of the anterior maxilla were reconstructed in

  1. An ecophysiological and developmental perspective on variation in vessel diameter.

    Science.gov (United States)

    Hacke, Uwe G; Spicer, Rachel; Schreiber, Stefan G; Plavcová, Lenka

    2017-06-01

    Variation in xylem vessel diameter is one of the most important parameters when evaluating plant water relations. This review provides a synthesis of the ecophysiological implications of variation in lumen diameter together with a summary of our current understanding of vessel development and its endogenous regulation. We analyzed inter-specific variation of the mean hydraulic vessel diameter (D v ) across biomes, intra-specific variation of D v under natural and controlled conditions, and intra-plant variation. We found that the D v measured in young branches tends to stay below 30 µm in regions experiencing winter frost, whereas it is highly variable in the tropical rainforest. Within a plant, the widest vessels are often found in the trunk and in large roots; smaller diameters have been reported for leaves and small lateral roots. D v varies in response to environmental factors and is not only a function of plant size. Despite the wealth of data on vessel diameter variation, the regulation of diameter is poorly understood. Polar auxin transport through the vascular cambium is a key regulator linking foliar and xylem development. Limited evidence suggests that auxin transport is also a determinant of vessel diameter. The role of auxin in cell expansion and in establishing longitudinal continuity during secondary growth deserve further study. © 2016 John Wiley & Sons Ltd.

  2. Diameter dependent electron transfer kinetics in semiconductor-enzyme complexes.

    Science.gov (United States)

    Brown, Katherine A; Song, Qing; Mulder, David W; King, Paul W

    2014-10-28

    Excited state electron transfer (ET) is a fundamental step for the catalytic conversion of solar energy into chemical energy. To understand the properties controlling ET between photoexcited nanoparticles and catalysts, the ET kinetics were measured for solution-phase complexes of CdTe quantum dots and Clostridium acetobutylicum [FeFe]-hydrogenase I (CaI) using time-resolved photoluminescence spectroscopy. Over a 2.0-3.5 nm diameter range of CdTe nanoparticles, the observed ET rate (kET) was sensitive to CaI concentration. To account for diameter effects on CaI binding, a Langmuir isotherm and two geometric binding models were created to estimate maximal CaI affinities and coverages at saturating concentrations. Normalizing the ET kinetics to CaI surface coverage for each CdTe diameter led to k(ET) values that were insensitive to diameter, despite a decrease in the free energy for photoexcited ET (ΔGET) with increasing diameter. The turnover frequency (TOF) of CaI in CdTe-CaI complexes was measured at several molar ratios. Normalization for diameter-dependent changes in CaI coverage showed an increase in TOF with diameter. These results suggest that k(ET) and H2 production for CdTe-CaI complexes are not strictly controlled by ΔG(ET) and that other factors must be considered.

  3. A longitudinal retrospective study of the analysis of the risk factors of implant failure by the application of generalized estimating equations.

    Science.gov (United States)

    Noda, Kinji; Arakawa, Hikaru; Kimura-Ono, Aya; Yamazaki, Seiya; Hara, Emilio Satoshi; Sonoyama, Wataru; Maekawa, Kenji; Okura, Kazuo; Shintani, Ayumi; Matsuka, Yoshizo; Kuboki, Takuo

    2015-07-01

    Many studies have identified risk factors for dental implant failure, although few have investigated the correlation among implant fixtures within single patients. A better analytical method may include repeated measures analysis including generalized estimating equations (GEE). This retrospective cohort study aimed to (1) identify the risk factors for failure of dental implantation and (2) evaluate an analytical method using GEE analysis. We analyzed data on early and late implant failures in 296 patients providing 721 rough surface dental implants (2.44 implants per patient). Potential predictors of implant failure included age, gender, smoking, location of implant, use of bone augmentation, number of remaining teeth, opposing tooth condition, fixture length, fixture diameter and type of suprastructure (fixed or removable partial denture). The likelihood of early and late implant failure was estimated by GEE. The early failure rate was 1.5% (11/721 implants, 7/296 patients) and the 10-year cumulative survival rate was 94.0% (7/710 implants, 5/293 patients). The GEE analysis revealed that a significant risk factor for early implant failure was smoking (pfailure were maxillary implant (p=0.02), posterior implant (panalysis showed that smoking was a risk factor for early implant failure, and several risk factors were identified for late implant failure. Copyright © 2015 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  4. [Experimental implantation of hydrogel into bone].

    Science.gov (United States)

    Korbelár, P; Vacík, J; Dylevský, I; Sulc, J; Hulvert, J

    1989-02-01

    In spite of the rapid development of various natural and artifical implants of bone tissue, bones or whole joints, no material was found as yet which would maximally resemble the structure of the bone tissue and would also be maximally compatible. The present study deals with the application possibilities of unsoluble hydrophilic gels (hydrogels) as substitutes of bone tissue in experiment. The study concerns above all their biocompatibility with regard to the porous qualities of the implant and to its chemical structure, and evaluates their behaviour in the spongious and compact bone. It was used polyhydroxyethylmethacrylate (polyHEMA) which is crossling with small amount of glycoldimethacrylate when by changing of ratio monomer: water is possible obtain from homogeneous to macroporous structure of polymers. The macroporous structure was increased and the surface of the macroporous structure of polymers. The macroporous structure was increased and the surface of the macroporous, sinterted HEMA modified and implanted. The so-called double porosity was thus obtained. The implants were prepared in the form of cylinders (3.5 mm in diameter) in 8 different modifications and surgically implanted into the subtrochanteric and supracondylic part of the rabbit femurs. 42 animals were operated on. The obtained preparations were then evaluated macroscopically, and histologically processed in half-thin cuts (3-4 micrones). 124 samples were thus obtained. Some samples were radiographically contrasting. The rabbits were killed at intervals from 1-6 months, i.e. 32-193 days. It was found that the hydrogels modifications used in the experiment are biocompatible, their compatibility increasing in dependence on the increasing porosity. The non-porous and microporous hydrogels are not compatible and are damarked. The sintered macroporous gel is surrounded by a thin fibrine membrane signifying a high degree of compatibility with the bone tissue. By adding metacrylate acid to the

  5. The underdilation of nitinol stents at TIPS implantation: Solution or illusion?

    International Nuclear Information System (INIS)

    Mollaiyan, Ashkan; Bettinger, Dominik; Rössle, Martin

    2017-01-01

    Purpose: This study investigates the behaviour of self-expanding nitinol stents at the time of TIPS-implantation and thereafter. Methods: Hundred consecutive patients with cirrhosis receiving a TIPS revision were included. The smallest stent diameter was measured radiologically immediately after implantation and before shunt revision. Accuracy of the measurement was assessed by comparing the nominal stent diameter with the largest stent diameter measured at the time of revision. Results: Pearson correlation between largest measured and nominal diameters was excellent (r = 0.952, p < 0.001) showing that measurements are accurate. At TIPS implantation all stents were markedly underdilated reaching only 76–92% of their nominal diameter. Smallest measured diameters were similar (8 mm) irrespective of the nominal diameter (8, 9, 10 mm) of the stent. In addition, smallest diameters of 10 mm stents were similar irrespective whether 8, 9 or 10 mm balloons were used. During a mean follow-up of 12.7 ± 17.8 months (median 3 months, range 1–81) stents expanded by 0.5–1.6 mm dependent on the nominal stent size (8, 9, 10 mm) and the grade of primary underdilation. No significant difference was found between Viatorr and bare stents. Conclusions: At TIPS-implantation, the compliance of the surrounding tissue predominantly determines the stent diameter. The nominal size of the stent or the dilatation balloon has little influence. Accurate adjustment of a desired pressure gradient is, therefore, not possible. During follow-up, stents expand towards their nominal diameter questioning the usefulness of underdilation.

  6. The underdilation of nitinol stents at TIPS implantation: Solution or illusion?

    Energy Technology Data Exchange (ETDEWEB)

    Mollaiyan, Ashkan [University Hospital, Department of Radiology, Hugstetterstrasse 55, 79106 Freiburg (Germany); Bettinger, Dominik [University Hospital, Department of Gastroenterology, Hugstetterstrasse 55, 79106 Freiburg (Germany); Berta-Ottenstein-Programme, Faculty of Medicine, University of Freiburg (Germany); Rössle, Martin, E-mail: Martin-Roessle@t-online.de [University Hospital, Department of Gastroenterology, Hugstetterstrasse 55, 79106 Freiburg (Germany); Praxiszentrum für Gastroenterologie, Bertoldstrasse 48, 79098 Freiburg (Germany)

    2017-04-15

    Purpose: This study investigates the behaviour of self-expanding nitinol stents at the time of TIPS-implantation and thereafter. Methods: Hundred consecutive patients with cirrhosis receiving a TIPS revision were included. The smallest stent diameter was measured radiologically immediately after implantation and before shunt revision. Accuracy of the measurement was assessed by comparing the nominal stent diameter with the largest stent diameter measured at the time of revision. Results: Pearson correlation between largest measured and nominal diameters was excellent (r = 0.952, p < 0.001) showing that measurements are accurate. At TIPS implantation all stents were markedly underdilated reaching only 76–92% of their nominal diameter. Smallest measured diameters were similar (8 mm) irrespective of the nominal diameter (8, 9, 10 mm) of the stent. In addition, smallest diameters of 10 mm stents were similar irrespective whether 8, 9 or 10 mm balloons were used. During a mean follow-up of 12.7 ± 17.8 months (median 3 months, range 1–81) stents expanded by 0.5–1.6 mm dependent on the nominal stent size (8, 9, 10 mm) and the grade of primary underdilation. No significant difference was found between Viatorr and bare stents. Conclusions: At TIPS-implantation, the compliance of the surrounding tissue predominantly determines the stent diameter. The nominal size of the stent or the dilatation balloon has little influence. Accurate adjustment of a desired pressure gradient is, therefore, not possible. During follow-up, stents expand towards their nominal diameter questioning the usefulness of underdilation.

  7. A Randomized Seven-Year Study on Performance of the Stemmed Metal M2a-Magnum and Ceramic C2a-Taper, and the Resurfacing ReCap Hip Implants

    DEFF Research Database (Denmark)

    Borgwardt, Arne; Borgwardt, Lotte; Zerahn, Bo

    2018-01-01

    BACKGROUND: The large-diameter metal-on-metal hip prostheses were expected to have low wear and reduced dislocation rate compared to the traditional metal-on-polyethylene implants. We compare 2 such prostheses, the ReCap resurfacing implant and the M2a-Magnum stemmed implant, with the C2a ceramic...

  8. Calibration of the radiometric asteroid scale using occultation diameters

    Science.gov (United States)

    Brown, R. H.; Morrison, D.; Telesco, C. M.; Brunk, W. E.

    1982-10-01

    The paper describes a new approach to the calibration of the radiometric asteroid scale, which relies on recent accurate occultation measurements of the diameters of 2 Pallas (Wasserman et al., 1979) and 3 Juno (Millis et al., 1981), and the Voyager diameter of J4 Callisto, as well as IR photometry of these objects obtained with the NASA 3-m Infrared Telescope Facility. It is shown that this calibration is internally consistent to better than 5%, and probably has an absolute accuracy of + or - 5%. It is noted that a revision of the TRIAD radiometric diameters downward is required to bring them into agreement with the new calibration.

  9. Changes in Bone Levels Around Mini-Implants in Edentulous Arches.

    Science.gov (United States)

    Mundt, Torsten; Schwahn, Christian; Biffar, Reiner; Heinemann, Friedhelm

    2015-01-01

    To evaluate changes in marginal bone levels around maxillary and mandibular mini-implants stabilizing complete dentures and to explore possible risk factors associated with bone loss. All eligible patients from nine private dental practices were invited to participate. Panoramic radiographs were obtained postoperatively and at the follow-up examination. The changes in bone level were estimated with linear mixed models that included the factors sex, age, jaw, region (anterior versus posterior), smoking habits, and loading concept. Of the 180 invited patients, 133 participated in the follow-up (response rate: 73.9%). Of 336 mini-implants in 54 maxillas and 402 mini-implants in 95 mandibles, 15 maxillary implants and 11 mandibular implants were lost after insertion, and 4 mandibular implants fractured. Radiographic evaluations in 11 participants were not possible. The mean marginal bone loss at the remaining 634 mini-implants in 122 patients was 0.8 mm in the maxilla and 0.5 mm in the mandible over a mean observation time of 2.2 ± 1.0 years. This difference in univariate estimation lost significance after adjusting for the other variables. Implants in former smokers showed more bone loss than implants in participants who had never smoked. Implants that were loaded 3 to 4 months after placement (delayed loading) showed more marginal bone loss than immediately loaded implants. No statistically significant differences were found between men and women, different age groups, or anterior and posterior implants. Mean marginal bone loss around mini-implants used to stabilize complete dentures was insignificantly higher in the maxilla than in the mandible after a mean observation period of 2.3 years. These values are comparable with marginal bone loss around standard-diameter implants. A previous smoking habit and delayed loading after implant placement with a low insertion torque were shown to be possible risk factors for bone loss.

  10. Load limit of mini-implants with reduced abutment height based on fatigue fracture resistance: experimental and finite element study.

    Science.gov (United States)

    Toyoshima, Yusuke; Wakabayashi, Noriyuki

    2015-01-01

    The primary objective of this study was to investigate the fracture resistance of experimental mini-implants with a reduced abutment height. The secondary objective was to assess the effects of implant diameter and bone level on the load limit, using finite element simulations. Two Ti-6A1-4V 1.8-mm-diameter implants were subjected to monotonic bending testing and fatigue tests incorporating 5 x 10(6) cycles (ISO 14801): a commercially available implant (c18), and an experimental implant with a reduced abutment height (e18). The load limit was estimated using the finite element models based on the maximum stress at failure in the experiments. For simulations, implants with increased diameters of 2.1 and 2.4 mm were also modeled, and the load limit was estimated for all models in a bone model. In the bending test, e18 revealed a higher mean load at yield stress than c18, and this was attributed to the reduced height of the former. An endurance limit of 140 N was detected for both c18 and e18 in the fatigue test, while the load limit of e18 was higher than that of c18. The estimated load limit increased as the implant diameter or the bone level increased, with the highest value of 510 N observed at a diameter of 2.4 mm. A higher load limit was evident in the experimental mini-implant with a reduced abutment height. The simulations indicated that the load limit increased with increased implant diameter and higher bone levels.

  11. 75 FR 11908 - Narrow Woven Ribbons With Woven Selvedge From China and Taiwan

    Science.gov (United States)

    2010-03-12

    ...)] Narrow Woven Ribbons With Woven Selvedge From China and Taiwan AGENCY: United States International Trade... less- than-fair-value imports from Taiwan of narrow woven ribbons with woven selvedge (``narrow woven... merchandise as ``* * * narrow woven ribbons with woven selvedge, in any length, but with a width (measured at...

  12. Tactile sensibility of single-tooth implants and natural teeth.

    Science.gov (United States)

    Enkling, Norbert; Nicolay, Claudia; Utz, Karl-Heinz; Jöhren, Peter; Wahl, Gerhard; Mericske-Stern, Regina

    2007-04-01

    The purpose of this randomized split-mouth clinical trial was to determine the active tactile sensibility between single-tooth implants and opposing natural teeth and to compare it with the tactile sensibility of pairs of natural teeth on the contralateral side in the same mouth (intraindividual comparison). The hypothesis was that the active tactile sensibilities of the implant side and control side are equivalent. Sixty two subjects (n=36 from Bonn, n=26 from Bern) with single-tooth implants (22 anterior and 40 posterior dental implants) were asked to bite on narrow copper foil strips varying in thickness (5-200 microm) and to decide whether or not they were able to identify a foreign body between their teeth. Active tactile sensibility was defined as the 50% threshold of correct answers estimated by means of the Weibull distribution. The results obtained for the interocclusal perception sensibility differed between subjects far more than they differed between natural teeth and implants in the same individual [implant/natural tooth: 16.7+/-11.3 microm (0.6-53.1 microm); natural tooth/natural tooth: 14.3+/-10.6 microm (0.5-68.2 microm)]. The intraindividual differences only amounted to a mean value of 2.4+/-9.4 microm (-15.1 to 27.5 microm). The result of our statistical calculations showed that the active tactile sensibility of single-tooth implants, both in the anterior and posterior region of the mouth, in combination with a natural opposing tooth is similar to that of pairs of opposing natural teeth (double t-test, equivalence margin: +/-8 microm, P80%). Hence, the implants could be integrated in the stomatognathic control circuit.

  13. Improved Design Basis for Laterally Loaded Large Diameter Pile

    DEFF Research Database (Denmark)

    Leth, Caspar Thrane

    in dry sand by use of centrifuge modelling and to compare the findings with the standard p-y curves. It has been chosen to apply piles with an embedment length of 6 to 10 times the diameter of the applied piles. The general static behaviour of monopiles in dry sand has based on centrifuge tests been...... initial response and a higher ultimate capacity. The initial stiffness of the soil-structure interaction measured in the centrifuge tests, equivalent to initial stiffness of p-y curves, shows a dependency of depth and diameter. Control issues in relation to cyclic tests have resulted in tests...... on the structure and the productivity of the turbine. Current design practice for monopiles are based on p-y curves developed for slender piles with a diameter of 0.6 m. The focus on the structure stiffness has entailed a significant research on the soil-structure interaction for large diameter monopiles...

  14. Porosity Assessment for Different Diameters of Coir Lignocellulosic Fibers

    Science.gov (United States)

    da Luz, Fernanda Santos; Paciornik, Sidnei; Monteiro, Sergio Neves; da Silva, Luiz Carlos; Tommasini, Flávio James; Candido, Verônica Scarpini

    2017-10-01

    The application of natural lignocellulosic fibers (LCFs) in engineering composites has increased interest in their properties and structural characteristics. In particular, the inherent porosity of an LCF markedly affects its density and the adhesion to polymer matrices. For the first time, both open and closed porosities of a natural LCF, for different diameter ranges, were assessed. Fibers extracted from the mesocarp of the coconut fruit were investigated by nondestructive methods of density measurements and x-ray microtomography (microCT). It was found that, for all diameter ranges, the closed porosity is significantly higher than the open porosity. The total porosity increases with diameter to around 60% for coir fibers with more than 503 μm in diameter. The amount and characteristics of these open and closed porosities were revealed by t test and Weibull statistics as well as by microCT.

  15. Synthesis of very small diameter silica nanofibers using sound waves.

    Science.gov (United States)

    Datskos, Panos; Chen, Jihua; Sharma, Jaswinder

    2014-07-14

    Silica nanofibers of an average diameter ≈30 nm and length ≈100 μm have been synthesized using an unprecedented strategy: sound waves. A new phenomenon, spinning off the nanofibers at silica rod tips, is also observed.

  16. Observations on placentome diameters in gestating West African ...

    African Journals Online (AJOL)

    ADEYEYE

    2015-09-09

    /10.4314/sokjvs.v13i3.4. Observations on placentome diameters in gestating West. African dwarf does experimentally infected with Trypanosoma brucei. OO Leigh. Department of Veterinary Surgery and Reproduction, ...

  17. Deriving muscle fiber diameter from recorded single fiber potential.

    Science.gov (United States)

    Zalewska, Ewa

    2017-12-01

    The aim of the study was to estimate muscle fiber diameters through analysis of single muscle fiber potentials (SFPs) recorded in the frontalis muscle of a healthy subject. Our previously developed analytical and graphic method to derive fiber diameter from the analysis of the negative peak duration and the amplitude of SFP, was applied to a sample of ten SFPs recorded in vivo. Muscle fiber diameters derived from the simulation method for the sample of frontalis muscle SFPs are consistent with anatomical data for this muscle. The results confirm the utility of proposed simulation method. Outlying data could be considered as the result of a contribution of other fibers to the potential recorded using an SFEMG electrode. Our graphic tool provides a rapid estimation of muscle fiber diameter. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  18. NEOWISE DIAMETERS AND ALBEDOS V1.0

    Data.gov (United States)

    National Aeronautics and Space Administration — This PDS data set represents a compilation of published diameters, optical albedos, near-infrared albedos, and beaming parameters for minor planets detected by...

  19. Heritability of retinal vessel diameters and blood pressure

    DEFF Research Database (Denmark)

    Taarnhøj, Nina C B B; Larsen, Michael; Sander, Birgit

    2006-01-01

    for CRVE, and 0.67 +/- 0.05 microm for AVR. No significant influence on artery or vein diameters was found for gender, smoking, body mass index (BMI), total cholesterol, fasting blood glucose, or 2-hour oral glucose tolerance test values. CONCLUSIONS: In healthy young adults with normal blood pressure......PURPOSE: To assess the relative influence of genetic and environmental effects on retinal vessel diameters and blood pressure in healthy adults, as well as the possible genetic connection between these two characteristics. METHODS: In 55 monozygotic and 50 dizygotic same-sex healthy twin pairs......%-80%) for CRAE, 83% (95% CI: 73%-89%) for CRVE, and 61% (95% CI: 44%-73%) for mean arterial blood pressure (MABP). Retinal artery diameter decreased with increasing age and increasing arterial blood pressure. Mean vessel diameters in the population were 165.8 +/- 14.9 microm for CRAE, 246.2 +/- 17.7 microm...

  20. Surface changes of implants after laser irradiation

    Science.gov (United States)

    Rechmann, Peter; Sadegh, Hamid M. M.; Goldin, Dan S.; Hennig, Thomas

    1999-05-01

    Periimplantitis is one of the major factors for the loss of dental implants. Due to the minor defense ability of the tissue surrounding the implant compared to natural teeth treatment of periimplantitis in the early stage is very important. Reducing bacteria with a laser might be the most successful step in therapy of periimplantitis. Aim of the study was to observe changes in surface morphology of seven different implants after irradiation with three different lasers. Two kinds of flat round samles were prepared by the manufacturers either identical to the body surface or to the cervical area of the corresponding implants. The samples were irradiated using different power settings. The lasers used were a CO2 laser (Uni Laser 450P, ASAH Medico Denmark; fiber guided, wavelength 10.6 μm, max. average power 8.3 W, "soft-pulse" and cw) an Er:YAG laser (KaVo Key Laser II, wavelength 2.94 μm, pulse duration 250-500μs, pulse energy 60-500 mJ, pulse repetition rate 1-15 Hz, focus diameter 620 μm, air-water cooling; Biberach, Germany; a frequency doubled Alexandrite laser (laboratory prototype, q-switched, fiber guided, wavelength 377 nm, pulse duration 1 μs, pulse repetition rate 30 Hz, water cooling). After irradiation the implant surfaces were investigated with a Scanning Electron Microscope. Ablation thresholds were determined. After CO2 laser irradiation no changes in surface morphology were observed whereas using the pulsed Er:YAG laser or frequency doubled Alexandrite laser even at low energies loss of integrity or melting of the surface was observed. The changes in surface morphology seem to depend very strongly on the type of surface coating.

  1. Hydroxyapatite implants with designed internal architecture.

    Science.gov (United States)

    Chu, T M; Halloran, J W; Hollister, S J; Feinberg, S E

    2001-06-01

    Porous hydroxyapatite (HA) has been used as a bone graft material in the clinics for decades. Traditionally, the pores in these HAs are either obtained from the coralline exoskeletal patterns or from the embedded organic particles in the starting HA powder. Both processes offer very limited control on the pore structure. A new method for manufacturing porous HA with designed pore channels has been developed. This method is essentially a lost-mold technique with negative molds made with Stereolithography and a highly loaded curable HA suspension as the ceramic carrier. Implants with designed channels and connection patterns were first generated from a Computer-Aided-Design (CAD) software and Computer Tomography (CT) data. The negative images of the designs were used to build the molds on a stereolithography apparatus with epoxy resins. A 40 vol% HA suspension in propoxylated neopentyl glycol diacrylate (PNPGDA) and iso-bornyl acrylate (IBA) was formulated. HA suspension was cast into the epoxy molds and cured into solid at 85 degrees C. The molds and acrylate binders were removed by pyrolysis, followed by HA green body sintering. With this method, implants with six different channel designs were built successfully and the designed channels were reproduced in the sintered HA implants. The channels created in the sintered HA implants were between 366 microm and 968 microm in diameter with standard deviations of 50 microm or less. The porosity created by the channels were between 26% and 52%. The results show that HA implants with designed connection pattern and well controlled channel size can be built with the technique developed in this study. Copyright 2001 Kluwer Academic Publishers

  2. Maintenance in dental implants

    Directory of Open Access Journals (Sweden)

    Giselle Póvoa Gomes

    2008-01-01

    Full Text Available In implants, maintenance is a decisive factor for obtaining success when implant supported overdentures and dentures are used. The present stud presents, a clinical case of a patient, a 70 year-old white man, with a completely edentulous mandibular alveolar ridge, severe bone resorption with presence of basal bone only, and absence of vestibule. Initially, treatment consisted of the placement of a mandibular overdenture, supported on three implants in the anterior inter-foramen region, as the left implant was transfixed in the basal bone of 2 to 3 millimeters. Eleven years later, another two implants were placed in the anterior area and an immediate load was performed up to the first molars, for the placement of an implant supported fixed. Throughout the entire treatment, meticulous maintenance was carried out, with follow-up for fourteen years, interrupted by the patient’s death. From the third month after the opening the three implants initially placed, the presence of keratinized mucosa, definition of the vestibule, maturation of the alveolar ridge and bone formation in the mento region were observed. It was concluded that good planning, allied to mastery of the technique and adequate maintenance were the prerequisites necessary for obtaining favorable results, success of the present case, and for the patient to have a better quality of life.

  3. Ultrasonic measurement of biparietal diameter and femur in foetal ...

    African Journals Online (AJOL)

    Our objective was to verify ultrasonic measurement of biparietal diameter and femur in foetal age determination in the second and third trimester of pregnancy. The prospective cross sectional ... (3) L'errur standard pour la longueur du femur était de 0.2552 contre 0.3009 pour l'estimation du diameter bi-pariétal. Les résultats ...

  4. Coulomb and nuclear excitations of narrow resonances in 17Ne

    Directory of Open Access Journals (Sweden)

    J. Marganiec

    2016-08-01

    Full Text Available New experimental data for dissociation of relativistic 17Ne projectiles incident on targets of lead, carbon, and polyethylene targets at GSI are presented. Special attention is paid to the excitation and decay of narrow resonant states in 17Ne. Distributions of internal energy in the O15+p+p three-body system have been determined together with angular and partial-energy correlations between the decay products in different energy regions. The analysis was done using existing experimental data on 17Ne and its mirror nucleus 17N. The isobaric multiplet mass equation is used for assignment of observed resonances and their spins and parities. A combination of data from the heavy and light targets yielded cross sections and transition probabilities for the Coulomb excitations of the narrow resonant states. The resulting transition probabilities provide information relevant for a better understanding of the 17Ne structure.

  5. Period effects, cohort effects, and the narrowing gender wage gap.

    Science.gov (United States)

    Campbell, Colin; Pearlman, Jessica

    2013-11-01

    Despite the abundance of sociological research on the gender wage gap, questions remain. In particular, the role of cohorts is under investigated. Using data from the Current Population Survey, we use age-period-cohort analysis to uniquely estimate age, period, and cohort effects on the gender wage gap. The narrowing of the gender wage gap that occurred between 1975 and 2009 is largely due to cohort effects. Since the mid-1990s, the gender wage gap has continued to close absent of period effects. While gains in female wages contributed to declines in the gender wage gap for cohorts born before 1950, for later cohorts the narrowing of the gender wage gap is primarily a result of declines in male wages. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. All-fiber noninterferometric narrow-transmission-bandpass filter.

    Science.gov (United States)

    Sáez-Rodríguez, D; Cruz, J L; Díez, A; Andrés, M V

    2012-10-15

    In-fiber mode engineering based on the combination of Bragg and long-period gratings (LPGs) permits the implementation of noninterferometric transmission filters with narrow passbands using standard single-mode fiber. The design of the bandpass filter is based on the coupling between propagating and counterpropagating cladding modes in two fiber Bragg gratings. A LPG located between the Bragg gratings transfers power from the input fundamental mode to a specific cladding mode and recouples the filtered signal to the output fundamental mode. The filter produces a series of narrow passbands of about 30 pm linewidth with a maximum transmittance above 60%, 20 dB isolation, and passband separation of about 1 nm, each corresponding to the contribution of a different cladding mode.

  7. Implants in the hand; Implantate der Hand

    Energy Technology Data Exchange (ETDEWEB)

    Wanivenhaus, A. [Medizinische Universitaet, Universitaetsklinik fuer Orthopaedie, Wien (Austria)

    2006-09-15

    Increasingly, implants in the region of hand joints and the wrist represent an alternative for the treatment of post-traumatic, inflamed, or degenerative joint damage. The diversity of hand functions also results in varied solutions, which are effective in their stability, mobility, and distraction. Different materials are necessary for this, and they require subtile radiological control. The native X-ray represents the substantial method to observe migration of the implants. Each interface between titanium, ceramic, zirconium, pyrocarbon, and silicon to the bone has to be assessed differently in order to obtain a relevant statement. The finger joints and to a limited extent the wrist represent the artificial joints with limited alternative therapy. Other implants in the hand should only be applied after strict indication and patient compliance, as arthrodesis and resection arthroplasty have shown very good long-term results. (orig.) [German] Implantate im Bereich der Gelenke der Hand und des Handgelenks stellen zunehmend Alternativen bei der Versorgung posttraumatischer, entzuendlicher oder degenerativer Gelenkschaeden dar. Die Vielfalt der Handfunktionen fuehrt auch zu unterschiedlichen Loesungen, die durch Stabilitaet, Mobilitaet und Distraktion wirksam werden. Dafuer sind unterschiedliche Materialien erforderlich, die eine subtile radiologische Kontrolle erfordern. Das Nativroentgen stellt das wesentlichste Verfahren zur Verlaufsbeobachtung von Implantaten dar. Das Interface zwischen Titan, Keramik, Zirkonium, Pyrokarbon und Silikon zum Knochen muss unterschiedlich bewertet werden, um relevante Aussagen treffen zu koennen. Die Fingergelenke und in begrenztem Ausmass auch das Handgelenk stellen Kunstgelenke mit geringen Alternativtherapiemoeglichkeiten dar. Die uebrigen Implantate der Hand sollten nur bei strenger Indikationsstellung und hoher Patientencompliance Anwendung finden, da Arthrodese oder Resektionsarthroplastik gute Langzeitresultate aufweisen. (orig.)

  8. Nanotechnology for dental implants.

    Science.gov (United States)

    Tomsia, Antoni P; Lee, Janice S; Wegst, Ulrike G K; Saiz, Eduardo

    2013-01-01

    With the advent of nanotechnology, an opportunity exists for the engineering of new dental implant materials. Metallic dental implants have been successfully used for decades, but they have shortcomings related to osseointegration and mechanical properties that do not match those of bone. Absent the development of an entirely new class of materials, faster osseointegration of currently available dental implants can be accomplished by various surface modifications. To date, there is no consensus regarding the preferred method(s) of implant surface modification, and further development will be required before the ideal implant surface can be created, let alone become available for clinical use. Current approaches can generally be categorized into three areas: ceramic coatings, surface functionalization, and patterning on the micro- to nanoscale. The distinctions among these are imprecise, as some or all of these approaches can be combined to improve in vivo implant performance. These surface improvements have resulted in durable implants with a high percentage of success and long-term function. Nanotechnology has provided another set of opportunities for the manipulation of implant surfaces in its capacity to mimic the surface topography formed by extracellular matrix components of natural tissue. The possibilities introduced by nanotechnology now permit the tailoring of implant chemistry and structure with an unprecedented degree of control. For the first time, tools are available that can be used to manipulate the physicochemical environment and monitor key cellular events at the molecular level. These new tools and capabilities will result in faster bone formation, reduced healing time, and rapid recovery to function.

  9. Catalytic growth of carbon nanotubes with large inner diameters

    Directory of Open Access Journals (Sweden)

    WEI REN ZHONG

    2005-02-01

    Full Text Available Carbon nanotubes (2.4 g/g catalyst, with large inner diameters were successfully synthesized through pyrolysis of methane on a Ni–Cu–Al catalyst by adding sodium carbonate into the carbon nanotubes growth system. The inner diameter of the carbon nanotubes prepared by this method is about 20–60 nm, while their outer diameter is about 40–80 nm. Transmission electron microscopy and X-ray diffraction were employed to investigate the morphology and microstructures of the carbon nanotubes. The analyses showed that these carbon nanotubes have large inner diameters and good graphitization. The addition of sodium carbonate into the reaction system brings about a slight decrease in the methane conversion and the yield of carbon. The experimental results showed that sodium carbonate is a mildly toxic material which influenced the catalytic activity of the Ni–Cu–Al catalyst and resulted in the formation of carbon nanotubes with large inner diameters. The growth mechanism of the carbon nanotubes with large inner diameters is discussed in this paper.

  10. The Argument for a Narrow Conception of 'Religious Autonomy'

    DEFF Research Database (Denmark)

    Christoffersen, Lisbet

    2015-01-01

    This article argues for a both horizontal and vertical narrow concept of collective freedom of Religion. The most recent ECtHR judgments as well as the US Supreme Court Hosanna-Tabor case leads theory to establish religious autonomy based on parallel legal roders. Nordic theory has been based on ...... on lack of acknowledgement of Canon Law, which is no longer possible. A future path might be to accept overlapping normative orders, however with secular courts as the final institutions....

  11. Narrow line profiles and interacting gas flows in active galaxies

    International Nuclear Information System (INIS)

    Mardaljevic, J.; Raine, D.J.; Smith, M.D.

    1986-01-01

    The 'catapult model' of the narrow line region involves both infalling and outflowing clouds interacting with an outflowing wind. The emission line profiles in this model are derived and the results compared with observation. Supersonic and subsonic winds in the interaction zone produce distinct line profiles, both of which are observed. Flat-topped profiles, the presence of broad wings, asymmetry and line shifts are discussed. A relationship between profile shape and X-ray properties is predicted. (author)

  12. Elongational viscosity of narrow molar mass distribution polystyrene

    DEFF Research Database (Denmark)

    Bach, Anders; Almdal, Kristoffer; Rasmussen, Henrik Koblitz

    2003-01-01

    Transient and steady elongational viscosity has been measured for two narrow molar mass distribution polystyrene melts of molar masses 200 000 and 390 000 by means of a filament stretching rheometer. Total Hencky strains of about five have been obtained. The transient elongational viscosity rises...... above the linear viscoelastic prediction at intermediate strains, indicating strain hardening. The steady elongational viscosities are monotone decreasing functions of elongation rate. At elongation rates larger than the inverse reptation time, the steady elongational viscosity scales linearly...

  13. Ultrahigh-efficiency, very narrow-passband, tunable optical filter

    Science.gov (United States)

    Sandford, Stephen P.; Thomas, Milfred E.

    1994-01-01

    Recently developed technologies have been uniquely integrated to produce optical filters with unprecedented performance. The precise design and fabrication of narrow-passband and high-efficiency optical filters with a central frequency of 532 nm are reported. Measurements with these filters demonstrate a performance that accurately mirrors the design specification, with one filter having a passband of 70 pm and an efficiency greater than 90% and the second filter having a passband of 7 pm and an efficiency greater than 80%.

  14. Low-frequency oscillations in narrow vibrated granular systems

    OpenAIRE

    Rivas, Nicolas; Luding, Stefan; Thornton, Anthony R

    2013-01-01

    We present simulations and a theoretical treatment of vertically vibrated granular media. The systems considered are confined in narrow quasi-two-dimensional and quasi-one-dimensional (column) geometries, where the vertical extension of the container is much larger than both horizontal lengths. The additional geometric constraint present in the column setup frustrates the convection state that is normally observed in wider geometries. This makes it possible to study collective oscillations of...

  15. Gain-switched all-fiber laser with narrow bandwidth

    DEFF Research Database (Denmark)

    Larsen, Casper; Giesberts, M.; Nyga, S.

    2013-01-01

    Gain-switching of a CW fiber laser is a simple and cost-effective approach to generate pulses using an all-fiber system. We report on the construction of a narrow bandwidth (below 0.1 nm) gain-switched fiber laser and optimize the pulse energy and pulse duration under this constraint. The extracted...... the bandwidth below 0.1 nm. This allows frequency doubling in a periodically poled lithium tantalate crystal with a reasonable conversion efficiency....

  16. Photoluminescence from narrow InAs-AlSb quantum wells

    Science.gov (United States)

    Brar, Berinder; Kroemer, Herbert; Ibbetson, James; English, John H.

    1993-01-01

    We report on photoluminescence spectra from narrow InAs-AlSb quantum wells. Strong, clearly resolved peaks for well widths from 2 to 8 monolayers were observed. Transmission electron micrographs show direct evidence for the structural quality of the quantum well structures. The transition energies of the narrowest wells suggest a strong influence of the AlSb X-barrier on the electronic states in the conduction band.

  17. Microscopic Study of Surface Microtopographic Characteristics of Dental Implants

    Science.gov (United States)

    Sezin, M.; Croharé, L.; Ibañez, J.C.

    2016-01-01

    Objective: To determine and compare the micro topographic characteristics of dental implants submitted to different surface treatments, using scanning electron microscopy (SEM). Materials and Methods: Implants were divided into 7 groups of 3 specimens each, according to the surface treatment used: group 1: Osseotite, BIOMET 3i; group 2: SLA surface, Institut Straumann AG; group 3: Oxalife surface, Tree-Oss implant; group 4: B&W implant surface; group 5: Q-implant surface; group 6: ML implant surface; group 7: RBM surface, Rosterdent implant. The surfaces were examined under SEM (Carl Zeiss FE-SEM-SIGMA). Image Proplus software was used to determine the number and mean diameter of pores per area unit (mm). The data obtained were analyzed with the Mann-Whitney test. A confocal laser microscope (LEXT-OLS4100 Olympus) was used to conduct the comparative study of surface roughness (Ra). Data were analyzed using Tukey's HSD test. Results: The largest average pore diameter calculated in microns was found in group 5 (3.45 µm+/-1.91) while the smallest in group 7 (1.47µm+/-1.29). Significant differences were observed among each one of the groups studied (p<0.05). The largest number of pores/mm2 was found in group 2 (229343) and the smallest number in group 4 (10937). Group 2 showed significant differences regarding the other groups (p<0.05). The greatest roughness (Ra) was observed in group 2 (0.975µm+/-0.115) and the smallest in group 4 (0.304µm+/-0.063). Group 2 was significantly different from the other groups (p<0.05). Conclusion: The micro topography observed in the different groups presented dissimilar and specific features, depending on the chemical treatment used for the surfaces.. PMID:27335615

  18. Polyhydroxybutyrate/valerate/polycaprolactone small-diameter vascular graft: Experimental study of integration into organism

    Energy Technology Data Exchange (ETDEWEB)

    Antonova, L. V., E-mail: antonova.la@mail.ru; Burago, A. Yu.; Matveeva, V. G.; Velikanova, E. A.; Mukhamadiyarov, R. A.; Glushkova, T. V.; Kudryavtseva, Y. A.; Barbarash, O. L.; Barbarash, L. S. [Research Institute for Complex Issues of Cardiovascular Diseases, Kemerovo (Russian Federation); Mironov, A. V. [Kemerovo Cardiology Dispensary, Kemerovo (Russian Federation)

    2015-10-27

    We prepared polyhydroxybutyrate/valerate (PHBV)/polylcaprolactone (PCL) small-diameter vascular grafts using electrospinning. Surface structure was assessed by scanning electron microscopy whilst physicomechanical properties were investigated by longitudinal uniaxial tension testing. Patency of grafts implanted into the rat abdominal aorta was evaluated using a Doppler ultrasonography at 2 week, 1 month and 12 month postimplantation. In addition, we assessed local histological features, along with IL-1β, IL-2, IL-4, IL-10, TNFa, TGF-β1, and VEGF serum levels. We revealed that only 2 (25%) grafts were not thrombosed at 2 week and 1 month postimplantation. However, at 12 month postimplantation a satisfactory histological pattern was observed in 50% of all cases, and we detected a monolayer of endothelial cells on the inner graft surface in half the cases. Regarding other grafts, we revealed minor connective tissue hyperplasia in 41.7% of the grafts and an inflammatory infiltrate in the part of the arterial wall in 8.3% of the grafts. We found that the IL-1β serum level was 3.5-fold higher in the group of experimental rats at 12 month postimplantation (p < 0.01). In addition, the IL-2 and IL-4 serum levels at 12 month postimplantation were 2- and 2.8-fold higher as compared to short-term implantation (2 weeks and 1 month) and control rats (p < 0.05) whilst the IL-10 serum level at 1 and 12 month postimplantation was more than 100-fold higher in comparison with 2 week postimplantation and control rats (p < 0.001). Serum VEGF was detected only at 12 month postimplantation. All in all, we created a biocompatible PHBV/PCL small-diameter vascular graft with a high surface area to volume ratio. A long-term patency of biodegradable vascular grafts after implantation into the rat abdominal aorta and the absence of a considerable immune response confirmed a high biocompatibility of such construct and the possibility of its use as a vascular graft.

  19. Polyhydroxybutyrate/valerate/polycaprolactone small-diameter vascular graft: Experimental study of integration into organism

    Science.gov (United States)

    Antonova, L. V.; Burago, A. Yu.; Mironov, A. V.; Matveeva, V. G.; Velikanova, E. A.; Mukhamadiyarov, R. A.; Glushkova, T. V.; Kudryavtseva, Y. A.; Barbarash, O. L.; Barbarash, L. S.

    2015-10-01

    We prepared polyhydroxybutyrate/valerate (PHBV)/polylcaprolactone (PCL) small-diameter vascular grafts using electrospinning. Surface structure was assessed by scanning electron microscopy whilst physicomechanical properties were investigated by longitudinal uniaxial tension testing. Patency of grafts implanted into the rat abdominal aorta was evaluated using a Doppler ultrasonography at 2 week, 1 month and 12 month postimplantation. In addition, we assessed local histological features, along with IL-1β, IL-2, IL-4, IL-10, TNFa, TGF-β1, and VEGF serum levels. We revealed that only 2 (25%) grafts were not thrombosed at 2 week and 1 month postimplantation. However, at 12 month postimplantation a satisfactory histological pattern was observed in 50% of all cases, and we detected a monolayer of endothelial cells on the inner graft surface in half the cases. Regarding other grafts, we revealed minor connective tissue hyperplasia in 41.7% of the grafts and an inflammatory infiltrate in the part of the arterial wall in 8.3% of the grafts. We found that the IL-1β serum level was 3.5-fold higher in the group of experimental rats at 12 month postimplantation (p < 0.01). In addition, the IL-2 and IL-4 serum levels at 12 month postimplantation were 2- and 2.8-fold higher as compared to short-term implantation (2 weeks and 1 month) and control rats (p < 0.05) whilst the IL-10 serum level at 1 and 12 month postimplantation was more than 100-fold higher in comparison with 2 week postimplantation and control rats (p < 0.001). Serum VEGF was detected only at 12 month postimplantation. All in all, we created a biocompatible PHBV/PCL small-diameter vascular graft with a high surface area to volume ratio. A long-term patency of biodegradable vascular grafts after implantation into the rat abdominal aorta and the absence of a considerable immune response confirmed a high biocompatibility of such construct and the possibility of its use as a vascular graft.

  20. Electron correlations in narrow energy bands: modified polar model approach

    Directory of Open Access Journals (Sweden)

    L. Didukh

    2008-09-01

    Full Text Available The electron correlations in narrow energy bands are examined within the framework of the modified form of polar model. This model permits to analyze the effect of strong Coulomb correlation, inter-atomic exchange and correlated hopping of electrons and explain some peculiarities of the properties of narrow-band materials, namely the metal-insulator transition with an increase of temperature, nonlinear concentration dependence of Curie temperature and peculiarities of transport properties of electronic subsystem. Using a variant of generalized Hartree-Fock approximation, the single-electron Green's function and quasi-particle energy spectrum of the model are calculated. Metal-insulator transition with the change of temperature is investigated in a system with correlated hopping. Processes of ferromagnetic ordering stabilization in the system with various forms of electronic DOS are studied. The static conductivity and effective spin-dependent masses of current carriers are calculated as a function of electron concentration at various DOS forms. The correlated hopping is shown to cause the electron-hole asymmetry of transport and ferromagnetic properties of narrow band materials.

  1. Modelling and Simulations of a Narrow Track Tilting Vehicle

    Directory of Open Access Journals (Sweden)

    JJ Chong

    2016-10-01

    Full Text Available Narrow track tilting vehicle is a new category of vehicle that combines the dynamical abilities of a passenger car with a motorcycle. In the presence of overturning moments during cornering, an accurate assessment of the lateral dynamics plays an important role to improve their stability and handling. In order to stabilise or control the narrow tilting vehicle, the demand tilt angle can be calculated from the vehicle’s lateral acceleration and controlled by either steering input of the vehicle or using additional titling actuator to reach this desired angle. The aim of this article is to present a new approach for developing the lateral dynamics model of a narrow track tilting vehicle. First, this approach utilises the well-known geometry ‘bicycle model’ and parameter estimation methods. Second, by using a tuning method, the unknown and uncertainties are taken into account and regulated through an optimisation procedure to minimise the model biases in order to improve the modelling accuracy. Therefore, the optimised model can be used as a platform to develop the vehicle control strategy. Numerical simulations have been performed in a comparison with the experimental data to validate the model accuracy.

  2. Why Ξ (1690 ) and Ξ (2120 ) are so narrow

    Science.gov (United States)

    Khemchandani, K. P.; Martínez Torres, A.; Hosaka, A.; Nagahiro, H.; Navarra, F. S.; Nielsen, M.

    2018-02-01

    The Ξ baryons are expected to be naturally narrower as compared to their nonstrange and strange counterparts since they have only one light quark and, thus, their decay involves producing either a light meson and doubly strange baryon or both meson and baryon with strangeness which involves, relatively, more energy. In fact, some Ξ 's have full widths of the order of even 10-20 MeV when, in principle, they have a large phase space to decay to some open channels. Such is the case of Ξ (1690 ), for which the width has been found to be of the order of 10 MeV in the latest BABAR and BELLE data. In this manuscript we study why some Ξ 's are so narrow. Based on a coupled channel calculation of the pseudoscalar meson-baryon and vector meson-baryon systems with chiral and hidden local symmetry Lagrangians, we find that the answer lies in the intricate hadron dynamics. We find that the known mass, width, spin-parity, and branching ratios of Ξ (1690 ) can be naturally explained in terms of coupled channel meson-baryon dynamics. We find another narrow resonance which can be related to Ξ (2120 ). We also look for exotic states Ξ+ and Ξ- but find none. In addition we provide the cross sections for K ¯Λ ,K ¯Σ →π Ξ which can be useful for understanding the enhanced yield of Ξ reported in recent studies of heavy ion collisions.

  3. Searching for Variability of NV Intrinsic Narrow Absorption Line Systems

    Science.gov (United States)

    Rodruck, Michael; Charlton, Jane; Ganguly, Rajib

    2018-01-01

    The majority of quasar absorption line systems with NV detected are found within the associated region (within 5000 km/s of the quasar redshift) and many/most are believed to be related to the quasar accretion disk wind or outflows. The most definite evidence that these NV absorbers are "intrinsic" is partial covering of the quasar continuum source and/or broad line region. Over 75 quasars containing NV narrow absorption lines have observations obtained at different times with the Keck/HIRES and the VLT/UVES spectrographs at high resolution. The interval between these observations range from months to a decade in the quasar rest frame. While variability is common for intrinsic broad and mini-broad absorption lines, intrinsic narrow absorption lines have been found to be less likely to vary, though systematic studies with large, high quality datasets have been limited. The variability timescales are useful for deriving gas densities and thus the distances from the central engines. This is important in mapping the quasar surroundings, understanding the accretion disk wind mechanism, and assessing the effect the wind has on the galaxy surroundings. We report on the results of a systematic study of variability of NV NALs, exploiting the overlap of targets for observations in the archives of Keck and VLT, and discuss the consequences for interpretation of the origin of intrinsic narrow absorption lines.

  4. Laser linewidth narrowing using transient spectral hole burning

    Energy Technology Data Exchange (ETDEWEB)

    Thiel, Charles W.; Cone, Rufus L. [Department of Physics, Montana State University, Bozeman, MT 59715 (United States); Böttger, Thomas, E-mail: tbottger@usfca.edu [Department of Physics and Astronomy, 2130 Fulton Street, University of San Francisco, San Francisco, CA 94117 (United States)

    2014-08-01

    We demonstrate significant narrowing of laser linewidths by high optical density materials with inhomogeneously broadened absorption. As a laser propagates through the material, the nonlinear spectral hole burning process causes a progressive self-filtering of the laser spectrum, potentially reaching values less than the homogeneous linewidth. The transient spectral hole dynamically adjusts itself to the instantaneous frequency of the laser, passively suppressing laser phase noise and side modes over the entire material absorption bandwidth without the need for electronic or optical feedback to the laser. Wide bandwidth laser phase noise suppression was demonstrated using Er{sup 3+} doped Y{sub 2}SiO{sub 5} and LiNbO{sub 3} at 1.5 μm by employing time-delayed self-heterodyne detection of an external cavity diode laser to study the spectral narrowing effect. Our method is not restricted to any particular wavelength or laser system and is attractive for a range of applications where ultra-low phase noise sources are required. - Highlights: • We demonstrate significant laser linewidths narrowing by high optical density materials. • Nonlinear spectral hole burning causes progressive self-filtering of laser spectrum. • Filter dynamically adjusts itself to the instantaneous frequency of the laser. • Demonstrated at 1.5 μm in Er{sup 3+} doped Y{sub 2}SiO{sub 5} and LiNbO{sub 3}. • Linewidth filtering is not restricted to any particular wavelength or laser system.

  5. Joint Space Narrowing in Patients With Pisotriquetral Osteoarthritis.

    Science.gov (United States)

    Ten Berg, Paul W L; Heeg, Erik; Strackee, Simon D; Streekstra, Geert J

    2017-09-01

    Patients with suspected pisotriquetral osteoarthritis may show joint space narrowing. However, the extent of joint space narrowing and its deviation from the joint space width (JSW) in normal anatomy is unknown. In this pathoanatomic study, we therefore compared the JSW in the pisotriquetral joint between osteoarthritic patient wrists and healthy wrists. We reviewed preoperative computed tomography (CT) scans of 8 wrists of patients with ulnar-sided wrist pain who underwent a pisiformectomy with confirmed pisotriquetral osteoarthritis at surgery. We also reviewed CT scans of 20 normal wrists from healthy volunteers serving as control group. Three-dimensional CT models of the pisiform and triquetrum were obtained from both affected and normal wrists, after which the minimum JSW was calculated in an automated fashion. In the patient group, the median (interquartile range) of the minimum JSW was 0.1 mm (0.0-0.2), and in the control group, 0.8 mm (0.3-0.9) ( P = .007). We showed that the pisotriquetral joint space in osteoarthritic patient wrists was significantly narrowed compared with healthy wrists. These results suggest that JSW evaluation has a potential diagnostic value in the work-up of patients with suspected pisotriquetral osteoarthritis. This is an interesting area for future clinical research, especially because no gold standard for diagnosing pisotriquetral osteoarthritis has been established yet.

  6. Optimization of dental implantation

    Science.gov (United States)

    Dol, Aleksandr V.; Ivanov, Dmitriy V.

    2017-02-01

    Modern dentistry can not exist without dental implantation. This work is devoted to study of the "bone-implant" system and to optimization of dental prostheses installation. Modern non-invasive methods such as MRI an 3D-scanning as well as numerical calculations and 3D-prototyping allow to optimize all of stages of dental prosthetics. An integrated approach to the planning of implant surgery can significantly reduce the risk of complications in the first few days after treatment, and throughout the period of operation of the prosthesis.

  7. Radiology of Implant Dentistry.

    Science.gov (United States)

    Al-Ekrish, Asma'a Abdurrahman

    2018-01-01

    The article presents an overview of the goal of imaging at each stage of implant therapy and the usefulness and limitations of multidetector computed tomography (MDCT) in achieving those goals. Various MDCT protocols of use in implant imaging also are presented, with an emphasis on dose reduction and the use of iterative reconstruction techniques. Also discussed are options for viewing and analysis of CT images, issues related to appropriate image reformatting and interpretation, interactive treatment planning, and transfer of information from the images to the surgical field during implant surgery using surgical guides and CT-guided navigation systems. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Implants quality in HDR prostate brachytherapy related to the number of needles used;Qualidade de implantes de prostata com BATD em funcao do numero de agulhas usadas

    Energy Technology Data Exchange (ETDEWEB)

    Moura, Dayanne E.E.S; Martins, Homero L. [Hospital A.C. Camargo, Sao Paulo, SP (Brazil). Servico de Fisica Medica

    2009-07-01

    This paper aims to relate the quality of prostate implants (HDR) with the amount of needles used. 51 needle insertions performed in the institution were analyzed. The maximum diameter, the maximum height and target volume delineated by radiation oncologist were measured and this compared with the prostate volume obtained by the radiologist. It was concluded that the prostate volume measured by the radiologist is not a reliable indication to determine how the implant will be done and that the increase in the number of needles implanted did not necessarily ensure a better dose distribution. (author)

  9. Dealing with dental implant failures

    Directory of Open Access Journals (Sweden)

    Liran Levin

    2008-06-01

    Full Text Available An implant-supported restoration offers a predictable treatment for tooth replacement. Reported success rates for dental implants are high. Nevertheless, failures that mandate immediate implant removal do occur. The consequences of implant removal jeopardize the clinician's efforts to accomplish satisfactory function and esthetics. For the patient, this usually involves further cost and additional procedures. The aim of this paper is to describe different methods and treatment modalities to deal with dental implant failure. The main topics for discussion include identifying the failing implant, implants replacing failed implants at the exact site, and the use of other restorative options.When an implant fails, a tailor made treatment plan should be provided to each patient according to all relevant variables. Patients should be informed regarding all possible treatment modalities following implant failure and give their consent to the most appropriate treatment option for them.

  10. Mathematical evaluation of the influence of multiple factors on implant stability quotient values in clinical practice: a retrospective study

    Directory of Open Access Journals (Sweden)

    Huang H

    2016-10-01

    Full Text Available Hairong Huang,1 Daniel Wismeijer,1 Xianhong Shao,2 Gang Wu1 1Department of Oral Implantology and Prosthetic Dentistry, Academic Centre for Dentistry Amsterdam (ACTA, MOVE Research Institute, VU University Amsterdam and University of Amsterdam, Amsterdam, Nord-Holland, the Netherlands; 2Best & Easy Dental Clinic, Hangzhou, Zhejiang Province, People’s Republic of China Objectives: The objective of this study is to mathematically evaluate the influence of multiple factors on implant stability quotient values in clinical practice.Patients and methods: Resonance frequency analysis was performed at T1 (measured immediately at the time of implant placement and at T2 (measured before dental restoration in 177 patients (329 implants. Using a multivariate linear regression model, we analyzed the influence of the following eleven candidate factors: sex, age, maxillary/mandibular location, bone type, immediate/delayed implantation, bone grafting (presence or absence, insertion torque, I-/II-stage healing pattern, implant diameter, implant length, and T1–T2 time interval.Results: The following factors were identified to significantly influence the implant stability quotient (ISQ values at T1: insertion torque, bone grafting, I-/II-stage healing pattern, immediate/delayed implantation, maxillary/mandibular location, implant diameter, and sex. In contrast, the ISQ values at T2 were significantly influenced only by three factors: implant diameter, T1–T2 time interval, and insertion torque.Conclusion: Among the eleven candidate factors, seven key factors were found to influence the T1-ISQ values, while only three key factors influenced the T2-ISQ values. Both T1 and T2-ISQ values were found to be influenced by implant diameter and insertion torque. T1 was influenced specifically by the sex of the patient, the location (maxillary or mandibular, the implantation mode (immediate/delayed implantation, the healing stage, and the absence or presence of bone

  11. Alveolar Bone Resorption Evaluation Around Single-piece Designed Bicortical Implants, Using Immediate Loading Protocol, Based on Orthopantomographs

    Directory of Open Access Journals (Sweden)

    Száva Dániel-Tamás

    2017-12-01

    Full Text Available Background: Inserting dental implants in severely atrophied jawbones is a great challenge for the dental practitioner. There are an increasing number of patients who choose dental implantanchored prosthetic restorations despite compromised bone quality and quantity. There have been numerous attempts in adapting implant design for the atrophic crestal bone. One-piece, needle-type basal implant design is a typical design for these cases. These implants are inserted in the remaining compact bone located in the basal aspect of the jawbones. If high primary stability is achieved, these implants are used for immediate loading protocol. From many points of view, this technique is based on contradictory principles compared to classic implant surgery and loading protocols. The aim of this study was to investigate the long-term success of basal one-piece short-diameter dental implants used for immediate loading protocol.

  12. Evaluation of a xenogeneic acellular collagen matrix as a small-diameter vascular graft in dogs--preliminary observations.

    Science.gov (United States)

    Nemcova, S; Noel, A A; Jost, C J; Gloviczki, P; Miller, V M; Brockbank, K G

    2001-01-01

    Autogenous veins are the materials of choice for arterial reconstruction. In the absence of autogenous material, prosthetic materials are used. However, vascular prostheses of less than 0.4 cm in diameter have low long-term patency. This study was designed to determine if cells would infiltrate an engineered xenogeneic biomaterial used as a small diameter arterial graft in dogs and, if so, to determine the phenotype of the infiltrating cells. Nine acellular xenogeneic grafts (0.4 cm in diameter, 5 cm long), composed of porcine collagen derived from the submucosa of the small intestine and type I bovine collagen, were implanted as end to-end interposition grafts in femoral arteries of five male mongrel dogs (total of nine grafts). All dogs received daily aspirin (325 mg). Patency of implanted grafts was monitored weekly by Duplex ultrasonography. After 9 weeks, or earlier in case of blood flow reduction by at least 75%, grafts were explanted and prepared for light or electron microscopy to evaluate cellularization. Eight of nine grafts remained patent up to 9 weeks. At explant, diameters were 0.31 +/- 0.02 cm at the midgraft, and 0.14 +/- 0.01 and 0.19 +/- 0.01 cm at the proximal and distal anastomoses. At explant, cells of mesenchymal origin (endothelial cells, smooth muscle cells, myofibroblasts) were embedded in the extracellular matrix of the graft scaffold. Minimal evidence of cellular inflammatory reaction and no aneurysmal dilatation or thrombus formation was detected. Variable degrees of hyperplasia were present at proximal and distal anastomoses. This preliminary study demonstrates that a collagen-based xenogeneic biomaterial provides a scaffold for cellularization when used for arterial reconstruction in dogs.

  13. Precipitation processes in implanted materials

    International Nuclear Information System (INIS)

    Borders, J.A.

    1978-01-01

    Ion implantation is a nonequilibrium process. It is possible to implant materials with impurities to concentration levels which exceed the solid solubilities. The return of the system to thermodynamic equilibrium is often accomplished by precipitation of the implanted species or a compound involving atoms of both the host and the implanted species. This may involve long time scales when taking place at room temperature or it may take place during the implantation

  14. Implant treatment planning: endodontic considerations.

    Science.gov (United States)

    Simonian, Krikor; Frydman, Alon; Verdugo, Fernando; Roges, Rafael; Kar, Kian

    2014-12-01

    Implants are a predictable and effective method for replacing missing teeth. Some clinicians have advocated extraction and replacement of compromised but treatable teeth on the assumption that implants will outperform endodontically and/or periodontally treated teeth. However, evidence shows that conventional therapy is as effective as implant treatment. With data on implants developing complications long term and a lack of predictable treatment for peri-implantitis, retaining and restoring the natural dentition should be the first choice when possible.

  15. Recent advances in dental implants

    OpenAIRE

    Hong, Do Gia Khang; Oh, Ji-hyeon

    2017-01-01

    Dental implants are a common treatment for the loss of teeth. This paper summarizes current knowledge on implant surfaces, immediate loading versus conventional loading, short implants, sinus lifting, and custom implants using three-dimensional printing. Most of the implant surface modifications showed good osseointegration results. Regarding biomolecular coatings, which have been recently developed and studied, good results were observed in animal experiments. Immediate loading had similar c...

  16. Microstructures of group III-nitrides after implantation with gallium

    International Nuclear Information System (INIS)

    Kench, P.J.

    2001-05-01

    bubbles. A capping layer was used in an attempt to control the degradation of the implanted layer mechanically, but this was unsuccessful. The evidence from XPS and electron diffraction complemented one another and suggested that Ga-N bonds were in fact present. Thermal and laser anneals were performed in an attempt to lessen the bubble and precipitate damage caused by the implantation of Ga into InN, however no improvement in microstructure uniformity was observed. Gallium implantations into silicon nitride performed by S. A. Almieda (1998) were also studied using various microstructural characterisation techniques. It was found that the implanted Ga existed in a dispersion of colloids (5 nm in diameter). These colloids were found to be void of N, which is surprising since Ga-N bonds were detected by XPS in these specimens. It is proposed that either a low percentage of N remained undetected in the colloids allowing Ga-N bonds to form, or more likely that Ga-N bonds were present at the boundary formed between the Ga colloid and the a-SiN x layer. The microstructure of the layer appeared to be unaffected by the nitrogen concentration in the original a-SiN x layer. Annealing caused a broadening of the Ga colloid depth range and a reduction in the diameter of the colloids. Using CALPHAD, phase diagrams for the Ga-ln-N and Ga-AI-N alloy systems have been proposed. It has been shown that thermodynamic arguments can explain the observations of Al and In precipitation following Ga implantation into AIN and InN, respectively. The coalescence of Ga to form Ga clusters after implantation into a-SiN x is also explained using thermodynamic arguments. (author)

  17. Failure Diameter of PBX 9502: Simulations with the SURFplus model

    Energy Technology Data Exchange (ETDEWEB)

    Menikoff, Ralph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-07-03

    SURFplus is a reactive burn model for high explosives aimed at modelling shock initiation and propagation of detonation waves. It utilizes the SURF model for the fast hot-spot reaction plus a slow reaction for the energy released by carbon clustering. A feature of the SURF model is that there is a partially decoupling between burn rate parameters and detonation wave properties. Previously, parameters for PBX 9502 that control shock ini- tiation had been calibrated to Pop plot data (distance-of-run to detonation as a function of shock pressure initiating the detonation). Here burn rate parameters for the high pres- sure regime are adjusted to t the failure diameter and the limiting detonation speed just above the failure diameter. Simulated results are shown for an uncon ned rate stick when the 9502 diameter is slightly above and slightly below the failure diameter. Just above the failure diameter, in the rest frame of the detonation wave, the front is sonic at the PBX/air interface. As a consequence, the lead shock in the neighborhood of the interface is supported by the detonation pressure in the interior of the explosive rather than the reaction immediately behind the front. In the interior, the sonic point occurs near the end of the fast hot-spot reaction. Consequently, the slow carbon clustering reaction can not a ect the failure diameter. Below the failure diameter, the radial extent of the detonation front decreases starting from the PBX/air interface. That is, the failure starts at the PBX boundary and propagates inward to the axis of the rate stick.

  18. Diameter measurements of polystyrene particles with atomic force microscopy

    Science.gov (United States)

    Garnaes, J.

    2011-09-01

    The size of (nano) particles is a key parameter used in controlling their function. The particle size is also important in order to understand their physical and chemical properties and regulate their number in health and safety issues. In this work, the geometric diameters of polystyrene spheres of nominal diameter 100 nm are measured using atomic force microscopy. The measurements are based on the apex height and on the average distance between neighbouring spheres when they form a close-packed monolayer on a flat mica substrate. The most important influence parameters for the determination of the geometric diameter are the lateral air gaps and deformation of the spheres. The lateral air gaps are caused by significant size variations of the individual spheres, and a correction is calculated based on the simulation of packing of spheres. The deformation of the spheres is caused mainly by capillary forces acting when they are in contact with each other or with the mica substrate. Based on calculated capillary forces and the literature values of the elastic properties of the polystyrene and mica, the deformation is estimated to be 2 nm with a standard uncertainty of 2 nm. The geometric diameter of the polystyrene spheres was measured with a combined standard uncertainty of ≈3 nm. The measured vertical diameter of 92.3 nm and the certified mobility equivalent diameter measured by differential mobility analysis (DMA) are marginally consistent at a confidence level of 95%. However, the measured lateral geometric diameter was 98.9 nm and is in good agreement with DMA.

  19. [Analysis of anatomy features for patients with narrow anterior chamber angle and primary iridociliary body cysts].

    Science.gov (United States)

    Li, Gui-gang; Ji, Cai-ni; Li, Xin-yu; Hu, Wei-kun; Hu, Jun; Wang, Jun-ming; Li, Tao; Li, Bin; Zhang, Hong

    2012-08-01

    To investigate the prevalence and anatomy features of iridociliary body cysts in patients with narrow anterior chamber angle. Retrospective case series study. The prevalence and anatomy features of iridociliary body cysts in 223 patients (402 eyes) were analyzed retrospectively with ultrasound biomicroscopy (UBM). All of the patients were examined for susceptive narrow anterior chamber angle without complaint. The age of the patients, the site, diameter and number of cysts, the anterior chamber angle and the central anterior chamber depth were measured. Iridociliary body cysts were found in 19 patients (23 eyes) out of 223 patients (402 eyes), the prevalence is 5.7%. Fifteen patients were unilateral and four patients bilateral. Two cases originated from the ciliary process, eighteen cases from the iris root, and three from both the root and posterior surface of the iris. Twenty one cases were single cysts while two cases were multiple cysts. The diameter of the cysts ranged from 0.5 to 3.1 mm, averaged (0.71 ± 0.53) mm. The average age and the central anterior chamber depth of the eyes with iridociliary body cysts were (55.32 ± 10.74) years and (2.25 ± 0.39) mm, with no significant difference (t = 0.534, 0.783; P > 0.05) as compared to that of patients without cysts, which were (57.46 ± 10.52) years and (2.14 ± 0.34) mm. The anterior chamber angle in iridociliary body cysts group was 8.2° (21.0°, 0.0°), with no significant difference (Z = -0.062, P > 0.05) as compared to that of patients without cysts, which was 8.9° (21.4°, 0.0°). The prevalence rate of iridociliary body cysts in this study is 5.7%, central anterior chamber depth and anterior chamber angle in patients with cysts do not differ form patients without cysts.

  20. Integrity of Narrow Epithelial Tubes in the C. elegans Excretory System Requires a Transient Luminal Matrix.

    Science.gov (United States)

    Gill, Hasreet K; Cohen, Jennifer D; Ayala-Figueroa, Jesus; Forman-Rubinsky, Rachel; Poggioli, Corey; Bickard, Kevin; Parry, Jean M; Pu, Pu; Hall, David H; Sundaram, Meera V

    2016-08-01

    Most epithelial cells secrete a glycoprotein-rich apical extracellular matrix that can have diverse but still poorly understood roles in development and physiology. Zona Pellucida (ZP) domain glycoproteins are common constituents of these matrices, and their loss in humans is associated with a number of diseases. Understanding of the functions, organization and regulation of apical matrices has been hampered by difficulties in imaging them both in vivo and ex vivo. We identified the PAN-Apple, mucin and ZP domain glycoprotein LET-653 as an early and transient apical matrix component that shapes developing epithelia in C. elegans. LET-653 has modest effects on shaping of the vulva and epidermis, but is essential to prevent lumen fragmentation in the very narrow, unicellular excretory duct tube. We were able to image the transient LET-653 matrix by both live confocal imaging and transmission electron microscopy. Structure/function and fluorescence recovery after photobleaching studies revealed that LET-653 exists in two separate luminal matrix pools, a loose fibrillar matrix in the central core of the lumen, to which it binds dynamically via its PAN domains, and an apical-membrane-associated matrix, to which it binds stably via its ZP domain. The PAN domains are both necessary and sufficient to confer a cyclic pattern of duct lumen localization that precedes each molt, while the ZP domain is required for lumen integrity. Ectopic expression of full-length LET-653, but not the PAN domains alone, could expand lumen diameter in the developing gut tube, where LET-653 is not normally expressed. Together, these data support a model in which the PAN domains regulate the ability of the LET-653 ZP domain to interact with other factors at the apical membrane, and this ZP domain interaction promotes expansion and maintenance of lumen diameter. These data identify a transient apical matrix component present prior to cuticle secretion in C. elegans, demonstrate critical roles for