WorldWideScience

Sample records for ceramic single crowns

  1. Reliability estimation for single-unit ceramic crown restorations.

    Science.gov (United States)

    Lekesiz, H

    2014-09-01

    The objective of this study was to evaluate the potential of a survival prediction method for the assessment of ceramic dental restorations. For this purpose, fast-fracture and fatigue reliabilities for 2 bilayer (metal ceramic alloy core veneered with fluorapatite leucite glass-ceramic, d.Sign/d.Sign-67, by Ivoclar; glass-infiltrated alumina core veneered with feldspathic porcelain, VM7/In-Ceram Alumina, by Vita) and 3 monolithic (leucite-reinforced glass-ceramic, Empress, and ProCAD, by Ivoclar; lithium-disilicate glass-ceramic, Empress 2, by Ivoclar) single posterior crown restorations were predicted, and fatigue predictions were compared with the long-term clinical data presented in the literature. Both perfectly bonded and completely debonded cases were analyzed for evaluation of the influence of the adhesive/restoration bonding quality on estimations. Material constants and stress distributions required for predictions were calculated from biaxial tests and finite element analysis, respectively. Based on the predictions, In-Ceram Alumina presents the best fast-fracture resistance, and ProCAD presents a comparable resistance for perfect bonding; however, ProCAD shows a significant reduction of resistance in case of complete debonding. Nevertheless, it is still better than Empress and comparable with Empress 2. In-Ceram Alumina and d.Sign have the highest long-term reliability, with almost 100% survivability even after 10 years. When compared with clinical failure rates reported in the literature, predictions show a promising match with clinical data, and this indicates the soundness of the settings used in the proposed predictions. © International & American Associations for Dental Research.

  2. CAD/CAM fabricated single-unit all-ceramic post-core-crown restoration

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    Thilla Sekar Vinothkumar

    2011-01-01

    Full Text Available This case report explains about an innovative treatment strategy for the management of damaged anterior teeth with reduced incisal clearance by means of a single-unit all-ceramic post-core-crown zirconia ceramic restoration fabricated by Computer-aided designing and computer-aided manufacturing (CAD/CAM technology. The reinforced zirconia ceramics allow fabrication of durable esthetic restorations in cases with high functional loading and the unification of the post, core, and crown in a single unit decreases the frequency of failure by creating a monobloc effect. In addition, the use of CAD/CAM technology for designing and fabricating ceramic restorations offers the option of expeditiously preparing these high-strength all-ceramic restorations.

  3. Influence of Abutment Material on the Stress of Implant-supported All-ceramic Single Crown

    Institute of Scientific and Technical Information of China (English)

    GAO Shaohuai; DUAN Haiying; LI Zhiyong

    2012-01-01

    In order to investigate the influence of abutment material on the stress of implant-supported all-ceramic single crown,a 3D finite element model of implant-supported mandibular first premolar was computed by COSMOS/M 2.85 software.Alumina,zirconia,and titanium were used as abutment materials respectively.Vertical 600 N and horizontal 225 N load was applied on the occlusal surface.The results show that the stress distribution of implant-supported single crown was similar for different abutment materials.Maximum stresses within the crown were higher when titanium abutment was used.Maximum stress of titanium abutment was lower than that of ceramic abutment.Within the screw and fixture,maximum stresses had no difference under vertical loading but higher as titanium abutment was used under horizontal loading.There was no difference of maximum stress within the bone when different abutment materials were used.The present findings indicate that the abutment material had no influence on the stress distribution of implant-supported allceramic single crown but maximum stress when the titanium abutment was lower than that of ceramic abument.

  4. Fracture load and failure analysis of zirconia single crowns veneered with pressed and layered ceramics after chewing simulation.

    Science.gov (United States)

    Stawarczyk, Bogna; Ozcan, Mutlu; Roos, Malgorzata; Trottmann, Albert; Hämmerle, Christoph H F

    2011-01-01

    This study determined the fracture load of zirconia crowns veneered with four overpressed and four layered ceramics after chewing simulation. The veneered zirconia crowns were cemented and subjected to chewing cycling. Subsequently, the specimens were loaded at an angle of 45° in a Universal Testing Machine to determine the fracture load. One-way ANOVA, followed by a post-hoc Scheffé test, t-test and Weibull statistic were performed. Overpressed crowns showed significantly lower fracture load (543-577 N) compared to layered ones (805-1067 N). No statistical difference was found between the fracture loads within the overpressed group. Within the layered groups, LV (1067 N) presented significantly higher results compared to LC (805 N). The mean values of all other groups were not significantly different. Single zirconia crowns veneered with overpressed ceramics exhibited lower fracture load than those of the layered ones after chewing simulation.

  5. All-ceramic or metal-ceramic tooth-supported fixed dental prostheses (FDPs)? A systematic review of the survival and complication rates. Part I: Single crowns (SCs).

    Science.gov (United States)

    Sailer, Irena; Makarov, Nikolay Alexandrovich; Thoma, Daniel Stefan; Zwahlen, Marcel; Pjetursson, Bjarni Elvar

    2015-06-01

    To assess the 5-year survival of metal-ceramic and all-ceramic tooth-supported single crowns (SCs) and to describe the incidence of biological, technical and esthetic complications. Medline (PubMed), Embase, Cochrane Central Register of Controlled Trials (CENTRAL) searches (2006-2013) were performed for clinical studies focusing on tooth-supported fixed dental prostheses (FDPs) with a mean follow-up of at least 3 years. This was complimented by an additional hand search and the inclusion of 34 studies from a previous systematic review [1,2]. Survival and complication rates were analyzed using robust Poisson's regression models to obtain summary estimates of 5-year proportions. Sixty-seven studies reporting on 4663 metal-ceramic and 9434 all-ceramic SCs fulfilled the inclusion criteria. Seventeen studies reported on metal-ceramic crowns, and 54 studies reported on all-ceramic crowns. Meta-analysis of the included studies indicated an estimated survival rate of metal-ceramic SCs of 94.7% (95% CI: 94.1-96.9%) after 5 years. This was similar to the estimated 5-year survival rate of leucit or lithium-disilicate reinforced glass ceramic SCs (96.6%; 95% CI: 94.9-96.7%), of glass infiltrated alumina SCs (94.6%; 95% CI: 92.7-96%) and densely sintered alumina and zirconia SCs (96%; 95% CI: 93.8-97.5%; 92.1%; 95% CI: 82.8-95.6%). In contrast, the 5-year survival rates of feldspathic/silica-based ceramic crowns were lower (pceramic and zirconia crowns exhibited significantly lower survival rates in the posterior region (pceramic fractures than metal-ceramic SCs (pceramic SCs than for metal-ceramic SCs. Survival rates of most types of all-ceramic SCs were similar to those reported for metal-ceramic SCs, both in anterior and posterior regions. Weaker feldspathic/silica-based ceramics should be limited to applications in the anterior region. Zirconia-based SCs should not be considered as primary option due to their high incidence of technical problems. Copyright © 2015 Academy

  6. Personal Factors Determining Patient Satisfaction with All-Ceramic Crown Treatment for Single Anterior Teeth.

    Science.gov (United States)

    Zou, Yun; Zhan, DeSong

    2016-01-01

    The Eysenck Personality Questionnaire's (EPQ) N value (neuroticism) was used to evaluate information from 158 patients before ceramic crown treatment. Patient satisfaction was also evaluated using a satisfaction questionnaire 2 weeks post treatment. Patient expectations were not correlated with sex, age, or N value, and sex was not correlated with patient satisfaction other than in relation to crown shape. Total esthetic satisfaction and feature improvement were positively correlated with age, while satisfaction for five specific criteria was negatively correlated with N value and overall expectation. These observations underscore the importance of considering the physical and psychologic aspects of patient care when planning dental treatment.

  7. Randomized, controlled clinical trial of bilayer ceramic and metal-ceramic crown performance.

    Science.gov (United States)

    Esquivel-Upshaw, Josephine; Rose, William; Oliveira, Erica; Yang, Mark; Clark, Arthur E; Anusavice, Kenneth

    2013-04-01

    Analyzing the clinical performance of restorative materials is important, as there is an expectation that these materials and procedures will restore teeth and do no harm. The objective of this research study was to characterize the clinical performance of metal-ceramic crowns, core ceramic crowns, and core ceramic/veneer ceramic crowns based on 11 clinical criteria. An IRB-approved, randomized, controlled clinical trial was conducted as a single-blind pilot study. The following three types of full crowns were fabricated: (1) metal-ceramic crown (MC) made from a Pd-Au-Ag-Sn-In alloy (Argedent 62) and a glass-ceramic veneer (IPS d.SIGN veneer); (2) non-veneered (glazed) lithium disilicate glass-ceramic crown (LDC) (IPS e.max Press core and e.max Ceram Glaze); and (3) veneered lithia disilicate glass-ceramic crown (LDC/V) with glass-ceramic veneer (IPS Empress 2 core and IPS Eris). Single-unit crowns were randomly assigned. Patients were recalled for each of 3 years and were evaluated by two calibrated clinicians. Thirty-six crowns were placed in 31 patients. A total of 12 crowns of each of the three crown types were studied. Eleven criteria were evaluated: tissue health, marginal integrity, secondary caries, proximal contact, anatomic contour, occlusion, surface texture, cracks/chips (fractures), color match, tooth sensitivity, and wear (of crowns and opposing enamel). Numerical rankings ranged from 1 to 4, with 4 being excellent, and 1 indicating a need for immediate replacement. Statistical analysis of the numerical rankings was performed using a Fisher's exact test. There was no statistically significant difference between performance of the core ceramic crowns and the two veneered crowns at year 1 and year 2 (p > 0.05). All crowns were rated either as excellent or good for each of the clinical criteria; however, between years 2 and 3, gradual roughening of the occlusal surface occurred in some of the ceramic-ceramic crowns, possibly caused by dissolution and

  8. Randomized, Controlled Clinical Trial of Bilayer Ceramic and Metal-Ceramic Crown Performance

    Science.gov (United States)

    Esquivel-Upshaw, Josephine; Rose, William; Oliveira, Erica; Yang, Mark; Clark, Arthur E.; Anusavice, Kenneth

    2013-01-01

    Purpose Analyzing the clinical performance of restorative materials is important, as there is an expectation that these materials and procedures will restore teeth and do no harm. The objective of this research study was to characterize the clinical performance of metal-ceramic crowns, core ceramic crowns, and core ceramic/veneer ceramic crowns based on 11 clinical criteria. Materials and Methods An IRB-approved, randomized, controlled clinical trial was conducted as a single-blind pilot study. The following three types of full crowns were fabricated: (1) metal-ceramic crown (MC) made from a Pd-Au-Ag-Sn-In alloy (Argedent 62) and a glass-ceramic veneer (IPS d.SIGN veneer); (2) non-veneered (glazed) lithium disilicate glass-ceramic crown (LDC) (IPS e.max Press core and e.max Ceram Glaze); and (3) veneered lithia disilicate glass-ceramic crown (LDC/V) with glass-ceramic veneer (IPS Empress 2 core and IPS Eris). Single-unit crowns were randomly assigned. Patients were recalled for each of 3 years and were evaluated by two calibrated clinicians. Thirty-six crowns were placed in 31 patients. A total of 12 crowns of each of the three crown types were studied. Eleven criteria were evaluated: tissue health, marginal integrity, secondary caries, proximal contact, anatomic contour, occlusion, surface texture, cracks/chips (fractures), color match, tooth sensitivity, and wear (of crowns and opposing enamel). Numerical rankings ranged from 1 to 4, with 4 being excellent, and 1 indicating a need for immediate replacement. Statistical analysis of the numerical rankings was performed using a Fisher’s exact test. Results There was no statistically significant difference between performance of the core ceramic crowns and the two veneered crowns at year 1 and year 2 (p > 0.05). All crowns were rated either as excellent or good for each of the clinical criteria; however, between years 2 and 3, gradual roughening of the occlusal surface occurred in some of the ceramic-ceramic crowns

  9. OCT evaluation of single ceramic crowns: comparison between conventional and chair-side CAD/CAM technologies

    Science.gov (United States)

    Gabor, A.; Jivanescu, A.; Zaharia, C.; Hategan, S.; Topala, F. I.; Levai, C. M.; Negrutiu, M. L.; Sinescu, C.; Duma, V.-F.; Bradu, A.; Podoleanu, A. Gh.

    2016-03-01

    Digital impressions were introduced to overcome some of the obstacles due to traditional impression materials and techniques. The aim of this in vitro study is to compare the accuracy of all ceramic crowns obtained with digital impression and CAD-CAM technology with the accuracy of those obtained with conventional impression techniques. Two groups of 10 crowns each have been considered. The digital data obtained from Group 1 have been processed and the all-ceramic crowns were milled with a CAD/CAM technology (CEREC MCX, Sirona). The all ceramic crowns in Group 2 were obtained with the classical technique of pressing (emax, Ivoclar, Vivadent). The evaluation of the marginal adaptation was performed with Time Domain Optical Coherence Tomography (TD OCT), working at a wavelength of 1300 nm. Tri-dimensional (3D) reconstructions of the selected areas were obtained. Based on the findings in this study, one may conclude that the marginal accuracy of all ceramic crowns fabricated with digital impression and the CAD/CAM technique is superior to the conventional impression technique.

  10. An In Vivo Evaluation of the Fit of Zirconium-Oxide Based, Ceramic Single Crowns with Vertical and Horizontal Finish Line Preparations.

    Science.gov (United States)

    Vigolo, Paolo; Mutinelli, Sabrina; Biscaro, Leonello; Stellini, Edoardo

    2015-12-01

    Different types of tooth preparations influence the marginal precision of zirconium-oxide based ceramic single crowns. In this in vivo study, the marginal fits of zirconium-oxide based ceramic single crowns with vertical and horizontal finish lines were compared. Forty-six teeth were chosen in eight patients indicated for extraction for implant placement. CAD/CAM technology was used for the production of 46 zirconium-oxide-based ceramic single crowns: 23 teeth were prepared with vertical finishing lines, 23 with horizontal finishing lines. One operator accomplished all clinical procedures. The zirconia crowns were cemented with glass ionomer cement. The teeth were extracted 1 month later. Marginal gaps along vertical planes were measured for each crown, using a total of four landmarks for each tooth by means of a microscope at 50× magnification. On conclusion of microscopic assessment, ESEM evaluation was completed on all specimens. The comparison of the gap between the two types of preparation was performed with a nonparametric test (two-sample Wilcoxon rank-sum test) with a level of significance fixed at p finish line preparations, the median value of the gap was 35.45 μm (Iqr, 0.33); for the vertical finish line group, the median value of the gap was 35.44 μm (Iqr, 0.40). The difference between the two groups was not statistically significant (two-sample Wilcoxon rank-sum test, p = 0.0872). Within the limitations of this study, the gaps of the zirconium-oxide-based ceramic CAD/CAM crowns with vertical and horizontal finish line preparations were not different. © 2015 by the American College of Prosthodontists.

  11. All-Ceramic Single Crown Restauration of Zirconia Oral Implants and Its Influence on Fracture Resistance: An Investigation in the Artificial Mouth

    Directory of Open Access Journals (Sweden)

    Ralf-Joachim Kohal

    2015-04-01

    Full Text Available The aim of the current investigation was to evaluate the fracture resistance of one-piece zirconia oral implants with and without all-ceramic incisor crowns after long-term thermomechanical cycling. A total of 48 implants were evaluated. The groups with crowns (C, 24 samples and without crowns (N, 24 samples were subdivided according to the loading protocol, resulting in three groups of 8 samples each: Group “0” was not exposed to cyclic loading, whereas groups “5” and “10” were loaded with 5 and 10 million chewing cycles, respectively. This resulted in 6 different groups: C0/N0, C5/N5 and C10/N10. Subsequently, all 48 implants were statically loaded to fracture and bending moments were calculated. All implants survived the artificial aging. For the static loading the following average bending moments were calculated: C0: 326 Ncm; C5: 339 Ncm; C10: 369 Ncm; N0: 339 Ncm; N5: 398 Ncm and N10: 355 Ncm. To a certain extent, thermomechanical cycling resulted in an increase of fracture resistance which did not prove to be statistically significant. Regarding its fracture resistance, the evaluated ceramic implant system made of Y-TZP seems to be able to resist physiological chewing forces long-term. Restauration with all-ceramic single crowns showed no negative influence on fracture resistance.

  12. Marginal Strength of Collarless Metal Ceramic Crown

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    Sikka Swati

    2010-01-01

    fracture strength at margins of metal ceramic crowns cemented to metal tooth analogs. Crowns evaluated with different marginal configurations, shoulder and shoulder bevel with 0 mm, 0.5 mm, 1 mm, and 1.5 mm, were selected. Methods. Maxillary right canine typhodont tooth was prepared to receive a metal ceramic crown with shoulder margin. This was duplicated to get 20 metal teeth analogs. Then the same tooth was reprepared to get shoulder bevel configuration. These crowns were then cemented onmetal teeth analogs and tested for fracture strength atmargin on an Instron testing machine. A progressive compressive load was applied using 6.3 mm diameter rod with crosshead speed of 2.5 mm per minute. Statisticaly analysis was performed with ANOVA, Student's “t” test and “f” test. Results. The fracture strength of collarless metal ceramic crowns under study exceeded the normal biting force. Therefore it can be suggested that collarless metal ceramic crowns with shoulder or shoulder bevel margins up to 1.5 mm framework reduction may be indicated for anteriormetal ceramic restorations. Significance. k Collarless metal ceramic crowns have proved to be successful for anterior fixed restorations. Hence, it may be subjected to more clinical trials.

  13. Fracture toughness of zirconia ceramic crowns made by feather-edge tooth preparation design

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    Mirković Nemanja

    2012-01-01

    Full Text Available Background/Aim. Fracture toughness determines functional crown strenght and prevents damages on ceramics during mastication. There is a lack of relevant literature data about fracture toughness of crowns made by feather-edge preparation. Mechanical testing of ceramic samples is supposed to show if feather-edge tooth preparation is a successful method for making ceramic crowns without any risk of reduction of their mechanical properties. This research was done to establish effects of feather-edge tooth preparation on fracture toughness of single zirconia ceramic crowns. Methods. The research was performed as an experimental study. Sixty (60 ceramic crowns were made on non-carious extracted human premolars. Thirty (30 crowns were made on the basis of feather-edge preparation (experimental group I. The group II included 30 crowns made on 1 mm rounded shoulder. Crowns fabrication was executed on a copy mill production system “Zirkonzahn” (Zirkonzahn GMBH, Gais, Germany. The spherical compression test was used to determine fracture toughness, using 6 mm diameter ceramic ball. Fracture load for damaging ceramic crown was recorded on a universal testing machine - Zwick, type 1464, with the speed of 0.05 mm/min. Results. The results of this research introduced significant differences between fracture toughness of ceramic samples in every examined group. However, fracture toughness of crowns from both group was above 2 000 N, what was double beyond a recommended value. The mean value of fracture toughness in the feather-edge group was 2 090 N, and in shoulder group it was 2 214 N. Conclusion. This research showed a high fracture toughness of zirconia crowns made on feather-edge preparation. The examined crowns showed a fracture resistance at a sufficient distance in relation to the minimum values of functional loads. Further research of functional loads of these crown is necessary, as well as research of marginal adaptation of cemented crowns and

  14. Zirconia crowns - the new standard for single-visit dentistry?

    Science.gov (United States)

    Wiedhahn, Klaus; Fritzsche, Günter; Wiedhahn, Claudine; Schenk, Olaf

    2016-01-01

    Zirconia crowns combine the advantages of metal restorations, such as minimally invasive tooth preparation and ease of cementation, with those of full ceramic crowns, such as low thermal conductivity and tooth color. With the introduction of a high-speed sintering procedure, it is possible to produce and cement zirconia crowns and small monolithic bridges in a Cerec Single Visit procedure. This new procedure is compared to established chairside methods.

  15. A 3-year follow-up study of all-ceramic single and multiple crowns performed in a private practice: a prospective case series

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    Gianluca M. Tartaglia

    2011-01-01

    Full Text Available OBJECTIVES: Zirconia-based prostheses are commonly used for aesthetic crown and fixed restorations, although follow-up data are limited, especially for implant-supported crowns. The aim of this study was to evaluate the threeyear clinical results of the installation of 463 zirconia core crowns by a general dental private practice. METHODS: This study followed 142 patients (69 men and 73 women; aged 28-82 years who had received 248 single crowns (202 tooth-supported, 36 implant-supported and 225 multiple units of up to six elements (81 toothsupported, 144 implant-supported. Clinical events, including fracture and loss of retention, secondary caries, and marginal integrity, were recorded. The overall failure rate was computed for the fractured and lost prostheses. Aesthetic, functional, and biological properties were rated, and patient satisfaction was investigated. RESULTS: During the three-year follow-up period, four patients were lost from the study (18 crowns, 4% of the total crowns. Three of the zirconia prostheses suffered fractures in more than three units (11 crowns; one- vs. three-year follow-up, p,0.05, Wilcoxon signed-rank test, and the cumulative prosthesis survival rate was 98.2%. Twelve units lost retention and were re-cemented, and no secondary caries of the abutment teeth were reported. The aesthetic, functional, and biological properties were generally well-rated, and there were no differences between tooth- and implant-supported crowns. The lowest scores were given regarding the anatomical form of the crowns, as some minor chipping was reported. Relatively low scores were also given for the periodontal response and the adjacent mucosa. Overall, patient satisfaction was high. CONCLUSIONS: At the three-year follow-up, the zirconia-core crowns appeared to be an effective clinical solution as they had favorable aesthetic and functional properties. Only the marginal fit of the prostheses should be improved upon.

  16. Fracture resistance of a selection of full-contour all-ceramic crowns: an in vitro study.

    Science.gov (United States)

    Zesewitz, Tim F; Knauber, Andreas W; Northdurft, Frank P

    2014-01-01

    This study aimed to evaluate the fracture resistance of monolithic single crowns made from zirconia (ZI), lithium disilicate (LS2), or feldspar ceramic (FC). Five groups of crowns representing a maxillary first molar were made with the appropriate dimensions according to the manufacturer's instructions. The ZI and LS2 crowns were luted adhesively or cemented conventionally on a metal abutment tooth analog. The feldspar ceramic crowns were luted adhesively. All specimens underwent axial loading until fracture. The crowns in the ZI groups possessed the highest fracture resistance independent of the mode of fixation.

  17. Survival Predictions of Ceramic Crowns Using Statistical Fracture Mechanics.

    Science.gov (United States)

    Nasrin, S; Katsube, N; Seghi, R R; Rokhlin, S I

    2017-01-01

    This work establishes a survival probability methodology for interface-initiated fatigue failures of monolithic ceramic crowns under simulated masticatory loading. A complete 3-dimensional (3D) finite element analysis model of a minimally reduced molar crown was developed using commercially available hardware and software. Estimates of material surface flaw distributions and fatigue parameters for 3 reinforced glass-ceramics (fluormica [FM], leucite [LR], and lithium disilicate [LD]) and a dense sintered yttrium-stabilized zirconia (YZ) were obtained from the literature and incorporated into the model. Utilizing the proposed fracture mechanics-based model, crown survival probability as a function of loading cycles was obtained from simulations performed on the 4 ceramic materials utilizing identical crown geometries and loading conditions. The weaker ceramic materials (FM and LR) resulted in lower survival rates than the more recently developed higher-strength ceramic materials (LD and YZ). The simulated 10-y survival rate of crowns fabricated from YZ was only slightly better than those fabricated from LD. In addition, 2 of the model crown systems (FM and LD) were expanded to determine regional-dependent failure probabilities. This analysis predicted that the LD-based crowns were more likely to fail from fractures initiating from margin areas, whereas the FM-based crowns showed a slightly higher probability of failure from fractures initiating from the occlusal table below the contact areas. These 2 predicted fracture initiation locations have some agreement with reported fractographic analyses of failed crowns. In this model, we considered the maximum tensile stress tangential to the interfacial surface, as opposed to the more universally reported maximum principal stress, because it more directly impacts crack propagation. While the accuracy of these predictions needs to be experimentally verified, the model can provide a fundamental understanding of the

  18. Fracture Strength of Zirconia and Alumina Ceramic Crowns Supported by Implants.

    Science.gov (United States)

    Traini, Tonino; Sorrentino, Roberto; Gherlone, Enrico; Perfetti, Federico; Bollero, Patrizio; Zarone, Ferdinando

    2015-07-01

    Due to the brittleness and limited tensile strength of the veneering glass-ceramic materials, the methods that combine strong core material (as zirconia or alumina) are still under debate. The present study aims to evaluate the fracture strength and the mechanism of failure through fractographic analysis of single all-ceramic crowns supported by implants. Forty premolar cores were fabricated with CAD/CAM technology using alumina (n = 20) and zirconia (n = 20). The specimens were veneered with glass-ceramic, cemented on titanium abutments, and subjected to loading test until fracture. SEM fractographic analysis was also performed. The fracture load was 1165 (±509) N for alumina and 1638 (±662) N for zirconia with a statistically significant difference between the two groups (P = 0.026). Fractographic analysis of alumina-glass-ceramic crowns, showed the presence of catastrophic cracks through the entire thickness of the alumina core; for the zirconia-glass-ceramic crowns, the cracks involved mainly the thickness of the ceramic veneering layer. The sandblast procedure of the zirconia core influenced crack path deflection. Few samples (n = 3) showed limited microcracks of the zirconia core. Zirconia showed a significantly higher fracture strength value in implant-supported restorations, indicating the role played by the high resistant cores for premolar crowns.

  19. Dental ceramics and the molar crown testing ground

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    Van P. Thompson

    2004-01-01

    Full Text Available All ceramic crowns are highly esthetic restorations and their popularity has risen with the demand for life-like and cosmetic dentistry. Recent ceramic research has concentrated on developing a fundamental understanding of ceramic damage modes as influenced by microstructure. Dental investigations have elucidated three damage modes for ceramic layers in the 0.5-2 mm thickness using point contacts that duplicate tooth cuspal radii; classic Hertzian cone cracking, yield (pseudo-plastic behavior, and flexural cracking. Constitutive equations based upon materials properties have been developed that predict the damage modes operational for a given ceramic and thickness. Ceramic thickness or thickness of the stiff supporting core in layer crowns is critical in flexural cracking as well as the flaw state of the inner aspect of the crown. The elastic module of the supporting structure and of the luting cement and its thickness play a role in flexural fracture. Clinical studies of ceramics extending over 16 years are compared to the above relationships and predictions. Recommendations for clinical practice are made based upon the above.

  20. Comparison of repair methods for ceramic-fused-to-metal crowns

    NARCIS (Netherlands)

    Ozcan, M.; Van Der Sleen, J.M.; Kurunmaki, H.; Vallittu, P.K.

    2006-01-01

    Purpose: The objective of this study was to evaluate the effect of four repair methods on the fracture load of repaired ceramic-fused-to-metal crowns. Materials and Methods: Metal-ceramic crowns were fractured, and the failure load was measured. The fractured metal-ceramic crowns (n = 9) were assign

  1. Comparison of repair methods for ceramic-fused-to-metal crowns

    NARCIS (Netherlands)

    Ozcan, M.; Van Der Sleen, J.M.; Kurunmaki, H.; Vallittu, P.K.

    2006-01-01

    Purpose: The objective of this study was to evaluate the effect of four repair methods on the fracture load of repaired ceramic-fused-to-metal crowns. Materials and Methods: Metal-ceramic crowns were fractured, and the failure load was measured. The fractured metal-ceramic crowns (n = 9) were

  2. Aesthetic comparison between crowns made with Cubo and metal-ceramic systems

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    Lis Regina Carneiro HOPPEN

    2010-06-01

    Full Text Available Introduction and objective: The objective of this study was to verify the influence of different materials used in the construction of infrastructures on the aesthetic result of restorations with ceramic coating. Material and methods: A patient that needed a single prosthetic crown on the maxillary central incisors was selected for treatment, one in the right maxillary central incisor (11 and another in the dental implant (21.Metal-free (Cubo system and metal-ceramic (MC crowns were made for each tooth and submitted to blind review by 11 dentists, who answered a questionnaire about ratios of opacity and translucency of the crowns in the oral cavity of the patient, where each answer corresponded to one score.Data was submitted to Wilcoxon test (α = 0.05. Results: Therewas no significant statistical difference between the metal-ceramic and Cubo system crowns (11: p = 0.107; 21: p = 0.739. The analysis of the scores also showed that for the same type of infrastructure there was no significant statistical difference between 11 and 21 (Cubo: p = 0.206; MC: p = 0.102. Conclusion: Within the limits of this study, it was concluded that, according to the visual perception of the evaluators,prosthetic crowns made with metal infrastructure and with ceramic infrastructure showed to be aesthetically similar and satisfactory.

  3. A 1-year randomised controlled trial comparing zirconia versus metal-ceramic implant supported single-tooth restorations

    DEFF Research Database (Denmark)

    Hosseini, Mandana; Worsaae, Nils; Schiodt, Morten

    2011-01-01

    To compare the biological, technical and aesthetic outcomes of single implant-supported all-ceramic versus metal-ceramic crowns.......To compare the biological, technical and aesthetic outcomes of single implant-supported all-ceramic versus metal-ceramic crowns....

  4. Internal fit of two all-ceramic systems and metal-ceramic crowns

    OpenAIRE

    Leandro Moura Martins; Fabio Cesar Lorenzoni; Alcides Oliveira de Melo; Luciana Mendonça da Silva; José Luiz G. de Oliveira; Pedro Cesar Garcia de Oliveira; Gerson Bonfante

    2012-01-01

    Objectives: The aim of this study was to investigate the internal fit (IF) of glass-infiltrated alumina (ICA - In-Ceram Alumina), yttria-stabilized tetragonal zirconia polycrystals (Y-TZP - IPS e.max ZirCAD), and metal-ceramic (MC - Ni-Cr alloy) crowns. Material and Methods: Sixty standardized resin-tooth replicas of a maxillary first molar were produced for crown placement and divided into 3 groups (n=20 each) according to the core material used (metal, ICA or Y-TZP). The IF of the crowns wa...

  5. Marginal and internal fit of all-ceramic crowns fabricated with two different CAD/CAM systems.

    Science.gov (United States)

    Lee, Kyu-Bok; Park, Charn-Woon; Kim, Kyo-Han; Kwon, Tae-Yub

    2008-05-01

    This study evaluated the accuracy of marginal and internal fit between the all-ceramic crowns manufactured by a conventional double-layer computer-aided design/computer-aided manufacturing (CAD/CAM) system and a single-layer system. Ten standardized crowns were fabricated from each of these two systems: conventional double-layer CAD/CAM system (Procera) and a single-layer system (Cerec 3D). The copings and completed crowns were seated on the abutments by a special device that facilitated uniform loading, and the marginal discrepancies were measured. Internal gaps were also measured using a low-viscosity silicone material. Marginal discrepancies of Procera copings were significantly smaller than those of Procera crowns and Cerec 3D crowns (p 0.05). On internal gaps, Cerec 3D crowns showed significantly larger internal gaps than Procera copings and crowns (p system demonstrated acceptable marginal and internal fit.

  6. Reliability of metalloceramic and zirconia-based ceramic crowns.

    Science.gov (United States)

    Silva, N R F A; Bonfante, E A; Zavanelli, R A; Thompson, V P; Ferencz, J L; Coelho, P G

    2010-10-01

    Despite the increasing utilization of all-ceramic crown systems, their mechanical performance relative to that of metal ceramic restorations (MCR) has yet to be determined. This investigation tested the hypothesis that MCR present higher reliability over two Y-TZP all-ceramic crown systems under mouth-motion fatigue conditions. A CAD-based tooth preparation with the average dimensions of a mandibular first molar was used as a master die to fabricate all restorations. One 0.5-mm Pd-Ag and two Y-TZP system cores were veneered with 1.5 mm porcelain. Crowns were cemented onto aged (60 days in water) composite (Z100, 3M/ESPE) reproductions of the die. Mouth-motion fatigue was performed, and use level probability Weibull curves were determined. Failure modes of all systems included chipping or fracture of the porcelain veneer initiating at the indentation site. Fatigue was an acceleration factor for all-ceramic systems, but not for the MCR system. The latter presented significantly higher reliability under mouth-motion cyclic mechanical testing.

  7. Influence of galvano-ceramic and metal-ceramic crowns on magnetic resonance imaging

    Institute of Scientific and Technical Information of China (English)

    CHEN Dong-ping; WU Guang-yao; WANG Yi-ning

    2010-01-01

    Background Magnetic resonance imaging (MRI) is prone to be deformed by artifacts caused by the presence of metallic materials. The aim of this study was to evaluate the artifacts from galvano-ceramic and metal-ceramic crowns in MRI, in order to analyze their influences on diagnostic interpretation of MRI.Methods Galvano-ceramic and metal-ceramic crowns (Bio98, Wiron99, SP-78, BioKC97) were fabricated with the same model. All materials were imaged by means of 1.5T MRI apparatus with three different sequences, T1-weighted spin-echo (T1-weighted SE), T2-weighted spin-echo (T2-weighted SE) and Gradient echo (GE). Mean and standard deviation of distilled water signal intensity (SI) around the sample in the region of interest (500 mm~2) enclosing the whole artifacts were determined, and compared for evaluation of the homogeneity of signal intensity. Images around the sample were acquired and evaluated.Results There were statistically significant differences in the values of signal intensity between acrylic resin control and BioKC97, Wiron99 in the three sequences (P0.05). Images showed that the greatest artifact was a 25 mm ring with distortion in Wiron99 in GE sequence.Conclusions This in vitro study suggested that galvano-ceramic crown had no influence on the MRI, while metal-ceramic crowns caused moderate artifacts in the MRI. Therefore, galvano-ceramic restoration is a valuable alternative in dentistry.

  8. Comparison of Fracture Toughness of All-Ceramic and Metal–Ceramic Cement Retained Implant Crowns: An In Vitro Study

    OpenAIRE

    Rao, S.; Chowdhary, R.

    2014-01-01

    To evaluate the fracture toughness of cement-retained implant-supported metal–ceramic molar crown with that of all-ceramic crowns, fabricated using IPS Empress 2 and yttria-stabilized zirconia copings. An dental implant and abutment was embedded in a clear polymethyl methacrylate model. A wax pattern reproducing the anatomy and dimension of a mandibular molar was made using inlay wax. Copings were made from the manufacturers guidelines for zirconia, metal ceramic and empress crown, in total o...

  9. Fabrication of all-ceramic crowns by a new method.

    Science.gov (United States)

    Masuda, Takayuki; Kakimoto, Kazutoshi; Takahashi, Kazuya; Komasa, Yutaka

    2016-01-01

    A new method of all-ceramic production using alumina coping has been developed. The present study investigates the influence of secondary firing (glass infiltration firing) conditions. Samples of porcelain build-up without secondary firing were also assessed. The suitability of coping that included secondary firing was found to be affected by the rate of temperature increase during the secondary firing. However, cracking developed in the fired porcelain if porcelain was built up onto secondarily-fired coping. In contrast, cracking did not occur with coping that was not secondarily fired. The bending strength after porcelain build-up was 70 MPa or higher, suggesting the possibility of clinical applications as an anterior crown. These findings establish that this is method of producing all-ceramic crowns that allows for low-cost manufacture in a short period of about 1 h.

  10. Effect of In-Ceram all-ceramic crown and metal-ceramic crowns on cell viability and related gene expression in fibroblast cell lines L929

    Institute of Scientific and Technical Information of China (English)

    Lei Shi; Liang Yang; Jie-Chun Huang; En-Bao He; Zhi-Hui Wu

    2016-01-01

    Objective:To study the effect of In-Ceram all-ceramic crown and metal-ceramic crowns on cell viability and related gene expression in fibroblast cell lines L929.Methods: Fibroblast cell lines L929 were cultured and treated with extract solution of In-Ceram all-ceramic crown, Ni-Cr alloy porcelain crown and Co-Cr alloy porcelain crown respectively, and then cell viability, serum cytokine contents as well as mRNA contents of Fas, FasL, Apo-1, mTOR and P70S6k in cells were detected.Results:Cell OD values of Ni-Cr alloy group and Co-Cr alloy group were significantly lower than that of negative control group; cell OD value of In-Ceram group was significantly higher than those of Ni-Cr alloy group and Co-Cr alloy group; TNF-α, IL-6 and IL-8 contents in cell culture medium of Ni-Cr alloy group and Co-Cr alloy group were significantly higher than those of negative control group, and TNF-α, IL-6 and IL-8 contents in cell culture medium of In-Ceram group were significantly lower than those of Ni-Cr alloy group and Co-Cr alloy group and not different from those of negative control group; mRNA contents of Fas, FasL and Apo-1 in cells of Ni-Cr alloy group and Co-Cr alloy group were higher than those of negative control group, mRNA contents of mTOR and P70S6k were lower than those of negative control group, mRNA contents of Fas, FasL and Apo-1 in cells of In-Ceram group were lower than those of Ni-Cr alloy group and Co-Cr alloy group and not different from those of negative control group, and mRNA contents of mTOR and P70S6k were higher than those of Ni-Cr alloy group and Co-Cr alloy group and not different from those of negative control group.Conclusion: In-Ceram all-ceramic crown has good histocompatibility and will not affect cell viability as well as generation of inflammatory factors and expression of apoptosis and proliferation-related genes in fibroblast cell lines L929.

  11. A 3-years follow up study on Zirconia Single Crown with no-covered by ceramics%咬合面无饰瓷氧化锆修复体的3年随访观察

    Institute of Scientific and Technical Information of China (English)

    孙晓琳; 刘桂凤; 陈志国

    2015-01-01

    Objective To evaluate the clinical effects of Zirconia Single Crown with no- covered by Ceramics. Methods 96 posterior teeth was received the restorations by Zirconia Single Crown which uncovered by low fusing porcelain at the side of occlusion.During the three- year follow- up period, clinical events,including fracture and loss of retention,marginal integrity and wear of opposite natural teeth were recorded and calculated. Results Two of the zirconia prostheses lost retention and were re- cemented,but didn't exist significant difference ( >0.05).And no fracture,secondary caries or excessive wear of opposite teeth were reported. Conclusion Zirconia Single Crow with no- covered by ceramics can be used in restorations of posterior single tooth in 3 years.%目的:评价咬合面无饰瓷氧化锆后牙单冠的临床效果。方法:本研究选取96例患者的单颗后牙的治疗后全冠修复,96颗后牙全部选择咬合面无饰瓷氧化锆全冠,经过3年随访,对修复体本身、对颌牙釉质磨耗情况以及患者满意度进行临床疗效评价,评价结果采用秩和检验。结果:96例修复体除2例出现修复体脱落现象以外,在修复体抗折性、边缘适合性、邻接关系方面均未发生改变,同时对颌牙磨耗的分级评价未发生显著改变改变,经检验未见统计学差异。结论:无饰面氧化锆后牙单冠进行3年观察能够满足临床治疗需要。

  12. Shading of ceramic crowns using digital tooth shade matching devices.

    Science.gov (United States)

    Baltzer, A; Kaufmann-Jinoian, V

    2005-04-01

    In the 1990s, there was great optimism due to the development of devices for measuring tooth shade. The frequently not so simple, visual determination of the shade of a tooth was to be done with the aid of a device which recognizes the shade and describes it accurately by reference to a color chart. However, the skepticism towards such devices was also great. It is known that the color effect frequently differs strongly when comparing a tooth from the shade guide with a metal ceramic crown, despite identical shade designation. Anyone who considers visual shade determination to be inadequate and places his hopes in digital shade matching devices will be disappointed. It is the shade-generating structures of the metal ceramic and frequently of the veneer layers that turn out to be too thin which, despite correct shade selection, cause a different color perception. Such problems have been reduced decisively with the development of fracture-proof hard porcelain caps (Vita In-Ceram) with optical characteristics similar to teeth. In addition, the Vita System 3D-Master tooth shade system developed in 1998 by Vita in cooperation with Dr. Hall from Australia, leads the practitioner to a better understanding of the primary tooth shade characteristics of "brightness (value)", "color intensity (chroma)" and "color (wave length of the visible light, hue)". These two innovations allow a more accurate estimate of the basic shade of a natural tooth (reference tooth) and the imitation in the laboratory of its natural, shade-generating structures. If digital shade measurement supplements the visual shade estimate, then a further improvement can be expected--especially in the recognition of the basic shade. Qualitative descriptions of subjective shade measurement of a natural tooth and of its imitation in the dental laboratory by ceramics can be found frequently in professional journals and publications. With digital tooth shade matching devices, which apart from the color code of

  13. Comparison of fracture toughness of all-ceramic and metal-ceramic cement retained implant crowns: an in vitro study.

    Science.gov (United States)

    Rao, S; Chowdhary, R

    2014-12-01

    To evaluate the fracture toughness of cement-retained implant-supported metal-ceramic molar crown with that of all-ceramic crowns, fabricated using IPS Empress 2 and yttria-stabilized zirconia copings. An dental implant and abutment was embedded in a clear polymethyl methacrylate model. A wax pattern reproducing the anatomy and dimension of a mandibular molar was made using inlay wax. Copings were made from the manufacturers guidelines for zirconia, metal ceramic and empress crown, in total of 21 copings, which were built for the crowns with metal layering ceramics specified by the manufacturers. The polymethylmethacrylate block-implant abutment complex was mounted on universal testing machine, and a static continuos vertical compressive load with a crosshead speed of 0.5 mm/min was applied. The breaking load and the peak load (in kilo Newtons) were recorded. The fractures for group I (zirconia-ceramic) and group II (metal-ceramic) occurred on the mesio-buccal aspect of the crowns involving the veneered ceramic layer while the catastrophic/bulk fracture was not observed. The mean value of breaking load for zirconia-ceramic, metal-ceramic and IPS-empress 2 was 3.4335, 3.071 and 1.0673 kN respectively. The mean value of peak load for zirconia-ceramic, metal-ceramic and IPS-empress 2 was 4.7365, 3.2757 and 1.566 kN respectively. It can be concluded that the zirconia-ceramic crown with the fracture toughness of 4.7365 ± 2.2676 kN has sufficient strength to allow clinical testing of these crowns as an alternative for metal-ceramic crowns (3.2757 ± 0.4681 kN).

  14. In vitro evaluation of the marginal fit of different all-ceramic crowns

    Directory of Open Access Journals (Sweden)

    Munir Tolga Yucel

    2013-09-01

    Conclusion: In-Ceram all-ceramic crowns showed the largest marginal gap, and Celay crowns showed the smallest marginal gap in both die groups. The marginal discrepancies found in this study were all within the clinically acceptable standard of 120 μm.

  15. Comparative fracture strength analysis of Lava and Digident CAD/CAM zirconia ceramic crowns

    OpenAIRE

    Kwon, Taek-Ka; Pak, Hyun-Soon; Yang, Jae-Ho; Han, Jung-Suk; Lee, Jai-Bong; Kim, Sung-Hun; Yeo, In-Sung

    2013-01-01

    PURPOSE All-ceramic crowns are subject to fracture during function. To minimize this common clinical complication, zirconium oxide has been used as the framework for all-ceramic crowns. The aim of this study was to compare the fracture strengths of two computer-aided design/computer-aided manufacturing (CAD/CAM) zirconia crown systems: Lava and Digident. MATERIALS AND METHODS Twenty Lava CAD/CAM zirconia crowns and twenty Digident CAD/CAM zirconia crowns were fabricated. A metal die was also ...

  16. Simulation of clinical fractures for three different all-ceramic crowns.

    Science.gov (United States)

    Oilo, Marit; Kvam, Ketil; Gjerdet, Nils R

    2014-06-01

    Comparison of fracture strength and fracture modes of different all-ceramic crown systems is not straightforward. Established methods for reliable testing of all-ceramic crowns are not currently available. Published in-vitro tests rarely simulate clinical failure modes and are therefore unsuited to distinguish between the materials. The in-vivo trials usually lack assessment of failure modes. Fractographic analyses show that clinical crowns usually fail from cracks initiating in the cervical margins, whereas in-vitro specimens fail from contact damage at the occlusal loading point. The aim of this study was to compare three all-ceramic systems using a clinically relevant test method that is able to simulate clinical failure modes. Ten incisor crowns of three types of all-ceramic systems were exposed to soft loading until fracture. The initiation and propagation of cracks in these crowns were compared with those of a reference group of crowns that failed during clinical use. All crowns fractured in a manner similar to fracture of the clinical reference crowns. The zirconia crowns fractured at statistically significantly higher loads than alumina and glass-ceramic crowns. Fracture initiation was in the core material, cervically in the approximal areas. © 2014 Eur J Oral Sci.

  17. Longevity of metal-ceramic crowns cemented with self-adhesive resin cement: a prospective clinical study

    Science.gov (United States)

    Brondani, Lucas Pradebon; Pereira-Cenci, Tatiana; Wandsher, Vinicius Felipe; Pereira, Gabriel Kalil; Valandro, Luis Felipe; Bergoli, César Dalmolin

    2017-04-10

    Resin cements are often used for single crown cementation due to their physical properties. Self-adhesive resin cements gained widespread due to their simplified technique compared to regular resin cement. However, there is lacking clinical evidence about the long-term behavior of this material. The aim of this prospective clinical trial was to assess the survival rates of metal-ceramic crowns cemented with self-adhesive resin cement up to six years. One hundred and twenty-nine subjects received 152 metal-ceramic crowns. The cementation procedures were standardized and performed by previously trained operators. The crowns were assessed as to primary outcome (debonding) and FDI criteria. Statistical analysis was performed using Kaplan-Meier statistics and descriptive analysis. Three failures occurred (debonding), resulting in a 97.6% survival rate. FDI criteria assessment resulted in scores 1 and 2 (acceptable clinical evaluation) for all surviving crowns. The use of self-adhesive resin cement is a feasible alternative for metal-ceramic crowns cementation, achieving high and adequate survival rates.

  18. A comparison of the marginal and internal adaptation of titanium and gold-platinum-palladium metal ceramic crowns.

    Science.gov (United States)

    Valderrama, S; Van Roekel, N; Andersson, M; Goodacre, C J; Munoz, C A

    1995-01-01

    The marginal and internal adaptation of metal ceramic crowns fabricated by electrical discharge machining and conventional metal ceramic alloys were compared. The crowns were cemented using zinc phosphate cement, embedded in epoxy resin, and sectioned in two planes: diagonal and buccolingual. The crowns were then measured at nine sites. The results showed that there were no statistical differences between the external marginal opening of the titanium and the gold-platinum-palladium crowns. The overall marginal discrepancies for the restorations in this study were 61 microns (+/- 34 microns) for the titanium metal ceramic crowns and 47 microns (+/- 17 microns) for the gold-platinum-palladium metal ceramic crowns.

  19. Strength of CAD/CAM-generated esthetic ceramic molar implant crowns

    OpenAIRE

    D. Wolf; Bindl, A; Schmidlin, P.R; Lüthy, H; Mörmann, W H

    2008-01-01

    PURPOSE: One-visit in-office CAD/CAM fabrication of esthetic ceramic crowns as a superstructure for posterior implants is quite new. The aim of the study was to evaluate the strength of esthetic ceramic CAD/CAM crowns with varied occlusal thickness and seated with adhesive and nonadhesive cements on titanium and zirconia abutments. MATERIALS AND METHODS: Esthetic ceramic CAD/CAM-generated molar crowns (n = 15 per group) with occlusal thicknesses of 0.5 mm and 1.5 mm were seated on titanium (1...

  20. Internal fit of two all-ceramic systems and metal-ceramic crowns

    Science.gov (United States)

    MARTINS, Leandro Moura; LORENZONI, Fabio Cesar; de MELO, Alcides Oliveira; da SILVA, Luciana Mendonça; de OLIVEIRA, José Luiz G.; de OLIVEIRA, Pedro Cesar Garcia; BONFANTE, Gerson

    2012-01-01

    Objectives The aim of this study was to investigate the internal fit (IF) of glass-infiltrated alumina (ICA - In-Ceram Alumina), yttria-stabilized tetragonal zirconia polycrystals (Y-TZP - IPS e.max ZirCAD), and metal-ceramic (MC - Ni-Cr alloy) crowns. Material and Methods Sixty standardized resin-tooth replicas of a maxillary first molar were produced for crown placement and divided into 3 groups (n=20 each) according to the core material used (metal, ICA or Y-TZP). The IF of the crowns was measured using the replica technique, which employs a light body polyvinyl siloxane impression material to simulate the cement layer thickness. The data were analyzed according to the surfaces obtained for the occlusal space (OS), axial space (AS) and total mean (TM) using two-way ANOVA with Tukey's multiple comparison test (p<0.05). Results No differences among the different areas were detected in the MC group. For the Y-TZP and ICA groups, AS was statistically lower than both OS and TM. No differences in AS were observed among the groups. However, OS and TM showed significantly higher values for ICA and Y-TZP groups than MC group. Comparisons of ICA and Y-TZP revealed that OS was significantly lower for Y-TZP group, whereas no differences were observed for TM. Conclusions The total mean achieved by all groups was within the range of clinical acceptability. However, the metal-ceramic group demonstrated significantly lower values than the all-ceramic groups, especially in OS. PMID:22666843

  1. Internal fit of two all-ceramic systems and metal-ceramic crowns

    Directory of Open Access Journals (Sweden)

    Leandro Moura Martins

    2012-04-01

    Full Text Available OBJECTIVES: The aim of this study was to investigate the internal fit (IF of glass-infiltrated alumina (ICA - In-Ceram Alumina, yttria-stabilized tetragonal zirconia polycrystals (Y-TZP - IPS e.max ZirCAD, and metal-ceramic (MC - Ni-Cr alloy crowns. MATERIAL AND METHODS: Sixty standardized resin-tooth replicas of a maxillary first molar were produced for crown placement and divided into 3 groups (n=20 each according to the core material used (metal, ICA or Y-TZP. The IF of the crowns was measured using the replica technique, which employs a light body polyvinyl siloxane impression material to simulate the cement layer thickness. The data were analyzed according to the surfaces obtained for the occlusal space (OS, axial space (AS and total mean (TM using two-way ANOVA with Tukey ’s multiple comparison test (p<0.05. RESULTS: No differences among the different areas were detected in the MC group. For the Y-TZP and ICA groups, AS was statistically lower than both OS and TM. No differences in AS were observed among the groups. However, OS and TM showed significantly higher values for ICA and Y-TZP groups than MC group. Comparisons of ICA and Y-TZP revealed that OS was significantly lower for Y-TZP group, whereas no differences were observed for TM. CONCLUSIONS: The total mean achieved by all groups was within the range of clinical acceptability. However, the metal-ceramic group demonstrated significantly lower values than the all-ceramic groups, especially in OS.

  2. Application of Replica Technique and SEM in Accuracy Measurement of Ceramic Crowns

    Science.gov (United States)

    Trifkovic, B.; Budak, I.; Todorovic, A.; Hodolic, J.; Puskar, T.; Jevremovic, D.; Vukelic, D.

    2012-01-01

    The paper presents a comparative study of the measuring values of the marginal gap related to the ceramic crowns made by dental CAD/CAM system using the replica technique and SEM. The study was conducted using three experimental groups, which consisted of ceramic crowns manufactured by the Cerec CAD/CAM system. The scanning procedure was carried out using three specialized dental 3D digitization systems from the Cerec family - two types of extraoral optical scanning systems and an intraoral optical scanner. Measurements of the marginal gap were carried out using the replica technique and SEM. The comparison of aggregate values of the marginal gap using the replica technique showed a statistically significant difference between the systems. The measured values of marginal gaps of ceramic crowns using the replica technique were significantly lower compared to those measured by SEM. The results indicate that the choice of technique for measuring the accuracy of ceramic crowns influences the final results of investigation.

  3. Evaluation of marginal fit of 2 CAD-CAM anatomic contour zirconia crown systems and lithium disilicate glass-ceramic crown.

    Science.gov (United States)

    Ji, Min-Kyung; Park, Ji-Hee; Park, Sang-Won; Yun, Kwi-Dug; Oh, Gye-Jeong; Lim, Hyun-Pil

    2015-08-01

    This study was to evaluate the marginal fit of two CAD-CAM anatomic contour zirconia crown systems compared to lithium disilicate glass-ceramic crowns. Shoulder and deep chamfer margin were formed on each acrylic resin tooth model of a maxillary first premolar. Two CAD-CAM systems (Prettau®Zirconia and ZENOSTAR®ZR translucent) and lithium disilicate glass ceramic (IPS e.max®press) crowns were made (n=16). Each crown was bonded to stone dies with resin cement (Rely X Unicem). Marginal gap and absolute marginal discrepancy of crowns were measured using a light microscope equipped with a digital camera (Leica DFC295) magnified by a factor of 100. Two-way analysis of variance (ANOVA) and post-hoc Tukey's HSD test were conducted to analyze the significance of crown marginal fit regarding the finish line configuration and the fabrication system. The mean marginal gap of lithium disilicate glass ceramic crowns (IPS e.max®press) was significantly lower than that of the CAD-CAM anatomic contour zirconia crown system (Prettau®Zirconia) (PCAD-CAM anatomic contour zirconia crown system (Prettau®Zirconia). In terms of absolute marginal discrepancy, the CAD-CAM anatomic contour zirconia crown system (ZENOSTAR®ZR translucent) had under-extended margin, whereas the CAD-CAM anatomic contour zirconia crown system (Prettau®Zirconia) and lithium disilicate glass ceramic crowns (IPS e.max®press) had overextended margins.

  4. All- Ceramic Crown Preparation and the Remained wall Thickness of the Pulp Chamber

    Directory of Open Access Journals (Sweden)

    Mohammadzadeh Akhlaghi N.

    2012-12-01

    Full Text Available tatement of Problem: A minimally invasive method of preparation is essential to prevent tooth structure weakening and pulp irritation; especially for mandibular anterior single-tooth all-ceramic crowns. According to many investigations, one of the most important reasons of pulp injury caused by tooth preparation for different restorative procedures is reduced “remained wall thickness” (RWT. In order to protect the pulp from irritation, it is necessary to maintain a 0.5 mm of RWT.Purpose: The purpose of the present study was to evaluate the effect of all-ceramic crown preparation on pulp chamber RWT of mandibular incisors.Materials and Method: Mesiodistal and buccolingual initial images of 24 ex-tracted mandibular incisors were provided. The pulp chamber initial wall thick-nesses of buccal, lingual and proximal surfaces of cervical, 1and 2 mm above the cervical areas and also the incisal surfaces of incisal sections were measured using digital radiography and Photoshop software. After all-ceramic crown preparation, images were provided at the same initial positions. The initial and remained pulp chamber wall thicknesses were statistically evaluated and analyzed by ANOVA, paired t-test and a post hoc Tukey test.Results: Repeated measures ANOVA showed that the mean of pre- or post-preparation wall thicknesses were not significantly different for each surface at the three horizontal levels (p> 0.05. However, there were significant differences between the surfaces for each section. Comparison of pre- and post-preparation wall thicknesses revealed significant differences (p< 0.05. Proximal surfaces of cervical sections had the least RWT (0.42±0.12.Conclusion: According to the results of the present study, the least amount of initial and remained wall thicknesses of pulp chamber were related to the proximal surfaces, particularly in cervical areas. Therefore a reduction of preparation to 0.7 mm is suggested to prevent future pulp injury for

  5. Influence of thermomechanical fatigue loading on the fracture resistance of all-ceramic posterior crowns.

    Science.gov (United States)

    Senyilmaz, Dilek Pinar; Canay, Senay; Heydecke, Guido; Strub, Joerg Rudolf

    2010-06-01

    This study evaluated the fracture resistance and the survival rate of different all-ceramic crowns in-vitro after thermomechanical fatigue loading in comparison to porcelain-fused-to-metal posterior crowns. Sixteen crowns for human mandibular first molars were made of each of the following: Cercon, IPS-Empress 2 In-Ceram Zirconia, Procera AllZircon and porcelain-fused-to-metal. Half of the specimens of each group was thermocycled and dynamically loaded using a chewing simulator All samples were thereafter tested for the maximum fracture resistance. The survival rates after 1-2 million cycles in the artificial mouth were 100% in all the tested crown systems. The chewing simulation and thermocycling did not significantly decrease the fracture strength of the ceramic crowns (P>0.005). The median fracture load of Cercon, Procera AllZircon, In-Ceram Zirconia and PFM was significantly higher than IPS-Empress 2 both for loaded and non loaded groups (PZirconia and PFM was not significant (P>0.005). All-ceramic systems showed fracture load values similar to those of porcelain-fused-to-metal molar crowns and therefore may be considered for use in clinical studies.

  6. Predictable aesthetic replacement of a metal-ceramic crown using CAD/CAM technology: a case report.

    Science.gov (United States)

    Poticny, Daniel; Conrad, Robert

    2005-08-01

    The currently available CAD/CAM technologies present clinicians with various clinical benefits that include durability, marginal adaptation, and precision aesthetics. The clinical and laboratory procedures associated with these CAD/CAM systems differ from one another, and practitioners must understand the indications for each. Office-based systems, as demonstrated in the following case presentation, allow excellent results to be achieved in a single patient visit and provide a viable alternative for today's practice. This case report describes the associated sequences for a posterior CAD/CAM restoration. Learning Objectives This article discusses a protocol for the use of CAD/CAM restorations in the aesthetic replacement of defective posterior crowns. Upon reading this article, the reader should have: * Greater understanding of the in-office CAD/CAM procedures used to fabricate single-visit crowns. * Improved awareness of the bonding protocol used for these all-ceramic crowns.

  7. Eleven-Year Retrospective Survival Study of 275 Veneered Lithium Disilicate Single Crowns.

    Science.gov (United States)

    Simeone, Piero; Gracis, Stefano

    2015-01-01

    The aim of the present clinical retrospective study was to evaluate the long-term survival and clinical performance of veneered lithium disilicate single restorations in anterior and posterior areas after up to 11 years. Following a rigid protocol, 275 lithium disilicate single crowns (35 IPS Empress II and 240 e.max Press) were cemented over 11 years, in 106 patients, using an adhesive technique; of these 106 were anterior (38.5%) and 169 posterior (61.5%) teeth. Teeth receiving endodontic therapy and composite reconstruction (50%) and teeth with preexisting metalceramic crowns, called prosthetic retreatments (PR; 65%), were included as well. Of the 106 patients enrolled in the study, 25 (23.5%) were diagnosed with bruxism habits, and 7 of these patients (6.6% of all patients) received full-mouth single lithium disilicate restorations (FMR). The exclusion criteria for this retrospective clinical study were: monolithic lithium disilicate crowns, teeth with cast post and cores, implant-supported all-ceramic crowns, active periodontitis, and/or poor oral hygiene. Clinical reevaluation was performed by the clinicians who prepared and luted them during maintenance appointments between January 2012 and October 2013. Number of restoration failures and characteristics of failures were recorded. Marginal adaptation and marginal discoloration were evaluated based on the Cvar-Ryge criteria. The overall cumulative survival rate was 98.2%. The failures recorded were the result of either mechanical failure or debonding. Five crowns failed mechanically-three because of chipping and two because of core fracture-and were replaced. None of the failed crowns was associated with the bruxers with FMR. A total of 15 crowns debonded (5.5% of all crowns); however, 11 belonged to the same patient who had endodontically treated and reconstructed abutments. In this retrospective clinical evaluation of up to 132 months, veneered lithium disilicate single crowns had a low failure rate.

  8. Tooth wear against ceramic crowns in posterior region:a systematic literature review

    Institute of Scientific and Technical Information of China (English)

    Rim Hmaidouch; Paul Weigl

    2013-01-01

    The objective of this systematic review was to assess tooth wear against ceramic crowns in posterior region in vitro and in vivo. An electronic PubMed search was conducted to identify studies on tooth wear against ceramic crowns in posterior region. The selected studies were analyzed in regard to type of crowns, natural antagonist, measuring protocol and outcome. From a yield of 1 000 titles, 43 articles were selected for full-text analysis;finally, no in vitro and only five in vivo studies met the inclusion criteria. As there is heterogeneity in design, used measuring method, ceramics and analysis-form, a meta-analysis was not possible. Results of these studies are very controversial which makes a scientifically valid comparison impossible. This review indicated that some all-ceramic crowns are as wear friendly as metal-ceramic crowns. Up to now, it has been impossible to associate tooth wear with any specific causal agent. The role of ceramic surface treatment that might be responsible for the changing in rate of tooth wear seems undetermined as yet through clinical trials. The literature reveals that studies on this topic are subject to a substantial amount of bias. Therefore, additional clinical studies, properly designed to diminish bias, are warranted.

  9. Clinical performance - a reflection of damage accumulation in ceramic dental crowns

    Energy Technology Data Exchange (ETDEWEB)

    Rekow, D.E. [Univ. of Medicine and Dentistry of New Jersey, Newark, NJ (United States). Dept. of Orthodontics; Thompson, V.P. [Univ. of Medicine and Dentistry of New Jersey, Newark, NJ (United States). New Jersey Dental School

    2001-07-01

    All-ceramic dental crowns have tremendous appeal for patients - their esthetics nearly match those of natural teeth. Unfortunately, the most esthetic materials are brittle and, consequently, are vulnerable to damage relating to shaping which is exacerbated during cyclic loading during normal chewing. Clinical performance of all-ceramic dental prostheses are directly dependent on damage introduced during fabrication and during fatigue loading associated with function. The accumulation of damage results in unacceptably high failure rates (where failure is defined as a complete fracture requiring replacement of the prosthesis). The relation between shaping damage and fatigue damage on clinical performance of all-ceramic dental crowns was investigated. Materials used commercially for all-ceramic crowns and investigated in this study included a series of different microstructures of machinable glass ceramics (Corning), aluminas and porcelains (Vita Zahnfabrik), and zirconia (Norton). As monolithic materials, strong, tough, fatigue-resistant materials are not sufficiently esthetic for crowns. Crowns fabricated from monolithic esthetic materials have high failure rates. Layering ceramics could provide acceptable strength through management of damage accumulation. (orig.)

  10. Stress and Reliability Analysis of a Metal-Ceramic Dental Crown

    Science.gov (United States)

    Anusavice, Kenneth J; Sokolowski, Todd M.; Hojjatie, Barry; Nemeth, Noel N.

    1996-01-01

    Interaction of mechanical and thermal stresses with the flaws and microcracks within the ceramic region of metal-ceramic dental crowns can result in catastrophic or delayed failure of these restorations. The objective of this study was to determine the combined influence of induced functional stresses and pre-existing flaws and microcracks on the time-dependent probability of failure of a metal-ceramic molar crown. A three-dimensional finite element model of a porcelain fused-to-metal (PFM) molar crown was developed using the ANSYS finite element program. The crown consisted of a body porcelain, opaque porcelain, and a metal substrate. The model had a 300 Newton load applied perpendicular to one cusp, a load of 30ON applied at 30 degrees from the perpendicular load case, directed toward the center, and a 600 Newton vertical load. Ceramic specimens were subjected to a biaxial flexure test and the load-to-failure of each specimen was measured. The results of the finite element stress analysis and the flexure tests were incorporated in the NASA developed CARES/LIFE program to determine the Weibull and fatigue parameters and time-dependent fracture reliability of the PFM crown. CARES/LIFE calculates the time-dependent reliability of monolithic ceramic components subjected to thermomechanical and/Or proof test loading. This program is an extension of the CARES (Ceramics Analysis and Reliability Evaluation of Structures) computer program.

  11. Wear Behavior of Ceramic CAD/CAM Crowns and Natural Antagonists

    Directory of Open Access Journals (Sweden)

    Ella A. Naumova

    2017-02-01

    Full Text Available Objective: Evaluation of wear behavior of computer-aided design/computer-aided manufacturing (CAD/CAM crowns from various restorative materials and natural antagonists. Method: Full CAD/CAM crowns fabricated with nanoceramic resin (Lava Ultimate (LU, a glass ceramic in a resin interpenetrating matrix (Vita Enamic (VE and a lithium silicate reinforced ceramic enriched with zirconia (Vita Suprinity (VS were cemented on human molars. The crown and antagonists were subjected to simulated chewing. 3D data sets, before and after the chewing simulation, were generated and matched. Occlusal surface roughness, vertical and volume loss of the crowns and antagonists were analyzed. Results: Crown roughness was significantly different between the LU and VE groups after chewing simulation. Crown vertical loss differed in all groups. The highest crown volume loss was found in the LU group, and the lowest in the VE group. Comparisons between the LU and VE groups and the LU and VS groups were significantly different. The highest antagonist volume loss was reached in the VE group, the lowest was in the LU group. Conclusion: Roughness increased after chewing simulation. LU crowns are the most natural antagonist-friendly; these were the most susceptible to vertical and volume loss. Of the tested materials, the VE crowns are the most stable regarding occlusion.

  12. Measuring residual stress in ceramic zirconia-porcelain dental crowns by nanoindentation.

    Science.gov (United States)

    Zhang, Y; Allahkarami, M; Hanan, J C

    2012-02-01

    Residual stress plays a critical role in failure of ceramic dental crowns. The magnitude and distribution of residual stress in the crown system are largely unknown. Determining the residual stress quantitatively is challenging since the crown has such complex contours and shapes. This work explored the feasibility and validity of measuring residual stress of zirconia and porcelain in ceramic crowns by nanoindentation. Nanoindentation tests were performed on the cross-section of a crown for both porcelain and zirconia along four critical locations: the thickest, thinnest and medium porcelain thicknesses. Zirconia and porcelain pieces, chipped off from the crown and annealed at 400 °C, were used as reference samples. The residual stress was determined by comparing the measured hardness of the stressed sample with that of the reference sample. Nanoindentation impression images were acquired through a scanning probe microscope (SPM) equipped with a Hysitron Triboindenter. Zirconia showed large pile-up. Residual stress is determined along the thickness of crowns at the chosen locations for both porcelain and zirconia. The measured results were compared with the results from X-ray diffraction (XRD) and finite element modeling (FEM). Results show there are large amounts of residual stresses in the dental crown and their magnitude differs between locations due to the complex shape of the crown. The average residual stress readings were as high as -637 MPa and 323 MPa for zirconia and porcelain respectively.

  13. Influence of different post core materials on the color of Empress 2 full ceramic crowns

    Institute of Scientific and Technical Information of China (English)

    GE Jing; WANG Xin-zhi; FENG Hai-lan

    2006-01-01

    Background For esthetic consideration, dentin color post core materials were normally used for all-ceramic crown restorations. However, in some cases, clinicians have to consider combining a full ceramic crown with a metal post core. Therefore, this experiment was conducted to test the esthetical possibility of applying cast metal post core in a full ceramic crown restoration.Methods The color of full ceramic crowns on gold and Nickel-Chrome post cores was compared with the color of the same crowns on tooth colored post cores. Different try-in pastes were used to imitate the influence of a composite cementation on the color of different restorative combinations. The majority of patients could not detect any color difference less than △E 1.8 between the two ceramic samples. So, △E 1.8 was taken as the objective evaluative criterion for the evaluation of color matching and patients' satisfaction.Results When the Empress 2 crown was combined with the gold alloy post core, the color of the resulting material was similar to that of a glass fiber reinforced resin post core (△E = 0.3). The gold alloy post core and the try-in paste did not show a perceptible color change in the full ceramic crowns, which indicated that the color of the crowns might not be susceptible to change between lab and clinic as well as during the process of composite cementation. Without an opaque covering the Ni-Cr post core would cause an unacceptable color effect on the crown (△E = 2.0), but with opaque covering, the color effect became more clinically satisfactory (△E=1.8).Conclusions It may be possible to apply a gold alloy post core in the Empress 2 full ceramic crown restoration when necessary. If a non-extractible Ni-Cr post core exists in the root canal, it might be possible to restore the tooth with an Empress 2 crown after coveting the labial surface of the core with one layer of opaque resin cement.

  14. Practice-based clinical evaluation of metal-ceramic and zirconia molar crowns: 3-year results.

    Science.gov (United States)

    Rinke, S; Schäfer, S; Lange, K; Gersdorff, N; Roediger, M

    2013-03-01

    This practice-based study evaluates the clinical performance of conventionally luted metal-ceramic and zirconia molar crowns fabricated with pronounced anatomical core design and a prolonged cooling period of the veneering porcelain. Fifty-three patients were treated from 07/2008 until 07/2009 with either metal-ceramic crowns (MCC) (high-noble alloy + low-fusing porcelain) or zirconia crowns (Cercon System, DeguDent, Germany). Forty-nine patients (30 women/19 men) with 100 restorations (metal-ceramic: 48/zirconia: 52, mean observational period: 36·5 ± 6 months) participated in a clinical follow-up examination and were included in the study. Time-dependent survival (in situ criteria), success (event-free restorations) and chipping rates (defects of the veneering ceramics) were calculated according to the Kaplan-Meier method and analysed in relation to the crown fabrication technique, using a Cox regression model (P zirconia: 2) were recorded (survival rate after 3 years: metal-ceramic: 97·6%, zirconia: 95·2%). Of the metal-ceramic restorations, 90·9% remained event-free (two ceramic fractures, one endodontic treatment), whereas the success rate for the zirconia was 86·8% (two ceramic fractures, one endodontic treatment, one secondary caries). No significant differences in survival (P = 0·53), success (P = 0·49) and ceramic fracture rates (P = 0·57) were detected. The combination of a pronounced anatomical core design and a modified firing of the veneering porcelain for the fabrication of zirconia molar crowns resulted in a 3-year survival, success and chipping rate comparable to MCC.

  15. Clinical performance and wear characteristics of veneered lithia-disilicate-based ceramic crowns.

    Science.gov (United States)

    Suputtamongkol, Kallaya; Anusavice, Kenneth J; Suchatlampong, Chatcharee; Sithiamnuai, Phira; Tulapornchai, Chantana

    2008-05-01

    The objectives of this study were to characterize the clinical performance and wear characteristics of lithia-disilicate-based ceramic crowns. Thirty posterior crowns were made using the heat-pressing technique and lithia-disilicate-based core ceramic. Subjects were recalled annually. The quality of crowns and adjacent gingival tissues were examined using nine criteria for acceptability. All crowns were examined and ranked from 4 (Excellent) to 1 (Unacceptable) for each criterion. Impressions were made for replica models at each appointment. Wear characteristics of dental ceramic and enamel were obtained by comparing the surface of the original model with the follow-up model using a laser scanner. Twenty-nine subjects returned for the 1-year recall examination. The maximum clenching force for the 30 subjects ranged from 125 to 815 N. All clinical criteria were ranked good to excellent at the 1-year recall exam and no fractures were observed. The mean occlusal wear volumes for the ceramic crowns after 1 year were 0.19 (0.065)mm3 for premolar sites and 0.34 (0.08)mm3 for molar sites. The mean occlusal wear volumes of opposing enamel after 1 year were 0.21 (0.06)mm3 for premolar teeth and 0.50 (0.22)mm3 for molar teeth. The mean occlusal wear volume of ceramic molar crowns was significantly lower than the volume of enamel wear of the opposing teeth (pceramic molar crowns was significantly lower than the enamel wear volume of the opposing teeth.

  16. A 3-year prospective study of implant-supported, single-tooth restorations of all-ceramic and metal-ceramic materials in patients with tooth agenesis.

    Science.gov (United States)

    Hosseini, Mandana; Worsaae, Nils; Schiødt, Morten; Gotfredsen, Klaus

    2013-10-01

    The purpose of this clinical study was to describe outcome variables of all-ceramic and metal-ceramic implant-supported, single-tooth restorations. A total of 59 patients (mean age: 27.9 years) with tooth agenesis and treated with 98 implant-supported single-tooth restorations were included in this study. Two patients did not attend baseline examination, but all patients were followed for 3 years. The implants supported 52 zirconia, 21 titanium and 25 gold alloy abutments, which retained 64 all-ceramic and 34 metal-ceramic crowns. At baseline and 3-year follow-up examinations, the biological outcome variables such as survival rate of implants, marginal bone level, modified Plaque Index (mPlI), modified Sulcus Bleeding Index (mBI) and biological complications were registered. The technical outcome variables included abutment and crown survival rate, marginal adaptation of crowns, cement excess and technical complications. The aesthetic outcome was assessed by using the Copenhagen Index Score, and the patient-reported outcomes were recorded using the OHIP-49 questionnaire. The statistical analyses were mainly performed by using mixed model of ANOVA for quantitative data and PROC NLMIXED for ordinal categorical data. The 3-year survival rate was 100% for implants and 97% for abutments and crowns. Significantly more marginal bone loss was registered at gold-alloy compared to zirconia abutments (P = 0.040). The mPlI and mBI were not significantly different at three abutment materials. The frequency of biological complications was higher at restorations with all-ceramic restorations than metal-ceramic crowns. Loss of retention, which was only observed at metal-ceramic crowns, was the most frequent technical complication, and the marginal adaptations of all-ceramic crowns were significantly less optimal than metal-ceramic crowns (P = 0.020). The professional-reported aesthetic outcome demonstrated significantly superior colour match of all-ceramic over metal-ceramic

  17. Clinical evaluation comparing the fit of all-ceramic crowns obtained from silicone and digital intraoral impressions

    NARCIS (Netherlands)

    Zarauz, C.; Valverde, A.; Martinez-Rus, F.; Hassan, B.; Pradies, G.

    2016-01-01

    Objectives The aim of this study is to compare the fit of all-ceramic crowns fabricated from conventional silicone impressions with the fit of all-ceramic crowns fabricated from intraoral digital impressions. Methods Twenty patients with 26 posterior teeth with a prosthetic demand were selected for

  18. Experimental Analyses for The Mechanical Behavior of Pressed All-Ceramic Molar Crowns with Anatomical Design

    Directory of Open Access Journals (Sweden)

    Porojan Liliana

    2017-01-01

    Full Text Available Ceramic restorations show considerable variation in strength and structural reliability regarding to the type of material, and design characteristics. The fracture of ceramics occurs with little or no plastic deformation, with cracks propagated in an unstable manner under applied tensile stresses. The aim of the study was to assess experimental analyses of pressed monolithic ceramic crowns with anatomical design used in the posterior areas in order to understand their mechanical behavior before following their clinical use. Experiments were conducted on a complete molar crown preparation. Experiments show different modes of fracture for the tested samples. Digital images from the fractured pieces of the crowns were used to verify the fragments in all cases final fracture occurred by splitting into two and often more parts. The graphically representation of the displacement depending on the load highlights a series of peaks that can be correlated with cracks occurred in crowns. The development of well-designed mechanical experiments could be useful to help to predict clinical survival of these new all-ceramic restorative techniques and materials. Because failure is often accompanied by complete cracking of the crowns, preliminary research should represents a compulsory goal.

  19. Modified Y-TZP core design improves all-ceramic crown reliability.

    Science.gov (United States)

    Silva, N R F A; Bonfante, E A; Rafferty, B T; Zavanelli, R A; Rekow, E D; Thompson, V P; Coelho, P G

    2011-01-01

    This study tested the hypothesis that all-ceramic core-veneer system crown reliability is improved by modification of the core design. We modeled a tooth preparation by reducing the height of proximal walls by 1.5 mm and the occlusal surface by 2.0 mm. The CAD-based tooth preparation was replicated and positioned in a dental articulator for core and veneer fabrication. Standard (0.5 mm uniform thickness) and modified (2.5 mm height lingual and proximal cervical areas) core designs were produced, followed by the application of veneer porcelain for a total thickness of 1.5 mm. The crowns were cemented to 30-day-aged composite dies and were either single-load-to-failure or step-stress-accelerated fatigue-tested. Use of level probability plots showed significantly higher reliability for the modified core design group. The fatigue fracture modes were veneer chipping not exposing the core for the standard group, and exposing the veneer core interface for the modified group.

  20. 全瓷冠与金属烤瓷冠的临床应用分析%Clinical application on all ceramic crowns and metal ceramic crowns

    Institute of Scientific and Technical Information of China (English)

    代伟; 刘阳

    2015-01-01

    Objective:To investigate the aesthetic effect and the change of periodontal tissue in the restoration of all ceramic crowns and metal ceramic crowns.Methods:108 cases of dental restoration restoration on a total of 168 teeth were selected,they were divided into two groups,with 84 teeth in each group,patients in the observation group were treated with zirconia all ceramic dental restoration,while in the control with Ni Cr alloy porcelain dental restoration.Results:After 1 years,the observation group did not appear cervical margin black line,while 39 teeth in the control group had appear black or marginal discoloration problem. Conclusion:Compared with metal ceramic crowns,all ceramic crowns can reduce the damage to the periodontal tissues,and the appearance and color are excellent,with higher simulation,however,in the crown and bridge it is not as good as the metal porcelain teeth.%目的:探讨全瓷冠与金属烤瓷冠修复的美学效果及牙周组织变化.方法:收治牙齿修复患者 108 例,共计168颗牙,随机分为两组,各84颗,观察组进行二氧化锆全瓷牙修复,对照组进行镍铬合金烤瓷牙修复.结果:1年后,观察组未出现颈缘黑线情况,对照组有39颗出现颈缘发黑、变色问题.结论:全瓷冠相较于金属烤瓷冠用于牙体修复可减少对牙周组织的损伤,而且外观与色泽较为优良,有更高的仿真性,然而在冠桥折断方面不如金属烤瓷牙.

  1. CAD/CAM Zirconia vs. slip-cast glass-infiltrated Alumina/Zirconia all-ceramic crowns: 2-year results of a randomized controlled clinical trial

    Directory of Open Access Journals (Sweden)

    Murat Cavit Çehreli

    2009-02-01

    Full Text Available The aim of this randomized controlled clinical trial was to compare the early clinical outcome of slip-cast glass-infiltrated Alumina/Zirconia and CAD/CAM Zirconia all-ceramic crowns. A total of 30 InCeram® Zirconia and Cercon® Zirconia crowns were fabricated and cemented with a glass ionomer cement in 20 patients. At baseline, 6-month, 1-year, and 2-year recall appointments, Californian Dental Association (CDA quality evaluation system was used to evaluate the prosthetic replacements, and plaque and gingival index scores were used to explore the periodontal outcome of the treatments. No clinical sign of marginal discoloration, persistent pain and secondary caries was detected in any of the restorations. All InCeram® Zirconia crowns survived during the 2-year period, although one nonvital tooth experienced root fracture coupled with the fracture of the veneering porcelain of the restoration. One Cercon® Zirconia restoration fractured and was replaced. According to the CDA criteria, marginal integrity was rated excellent for InCeram® Zirconia (73% and Cercon® Zirconia (80% restorations, respectively. Slight color mismatch rate was higher for InCeram® Zirconia restorations (66% than Cercon® Zirconia (26% restorations. Plaque and gingival index scores were mostly zero and almost constant over time. Time-dependent changes in plaque and gingival index scores within and between groups were statistically similar (p>0.05. This clinical study demonstrates that single-tooth InCeram® Zirconia and Cercon® Zirconia crowns have comparable early clinical outcome, both seem as acceptable treatment modalities, and most importantly, all-ceramic alumina crowns strengthened by 25% zirconia can sufficiently withstand functional load in the posterior zone.

  2. Chipping resistance of graded zirconia ceramics for dental crowns.

    Science.gov (United States)

    Zhang, Y; Chai, H; Lee, J J-W; Lawn, B R

    2012-03-01

    A serious drawback of veneering porcelains is a pronounced susceptibility to chipping. Glass-infiltrated dense zirconia structures can now be produced with esthetic quality, making them an attractive alternative. In this study, we examined the hypothesis that such infiltrated structures are much more chip-resistant than conventional porcelains, and at least as chip-resistant as non-infiltrated zirconia. A sharp indenter was used to produce chips in flat and anatomically correct glass-infiltrated zirconia crown materials, and critical loads were measured as a function of distance from the specimen edge (flat) or side wall (crown). Control data were obtained on zirconia specimens without infiltration and on crowns veneered with porcelains. The results confirmed that the resistance to chipping in graded zirconia is more than 4 times higher than that of porcelain-veneered zirconia and is at least as high as that of non-veneered zirconia.

  3. Influence of surface treatment and cyclic loading on the durability of repaired all-ceramic crowns

    Directory of Open Access Journals (Sweden)

    Ahmed Attia

    2010-04-01

    Full Text Available OBJECTIVE: This study investigated the durability of repaired all-ceramic crowns after cyclic loading. MATERIAL AND METHODS: Eighty In-ceram zirconia crowns were fabricated to restore prepared maxillary premolars. Resin cement was used for cementation of crowns. Palatal cusps were removed to simulate fracture of veneering porcelain and divided into 4 groups (n = 20. Fracture site was treated before repair as follows: roughening with diamond bur, (DB; air abrasion using 50 µm Al2O3, (AA and silica coating using Cojet system followed by silane application, (SC. Control group (CG 20 specimens were left without fracture. Palatal cusps were repaired using composite resin. Specimens were stored in water bath at 37ºC for one week. Ten specimens of each group were subjected to cyclic loading. Fracture load (N was recorded for each specimen using a universal testing machine. Two-way analysis of variance (ANOVA and Tukey honestly significant difference (HSD test (a=.05 were used for statistical analysis. RESULTS: There was statistically significant difference between control and tested groups, (p<0.001. Post Hoc analysis with the Tukey HSD test showed that cyclic loading fatigue significantly decreased means fracture load of control and test groups as follows (CG, 950.4±62.6 / 872.3±87.4, P = 0.0004, (DB, 624.2 ±38 / 425.5± 31.7, P <.001, (AA, 711.5 ±15.5 / 490 ± 25.2, p <0.001 and (SC, 788.7 ± 18.1 / 610.2 ± 25.2, P <.001, while silica coating and silane application significantly increased fracture load of repaired crowns (p<0.05. CONCLUSION: Repair of fractured In-ceram zirconia crowns after chairside treatment of the fracture site by silica coating and silane application could improve longevity of repaired In-ceram zirconia crowns.

  4. Wear of primary teeth caused by opposed all-ceramic or stainless steel crowns

    Science.gov (United States)

    Bae, Ik-Hyun; Noh, Tae-Hwan; Ju, Sung-Won; Lee, Tae-Kyoung; Ahn, Jin-Soo; Jeong, Tae-Sung

    2016-01-01

    PURPOSE This study was conducted to evaluate the effects of full-coverage all-ceramic zirconia, lithium disilicate glass-ceramic, leucite glass-ceramic, or stainless steel crowns on antagonistic primary tooth wear. MATERIALS AND METHODS There were four study groups: the stainless steel (Steel) group, the leucite glass-ceramic (Leucite) group, the lithium disilicate glass-ceramic (Lithium) group, and the monolithic zirconia (Zirconia) group. Ten flat crown specimens were prepared per group; opposing teeth were prepared using primary canines. A wear test was conducted over 100,000 chewing cycles using a dual-axis chewing simulator and a 50 N masticating force, and wear losses of antagonistic teeth and restorative materials were calculated using a three-dimensional profiling system and an electronic scale, respectively. Statistical significance was determined using One-way ANOVA and Tukey's test (P.05). CONCLUSION Leucite glass-ceramic and lithium disilicate glass-ceramic cause more primary tooth wear than stainless steel or zirconia. PMID:26949487

  5. Effect of luting media on the compressive strengths of two types of all-ceramic crown.

    Science.gov (United States)

    McCormick, J T; Rowland, W; Shillingburg, H T; Duncanson, M G

    1993-06-01

    This study evaluated the effect of selected luting media on the compressive strength of two types of all-ceramic crown. Tooth preparation was standardized; each preparation had a shoulder width of approximately 1.2 mm, and all internal preparation angles were rounded. Hi-Ceram and Dicor all-ceramic crowns were fabricated and cemented into the preparations with zinc phosphate, glass-ionomer, or composite resin cement. Coronal compressive fracture strengths were determined, using a set of unrestored teeth as a control. There were no statistically significant differences among the mean compressive strengths of the three luting media, and there was no statistically significant difference between the mean compressive strength of Dicor and that of the natural tooth control.

  6. Effect of Different Luting Agents on the Retention of Lithium Disilicate Ceramic Crowns

    Directory of Open Access Journals (Sweden)

    Nicola Mobilio

    2015-04-01

    Full Text Available No studies are available that evaluate the retention of disilicate crowns according to different cementation procedures. The purpose of this study was to measure the retention of lithium disilicate crowns cemented using two different cementation systems. Twenty extracted mandibular premolars were prepared. Anatomic crowns were waxed and hot pressed using lithium disilicate ceramic. Teeth were divided into two groups (n = 10: (1 self-curing luting composite and (2 glass-ionomer cement (GIC. After cementation, the crowns were embedded in acrylic resin block with a screw base. Each specimen was pulled along the path of insertion in Universal Testing Machine. Failure load in Newtons (N and failure mode were recorded for each specimen. Failure mode was classified as decementation or fracture. Failure load data were analyzed using one-way analysis of variance (ANOVA. Failure modes were compared using Pearson’s Chi-square test. Mean failure load was 306.6(±193.8 N for composite group and 94.7(±48.2 N for GIC group (p = 0.004. Disilicate crown cemented with luting composite most often failed by fracture; otherwise, crown cemented with glass-ionomer cement most often failed by decementation (p = 0.02. Disilicate full crown cemented with luting composite showed higher failure load compared with conventional cementation with glass-ionomer cement.

  7. Chairside Fabrication of an All-Ceramic Partial Crown Using a Zirconia-Reinforced Lithium Silicate Ceramic

    Science.gov (United States)

    Pabel, Anne-Kathrin; Rödiger, Matthias

    2016-01-01

    The chairside fabrication of a monolithic partial crown using a zirconia-reinforced lithium silicate (ZLS) ceramic is described. The fully digitized model-free workflow in a dental practice is possible due to the use of a powder-free intraoral scanner and the computer-aided design/computer-assisted manufacturing (CAD/CAM) of the restorations. The innovative ZLS material offers a singular combination of fracture strength (>370 Mpa), optimum polishing characteristics, and excellent optical properties. Therefore, this ceramic is an interesting alternative material for monolithic restorations produced in a digital workflow. PMID:27042362

  8. Chairside Fabrication of an All-Ceramic Partial Crown Using a Zirconia-Reinforced Lithium Silicate Ceramic

    Directory of Open Access Journals (Sweden)

    Sven Rinke

    2016-01-01

    Full Text Available The chairside fabrication of a monolithic partial crown using a zirconia-reinforced lithium silicate (ZLS ceramic is described. The fully digitized model-free workflow in a dental practice is possible due to the use of a powder-free intraoral scanner and the computer-aided design/computer-assisted manufacturing (CAD/CAM of the restorations. The innovative ZLS material offers a singular combination of fracture strength (>370 Mpa, optimum polishing characteristics, and excellent optical properties. Therefore, this ceramic is an interesting alternative material for monolithic restorations produced in a digital workflow.

  9. The reproducibility and accuracy of internal fit of Cerec 3D CAD/CAM all ceramic crowns.

    LENUS (Irish Health Repository)

    D'Arcy, Brian L

    2009-06-01

    The objective of this study was to evaluate the reproducibility and accuracy of internal fit using Cerec 3D CAD\\/CAM (computer aided design\\/computer aided manufacturing) all-ceramic crowns and to investigate the proximal contact point areas between the crowns and neighbouring teeth, in terms of location and the presence or absence of contact. A total of 48 crowns were milled and divided into two groups of twenty-four each. One group consisted of testing a Control die and the other group consisted of testing single Replica stone die duplicates of the Control die. The Internal Marginal Gap, Axio-Occlusal Transition Gap and Occlusal Gap were measured on each crown in both groups. No significant differences were identified between the mean thickness of the Marginal Gap, the Axio-Occlusal Transition Gap and the Occlusal Gap of the Control die when compared with the Replica dies indicating uniformity and consistency of the accuracy of fit and therefore die replication.

  10. Effect of elasticity on stress distribution in CAD/CAM dental crowns: Glass ceramic vs. polymer-matrix composite.

    Science.gov (United States)

    Duan, Yuanyuan; Griggs, Jason A

    2015-06-01

    Further investigations are required to evaluate the mechanical behaviour of newly developed polymer-matrix composite (PMC) blocks for computer-aided design/computer-aided manufacturing (CAD/CAM) applications. The purpose of this study was to investigate the effect of elasticity on the stress distribution in dental crowns made of glass-ceramic and PMC materials using finite element (FE) analysis. Elastic constants of two materials were determined by ultrasonic pulse velocity using an acoustic thickness gauge. Three-dimensional solid models of a full-coverage dental crown on a first mandibular molar were generated based on X-ray micro-CT scanning images. A variety of load case-material property combinations were simulated and conducted using FE analysis. The first principal stress distribution in the crown and luting agent was plotted and analyzed. The glass-ceramic crown had stress concentrations on the occlusal surface surrounding the area of loading and the cemented surface underneath the area of loading, while the PMC crown had only stress concentration on the occlusal surface. The PMC crown had lower maximum stress than the glass-ceramic crown in all load cases, but this difference was not substantial when the loading had a lateral component. Eccentric loading did not substantially increase the maximum stress in the prosthesis. Both materials are resistant to fracture with physiological occlusal load. The PMC crown had lower maximum stress than the glass-ceramic crown, but the effect of a lateral loading component was more pronounced for a PMC crown than for a glass-ceramic crown. Knowledge of the stress distribution in dental crowns with low modulus of elasticity will aid clinicians in planning treatments that include such restorations. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Metal-ceramic dowel crown restorations for severely damaged teeth: A clinical report

    Directory of Open Access Journals (Sweden)

    Yuzugullu Bulem

    2009-01-01

    Full Text Available This clinical report describes an alternative prosthodontic treatment of a patient who had severely damaged endodontically-treated first molar teeth in all quadrants of her mouth. The young patient′s severely damaged permanent molar teeth were treated with a restoration combining the advantage of the esthetics of dental porcelain, reinforced with the underlying cast gold dowel crown. Using this technique, the remaining sound tooth structure was preserved with function and esthetics accomplished. The described metal-ceramic one piece dowel crown restoration seemed to perform without any problems for the 12 month evaluation time.

  12. Effect of the shades of background substructures on the overall color of zirconia-based all-ceramic crowns

    OpenAIRE

    Suputtamongkol, Kallaya; Tulapornchai, Chantana; Mamani, Jatuphol; Kamchatphai, Wannaporn; Thongpun, Noparat

    2013-01-01

    PURPOSE The objective of this study was to determine the effect of the color of a background substructure on the overall color of a zirconia-based all-ceramic crown. MATERIALS AND METHODS Twenty one posterior zirconia crowns were made for twenty subjects. Seven premolar crowns and six molar crowns were cemented onto abutments with metal post and core in the first and second group. In the third group, eight molar crowns were cemented onto abutments with a prefabricated post and composite core ...

  13. The Effect of Molar Preparation Axial Height on Retention of Adhesively-luted CAD/CAM Ceramic Crowns

    Science.gov (United States)

    2015-04-29

    Retention of Adhesively -luted CAD/CAM Ceramic Crowns 7. Intended publication/meeting: International Association of Dental Research Annual Meeting...Postgraduate Dental School The Effect of Molar Preparation Axial Height on Retention of Adhesively -luted CAD/CAM Ceramic Crowns Robert E...Capt (Dr.) Robert Wake 2. Academic Title: AEGD Dental Resident 3. School/Department/Center: AF Postgraduate Dental School, Keesler AFB. MS 4 . Phone

  14. Fracture load of implant-supported zirconia all-ceramic crowns luted with various cements.

    Science.gov (United States)

    Lim, Hyun-Pil; Yoo, Jeong-Min; Park, Sang-Won; Yang, Hong-So

    2010-01-01

    This study compared the fracture load and failure types of implant-supported zirconia all-ceramic crowns cemented with various luting agents. The ceramic frameworks were fabricated from a presintered yttria-stabilized zirconium dioxide block using computer-aided design/computer-assisted manufacturing technology, and were then veneered with feldspathic porcelain. Three luting agents were used. Composite resin cement (1,560.78 +/- 39.43 N) showed the highest mean fracture load, followed by acrylic/urethane cement (1,116.20 +/- 77.32 N) and zinc oxide eugenol cement (741.21 +/- 41.95 N) (P < .05). The types of failure varied between groups.

  15. Micro-CT evaluation of the marginal fit of CAD/CAM all ceramic crowns

    Science.gov (United States)

    Brenes, Christian

    Objectives: Evaluate the marginal fit of CAD/CAM all ceramic crowns made from lithium disilicate and zirconia using two different fabrication protocols (model and model-less). METHODS: Forty anterior all ceramic restorations (20 lithium disilicate, 20 zirconia) were fabricated using a CEREC Bluecam scanner. Two different fabrication methods were used: a full digital approach and a printed model. Completed crowns were cemented and marginal gap was evaluated using Micro-CT. Each specimen was analyzed in sagittal and trans-axial orientations, allowing a 360° evaluation of the vertical and horizontal fit. RESULTS: Vertical measurements in the lingual, distal and mesial views had and estimated marginal gap from 101.9 to 133.9 microns for E-max crowns and 126.4 to 165.4 microns for zirconia. No significant differences were found between model and model-less techniques. CONCLUSION: Lithium disilicate restorations exhibited a more accurate and consistent marginal adaptation when compared to zirconia crowns. No statistically significant differences were observed when comparing model or model-less approaches.

  16. Dentist material selection for single-unit crowns: Findings from the National Dental Practice-Based Research Network.

    Science.gov (United States)

    Makhija, Sonia K; Lawson, Nathaniel C; Gilbert, Gregg H; Litaker, Mark S; McClelland, Jocelyn A; Louis, David R; Gordan, Valeria V; Pihlstrom, Daniel J; Meyerowitz, Cyril; Mungia, Rahma; McCracken, Michael S

    2016-12-01

    Dentists enrolled in the National Dental Practice-Based Research Network completed a study questionnaire about techniques and materials used for single-unit crowns and an enrollment questionnaire about dentist/practice characteristics. The objectives were to quantify dentists' material recommendations and test the hypothesis that dentist's and practice's characteristics are significantly associated with these recommendations. Surveyed dentists responded to a contextual scenario asking what material they would use for a single-unit crown on an anterior and posterior tooth. Material choices included: full metal, porcelain-fused-to-metal (PFM), all-zirconia, layered zirconia, lithium disilicate, leucite-reinforced ceramic, or other. 1777 of 2132 eligible dentists responded (83%). The top 3 choices for anterior crowns were lithium disilicate (54%), layered zirconia (17%), and leucite-reinforced glass ceramic (13%). There were significant differences (p<0.05) by dentist's gender, race, years since graduation, practice type, region, practice busyness, hours worked/week, and location type. The top 3 choices for posterior crowns were all-zirconia (32%), PFM (31%), and lithium disilicate (21%). There were significant differences (p<0.05) by dentist's gender, practice type, region, practice busyness, insurance coverage, hours worked/week, and location type. Network dentists use a broad range of materials for single-unit crowns for anterior and posterior teeth, adopting newer materials into their practices as they become available. Material choices are significantly associated with dentist's and practice's characteristics. Decisions for crown material may be influenced by factors unrelated to tooth and patient variables. Dentists should be cognizant of this when developing an evidence-based approach to selecting crown material. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Five-year results of a prospective randomised controlled clinical trial of posterior computer-aided design-computer-aided manufacturing ZrSiO4 -ceramic crowns.

    Science.gov (United States)

    Passia, N; Stampf, S; Strub, J R

    2013-08-01

    The aim of this prospective randomised controlled clinical trial was to evaluate the clinical outcome of shrinkage-free ZrSiO4 -ceramic full-coverage crowns on premolars and molars in comparison with conventional gold crowns over a 5-year period. Two hundred and twenty-three patients were included and randomly divided into two treatment groups. One hundred and twenty-three patients were restored with 123 ZrSiO4 -ceramic crowns, and 100 patients received 100 gold crowns, which served as the control. All crowns were conventionally cemented with glass-ionomer cement. After an observation period of 6, 12, 24, 36, 48 and 60 months, the survival probability (Kaplan-Meier) for the shrinkage-free ZrSiO4 -ceramic crowns was 98·3%, 92·0%, 84·7%, 79% and 73·2% and for the gold crowns, 99%, 97·9%, 95·7%, 94·6% and 92·3%, respectively. The difference between the test and control group was statistically significant (P = 0·0027). The gold crowns showed a better marginal integrity with less marginal discoloration than the ceramic crowns. The most common failure in the ceramic crown group was fracture of the crown. The 60-month results of this prospective randomised controlled clinical trial suggest that the use of these shrinkage-free ZrSiO4 -ceramic crowns in posterior tooth restorations cannot be recommended.

  18. Cervical end preparation design on collarless metal ceramic crown to the decrease of bacterial colony

    Directory of Open Access Journals (Sweden)

    Edy Machmud

    2010-09-01

    Full Text Available Background: Cervical end preparation design is an important procedure in fixed partial denture. If the cervical end preparation design is inadequate, dental plaque will easily be formed and this may indicate the beginning of periodontal disease. Purpose: This study was aimed to analyze the effect of cervical end preparation design on collarless metal ceramic crown towards the decrease of bacterium colony number. Methods: This study was quasi-experimental study applying pre and post test on a control group involving 48 subjects with shoulder, bevel shoulder, and deep chamfer cervical end preparation. The bacterium colonies were examined on the 1st, 7th, and 21st days after the insertion of collarless metal ceramic crown. Results: The study showed that bacterium colony increased significantly in deep chamfer and bevel shoulder preparation design between the treatment group and the control group (p<0.05. In shoulder preparation there was not significant different between the treatment group and the control group (p>0.05. Conclusion: Compared to the bevel shoulder and deep chamfer, shoulder design is the best design for collarless metal ceramic crown restoration.Latar belakang: Desain preparasi tepi servikal merupakan suatu tahap yang sangat menentukan dalam pembuatan gigi tiruan cekat. Apabila desain preparasi tepi servikal tidak adekuat dapat menyebabkan pembentukan plak gigi pada daerah tersebut. Keadaan ini merupakan tahap awal terjadinya penyakit periodontal. Tujuan: Untuk menganalisis pengaruh desain preparasi tepi servikal yang dibuat pada mahkota collarless metal ceramic untuk mengurangi jumlah bakterium koloni. Metode: Penelitian ini adalah penelitian eksperimental semu dengan metode pre and post test dan kelompok kontrol terhadap 48 subyek penelitian. Dilakukan preparasi gigi dan pembuatan akhiran preparasi tepi servikal shoulder, bevel shoulder, dan deep chamfer pada subyek penelitian. Pemeriksaan koloni bakteri dilakukan pada hari ke-1

  19. The Effect of Different Finishing Lines on the Marginal Fitness of Full Contour Zirconia and Glass Ceramic CAD/CAM Crowns (An in-vitro study

    Directory of Open Access Journals (Sweden)

    ZAK Al-Zubaidi

    2015-09-01

    Full Text Available Purpose: The aim of this study was to evaluate the effect of two gingival finishing lines (90° shoulder and deep chamfer on the marginal fitness of two types of full anatomic all-ceramic crowns; zirconia crowns (Zikonzhan and glass ceramic crowns (IPS e-max CAD milled with CAD/CAM system. Materials and Methods: Two dentoform teeth of left maxillary first molar were prepared with chamfer finishing line (CFL and shoulder finishing line (SFL, respectively and duplicated to Nickel-Chromium master dies. Thirty two crowns were fabricated and grouped as follows: Group I: 8 zirconia crowns on CFL; Group II: 8 zirconia crowns on SFL; Group III: 8 glass ceramic crowns on CFL and Group IV: 8 glass ceramic crowns on SFL. Marginal gaps were measured at 4 indentations, each one was at center of each tooth surface and collectively 16 points were measured by using stereomicroscope (160X. The data were analyzed by One-way ANOVA and student t-tests. Results: Group I produced the least marginal gap (73.55µm; followed by Group II (92.60µm, and Group III (151.45µm and the highest marginal gap was recorded by Group IV (162.34µm. Statistical analysis of the data showed that SFL produced significantly greater marginal gap on zirconia crowns in comparison with CFL. However, in glass ceramic crowns, CFL revealed less marginal gap compared to SFL but statistically was not significant. On the other hand, glass ceramic crowns significantly produced a greater marginal gap in comparison to zirconia crowns regardless type of finishing line. Conclusions: deep chamfer margin could be more preferable finishing line than 90° shoulder especially for zirconia full crowns. Furthermore, zirconia crowns could be more advisable than glass ceramic crowns in respect to marginal adaptation.

  20. Marginal distortion of thermally incompatible metal ceramic crowns with overextended margins.

    Science.gov (United States)

    Nakamura, Y; Anusavice, K J

    1998-01-01

    The present study tested the hypothesis that metal ceramic crowns with a varying axial height are more susceptible to marginal distortion during mechanical and thermal processing treatments than crowns with a uniform axial height. Copings of Pd-Cu-Ga alloy with buccal margin extensions of 0, 1.5, and 3.0 mm were prepared. Oxidized copings were veneered with experimental opaque porcelain with a mean thermal contraction coefficient (25 degrees C to 500 degrees C) that was either 2.1 ppm/degree C below (delta alpha = +2.1 ppm/degree C) or 0.1 ppm/degree C above (delta alpha = -0.1 ppm/degree C) that of the alloy. Nine groups of six specimens each were prepared for analysis. Eighteen copings from these 54 specimens were used as porcelain-free controls. All specimens were subjected to a 10-step procedure including grinding, oxidation, firing of four opaque porcelain layers (O1: 0.15 mm; O2: 0.15 mm; O3: 0.5 mm; O4: 0.5 mm), glazing, abrasive blasting for 15 seconds, removal of ceramic by dissolution in hydrogen fluoride, and a postannealing treatment. The control specimens were also subjected to this procedure with the exception of the firing of four layers of porcelain, which were not applied. Marginal gap width was determined using a measuring microscope at a magnification of 30x. Analysis of variance revealed a significant difference in mean gap width as a function of axial length. The largest gap change was associated with a 3.0-mm buccal extension and the negative mismatch condition (delta alpha < 0). Marginal distortion of crowns decreases as the axial length becomes more uniform. Analysis of crown distortion based on differences in the mean contraction coefficients of metal and porcelain alone is not recommended because it ignores the effects of metal grinding, metal sandblasting, and transient stress.

  1. Ceramic fragments and metal-free full crowns: a conservative esthetic option for closing diastemas and rehabilitating smiles.

    Science.gov (United States)

    Miranda, M E; Olivieri, K A; Rigolin, F J; Basting, R T

    2013-01-01

    Dental ceramics make it possible to restore anterior teeth that have been esthetically compromised, presenting a high resistance to wear, biocompatibility, color stability, and low thermal conductivity. The development of different types of ceramic and techniques for adhesive cementation have made it possible to produce more conservative restorations without involving the healthy dental structure and with minimally invasive preparation, such as the bonding of ceramic fragments. The purpose of this article is to describe a clinical case in which diastemas were closed by using nanofluorapatite ceramic (e.max Ceram, Ivoclar-Vivadent) fragments on teeth 7 and 10 with minimal tooth preparation and metal-free ceramic crowns (e-max Ceram) reinforced with zirconia copings through a computer-aided design/computer-aided manufacturing system (Lava, 3M-ESPE) on teeth 8 and 9.

  2. Investigation of the time-dependent wear behavior of veneering ceramic in porcelain fused to metal crowns during chewing simulations.

    Science.gov (United States)

    Guo, Jiawen; Tian, Beimin; Wei, Ran; Wang, Weiguo; Zhang, Hongyun; Wu, Xiaohong; He, Lin; Zhang, Shaofeng

    2014-12-01

    The excessive abrasion of occlusal surfaces in ceramic crowns limits the service life of restorations and their clinical results. However, little is known about the time-dependent wear behavior of ceramic restorations during the chewing process. The aim of this in vitro study was to investigate the dynamic evolution of the wear behavior of veneering porcelain in PFM crowns as wear progressed, as tested in a chewing simulator. Twenty anatomical metal-ceramic crowns were prepared using Ceramco III as the veneering porcelain. Stainless steel balls served as antagonists. The specimens were dynamically loaded in a chewing simulator with 350N up to 2.4×10(6) loading cycles, with additional thermal cycling between 5 and 55°C. During the testing, several checkpoints were applied to measure the substance loss of the crowns' occlusal surfaces and to evaluate the microstructure of the worn areas. After 2.4×10(6) cycles, the entire wear process of the veneering porcelain in the PFM crowns revealed three wear stages (running-in, steady and severe wear stages). The occlusal surfaces showed traces of intensive wear on the worn areas during the running-in wear stage, and they exhibited the propagation of cracks in the subsurface during steady wear stage. When the severe wear stage was reached, the cracks penetrated the ceramic layer, causing the separation of porcelain pieces. It also exhibited a good correlation among the microstructure, the wear loss and the wear rate of worn ceramic restorations. The results suggest that under the conditions of simulated masticatory movement, the wear performance of the veneering porcelain in PFM crowns indicates the apparent similarity of the tribological characteristics of the traditional mechanical system. Additionally, the evaluation of the wear behavior of ceramic restorations should be based on these three wear stages.

  3. Machining accuracy of CAD/CAM ceramic crowns fabricated with repeated machining using the same diamond bur.

    Science.gov (United States)

    Tomita, Sachiko; Shin-Ya, Akiyoshi; Gomi, Harunori; Matsuda, Tetsuji; Katagiri, Shingo; Shin-Ya, Akikazu; Suzuki, Hitosi; Yara, Atsushi; Ogura, Hideo; Hotta, Yasuhiro; Miyazaki, Takashi; Sakamoto, Yuuki

    2005-03-01

    The purpose of this study was to investigate the effect of repeated machining up to 51 times using the same diamond bur on machining accuracy of inner and outer surfaces of CAD/CAM (computer-aided designing and computer-aided manufacturing) machined ceramic crowns. The surface topography of machined crowns was examined using photographs. It was found that machining accuracy was not affected by the number of machining times. In all measuring points, the inner surface was machined to a dimension larger than the die model (i.e., increased gap), whereas the outer surface was machined to a dimension smaller than the crown model (i.e., smaller crown). Photo observation showed that cervical contour was machined in a clear, rounded form from 1st to 11th crowns.

  4. Influence of cervical finish line type on the marginal adaptation of zirconia ceramic crowns.

    Science.gov (United States)

    Comlekoglu, Muharrem; Dundar, Mine; Ozcan, Mutlu; Gungor, Mehmet; Gokce, Bulent; Artunc, Celal

    2009-01-01

    The current study evaluated the effect of different cervical finish line designs on the marginal adaptation of a zirconia ceramic. Four different marginal finish lines (c: chamfer, mc: mini-chamfer, fe: feather-edge and s: rounded shoulder) were prepared on phantom incisors. Die models for each preparation group (N = 28, n = 7 per finish line design group) were made of epoxy resin. Y-TZP (ICE Zirkon) frameworks were manufactured by a copy-milling system (Zirconzahn) using prefabricated blanks and tried on the master models for initial adaptation of the framework; they were then sintered, followed by veneering (Zirconzahn). The finished crowns were cemented with a polycarboxylate cement (Poly F) under 300 g load and ultrasonically cleaned. The specimens were sliced and the marginal gap was measured, considering absolute marginal opening (AMO) and marginal opening (MO) for each coping under a stereomicroscope with image processing software (Lucia). The measurements were statistically analyzed using the Kruskal Wallis, Mann Whitney and Wilcoxon Signed Ranks tests at a significance level of alpha = 0.01. Means of AMO measurement (microm) for the feather-edge finish line (87 +/- 10) was significantly lower than that of the chamfer (144 +/- 14), shoulder (114 +/- 16) and mini-chamfer finish line types (114 +/- 11) (p finish line (68 +/- 9) (p finish line type had an influence on the marginal adaptation of the tested zirconia ceramic. Although the feather-edge finish line resulted in lower AMO and MO values, with its proven mechanical disadvantage, it cannot be recommended in clinical applications of zirconia crowns. This type of finish line has acted solely as a control group to test the null hypothesis in the current study. For better marginal adaptation, both shoulder and mini-chamfer finish line types could be suggested for zirconia crowns.

  5. Estimation of the reliability of all-ceramic crowns using finite element models and the stress-strength interference theory.

    Science.gov (United States)

    Li, Yan; Chen, Jianjun; Liu, Jipeng; Zhang, Lei; Wang, Weiguo; Zhang, Shaofeng

    2013-09-01

    The reliability of all-ceramic crowns is of concern to both patients and doctors. This study introduces a new methodology for quantifying the reliability of all-ceramic crowns based on the stress-strength interference theory and finite element models. The variables selected for the reliability analysis include the magnitude of the occlusal contact area, the occlusal load and the residual thermal stress. The calculated reliabilities of crowns under different loading conditions showed that too small occlusal contact areas or too great a difference of the thermal coefficient between veneer and core layer led to high failure possibilities. There results were consistent with many previous reports. Therefore, the methodology is shown to be a valuable method for analyzing the reliabilities of the restorations in the complicated oral environment.

  6. The comparative evaluation of the translucency of crowns fabricated with three different all-ceramic materials: an in vitro study.

    Science.gov (United States)

    Sravanthi, Y; Ramani, Y V; Rathod, Asha M; Ram, Sabita M; Turakhia, Hetal

    2015-02-01

    All-ceramic crowns with different core materials of different strength and aesthetics are available in recent years. The aesthetics of the crown depends mainly on the shade and translucency. Clinician should be aware of the quality and characteristics of these materials so that they will be able to opt for good material for successful clinical use. The aim of this study was to evaluate and compare the translucency of crowns fabricated with three different commercially available all-ceramic materials viz. Alumina - CAD-CAM Procera, Lithium disilicate - Pressable IPS e.max Press, Zirconia - CAD-CAM Lava. All-ceramic crowns (5 per each group and total of 15 samples) were made of Alumina - CAD-CAM Procera (Group I), Lithium disilicate - Pressable IPS e.max Press (Group II), Zirconia - CAD-CAM Lava (Group III) and veneered with their respective layering ceramic. Evaluation for the Translucency (CR=Yb/Yw) over the White (Yw) and Black (Yb) backgrounds at the Incisal, Middle, Cervical, Mesial and Distal thirds of each crown were done using the Spectrophotometer. The results obtained were statistically analyzed by Paired t-test (pfair idea to clinician for the choice of material in different zones during replacement and suitability for restoration in aesthetic zone. Selection of all ceramic system depends on the translucency needed for successful prosthesis of artificial tooth so that it mimics patient's natural dentition. The qualitative measurement of translucency will give the evidence for the clinicians during selection of high or low value translucent tooth for successful replacement. Lithium disilicate - Pressable IPS e.max Press is having better translucency in comparison with other two materials in our study.

  7. Effects of coronal substrates and water storage on the microhardness of a resin cement used for luting ceramic crowns

    Directory of Open Access Journals (Sweden)

    Luana Menezes de MENDONÇA

    2014-07-01

    Full Text Available Composite resin and metallic posts are the materials most employed for reconstruction of teeth presenting partial or total destruction of crowns. Resin-based cements have been widely used for cementation of ceramic crowns. The success of cementation depends on the achievement of adequate cement curing. Objectives: To evaluate the microhardness of Variolink® II (Ivoclar Vivadent, Schaan, Liechtenstein, used for cementing ceramic crowns onto three different coronal substrate preparations (dentin, metal, and composite resin, after 7 days and 3 months of water storage. The evaluation was performed along the cement line in the cervical, medium and occlusal thirds on the buccal and lingual aspects, and on the occlusal surface. Material and Methods: Thirty molars were distributed in three groups (N=10 according to the type of coronal substrate: Group D- the prepared surfaces were kept in dentin; Groups M (metal and R (resin- the crowns were sectioned at the level of the cementoenamel junction and restored with metallic cast posts or resin build-up cores, respectively. The crowns were fabricated in ceramic IPS e.max® Press (Ivoclar Vivadent, Schaan, Liechtenstein and luted with Variolink II. After 7 days of water storage, 5 specimens of each group were sectioned in buccolingual direction for microhardness measurements. The other specimens (N=5 were kept stored in deionized water at 37ºC for three months, followed by sectioning and microhardness measurements. Results: Data were first analyzed by three-way ANOVA that did not reveal significant differences between thirds and occlusal surface (p=0.231. Two-way ANOVA showed significant effect of substrates (p<0.001 and the Tukey test revealed that microhardness was significantly lower when crowns were cemented on resin cores and tested after 7 days of water storage (p=0.007. Conclusion: The type of material employed for coronal reconstruction of preparations for prosthetic purposes may influence the

  8. Laser all-ceramic crown removal and pulpal temperature--a laboratory proof-of-principle study.

    Science.gov (United States)

    Rechmann, P; Buu, N C H; Rechmann, B M T; Finzen, F C

    2015-11-01

    The objective of this proof-of-principle laboratory pilot study was to evaluate the temperature increase in the pulp chamber in a worst case scenario during Er:YAG laser debonding of all-ceramic crowns. Twenty extracted molars were prepared to receive all-ceramic IPS E.max CAD full contour crowns. The crowns were bonded to the teeth with Ivoclar Multilink Automix. Times for laser debonding and temperature rise in the pulp chamber using micro-thermocouples were measured. The Er:YAG was used with 560 mJ/pulse. The irradiation was applied at a distance of 5 mm from the crown surface. Additional air-water spray for cooling was utilized. Each all-ceramic crown was successfully laser debonded with an average debonding time of 135 ± 35 s. No crown fractured, and no damage to the underlying dentin was detected. The bonding cement deteriorated, but no carbonization at the dentin/cement interface occurred. The temperature rise in the pulp chamber averaged 5.4° ± 2.2 °C. During 8 out of the 20 crown removals, the temperature rise exceeded 5.5 °C, lasting 5 to 43 s (average 18.8 ± 11.6 s). A temperature rise of 11.5 °C occurred only once, while seven times the temperature rise was limited to 6.8 ± 0.5 °C. Temperature rises above 5.5 °C occurred only when the laser was applied from one side and additional cooling from the side opposite the irradiation. Er:YAG laser energy can successfully be used to efficiently debond all-ceramic crowns from natural teeth. Temperature rises exceeding 5.5 °C only occur when an additional air/water cooling from a dental syringe is inaccurately directed. To avoid possible thermal damage and to allow further heat diffusion, clinically temperature-reduced water might be applied.

  9. A 1-year randomised controlled trial comparing zirconia versus metal-ceramic implant supported single-tooth restorations

    DEFF Research Database (Denmark)

    Hosseini, Mandana; Worsaae, Nils; Schiødt, Morten

    2011-01-01

    inflammatory reactions were registered at AC restorations. Two technical complications, one loss of retention and one chipping of veneering porcelain were recorded at two metal-ceramic crowns. The marginal adaptation of the all-ceramic crowns was significantly less optimal than the metal-ceramic crowns (P = 0...

  10. All-ceramic single-tooth restorations: choosing the material to match the preparation--preparing the tooth to match the material.

    Science.gov (United States)

    Baltzer, A

    2008-01-01

    prominently in the discussions between dentists and dental technician. Unfavorable preparation shapes for single crowns will necessitate compromises in terms of the choice of materials that result in high cost but do not offer anything in the way of higher fracture resistance. What constitutes an appropriate all-ceramic restoration for a single tooth? Do all-ceramic single crowns require the same material bulk as multi-unit bridges? Everything would indicate that a suitable preparation geometry allows feldspathic ceramic monoblock crowns to be milled that do not require any extensive finishing efforts such as thermal annealing or in-laboratory veneering while at the same time demanding no compromises in terms of esthetics and load-bearing capacity.

  11. Clinical retrospective analysis of all-ceramic single crown in terms of fracture resistance with CAD/CAM zirconia-base:a four-year follow-up%CAD/CAM氧化锆全瓷单冠抗折裂随访4年临床分析

    Institute of Scientific and Technical Information of China (English)

    郑茜聪; 蔡志斌

    2015-01-01

    Objective To evaluate the fracture resistance of CAD / CAM zirconia all-ceramic crowns. Methods 284 all-ceramic crowns were fabricated for 189 patients. 226 restorations of 156 patients were clinically followed up for 2. 5-5. 5 years. The site of crown, fracture or breakage,loose or dislodgement were observed. Results The fracture rate was 0. 9% at 1 year after the insertion date, 2. 1% after two years,3. 3% after three years,7. 1% after four years. Overall the fracture rate was 9. 7% with 226 restorations. Base crown fracture took place in two cases. A statistically significant difference was found for fractures when the opposing dentition of natural teeth and fixed restorations were compared (P = 0. 034). The fractures were most commonly noted when the opposing dentition was a fixed metal ceramic or other ceramic restorations. Conclusions The fracture resistance of CAD / CAM zirconia all-ceramic crowns was acceptable clinically and it can be a preferred esthetic restoration.%目的:回顾分析评价CAD / CAM 氧化锆全瓷单冠抗折裂性能。方法为189例患者制作CAD / CAM 氧化锆全瓷冠284颗,随访到156例患者的226颗全瓷冠,随访2.5~5.5年,对修复体的位置、崩瓷、基底冠折断、修复体松动脱落等情况进行观察。结果 CAD / CAM 全瓷冠1年的折裂率0.9%,2年的折裂率为2.1%,3年的折裂率为3.3%,4年的折裂率为7.1%,观察期间全瓷冠的总折裂率为9.7%。其中2例患者发生基底冠折裂。当对颌分别为天然牙或瓷修复体时,全瓷冠的折裂率有显著性差异( P =0.034)。全瓷冠的折裂后牙明显高于前牙区(P <0.01)。结论 CAD / CAM 氧化锆全瓷冠整体抗折裂性能临床可接受,可作为临床首选的美学修复体。

  12. Influence of marginal fit and cement types on microleakage of all-ceramic crown systems

    Directory of Open Access Journals (Sweden)

    Ece Yüksel

    2011-06-01

    Full Text Available The purpose of this study was to evaluate the effects of both marginal fit and cementing with different luting agents on the microleakage of all-ceramic crown systems. Thirty-six extracted upper central incisors were prepared for full-coverage crowns and were divided into three groups. Group 1: CAD/CAM-fabricated ZrO2, Group 2: Heat-pressed lithium-disilicate, and Group 3: Cast Cr-Co copings as the control group. Copings were made following standard techniques, and groups were assigned cementation with either self-adhesive resin cement (A or glass-ionomer luting cement (B. The specimens were subjected to thermocycling, immersed in basic fuchsin solution, sectioned mesiodistally and buccolingually. The surface of each section was digitally photographed under a stereomicroscope. Microleakage was scored using a five-point scale, and the marginal gap was measured using image analysis software. Data were statistically analyzed using 2-way ANOVA, Kruskal-Wallis, and Mann-Whitney U tests (α: 0.05. The marginal discrepancy of each group was 82.7 ± 7 µm, 92.6 ± 4 µm and 96.5 ± 7 µm respectively. Group 1 showed significantly smaller gaps than Group 3 (P = 0.042. Self-adhesive resin cement (A showed a lower level of microleakage than glass-ionomer luting cement (B in all groups (P = 0.029. Microleakage scores of '0' were 83% for 1A, 50% for 1B, 50% for 2A, 16% for 2B, 33% for 3A and none for 3B. Marginal discrepancy and cement type both had significant effects on microleakage. Lower levels of microleakage were recorded with self-adhesive resin cement, while CAD/CAM-fabricated ZrO2 copings showed smaller marginal discrepancy and less microleakage in comparison to cast Cr-Co.

  13. The Advantage of Intraoral Digital Impressions on All-ceramic Crowns%口内数字印模用于全瓷冠修复的优势

    Institute of Scientific and Technical Information of China (English)

    房磊; 陈萌萌; 孙越; 张春霞; 肖威娜

    2016-01-01

    To study the advantages of intraoral digital impression in the preparation of all ceramic crowns. 2014 and 2015 in the hospital, Department of Stomatology, the requirements of all ceramic single crown repair of 40 patients with, a total of 40 teeth teeth, were divided to two groups, with 20 cases in each group, 20 teeth, respectively, to take the traditional impression way for preparing gypsum model and intraoral digital impression made digital impression, make all ceramic crown in the restoration of teeth respectively, to observe and record operating time of the two groups all ceramic crown on the edge of the dense degree and production model, two groups compared to determine the advantages of digital impression. The two groups all ceramic crown edge sealing degree can group the success rate is better than the traditional digital impression impression group. The digital impression group operation time is much shorter than the traditional impression group is obviously superior to the traditional model. Intraoral digital impression in all ceramic crown preparation has obvious advantages, high precision, and to save time, materials, and improve the comfort degree of patients satisfaction.%为研究口内数字印模在全瓷冠修复方面的应用优势,选取2014年1月———2015年5月,在本院口腔科就诊要求全瓷单冠修复的患者40人、共40颗牙齿,随机分为a、b两组,每组20人、20颗牙齿,a组采取传统印模方式制取石膏模型,b组采用口内数字印模方式取得数字化印模,分别制作全瓷冠修复牙齿,观察记录两组全瓷冠边缘的密合程度及制取模型所用的操作时间,两组比较,以判断数字印模的优势。发现两组全瓷冠边缘的密合程度均可,数字印模组成功率优于传统印模组。数字印模组操作时间大大短于传统印模组,明显优于传统印模组。说明口内数字印模在全瓷冠制取方面有明显优势,精准度高且

  14. Fit of zirconia all-ceramic crowns with different cervical margin designs, before and after porcelain firing and glazing.

    Science.gov (United States)

    Miura, Shoko; Inagaki, Ryoichi; Kasahara, Shin; Yoda, Masanobu

    2014-01-01

    The purpose of this study is to investigate the fit of zirconia cores and all-ceramic crowns prepared with different cervical margin designs. The radius of curvature between the axial wall and the occlusal surface was set to 1 mm in an abutment using the cervical shoulder marginal design (S) and to 0.2 and 0.5 mm in abutments with round shoulders (0.2RS and 0.5RS, respectively). The internal gaps of the cores were 45-138 μm (S), 41-141 μm (0.2RS), and 43-133 μm (0.5RS). The internal gaps of the all-ceramic crowns were 40-115 μm (S), 45-113 μm (0.2RS), and 42-126 μm (0.5RS). There were no significant differences in one-way ANOVA for any region in any marginal design before and after firing the porcelain. The marginal gaps between the all-ceramic crowns and dies were 27 ± 25 (S), 30 ± 29 (0.2RS), and 24 ± 27 μm (0.5RS), again with no significant differences in one-way ANOVA.

  15. The Effect of Different Finishing Lines on the Marginal Fitness of Full Contour Zirconia and Glass Ceramic CAD/CAM Crowns (An in-vitro study)

    OpenAIRE

    ZAK Al-Zubaidi; AMW Al-Shamma

    2015-01-01

    Purpose: The aim of this study was to evaluate the effect of two gingival finishing lines (90° shoulder and deep chamfer) on the marginal fitness of two types of full anatomic all-ceramic crowns; zirconia crowns (Zikonzhan) and glass ceramic crowns (IPS e-max CAD) milled with CAD/CAM system. Materials and Methods: Two dentoform teeth of left maxillary first molar were prepared with chamfer finishing line (CFL) and shoulder finishing line (SFL), respectively and duplicated to Nickel-Chromium m...

  16. The influence of zirconia coping designs on the fracture load of all-ceramic molar crowns.

    Science.gov (United States)

    Kokubo, Yuji; Tsumita, Mitsuyoshi; Kano, Takamitsu; Fukushima, Shunji

    2011-01-01

    This study investigated the influence of zirconia coping designs on the fracture load of all-ceramic crown. Four kinds of zirconia copings were designed (a: Conventional zirconia coping with flat occlusal surface: thickness of the each coping is 0.6 mm evenly, and at the cervical margin area, the coping is adjusted sharply so as to fit preparation margin, b: Conventional zirconia coping with shoulder collar of 1 mm: thickness of the each coping is 0.6 mm evenly, and there is a collar of 0.6 mm from the margin, c: Zirconia coping with following original cuspal configuration (concave): two inclined cusp planes, and at the cervical margin area, the coping is adjusted sharply so as to fit preparation margin, and d: Zirconia coping with supporting configuration on the occlusal area: supporting configuration against the occlusal force, and at the cervical margin area, the coping is adjusted sharply so as to fit preparation margin) and porcelain was fired. Vertical and lateral load were conducted until fracture. Coping design affected the fracture load; conventional uniform thickness coping design showed the lowest load (a), whereas cuspal configuration to perform even thickness of porcelain showed the highest fracture load both load directions (c).

  17. Clinical marginal and internal adaptation of CAD/CAM milling, laser sintering, and cast metal ceramic crowns.

    Science.gov (United States)

    Tamac, Ece; Toksavul, Suna; Toman, Muhittin

    2014-10-01

    Metal ceramic crowns are widely used in clinical practice, but comparisons of the clinical adaptation of restorations made with different processing techniques are lacking. The purpose of this study was to compare the clinical marginal and internal adaptation of metal ceramic crowns fabricated with 3 different techniques: computer-aided design and computer-aided manufacturing (CAD/CAM) milling (CCM), direct metal laser sintering (DMLS), and traditional casting (TC). Twenty CCM, 20 DMLS, and 20 TC metal ceramic crowns were fabricated for 42 patients. Before luting the crowns, silicone replicas were obtained to measure marginal gap and internal adaptation that was evaluated at 3 regions: axial wall, axio-occlusal angle, and occlusal surface. Measurements were made with a reflected light binocular stereomicroscope at 20× magnification and analyzed with 1-way analysis of variance (ANOVA) and the Bonferroni post hoc test (α=.05). The mean marginal gap values were 86.64 μm for CCM, 96.23 μm for DMLS, and 75.92 μm for TC. The means at the axial wall region were 117.5 μm for the CCM group, 139.02 μm for the DMLS group, and 121.38 μm for the TC group. One-way ANOVA revealed no statistically significant differences among the groups for measurements at the marginal gap (P=.082) and the axial wall region (P=.114). The means at the axio-occlusal region were 142.1 μm for CCM, 188.12 μm for DMLS, and 140.63 μm for TC, and those at the occlusal surface region were 265.73 μm for CCM, 290.39 μm for DMLS, and 201.09 μm for TC. The mean values of group DMLS were significantly higher at the axio-occlusal region and the occlusal surface region than those of other groups (Pmetal ceramic crowns performed similarly in terms of clinical marginal and axial wall adaptation. The cement film thickness at the occlusal region and axio-occlusal region were higher for DMLS crowns. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc

  18. Influence of implant position on clinical crown length and peri-implant soft tissue dimensions at implant-supported single crowns replacing maxillary central incisors

    DEFF Research Database (Denmark)

    Peng, Min; Fei, Wei; Hosseini, Mandana

    2013-01-01

    The aims of the present study were to evaluate the influence of implant position on clinical crown length and marginal soft tissue dimensions at implant-supported single crowns of maxillary central incisors, and to validate the papilla index score (PIS). Twenty-five patients, who had lost one of ...

  19. Evaluation of marginal and internal gaps of metal ceramic crowns obtained from conventional impressions and casting techniques with those obtained from digital techniques.

    Science.gov (United States)

    Rai, Rathika; Kumar, S Arun; Prabhu, R; Govindan, Ranjani Thillai; Tanveer, Faiz Mohamed

    2017-01-01

    Accuracy in fit of cast metal restoration has always remained as one of the primary factors in determining the success of the restoration. A well-fitting restoration needs to be accurate both along its margin and with regard to its internal surface. The aim of the study is to evaluate the marginal fit of metal ceramic crowns obtained by conventional inlay casting wax pattern using conventional impression with the metal ceramic crowns obtained by computer-aided design and computer-aided manufacturing (CAD/CAM) technique using direct and indirect optical scanning. This in vitro study on preformed custom-made stainless steel models with former assembly that resembles prepared tooth surfaces of standardized dimensions comprised three groups: the first group included ten samples of metal ceramic crowns fabricated with conventional technique, the second group included CAD/CAM-milled direct metal laser sintering (DMLS) crowns using indirect scanning, and the third group included DMLS crowns fabricated by direct scanning of the stainless steel model. The vertical marginal gap and the internal gap were evaluated with the stereomicroscope (Zoomstar 4); post hoc Turkey's test was used for statistical analysis. One-way analysis of variance method was used to compare the mean values. Metal ceramic crowns obtained from direct optical scanning showed the least marginal and internal gap when compared to the castings obtained from inlay casting wax and indirect optical scanning. Indirect and direct optical scanning had yielded results within clinically acceptable range.

  20. A practice-based clinical evaluation of the survival and success of metal-ceramic and zirconia molar crowns: 5-year results.

    Science.gov (United States)

    Rinke, S; Kramer, K; Bürgers, R; Roediger, M

    2016-02-01

    This practice-based study evaluates the survival and success of conventionally luted metal-ceramic and zirconia molar crowns fabricated by using a prolonged cooling period for the veneering porcelain. Fifty-three patients were treated from 07/2008 to 07/2009 with either metal-ceramic crowns (MCC) or zirconia crowns (ZC). Forty-five patients (26 female) with 91 restorations (obser-vational period: 64.0 ± 4.8 months) participated in a clinical follow-up examination and were included in the study. Estimated cumulative survival (ECSv), success (ECSc) and veneering ceramic success (ECVCSc) were calculated (Kaplan-Meier) and analysed by the crown fabrication technique and the position of the restoration (Cox regression model) (P crowns placed on tooth-neighboured abutments (n = 47), (5-year VCF-rate: 4.3%). In the present study, zirconia molar crowns demonstrated a 5-year ECSv, ECSc and ECVCSc comparable to MCCs. Irrespective of the fabrication technique, crowns on terminal abutments bear a significantly increased risk for VCFs. Clinical investigations with an increased number of restorations are needed.

  1. Esthetic restoration of infra-occluded retained primary mandibular incisors with all-ceramic crowns in adult dentition.

    Science.gov (United States)

    Hsu, Kuang-Wei; Shen, Yu-Fu

    2004-12-01

    The prevalence of hypodontia is reported to be between 1.5% to 10% in the permanent dentition. In the anterior teeth, maxillary lateral incisors and mandibular central incisors are the most frequently involved teeth. This causes esthetic problems for the patient. Several reports have focused on restoration of retained maxillary primary anterior teeth, but none have described restoration of retained mandibular primary incisors. This clinical report describes the restoration of infra-occluded retained primary mandibular central incisors of a 17 year-old girl diagnosed with hypodontia. All-ceramic crowns made with computer-aided design/ computer-aided manufacturing technology were used to restore the teeth incisally and interproximally. Due to a relatively short root length and inadequate crown-root ratio, the primary mandibular central incisors were splinted and adjusted to distribute the protrusive force evenly across the maxillary and mandibular incisors. Functional and esthetic results were achieved.

  2. Time-dependent fracture probability of bilayer, lithium-disilicate-based, glass-ceramic, molar crowns as a function of core/veneer thickness ratio and load orientation.

    Science.gov (United States)

    Anusavice, Kenneth J; Jadaan, Osama M; Esquivel-Upshaw, Josephine F

    2013-11-01

    Recent reports on bilayer ceramic crown prostheses suggest that fractures of the veneering ceramic represent the most common reason for prosthesis failure. The aims of this study were to test the hypotheses that: (1) an increase in core ceramic/veneer ceramic thickness ratio for a crown thickness of 1.6mm reduces the time-dependent fracture probability (Pf) of bilayer crowns with a lithium-disilicate-based glass-ceramic core, and (2) oblique loading, within the central fossa, increases Pf for 1.6-mm-thick crowns compared with vertical loading. Time-dependent fracture probabilities were calculated for 1.6-mm-thick, veneered lithium-disilicate-based glass-ceramic molar crowns as a function of core/veneer thickness ratio and load orientation in the central fossa area. Time-dependent fracture probability analyses were computed by CARES/Life software and finite element analysis, using dynamic fatigue strength data for monolithic discs of a lithium-disilicate glass-ceramic core (Empress 2), and ceramic veneer (Empress 2 Veneer Ceramic). Predicted fracture probabilities (Pf) for centrally loaded 1.6-mm-thick bilayer crowns over periods of 1, 5, and 10 years are 1.2%, 2.7%, and 3.5%, respectively, for a core/veneer thickness ratio of 1.0 (0.8mm/0.8mm), and 2.5%, 5.1%, and 7.0%, respectively, for a core/veneer thickness ratio of 0.33 (0.4mm/1.2mm). CARES/Life results support the proposed crown design and load orientation hypotheses. The application of dynamic fatigue data, finite element stress analysis, and CARES/Life analysis represent an optimal approach to optimize fixed dental prosthesis designs produced from dental ceramics and to predict time-dependent fracture probabilities of ceramic-based fixed dental prostheses that can minimize the risk for clinical failures. Copyright © 2013 Academy of Dental Materials. All rights reserved.

  3. Effect of frame design and veneering material on biomechanical behavior of zirconia dental crowns veneered with overpressing ceramics.

    Science.gov (United States)

    Porojan, Liliana; Topală, Florin; Porojan, Sorin; Savencu, Cristina

    2017-05-31

    The objective of this investigation was to compare alternative framework designs of molar zirconia crowns veneered with various overpressing ceramics and to predict the biomechanical behavior based on the stress evaluation. The hypothesis of the study is that the zirconia framework design and type of the veneering material, using the same technological procedure, may influence the biomechanical behavior of the restorations. Three geometric models with differential coping designs (uniform thickness, cutback and buccal reduction) were developed and two types of hot-pressed ceramics (leucite and lithium disilicate reinforced) were analyzed for the veneers. Using finite element analysis (FEA), maximum principle stresses were recorded in the tooth structures and in the restorations for all the developed designs. Results led to the conclusion that the hypothesis was accepted.

  4. Influence of implant position on clinical crown length and peri-implant soft tissue dimensions at implant-supported single crowns replacing maxillary central incisors

    DEFF Research Database (Denmark)

    Peng, Min; Fei, Wei; Hosseini, Mandana

    2013-01-01

    as controls. Paired sample t-testand Pearson´s correlation analysis were used to analyze implant position, dimension of crownand papilla fill.Cohen’s ¿ andSpearman correlation were used to validate the PIS.The implant-supported crown was statistically longer than the contra-lateral tooth......The aims of the present study were to evaluate the influence of implant position on clinical crown length and marginal soft tissue dimensions at implant-supported single crowns of maxillary central incisors, and to validate the papilla index score (PIS). Twenty-five patients, who had lost one......, and there was significant correlation between the oro-facial position of the implant and the crown length difference (r=.607, p=.001). The distalpapilla was significantly shorter than the mesialpapilla at implant-supported crowns (p

  5. Functionalization of oxidized single-walled carbon nanotubes with 4-benzo-9-crown-3 ether

    Indian Academy of Sciences (India)

    Ardeshir Khazaei; Maryam Kiani Borazjani; Khadijeh Mansouri Moradian

    2012-09-01

    Functionalization of oxidized single-walled carbon nanotubes (SWCNTs) by a zwitterionic interaction (COO−NH$^{+}_{3}$) between protonated amine on crown ether and an oxyanion from a carboxylic acid group on SWCNT has been described. This ionic interaction has led to a considerable increase in the solubility of SWCNTs in both organic and aqueous solvents such as ethanol, dimethyl sulphoxide, dimethylformamide, and H2O. The highest solubility was attained in DMF and DMSO. The ionic bonded 4-benzo-9-crown-3 ether allowed the hosting of Li+. The ionic bond of crown ether (4-(benzo-9-crown-3)) to SWCNT was identified and confirmed by infrared spectroscopy, transmission electron-microscopy, atomic force microscopy and thermogravimetric analysis methods.

  6. CAD/CAM Zirconia vs. slip-cast glass-infiltrated Alumina/Zirconia all-ceramic crowns: 2-year results of a randomized controlled clinical trial

    OpenAIRE

    Murat Cavit Çehreli; Ali Murat Kökat; Kivanç Akça

    2009-01-01

    The aim of this randomized controlled clinical trial was to compare the early clinical outcome of slip-cast glass-infiltrated Alumina/Zirconia and CAD/CAM Zirconia all-ceramic crowns. A total of 30 InCeram® Zirconia and Cercon® Zirconia crowns were fabricated and cemented with a glass ionomer cement in 20 patients. At baseline, 6-month, 1-year, and 2-year recall appointments, Californian Dental Association (CDA) quality evaluation system was used to evaluate the prosthetic replacements, and p...

  7. 玻璃纤维桩加全瓷冠修复前牙残根残冠的效果%Effects of glass fiber post plus all-ceramic crown on reparation of anterior teeth residual root and crown

    Institute of Scientific and Technical Information of China (English)

    郑加军; 李瑛; 彭庭莉; 谢良宪

    2012-01-01

    目的 观察玻璃纤维桩+全瓷冠修复前牙残根残冠的效果.方法 选择我科进行前牙残根、残冠修复治疗患者76例82颗患牙,采用玻璃纤维桩+全瓷冠修复,完成后6~12个月对患者进行随访,观察有无冠桩脱落、折断、松动以及牙龈、牙冠的色泽改变情况.结果 82颗患牙中,有1颗出现冠脱落,1例出现根尖叩痛.全部82颗患牙均未出现根折、桩核脱落,无继发龋坏,冠及龈边缘无变色,色泽美观.结论 玻璃纤维桩+全瓷冠修复前牙残根残冠临床效果良好.%Objective To observe the effects of glass fiber post plus all - ceramic crown on the reparation of anterior teeth residual root and crown. Methods 76 patients ( 82 front teeth ) receiving the reparation of anterior teeth residual root and crown in our department were selected and received the reparation by glass fiber post plus all - ceramic crown. Follow up was made 6-12 months after the reparation. Observe was made in whether there were any non - crown post shedding, split, and loosening and the changes in the color of gingival gum and crown. Results There were 1 tooth with the crown shedding and 1 case of percussion pain in the root among the 82 teeth. There was no split, loss of post - core, and secondary caries among all the 82 teeth. The color of their crown and gingival margin did not change. Conclusion Glass fiber post plus all - ceramic crown have good effect on the reparation of anterior teeth residual root and crown.

  8. Clinical evaluation of IPS e.max Press all-ceramic crown and porcelain fused metal crown restorations%IPS e.max Press铸瓷与烤瓷全冠修复效果的临床观察

    Institute of Scientific and Technical Information of China (English)

    朱政; 高姗; 陈金华

    2012-01-01

    目的:评价比较IPS e.max Press铸瓷全冠、贵金属烤瓷全冠、镍铬合金烤瓷全冠的临床修复效果.方法:选择IPS e.max Press铸瓷全冠、贵金属烤瓷全冠、镍铬合金烤瓷全冠等3种材料修复上中切牙的患者各90例,参照美国公共卫生服务的相关标准对完成修复后即刻与12个月的修复体进行临床检查和相关评价,内容包括修复体颜色、牙龈边缘着色、继发龋、边缘密合度、牙龈健康状况等.结果:在修复体颜色与牙龈健康状况方面,IPS e.max Press铸瓷全冠与贵金属烤瓷全冠均显著优于镍铬合金烤瓷全冠(P<0.05);在牙龈边缘着色和边缘密合度方面,IPS e.max Press铸瓷全冠、贵金属烤瓷全冠与镍铬合金烤瓷全冠均存在显著性差异(P<0.05),IPS e.max Press铸瓷全冠最佳,贵金属烤瓷全冠次之;3组修复体均未发生继发龋.结论:IPSe.max Press铸瓷全冠修复的临床效果优良,贵金属烤瓷全冠次之,均优于镍铬合金烤瓷全冠.%Objective:To observe the clinical outcome of IPS e. max Press all-ceramic crown,gold alloy porcelain fused metal (PFM) crown and Ni-Cr alloy PFM crown restorations. Methods: Three groups of patients were treated with IPS e. max Press all-ceramic crown,gold alloy PFM crown or Ni-Cr alloy PFM crown restorations separately. The crown restorations were evaluated with the USPHS criteria for color match, marginal discoloration, secondary caries, marginal adaptation and gingival health immediately and after a period of 12 months. Results:The clinical outcome of both IPS e. max Press all-ceramic crown and gold alloy PFM crown restorations was better than Ni-Cr alloy PFM crown restorations for color match and gingival health. There was statistically significant difference in 3 groups for marginal discoloration and marginal adaptation, in which IPS e. max Press all-ceramic crown restoration was the best and gold alloy PFM crown restoration was better than Ni-Cr alloy

  9. Color differences between all-ceramic crowns and metal-ceramic crowns%氧化铝全瓷冠、镍铬合金烤瓷冠和天然牙之间色度差的比较研究

    Institute of Scientific and Technical Information of China (English)

    宋育萱; 宋欣; 毛红

    2012-01-01

    目的 明确氧化铝全瓷冠、镍铬合金烤瓷冠以及天然牙三者之间的颜色差异.方法 选择上前牙氧化铝烤瓷冠修复病例43例,用Vitapan classic比色板比色,同牙模型制作氧化铝烤瓷冠和镍铬合金烤瓷冠,用Crystaleye电脑比色仪分别读取氧化铝烤瓷冠,镍铬合金烤瓷冠和天然牙的颈,中,切三部的L*a*b*值,计算各部的色度差值.结果 氧化铝烤瓷冠与天然牙在颈,中,切部的色度差值小于2.75,肉眼无明显的感知差.镍铬合金烤瓷冠与天然牙和氧化铝烤瓷冠在颈部和中部的色度差值大于2.75,肉眼有明显的感知差,切端的色度差值小于2.75.结论 用Vitapan classic比色板比色条件下,镍铬合金烤瓷冠与天然牙切端相似,颈部和中部有明显的内眼感知差.氧化铝烤瓷冠与天然牙的色度有比较高的相似性.%Objective To evaluate the differences in color among In-ceram all ceramic crown, metal ceramic restoration, and the natural tooth. Methods Fourty-three participants with maxillary anterior all ceramic restorations were included in this study. Metal ceramic restorations were made with the same model as that used in full ceramic restorations. The color values of the In-ceram all ceramic crown, metal ceramic restoration, and the namesake tooth were measured hy using a denial spectrophotometer shade -mactching device Olympua Crystaleye. The coigr parameters (CIE1976 Lab )of cervical, body, incisal area of tooth were recorded. The ΔEa*b* between ln-teram all ceramic crown, metal ceramic restoration, and the natural tooth was calculated. Results The ΔEa*h* between In-ceram all ceramic crown and the natural tooth was Jess than 2.75.The ΔEa*b* in cervical or body area between metal ceramic restoration and the natural tooth or In-ceram all ceramic crown and metal ceramic restoration was more than 2.75. The ΔEa*h* in incisal area between metal ceramic restoration and the natural tooth or In-ceram all ceramic crown

  10. 二氧化锆全瓷冠对牙龈健康的影响%Effect of zirconia all-ceramic crowns on gingival health

    Institute of Scientific and Technical Information of China (English)

    张非煜; 吕亚林; 董坚; 李俨; 张伟; 李国庆

    2013-01-01

    Objective To compare the effect of anterior teeth clinical restoration with zirconia all-ceramic crowns and cast all-ceramic crowns.Methods All 49 patients with 73 crowns were enrolled in zirconia group.Those anterior teeth were restored with zirconia all-ceramic crowns.The control group were selected with 32 crowns from 25 patients with cast all-ceramic crowns.One day,3 months,6 months,1 year after restoration were the time points.Marginal integrity was observed according to the standards specified by the Califcrnia Dental Association.Results All 73 zirconia ceramic crowns repairs were completed on day 1 and 3 months,6 months after restoration in zirconia group.72 anterior teeth got grade Ⅰ,1 anterior tooth got grade Ⅱ ; 1 year after the repair,70 anterior teeth got grade Ⅰ and 3 anterior teeth got grade Ⅱ.All 32 casting all-ceramic crowns restorations were completed in one day,3 months,6 months,1 year after the restoration.31 anterior teeth got grade Ⅰ,1 anterior teeth got grade Ⅱ.The clinical effects of the two types of all-ceramic crown showed no statistical difference.Conclusion Zirconia all ceramic crown has the similar gingival effect as the cast all-ceramic crowns and both of those kinds of restorations are ideal for anterior teeth repair.%目的 分析前牙美容修复中二氧化锆全瓷冠对牙龈健康的影响.方法 49例患者共73颗前牙采用二氧化锆全瓷冠修复,设为二氧化锆组;对照组选择25例患者共32颗前牙采用铸造全瓷冠修复.分别在修复后1d和3、6、12个月参照美国加利福尼亚州牙科协会制定的标准,观察牙龈健康状况.结果 二氧化锆组在修复完成第1天及第3、6个月时,牙龈健康分级Ⅰ、Ⅱ级均分别为72、1颗;修复后12个月,Ⅰ、Ⅱ级分别为70、3颗.对照组在修复完成第1天及第3、6、12个月时,牙龈健康分级Ⅰ、Ⅱ级均分别为72、1颗.2种全瓷冠的临床效果差异无统计学意义(P>0.05).结论 二氧化

  11. Clinical results of α- Ceramic 88 gold alloy for metal-ceramic-crowns%傲丹特烤瓷用金合金临床试验观察

    Institute of Scientific and Technical Information of China (English)

    李阳; 王新知

    2012-01-01

    Objective To evaluate the clinical effect of metal -ceramic-crowns made of α- Ceramic 88 gold alloy. Methods Fifty-one patients with defected incisors or premolars were restored with α— Ceramic 88 gold alloy PFMs. Fifty cases as control were restored with HERA Bio N gold alloy PFMs. Before cementation, the fitness of the crowns was examined using a polyether indicator paste. The thickness of the polyether films at marginal sites was measured by the GALILEEO EZ image measuring system. All patients were followed up for 6 tol2 months. The clinical index was recorded at the time of delivery and return visit, including casting defects of the copings , marginal polishing performance , porcelain fracture,visual estimation of the marginal fitness ,mucosal allergy and adverse reactions. Results The α-Ceramic 88 gold alloy group showed as good clinical performance and biosafety as the control group . The mean thickness of the polyether films was not significantly different between the two alloys. Conclusion The clinical performance of α— Ceramic 88 gold alloy was as good as the HERA Bio N gold and fulfilled the requirement of clinical application .%目的 评价国产傲丹特α- Ceramic 88烤瓷用金合金的临床应用效果.方法 选取志愿患者101名,对每名患者的1颗缺损前牙或双尖牙进行烤瓷全冠修复,其中试验组51名,采用傲丹特α- Ceramic 88烤瓷用金合金;对照组50名,采用古莎-贺利氏Bio N烤瓷用金合金.两组均制取基底冠与牙体预备体之间的聚醚密合性检测膜,用GALILEO EZ612-300影像测量系统检测聚醚膜厚度,对比两组金合金烤瓷全冠的密合性.在患者试戴基底冠、初次戴牙、戴牙6~12个月复查时,记录各项临床观察指标:烤瓷冠内冠有无铸造缺陷、临床探查内冠边缘密合性、边缘抛光性、有无口腔黏膜过敏反应、牙周组织有无红肿,有无不良事件.结果 试验组及对照组临床观察各项指标均合格,应用

  12. Evaluation of marginal and internal gaps of metal ceramic crowns obtained from conventional impressions and casting techniques with those obtained from digital techniques

    Directory of Open Access Journals (Sweden)

    Rathika Rai

    2017-01-01

    Full Text Available Background: Accuracy in fit of cast metal restoration has always remained as one of the primary factors in determining the success of the restoration. A well-fitting restoration needs to be accurate both along its margin and with regard to its internal surface. Aim: The aim of the study is to evaluate the marginal fit of metal ceramic crowns obtained by conventional inlay casting wax pattern using conventional impression with the metal ceramic crowns obtained by computer-aided design and computer-aided manufacturing (CAD/CAM technique using direct and indirect optical scanning. Materials and Methods: This in vitro study on preformed custom-made stainless steel models with former assembly that resembles prepared tooth surfaces of standardized dimensions comprised three groups: the first group included ten samples of metal ceramic crowns fabricated with conventional technique, the second group included CAD/CAM-milled direct metal laser sintering (DMLS crowns using indirect scanning, and the third group included DMLS crowns fabricated by direct scanning of the stainless steel model. The vertical marginal gap and the internal gap were evaluated with the stereomicroscope (Zoomstar 4; post hoc Turkey's test was used for statistical analysis. One-way analysis of variance method was used to compare the mean values. Results and Conclusion: Metal ceramic crowns obtained from direct optical scanning showed the least marginal and internal gap when compared to the castings obtained from inlay casting wax and indirect optical scanning. Indirect and direct optical scanning had yielded results within clinically acceptable range.

  13. 四种材料冠修复体对上颌前牙修复效果的比较%Comparative study on the effect of anterior teeth resteration by 4 kinds of ceramic crowns

    Institute of Scientific and Technical Information of China (English)

    王志凌; 陈立强; 陈鹏; 蒋志平; 高铭武; 李宁毅

    2011-01-01

    [Objective] To compare the effect of crown made by 4 different kinds material in resteration of maxillary anterior tooth. [Methods] The effect was evaluated by the following indices including color, marginal adaptation, gingival border stainjracture of the crown and status of the gingival. [ Results ] Galvanized forming ceramic crown and Cercon all-ceramic crown were better than Ni-Cr alloy ceramic crown and Co-Cr alloy ceramic crown in all aspects. [Conclusion] Galvanized forming ceramic crown and Cercon all-ceramic crown are favorable choice to restore the maxillary anterior tooth,and the Co-Cr alloy ceramic crown is better than Ni-Cr alloy ceramic crown.%[目的]比较四种材料制成的冠修复体修复上颌前牙的临床应用效果.[方法]从修复体颜色,冠边缘适合性,颈缘着色,修复体折裂和牙龈健康状况等五个方面对修复效果进行比较评价.[结果]金沉积瓷冠和泽康氧化锆全瓷冠在各个方面均优于镍铬和钴铬烤瓷冠.[结论]金沉积瓷冠和泽康氧化锆全瓷冠是上颌前牙的理想修复方式,而钴铬合金烤瓷冠优于镍铬合金烤瓷冠.

  14. Restoring the gingival contour by means of provisional resin crowns after single-implant treatment.

    Science.gov (United States)

    Jemt, T

    1999-02-01

    A consecutive group of 55 patients was treated with 63 single-implant restorations. The soft tissue was allowed to heal to either provisional resin crowns (n = 25) that were placed at the time of second-stage surgery, or to healing abutments (n = 38) before final crown insertion. An index that assessed the size of the interproximal mucosa adjacent to the single-implant restorations was used to evaluate the volume of the papillae 2 years after crown insertion. The results indicated that the use of provisional crowns may restore soft tissue contour faster than healing abutments alone, but the papillae adjacent to single-implant restorations presented similar volume in both groups after 2 years in function. Furthermore, the mean marginal bone loss at the implants was 0.9 mm after 1 year, and no differences were observed between the 2 groups. The present data focus on the need for more scientific data to evaluate different clinical procedures for optimizing esthetic results in implant dentistry.

  15. 热压铸陶瓷二代(IPS-EMPRESS Ⅱ)与肩台瓷修复体颈缘效果三年临床评估%Comparison of the cervical margin fitness between IPS-Empress Ⅱ pressable all ceramic crowns and porcerlain fused to metal crowns with shoulder ceramic margin with 3 years' follow-up

    Institute of Scientific and Technical Information of China (English)

    刘朴; 孔敏; 代育桐

    2009-01-01

    目的 评估比较热压铸瓷二代(IPS-Empress)修复体和肩台瓷(IPS-Margin)金瓷修复体颈缘的临床效果.方法 临床为63例患者的90颗患牙进行IPS-Empress热压铸陶瓷全冠修复,为98例患者的129颗患牙进行有肩台瓷的PFM全冠修复.永久性粘结后6个月和36个月复诊,比较修复体颈缘临床效果.结果 在比较后发现铸瓷全冠和肩台瓷在牙龈变色,颈缘适合度,牙龈炎症三方面均无显著性差异.结论 肩台瓷修复体与全瓷修复体能达到相同的颈缘效果.对想解决颈缘问题又无力支付全瓷冠的修复患者来说,肩台瓷不失为一种好的选择.%Objective To evaluate and compare the cervical margin fitness and gingival discoloration between IPS-EMPRESS Ⅱ all ceramic crown and PFM crown with shoulder ceramic margin.Methods Ninty teeth of 63 patients were restored with IPS-EMPRESS Ⅱ pressable ceramic crowns and 129 teeth of 98 patients were restored with PFM crowns with shoulder ceramic margins. The marginal fitness, gingival discoloration, and gingival health of all these restorations were examined at 6 months, and 36 months after permanent luting respectively.Results There was no statistical difference for gingival discoloration, marginal fitness and gingival health between IPS-Empress II and PFM crown with shoulder ceramic margin (P>0.05).Conclusion Both PFM crown with shoulder ceramic margin and IPS-Empress Ⅱ ceramic crown satisfied the esthetic demand in the cervical margin area. PFM crown with shoulder ceramic margin is a reliable and ideal choice for the low-budget patients with the desire of esthetic cervical margin.

  16. Composite Bonding to Stainless Steel Crowns Using a New Universal Bonding and Single-Bottle Systems

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Hattan

    2013-01-01

    Full Text Available Aim. The aim of this study is to evaluate the shear bond strength of nanocomposite to stainless steel crowns using a new universal bonding system. Material and Methods. Eighty (80 stainless steel crowns (SSCs were divided into four groups (20 each. Packable nanocomposite was bonded to the lingual surface of the crowns in the following methods: Group A without adhesive (control group, Group B using a new universal adhesive system (Scotchbond Universal Adhesive, 3M ESPE, Seefeld, Germany, and Group C and Group D using two different brands of single-bottle adhesive systems. Shear bond strengths were calculated and the types of failure also were recorded. Results. The shear strength of Group B was significantly greater than that of other groups. No significant differences were found between the shear bond strengths of Groups C and D. The control group had significantly lower shear bond strength ( to composite than the groups that utilized bonding agents. Conclusion. Composites bonding to stainless steel crowns using the new universal bonding agent (Scotchbond Universal Adhesive, 3M ESPE, Seefeld, Germany show significantly greater shear bond strengths and fewer adhesive failures when compared to traditional single-bottle systems.

  17. Composite bonding to stainless steel crowns using a new universal bonding and single-bottle systems.

    Science.gov (United States)

    Hattan, Mohammad Ali; Pani, Sharat Chandra; Alomari, Mohammad

    2013-01-01

    Aim. The aim of this study is to evaluate the shear bond strength of nanocomposite to stainless steel crowns using a new universal bonding system. Material and Methods. Eighty (80) stainless steel crowns (SSCs) were divided into four groups (20 each). Packable nanocomposite was bonded to the lingual surface of the crowns in the following methods: Group A without adhesive (control group), Group B using a new universal adhesive system (Scotchbond Universal Adhesive, 3M ESPE, Seefeld, Germany), and Group C and Group D using two different brands of single-bottle adhesive systems. Shear bond strengths were calculated and the types of failure also were recorded. Results. The shear strength of Group B was significantly greater than that of other groups. No significant differences were found between the shear bond strengths of Groups C and D. The control group had significantly lower shear bond strength (P steel crowns using the new universal bonding agent (Scotchbond Universal Adhesive, 3M ESPE, Seefeld, Germany) show significantly greater shear bond strengths and fewer adhesive failures when compared to traditional single-bottle systems.

  18. Marginal fit of all-ceramic crowns fabricated using two extraoral CAD/CAM systems in comparison with the conventional technique.

    Science.gov (United States)

    Alqahtani, Fawaz

    2017-01-01

    The purpose of this study was to determine the effect of two extraoral computer-aided design (CAD) and computer-aided manufacturing (CAM) systems, in comparison with conventional techniques, on the marginal fit of monolithic CAD/CAM lithium disilicate ceramic crowns. This is an in vitro interventional study. The study was carried out at the Department of Prosthodontics, School of Dentistry, Prince Sattam Bin Abdul-Aziz University, Saudi Arabia, from December 2015 to April 2016. A marginal gap of 60 lithium disilicate crowns was evaluated by scanning electron microscopy. In total, 20 pressable lithium disilicate (IPS e.max Press [Ivoclar Vivadent]) ceramic crowns were fabricated using the conventional lost-wax technique as a control group. The experimental all-ceramic crowns were produced based on a scan stone model and milled using two extraoral CAD/CAM systems: the Cerec group was fabricated using the Cerec CAD/CAM system, and the Trios group was fabricated using Trios CAD and milled using Wieland Zenotec CAM. One-way analysis of variance (ANOVA) and the Scheffe post hoc test were used for statistical comparison of the groups (α=0.05). The mean (±standard deviation) of the marginal gap of each group was as follows: the Control group was 91.15 (±15.35) µm, the Cerec group was 111.07 (±6.33) µm, and the Trios group was 60.17 (±11.09) µm. One-way ANOVA and the Scheffe post hoc test showed a statistically significant difference in the marginal gap between all groups. It can be concluded from the current study that all-ceramic crowns, fabricated using the CAD/CAM system, show a marginal accuracy that is acceptable in clinical environments. The Trios CAD group displayed the smallest marginal gap.

  19. An interdisciplinary approach to reconstruct a fractured tooth under an intact all ceramic crown: Case report with four years follow up

    Directory of Open Access Journals (Sweden)

    Sudhir Bhandari

    2011-01-01

    Full Text Available Trauma causing the fracture of a restored tooth with the extracoronal full coverage prosthesis remaining intact is a common occurrence in dental practice. Reconstruction of the damaged tooth foundation and recementation of the crown can pose quite a challenge for the restorative dentist. This case report describes an innovative interdisciplinary chairside technique for the recementation of an all-ceramic crown on a fractured maxillary central incisor. The course of care described is effective, affordable, and saves time in comparison with other treatment options for such clinical situations.

  20. Fracture Resistance and Mode of Failure of Ceramic versus Titanium Implant Abutments and Single Implant-Supported Restorations.

    Science.gov (United States)

    Sghaireen, Mohd G

    2015-06-01

    The material of choice for implant-supported restorations is affected by esthetic requirements and type of abutment. This study compares the fracture resistance of different types of implant abutments and implant-supported restorations and their mode of failure. Forty-five Oraltronics Pitt-Easy implants (Oraltronics Dental Implant Technology GmbH, Bremen, Germany) (4 mm diameter, 10 mm length) were embedded in clear autopolymerizing acrylic resin. The implants were randomly divided into three groups, A, B and C, of 15 implants each. In group A, titanium abutments and metal-ceramic crowns were used. In group B, zirconia ceramic abutments and In-Ceram Alumina crowns were used. In group C, zirconia ceramic abutments and IPS Empress Esthetic crowns were used. Specimens were tested to failure by applying load at 130° from horizontal plane using an Instron Universal Testing Machine. Subsequently, the mode of failure of each specimen was identified. Fracture resistance was significantly different between groups (p ceramic crowns supported by titanium abutments (p = .000). IPS Empress crowns supported by zirconia abutments had the lowest fracture loads (p = .000). Fracture modes of metal-ceramic crowns supported by titanium abutments included screw fracture and screw bending. Fracture of both crown and abutment was the dominant mode of failure of In-Ceram/IPS Empress crowns supported by zirconia abutments. Metal-ceramic crowns supported by titanium abutments were more resistant to fracture than In-Ceram crowns supported by zirconia abutments, which in turn were more resistant to fracture than IPS Empress crowns supported by zirconia abutments. In addition, failure modes of restorations supported by zirconia abutments were more catastrophic than those for restorations supported by titanium abutments. © 2013 Wiley Periodicals, Inc.

  1. Treatment recommendations for single-unit crowns: Findings from The National Dental Practice-Based Research Network.

    Science.gov (United States)

    McCracken, Michael S; Louis, David R; Litaker, Mark S; Minyé, Helena M; Mungia, Rahma; Gordan, Valeria V; Marshall, Don G; Gilbert, Gregg H

    2016-11-01

    The objectives of this study were to quantify practitioner variation in likelihood to recommend a crown and test whether certain dentist, practice, and clinical factors are associated significantly with this likelihood. Dentists in The National Dental Practice-Based Research Network completed a questionnaire about indications for single-unit crowns. In 4 clinical scenarios, practitioners ranked their likelihood of recommending a single-unit crown. The authors used these responses to calculate a dentist-specific crown factor (range, 0-12). A higher score implied a higher likelihood of recommending a crown. The authors tested certain characteristics for statistically significant associations with the crown factor. A total of 1,777 of 2,132 eligible dentists (83%) responded. Practitioners were most likely to recommend crowns for teeth that were fractured, cracked, or endodontically treated or had a broken restoration. Practitioners overwhelmingly recommended crowns for posterior teeth treated endodontically (94%). Practice owners, practitioners in the Southwest, and practitioners with a balanced workload were more likely to recommend crowns, as were practitioners who used optical scanners for digital impressions. There is substantial variation in the likelihood of recommending a crown. Although consensus exists in some areas (posterior endodontic treatment), variation dominates in others (size of an existing restoration). Recommendations varied according to type of practice, network region, practice busyness, patient insurance status, and use of optical scanners. Recommendations for crowns may be influenced by factors unrelated to tooth and patient variables. A concern for tooth fracture-whether from endodontic treatment, fractured teeth, or large restorations-prompted many clinicians to recommend crowns. Copyright © 2016 American Dental Association. Published by Elsevier Inc. All rights reserved.

  2. 二氧化锆全瓷冠与镍铬合金烤瓷冠临床应用比较%Comparison of clinical application of zirconia all-ceramic crowns and Ni-Cr alloy crowns

    Institute of Scientific and Technical Information of China (English)

    周俊红

    2015-01-01

    Objective To observe and compare clinical effects of the zirconia all-ceramic crowns and Ni-Cr alloy crowns. Methods 80 patients of dentistry with 106 tooth in Department of Stomatology, Zhongguancun Hospital from February 2011 to February 2012 were selected, 40 patients with 56 tooth were treated with zirconia all-ceramic crowns and were chosen as zirconia all-ceramic crowns group; 40 patients with 50 tooth were treated with Ni-Cr alloy crowns and were chosen as Ni-Cr alloy crowns group. The items of restoration retainer, restoration contour, marginal accuracy, gingival situation, secondary caries between the two groups at repairmen time and 1 year after the repairmen were compared. Results①The two groups were all reached grade A in each indicator at repairmen time. The gingival tissue of grade A in zirconia all-ceramic crowns group [96.4% (54/56)] was higher than that in Ni-Cr alloy crowns group [86.0% (43/50)] 1 year after the repairmen, the difference was statistically significant (P0.05).②The differences of plaque index in the zirconia all-ceramic crowns group and the Ni-Cr alloy crowns group between 1 year after the repairmen [(0.92±0.36), (0.89±0.40)] and before the repairmen [(0.88±0.41), (0.88±0.41)] were all not statistically significant (P> 0.05). The differences of periodontal probing depth in the zirconia all-ceramic crowns group and the Ni-Cr alloy crowns group between 1 year after the repairmen [(2.41±0.20), (2.40±0.20) mm] and before the repairmen [(2.26±0.23), (2.28±0.21) mm] were all not statistically significant (P>0.05). Con-clusion The clinical effect of Zirconia all-ceramic crowns is better than Ni-Cr alloy crowns.%目的:观察比较镍铬合金烤瓷冠和二氧化锆全瓷冠的临床应用效果。方法选取中关村医院口腔科2011年2月~2012年2月治疗的牙科患者80例106颗患牙,其中40例患者共56颗牙采用二氧化锆全瓷冠修复,设为二氧化锆全瓷冠组;40例患者50颗牙采用镍铬合

  3. Restoration of incisal half with edge-up technique using ceramic partial crown in turner′s hypoplasia: A case report

    Directory of Open Access Journals (Sweden)

    Shreya Hegde

    2014-01-01

    Full Text Available This case report describes a rare treatment modality for Turner′s hypoplasia done with a very conservative approach for the esthetic and functional problem of the defect. Diagnosis was made as Turner′s hypoplasia of upper two central incisors with proximal caries. Treatment planning was done after considering many factors such as conservation of tooth structure, esthetics, occlusion and economy. Tooth preparation was done to receive Edge-up, all ceramic partial crowns for both the upper central incisors,using pressable all ceramic material and cemented with resin cement.

  4. Mirror-image anterior crown fabrication with computer-aided design and rapid prototyping technology: a clinical report.

    Science.gov (United States)

    Cho, Seok-Hwan; Chang, Won-Gun

    2013-02-01

    This clinical report describes the fabrication of a maxillary central incisor single crown with rapid prototyping (RP) technology. A patient with a recently replaced metal ceramic crown had discomfort due to the nonanatomic lingual contour of the crown. With computer-aided design (CAD) software and rapid prototyping (RP) technology, the shape of the contralateral central incisor was duplicated and reproduced to make a mirror-image for a new crown. The prosthodontic planning and treatment approach are discussed.

  5. Marginal fit of all-ceramic crowns fabricated using two extraoral CAD/CAM systems in comparison with the conventional technique

    Directory of Open Access Journals (Sweden)

    Alqahtani F

    2017-03-01

    Full Text Available Fawaz Alqahtani1,2 1Department of Prosthodontics, 2Higher Education and Scientific Research, School of Dentistry, Prince Sattam Bin Abdul-Aziz University, Al-kharj, Saudi Arabia Objective: The purpose of this study was to determine the effect of two extraoral computer-aided design (CAD and computer-aided manufacturing (CAM systems, in comparison with conventional techniques, on the marginal fit of monolithic CAD/CAM lithium disilicate ceramic crowns. Study design: This is an in vitro interventional study. Place and duration of study: The study was carried out at the Department of Prosthodontics, School of Dentistry, Prince Sattam Bin Abdul-Aziz University, Saudi Arabia, from December 2015 to April 2016. Methodology: A marginal gap of 60 lithium disilicate crowns was evaluated by scanning electron microscopy. In total, 20 pressable lithium disilicate (IPS e.max Press [Ivoclar ­Vivadent] ceramic crowns were fabricated using the conventional lost-wax technique as a control group. The experimental all-ceramic crowns were produced based on a scan stone model and milled using two extraoral CAD/CAM systems: the Cerec group was fabricated using the Cerec CAD/CAM system, and the Trios group was fabricated using Trios CAD and milled using Wieland Zenotec CAM. One-way analysis of variance (ANOVA and the Scheffe post hoc test were used for statistical comparison of the groups (α=0.05. Results: The mean (±standard deviation of the marginal gap of each group was as follows: the Control group was 91.15 (±15.35 µm, the Cerec group was 111.07 (±6.33 µm, and the Trios group was 60.17 (±11.09 µm. One-way ANOVA and the Scheffe post hoc test showed a statistically significant difference in the marginal gap between all groups. Conclusion: It can be concluded from the current study that all-ceramic crowns, fabricated using the CAD/CAM system, show a marginal accuracy that is acceptable in clinical environments. The Trios CAD group displayed the smallest

  6. Evaluation of the onset of failure under mechanical and thermal stresses on luting agent for metal-ceramic and metal crowns by finite element analysis

    Directory of Open Access Journals (Sweden)

    Hema Agnihotri

    2010-01-01

    Full Text Available Long-term clinical failures of cemented prosthesis depend, to a large extent, on the integrity of the luting agent. The causative factors that lead to microfracture and, hence, failure of the luting agents are the stresses acting inside the oral cavity. Therefore, the present study was designed to develop an understanding of the relationship between stresses in the tooth and the failure potential of the luting agent. Two-dimensional finite element stress analysis was performed on the mandibular second premolar. The behavior of zinc-phosphate and glass-ionomer were studied under different crowns (metal-ceramic and metal crown and loading conditions (mechanical force of 450 N acting vertically over the occlusal surface, thermal loads of 60° and 0°C. It was observed from the study that failure threshold of the luting agent was influenced both by the elastic modulus of the luting agent and by the type of the crown.

  7. Marginal fit of all-ceramic crowns fabricated using two extraoral CAD/CAM systems in comparison with the conventional technique

    OpenAIRE

    Alqahtani F

    2017-01-01

    Fawaz Alqahtani1,2 1Department of Prosthodontics, 2Higher Education and Scientific Research, School of Dentistry, Prince Sattam Bin Abdul-Aziz University, Al-kharj, Saudi Arabia Objective: The purpose of this study was to determine the effect of two extraoral computer-aided design (CAD) and computer-aided manufacturing (CAM) systems, in comparison with conventional techniques, on the marginal fit of monolithic CAD/CAM lithium disilicate ceramic crowns. Study design: This is an in vitro interv...

  8. 全瓷冠修复对高血糖患者龈沟液成分影响的分析%Effect of hyperglycemia on gingival crevicular fluid after restoration of ceramic crown

    Institute of Scientific and Technical Information of China (English)

    隋晶; 李斌; 黄毓秋; 张晓燕

    2014-01-01

    Objective:To investigate the effect of hyperglycemia on gingival crevicular fluid after restoration of ceramic crown.Method:80 patients (40 male and 40 female) were randomly selected from the 40 to 50-year-old patients treated in our department in the past two years who were indicated for single ceramic crown. All the patients were treated with routine periodontal prophylaxis and restoration of all-ceramic crowns. The gross secretory volume of gingival crevicular fluid, ALP, IL-1 and TNF-αwere measured before and 2 months after restoration.Results:Among patients with normal blood glucose, there were no significant changes on gross secretory volume of gingival crevicular fluid, ALP, IL-1 and TNF-αlevels 2 months after restoration of all-ceramic crowns. Among patients with hyperglycemia, gross secretory volume of gingival crevicular fluid, IL-1 and TNF-αlevels significantly increased 2 months after restoration of all-ceramic crowns, but level of ALP did not change significantly.Conclusion:Hyperglycemia could promote gingival crevicular fluid secretion, and IL-1, TNF-αlevels in gingival crevicular fluid after restoration of ceramic crown.%目的:探讨高血糖对全瓷冠固定修复后龈沟液成分的影响。方法:选取近两年在我院口腔修复科就诊的40-50岁,需进行全瓷单冠修复的患者80例为受试对象,其中男性40例,女性40例,常规牙周洁治后采用全瓷单冠修复,分别在修复前以及修复后2个月检测基牙龈沟液的分泌量以及碱性磷酸酶,白细胞介素1β和肿瘤坏死因子α水平。结果:正常血糖患者全瓷修复后2个月基牙龈沟液分泌量,碱性磷酸酶,白细胞介素1和肿瘤坏死因子α水平均无明显升高。高糖组修复后2个月基牙龈沟液分泌量,白细胞介素1和肿瘤坏死因子α显著高于修复前,但碱性磷酸酶水平与修复前比较差异无统计学意义。结论:高糖环境可使全瓷冠修复后患者龈沟液

  9. Discriminating single-molecule sensing by crown-ether-based molecular junctions

    Science.gov (United States)

    Ismael, Ali K.; Al-Jobory, Alaa; Grace, Iain; Lambert, Colin J.

    2017-02-01

    Crown-ether molecules are well known to selectively bind alkali atoms, so by incorporating these within wires, any change in electrical conductance of the wire upon binding leads to discriminating sensing. Using a density functional theory-based approach to quantum transport, we investigate the potential sensing capabilities of single-molecule junctions formed from crown ethers attached to anthraquinone units, which are in turn attached to gold electrodes via alkyl chains. We calculate the change in electrical conductance for binding of three different alkali ions (lithium, sodium, and potassium). Depending on the nature of the ionic analyte, the conductance is enhanced by different amounts. This change in electrical conductance is due to charge transfer from the ion to molecular wire causing the molecular resonances to shift closer to the electrode Fermi energy.

  10. Marginal Adaptation of Metal Ceramic Crowns Cast from Four Different Base Metal Alloys before and after Porcelain Application

    Directory of Open Access Journals (Sweden)

    Ali Hafezeqoran

    2015-04-01

    Material and Method: In this experimental study, a sound maxillary first premolar was prepared with chamfer and shoulder-bevel finish lines in palatal and buccal surfaces, respectively. Then the metal die was fabricated. Six points were marked 1 mm apical to the margin in the buccal and palatal surfaces. Forty impressions were taken from metal die by polyether impression material. Then, 10 frameworks were fabricated with each alloy type on stone dies. The vertical margin discrepancy between the frameworks and the marked points on metal dies were measured before and after porcelain firing. Paired sample t-test and One-way ANOVA, followed by multiple comparison tests (Tukey test were used to evaluate data. In this study, statistical significance was defined at p<0.05. Results: Before porcelain firing, T3 alloy showed the lowest marginal discrepancy on chamfer finish line (13.13 ± (1.26; but, the highest values were for Supermcast V copings and shoulder-bevel finish after porcelain application (30.83 ± (2.01. The mean marginal discrepancies of buccal and palatal surfaces before porcelain application were significantly lower for all alloy types (p<0.001. Conclusion:  The marginal adaptation of all four metal alloys was clinically acceptable and the thermal cycles of porcelain firing affected marginal adaptation.   Keywords: Crown; Marginal adaptation; Metal ceramic alloys

  11. Selection and application of oral all-ceramic crown materials%口腔全瓷冠修复材料的选择及应用

    Institute of Scientific and Technical Information of China (English)

    程谨春

    2011-01-01

    BACKGROUND: Compared with porcelain fused to metal crown, the all-ceramic crown materials have been more and more applied in clinical anterior teeth restoration due to natural and stable color, low thermal conductivity, non-electric conductivity, wear resistance, good biocompatibility, non-transparent metallic, and relatively simple operations.OBJECTIVE: To summarize the characteristics, production methods and clinical application of different all-ceramic crown materials.METHODS: A computer-based online retrieval was performed in Wanfang database and Medline database between 2001 and 2011 for articles regarding the characteristics, production methods, physical and mechanical strength, chemical and biological compatibility, aesthetic appearance and clinical application of different all-ceramic crown materials.RESULTS AND CONCLUSION: Currently, the clinically used all-ceramic materials can be divided into slip casting porcelain,casting ceramic, heat-pressed glass ceramic, glass-infiltrated ceramics, densely-sintered aluminum oxide polycrystalline, partially stabilized tetragonal zirconium oxide polycrystalline, and nano-composite ceramic. Different materials have its specific mechanical properties and clinical indications, so clinical selection must be based on specific conditions. With the advance of high-strength ceramic studies, all-ceramic restorations become widely applied, and high-aluminum ceramic represented by In-ceram and zirconia all-ceramic crowns can achieve good effects within a short and long term, foreign clinical experiments have conducted the enlargement from anterior crown to rear crown and bridge. To insure optimum long-term clinical results of all-ceramic crown restorations, the key is to overcome the fragmentation of dental prosthesis, mainly through modifying the composition, improving the anti -smash property of ceramic materials, and a series of prevention measures.%背景:相对于金属烤瓷冠而言,全瓷冠具有色泽稳定自然,导

  12. Outcome of bonded vs all-ceramic and metal- ceramic fixed prostheses for single tooth replacement.

    Science.gov (United States)

    Karl, Matthias

    2016-01-01

    The conventional treatment of a single missing tooth is most frequently based on the provision of a fixed dental prosthesis (FDPs). A variety of designs and restorative materials are available which have an impact on the treatment outcome. Consequently, it was the aim of this review to compare resin-bonded, all-ceramic and metal-ceramic FDPs based on existing evidence. An electronic literature search using "metal-ceramic" AND "fixed dental prosthesis" AND "clinical, all-ceramic" AND "fixed dental prosthesis" AND "clinical, resin-bonded" AND "fixed dental prosthesis" AND "clinical, fiber reinforced composite" AND "clinical, monolithic" AND "zirconia" AND "clinical" was conducted and supplemented by the manual searching of bibliographies from articles already included. A total of 258 relevant articles were identified. Metal-ceramic FDPs still show the highest survival rates of all tooth-supported restorations. Depending on the ceramic system used, all-ceramic restorations may reach comparable survival rates while the technical complications, i.e. chipping fractures of veneering materials in particular, are more frequent. Resin-bonded FDPs can be seen as long-term provisional restorations with the survival rate being higher in anterior locations and when a cantilever design is applied. Inlay-retained FDPs and the use of fiber-reinforced composites overall results in a compromised long-term prognosis. Recently advocated monolithic zirconia restorations bear the risk of low temperature degradation. Several variables affect treatment planning for a given patient situation, with survival and success rates of different restorative options representing only one factor. The broad variety of designs and materials available for conventional tooth-supported restorations should still be considered as a viable treatment option for single tooth replacement.

  13. Clinical Comparison of Zirconia All - ceramic Crown and Porcelain Fused to Metal Crown Restoration%二氧化锆全瓷冠与普通金属烤瓷冠修复的临床比较

    Institute of Scientific and Technical Information of China (English)

    张武

    2014-01-01

    目的:探讨临床使用二氧化锆全瓷冠与普通金属烤瓷冠修复的治疗效果对比。方法选择110例患者共146颗牙,随机分成两组,每组73颗牙。实验组采用二氧化锆全瓷冠进行修复;对照组采用普通金属烤瓷冠进行修复。按照美国公共健康协会制定标准评估修复情况。结果实验组全瓷冠的边缘完整性,牙龈状态,颜色等方面均表现良好,全瓷冠出现崩瓷占5.5%;对照组边缘完整性占93.15%,牙龈形态良好占95.9%,颜色表现良好占2.7%,冠出现崩瓷占8.2%。结论二氧化锆全瓷冠临床上的修复效果良好,值得临床推广使用。%Objective To comPare the theraPeutic effects of zirconia all - ceramic crown and Porcelain fused to metal crown restoration. Methods 110 Patients with a total of 146 teeth were randomly assigned into two grouPs with 73 teeth in each grouP. Zirconia all - ceramic crown restoration was used in exPerimental grouP,and Porcelain fused to metal crown restoration was used in the control grouP. Restorations were assessed according to the criteria established by United States Public Health Service(USPHS). Results Marginal integrity,gingival state and color were good in exPerimental grouP with 5. 5% fractured Porcelain. 93. 15% were good in marginal integrity,95. 9% were good in gin-gival state,2. 7% were good in color with 8. 2% fractured Porcelain in control grouP. Conclusion RePairing effects of zirconia all - ceramic crown are good,which is worth of clinical Promotion.

  14. In vitro chipping behaviour of all-ceramic crowns with a zirconia framework and feldspathic veneering: comparison of CAD/CAM-produced veneer with manually layered veneer.

    Science.gov (United States)

    Schmitter, M; Mueller, D; Rues, S

    2013-07-01

    The purpose of this in vitro study was to assess the breaking load of zirconia-based crowns veneered with either CAD/CAM-produced or manually layered feldspathic ceramic. Thirty-two identical zirconia frameworks (Sirona inCoris ZI, mono L F1), 0·6 mm thick with an anatomically shaped occlusal area, were constructed (Sirona inLab 3.80). Sixteen of the crowns were then veneered by the use of CAD/CAM-fabricated feldspathic ceramic (CEREC Bloc, Sirona) and 16 by the use of hand-layered ceramic. The CAD/CAM-manufactured veneer was attached to the frameworks by the use of Panavia 2.0 (Kuraray). Half of the specimens were loaded until failure without artificial ageing; the other half of the specimens underwent thermal cycling and cyclic loading (1·2 million chewing cycles, force magnitude F(max) = 108 N) before the assessment of the ultimate load. To investigate the new technique further, finite element (FE) computations were conducted on the basis of the original geometry. Statistical assessment was made by the use of non-parametric tests. Initial breaking load was significantly higher in the hand-layered group than in the CAD/CAM group (mean: 1165·86 N versus 395·45 N). During chewing simulation, however, 87·5% (7/8) of the crowns in the hand-layered group failed, whereas no crown in the CAD/CAM group failed. The CAD/CAM-produced veneer was significantly less sensitive to ageing than the hand-layered veneer.

  15. Wear of metal-free resin composite crowns after three years in service.

    Science.gov (United States)

    Zenthöfer, Andreas; Rammelsberg, Peter; Schmitt, Clemens; Ohlmann, Brigitte

    2013-01-01

    To compare differences between the wear behavior of two types of metal-free resin composite crown with a control after three years in clinical service. Sixty-six participants needing one to three posterior single crowns were fitted with 120 crowns. Abutment teeth were randomly assigned to three groups: 40 resin composite crowns with fiber-reinforced framework, 40 resin composite crowns without fiber-reinforced framework, and 40 metal-ceramic crowns. To assess wear, gypsum replicas of the crowns were fabricated and scanned with a 3D laser scanner at baseline and after three years. Differences between the groups were analyzed by use of mixed-effects regression models. Wear of resin composite crowns with fiber-reinforced framework (p=0.0043) and resin composite crowns without framework (p=0.0246) was significantly greater than in the metal-ceramic group. Wear of metal-free resin composite crowns after three years was significantly greater than that of metal-ceramic crowns, but the wear was still clinically acceptable.

  16. Effect of different ferrule designs on the fracture resistance and failure pattern of endodontically treated teeth restored with fiber posts and all-ceramic crowns

    Directory of Open Access Journals (Sweden)

    Haneef Sherfudhin

    2011-02-01

    Full Text Available OBJECTIVE: This study investigated the effect of different ferrule heights on endodontically treated premolars. MATERIAL AND METHODS: Fifty sound mandibular first premolars were endodontically treated and then restored with 7-mm fiber post (FRC Postec Plus #1 Ivoclar-Vivadent luted with self-polymerized resin cement (Multilink, Ivoclar Vivadent while the coronal section was restored with hybrid composite core build-up material (Tetric Ceram, Ivoclar-Vivadent, which received all-ceramic crown. Different ferrule heights were investigated: 1-mm circumferential ferrule without post and core (group 1 used as control, a circumferential 1-mm ferrule (group 2, non-uniform ferrule 2-mm buccally and 1-mm lingually (group 3, non-uniform ferrule 3-mm buccally and 2-mm lingually (group 4, and finally no ferrule preparation (group 5. The fracture load and failure pattern of the tested groups were investigated by applying axial load to the ceramic crowns (n=10. Data were analyzed statistically by one-way ANOVA and Tukey's post-hoc test was used for pair-wise comparisons (α=0.05. RESULTS: There were no significant differences among the failure load of all tested groups (P<0.780. The control group had the lowest fracture resistance (891.43±202.22 N and the highest catastrophic failure rate (P<0.05. Compared to the control group, the use of fiber post reduced the percentage of catastrophic failure while increasing the ferrule height did not influence the fracture resistance of the restored specimens. CONCLUSIONS: Within the limitations of this study, increasing the ferrule length did not influence the fracture resistance of endodontically treated teeth restored with glass ceramic crowns. Insertion of a fiber post could reduce the percentage of catastrophic failure of these restorations under function.

  17. 前牙全瓷冠饰瓷崩裂断口形貌分析%Fractographic analysis of clinically failed anterior all ceramic crowns

    Institute of Scientific and Technical Information of China (English)

    杜倩; 周敏波; 张新平; 赵克

    2012-01-01

    Objective To identify the site of crack initiation and propagation path of clinically failed all ceramic crowns by fractographic analysis.Methods Three clinically failed anterior IPS Empress Ⅱ crowns and two anterior In-Ceram alumina crowns were retrieved.Fracture surfaces were examined using both optical stereo and scanning electron microscopy.Fractographic theory and fracture mechanics principles were applied to disclose the damage characteristics and fracture mode.Results All the crowns failed by cohesive failure within the veneer on the labial surface.Critical crack originated at the incisal contact area and propagated gingivally. Porosity was found withiu the veneer because of slurry preparation and the sintering of veneer powder.Conclusions Cohesive failure within the veneer is the main failure mode of all ceramic crown.Veneer becomes vulnerable when flaws are present. To reduce the chances of chipping,multi-point occlusal contacts are recommended,and layering and sintering technique of veneering layer should also be improved.%目的 通过断口形貌观察分析临床失效的前牙全瓷冠,分析疲劳损伤的起源和发展,以期为优化全瓷冠桥修复体的临床设计及修复工艺提供依据.方法 收集临床失效前牙二硅酸锂基瓷冠( IPS EmpressⅡ)3例,玻璃渗透氧化铝瓷冠(In-Ceram)2例,采用体视显微镜和扫描电子显微镜观察断裂面,分析特征形貌.结果 5例全瓷冠主要失效模式均为唇侧饰瓷内聚破坏,裂纹起源于切端咬合接触区,并由切端向龈端扩展,裂纹源附近饰瓷内部见较多气孔缺陷.结论 饰瓷内聚破坏是全瓷修复失效的重要原因;饰瓷内部易出现制作缺陷,成为双层瓷修复体的薄弱环节;改良饰瓷制作及烧结工艺,设计多点咬合接触将有助于减少饰瓷崩瓷.

  18. Thermal conductivity of single crystal and ceramic AlN

    Science.gov (United States)

    AlShaikhi, A.; Srivastava, G. P.

    2008-04-01

    We have applied the Callaway theory and used a detailed account of three-phonon scattering processes to calculate the thermal conductivity of three AlN single crystal samples containing different amounts of oxygen and two AlN ceramic samples with different grain sizes and oxygen contamination levels. The N-drift contribution to the total conductivity has been quantified. The influence on the thermal conductivity of oxygen-related defects, and grain boundaries in ceramic samples, has been investigated. The theoretical results obtained from this work are in good agreement with available experimental data. Our calculations suggest that the "effective" boundary length is greater than the reported grain size for each of the two ceramic samples studied by Watari et al. [J. Mater. Res. 17, 2940 (2002)].

  19. Comparison of counteract compression properties of different ceramic crowns for implant abutment%不同基底材料的瓷修复体用于种植修复时抵抗压力载荷的比较

    Institute of Scientific and Technical Information of China (English)

    肖剑锐; 韩小宪; 林雪梅; 陈宇轩; 孔亮

    2012-01-01

    Objective To compare the counteract compression properties of different ceramic crowns for implant abutment. Methods Co-Cr alloy ceramic crowns, Titanium ceramic crowns, gold alloy ceramic crowns and whole ceramic crowns were made for the Ti-abutment and the abutment tooth in vitro (the control group). Cyclic loads were applied on the crowns and the Max loading frequencies were recorded when the ceramic showed cracks.Results The Max loading frequency in the abutment tooth crowns were 159.3±6.7,147.7±2.4,149.5±3.3 and 138.6±7.1 respectively, and those were 167.6±2.7,149.7±6.5,152.8±4.3 and 122.0±4.6 in the Ti-abutmenl crowns. The Co-Cr alloy ceramic crowns in Ti-abutment could endure more loading frequencies than in the abutment tooth (P<0.05), and the whole ceramic crowns showed the contrast (P<0.05). In the Ti-abutment, Co-Cr alloy ceramic crowns endured most loading frequencies, and the whole ceramic crowns showed the least (P<0.05). Conclusion For Ti-abutment, Co-Cr alloy ceramic crown showed the best counteract compression properties and whole ceramic crowns showed the worst.%目的 比较不同基底材料的瓷修复体用于种植修复时的抗压强度.方法 分别基于离体牙(对照组)和种植基台制作钴铬合金烤瓷、钛烤瓷、贵金属烤瓷(75%Au合金)和全瓷修复体,粘接后在咬合面进行循环加载,直至出现修复体瓷层破坏,记录最大加载次数.结果 四种修复体,用于离体基牙时出现破坏的最大加载次数(万次)分别为159.3±6.7,147.7±2.4,149.5±3.3和138.6±7.1;用于种植基台时分别为167.6±2.7,149.7±6.5,152.8±4.3和122.0±4.6.钴铬烤瓷修复用于种植基台时比用于离体基牙时可承受更多的加载次数(P<0.05),而全瓷修复体则相反(P<0.05);用于种植基台修复时,钴铬烤瓷承受加载次数较多,而全瓷修复体可承受的加载次数最少,均有统计学意义(P<0.05),钛烤瓷及贵金属烤瓷居中.结论 针对种植体基

  20. Strength and marginal fit of full and partial porcelain crowns on Brånemark implants.

    Science.gov (United States)

    Kersten, S; Tiedemann, C

    2000-02-01

    The aim of the present study was to evaluate strength and marginal fit of different designed single crowns screwed on titanium implants (Brånemark) without the usage of any abutment. Seven test groups with 10 specimens each (standardized maxillary central incisor crowns) were fabricated of Empress (staining/veneering technique), metal-based Empress (staining/veneering technique), metal-based In-Ceram and metal ceramic (with/without cervical porcelain margin). The marginal fit of 5 specimens of each group was evaluated (SEM-Analysis) and the crowns were incisally loaded at a 30 degrees angle in a Zwick testing machine until fracture. The 5 remaining specimens underwent a marginal evaluation (SEM-analyses) before and after thermo-mechanical stressing (tms) and were loaded in the Zwick testing machine as well. All Empress ceramic crowns without metal reinforcement fractured during fixing procedure on the implant (32 N cm). The gap medians of the fixed crowns ranged from 11 microns (metal ceramic crowns) to 34 microns (metal ceramic crowns with porcelain margin). No significant differences in gap width were observed before and after tms. In the strength analyses screw-binding forces (SBF) of about 135 N were registered in all test groups. Fracture failure forces (FFF) reached up to 280 N. The indication of the crown designs presented in this study is limited in clinical use because of low stability and esthetics.

  1. Research and application of ceramic crown and related ceramic splicing agent%全瓷冠及其相关陶瓷粘接剂的研究与应用

    Institute of Scientific and Technical Information of China (English)

    翁蓓军; 李国强

    2011-01-01

    BACKGROUND: Ceramic crown reparation is one of the developing tendencies of oral fixed dentures. Ceramic crown reparation depends on upstanding resin splicing agent in order to ensure its clinical success. Nowadays, ceramic crown reparation resin splicing agent and dentinal splicing technique, as well as surface treatment technology of porcelain are still being explored and improved, so as to further improve clinical splicing effects.OBJECTIVE: To review the research progress on ceramic crown and related ceramic splicing agent. METHODS: The literatures related to ceramic crown and ceramic splicing agent from PubMed database (2000/2010) and Wanfang database were retrieved by the first author, with the key words of “ceramic crown, bond, interface” in English and Chinese, respectively. Finally, 24 documents were included.RESULTS AND CONCLUSION: Ideal resin splicing agent which should have the characters of low consistency, fine flowability,and the thickness do not affect restoration, high intensity, wear-resisting and so on. Ceramic crown is a new dental prosthetic restoration. It is becoming gradually widespread in cl inical application, and there are a lot of new adhesives developed in recent years. The performance difference of bonding materials and the evaluations of effect on ceramic crow adhesives are not the same. The article summarizes the research progress on ceramic crown and related ceramic splicing agent at home and abroad presently and recommends the performance, surface treatment and splicing techniques of the adhesives systematically, which can provide theoretical basis for clinical application extensively.%背景:全瓷修复是当今口腔固定修复的发展趋势之一,全瓷修复体依赖良好的树脂粘接剂以保证其临床成功.目前,全瓷修复树脂粘接剂与牙本质的粘接技术及瓷表面处理技术仍在不断探索改进之中,以期进一步提高临床粘接效果.目的:总结全瓷冠及其相关陶瓷粘接剂的

  2. Clinical application of the surgical crown lengthening combining all ceramic crown after failure of the anterior teeth PFM crown restoration%牙冠延长术结合全瓷冠修复在前牙烤瓷冠失败病例的应用

    Institute of Scientific and Technical Information of China (English)

    李雪峰

    2013-01-01

    目的:探讨应用牙冠延长术结合全瓷冠技术治疗前牙生物学宽度不足导致不良烤瓷冠修复的临床疗效。方法选取26例因生物学宽度不足导致的前牙修复失败病例,进行完善牙周治疗,根管治疗,并进行牙冠延长术后全瓷冠修复,观察术前,术后六周以及修复后三个月以及修复六个月的PD(探诊深度), SBI(出血指数)并予以记录。结果24例患者治疗效果较好,两例术后牙龈高度不对称,患者不甚满意。结论牙冠延长术结合全瓷冠修复可以较好的解决前牙不良烤瓷冠修复的再治疗问题。%Objective To investigate the effect after crown lengthening surgery combining all ceramic crown on anterior teeth failure of PFM crown restoration because of insufficient biological width Methods Select 26 failure cases of anterior teeth caused by insufficient biological width , repair to perfect the periodontal treatment, root canal treatment, and crown lengthening surgery. After treatment all teeth were restored by all ceramic crown, At baseline, 6 weeks after surgery and 3 months and 6 months after the restoration BOP and PD were recorded and analyzed. Results 24 patients treatment effect is good, two cases of postoperative were not very satisfied because of gum hight asymmetric. Conclusion Crown lengthening sursery combining all ceramic crown restoration can solve the failure PFM restoration on anterior teeth.

  3. An efficient approach to 3D single tree-crown delineation in LiDAR data

    Science.gov (United States)

    Mongus, Domen; Žalik, Borut

    2015-10-01

    This paper proposes a new method for 3D delineation of single tree-crowns in LiDAR data by exploiting the complementaries of treetop and tree trunk detections. A unified mathematical framework is provided based on the graph theory, allowing for all the segmentations to be achieved using marker-controlled watersheds. Treetops are defined by detecting concave neighbourhoods within the canopy height model using locally fitted surfaces. These serve as markers for watershed segmentation of the canopy layer where possible oversegmentation is reduced by merging the regions based on their heights, areas, and shapes. Additional tree crowns are delineated from mid- and under-storey layers based on tree trunk detection. A new approach for estimating the verticalities of the points' distributions is proposed for this purpose. The watershed segmentation is then applied on a density function within the voxel space, while boundaries of delineated trees from the canopy layer are used to prevent the overspreading of regions. The experiments show an approximately 6% increase in the efficiency of the proposed treetop definition based on locally fitted surfaces in comparison with the traditionally used local maxima of the smoothed canopy height model. In addition, 4% increase in the efficiency is achieved by the proposed tree trunk detection. Although the tree trunk detection alone is dependent on the data density, supplementing it with the treetop detection the proposed approach is efficient even when dealing with low density point-clouds.

  4. 全瓷冠与金属烤瓷冠在全牙义齿修复中的综合效果分析%Comparative Analysis of the Comprehensive Effect of All-ceramic Crowns and Metal Ceramic Crowns in the Application of Full Denture Prosthesis

    Institute of Scientific and Technical Information of China (English)

    李光泽

    2013-01-01

    Objective To observe the effect of all-ceramic crowns and metal ceramic crowns in the application of full denture prosthesis. Methods 86 patients who received full denture prosthesis in the Yunnan Transportation Center Hospital of Yunnan Province from January 2012 to September 2012 were chosen as the research object. According to the order of patients admission tag,patients with the odd tag were as the control group,patients with the even were as the observation group, and 43 patients in each group. Patients in the control group received metal ceramic crown repair, and patients in the observation group received all-ceramic crown repair. Patients in the two groups were followed up for 12 months to 24 months, and the black line on the gingival cervical margin, periodontal damage and porcelain crowns crack were compared between the two groups. Results The cervical margin black line ratios in the observation group and the control group were 2.33%(1/43) and 18.60% (8/43), the difference was statistically significant ( <0.05) . 11.63% (5/43) of patients in the observation group appeared cracks and fracture, compared with the control group of 2.33% (1/43), there was a statistically significant difference ( <0.05) . Conclusion Compared with etal ceramic crowns, all-ceramic crowns in full denture prosthesis have less injury in periodontal tissue and weaker anti-crack intensity, so the clinicians should choose the all-ceramic crowns based on the patients' indications.%目的:观察全瓷冠与金属烤瓷冠在全牙义齿修复中的应用效果.方法选择云南省交通中心医院2012年1月至2012年9月的86例进行全牙义齿修复的患者作为研究对象,按照患者入院的先后顺序标记,奇数作为对照组,偶数作为观察组,每组43例.对照组采用金属烤瓷冠,观察组采用全瓷冠进行修复,随访12个月~24个月比较2组牙龈颈缘黑线情况、牙周损害情况及牙冠裂瓷.结果观察组与对照组

  5. Influence of substructure design and occlusal reduction on the stress distribution in metal ceramic complete crowns: 3D finite element analysis.

    Science.gov (United States)

    Motta, Andréa Barreira; Pereira, Luiz Carlos; Duda, Fernando Pereira; Anusavice, Kenneth J

    2014-07-01

    Occlusal reduction is considered a fundamental step for providing adequate and uniform space for the ceramic prosthesis; however, a flat occlusal surface is usually found. The prosthesis design influences the resistance to deformation and the stress state within the ceramic. This finite element (FE) study analyzes the influence of changing the substructure design on the stress distribution of a metal-ceramic crown in a premolar tooth with three types of occlusal reduction. Each part of three-dimensional metal ceramic complete crown models was designed according to the space provided by different levels of occlusal reduction and the same external morphology of the tooth. Three models were designed: (1) correct occlusal reduction with a uniform thickness of the substructure (0.3 mm) and the veneering porcelain (1.5 mm); (2) flat occlusal reduction with different thicknesses of veneering porcelain to produce a uniform substructure; and (3) a flat occlusal reduction with different thicknesses of substructure for a uniform thickness of veneering porcelain. Stress distributions were very similar in the three models. The highest tensile stresses were concentrated immediately below the midline fissure in both the veneering porcelain and the metal alloy substructure. Although models with flat occlusal reduction had lower stress values, this preparation results from a reduction that removes a greater amount of sound tissue, which may increase the probability of dental pulp injury. Occlusal reduction must be anatomic; however, when a flat occlusal reduction already exists, the substructure must reproduce the correct anatomic form to allow a uniform thickness of the veneering porcelain. © 2014 by the American College of Prosthodontists.

  6. Clinical study of zirconia all-ceramic crown and zirconia crown in molar fix prothesis%氧化锆全瓷冠与全锆冠后牙固定修复的临床研究

    Institute of Scientific and Technical Information of China (English)

    彭利辉; 钟爱喜; 潘小波; 刘光雪; 李荣婷

    2014-01-01

    目的比较氧化锆全瓷冠与全锆冠在后牙固定修复中的临床综合修复效果。方法36例后牙缺失需修复的患者,其中19例66颗牙行氧化锆全瓷冠桥修复,17例60颗牙行氧化锆全锆冠桥修复。追踪观察1~3年,由修复科医师对义齿的边缘适合性、牙龈健康情况、牙冠外形、色泽、是否崩瓷、破裂等进行评价。结果两组病例修复效果在所检查的指标中比较差异均无统计学意义( P>0.05)。结论氧化锆全瓷冠与全锆冠在边缘密合性、美观性及抗折强度方面,均能满足临床要求。但在合龈距离较短的病例中,全锆冠的修复更具优势。%Objective To compare the repairing effects between the zirconia all-ceramic crown bridge and zirconia bridge in aesthetics restoration of molars .Methods Thirty-six patients were restorated with the all-ceramic crown bridge(19 patients 66 molars) and zirconia ( bridge 17 patients 60 molars), followed up for 1 ~3 years, checked and appraised the marginal adaptation ,form,colour of the crowns ,the gingiva and crown fracture by one doc-tor.Results There was no statistically difference in the effects between the two kinds of restorations .Conclusion The two kinds of restoration can meet clinical needs in the marginal adaptation ,aesthetics and the flexural strength . The zirconia bridge is better in patients with shorter occlusogingival distance .

  7. Development of an expert system for the simulation model for casting metal substructure of a metal-ceramic crown design.

    Science.gov (United States)

    Matin, Ivan; Hadzistevic, Miodrag; Vukelic, Djordje; Potran, Michal; Brajlih, Tomaz

    2017-07-01

    Nowadays, the integrated CAD/CAE systems are favored solutions for the design of simulation models for casting metal substructures of metal-ceramic crowns. The worldwide authors have used different approaches to solve the problems using an expert system. Despite substantial research progress in the design of experts systems for the simulation model design and manufacturing have insufficiently considered the specifics of casting in dentistry, especially the need for further CAD, RE, CAE for the estimation of casting parameters and the control of the casting machine. The novel expert system performs the following: CAD modeling of the simulation model for casting, fast modeling of gate design, CAD eligibility and cast ability check of the model, estimation and running of the program code for the casting machine, as well as manufacturing time reduction of the metal substructure. The authors propose an integration method using common data model approach, blackboard architecture, rule-based reasoning and iterative redesign method. Arithmetic mean roughness values was determinated with constant Gauss low-pass filter (cut-off length of 2.5mm) according to ISO 4287 using Mahr MARSURF PS1. Dimensional deviation between the designed model and manufactured cast was determined using the coordinate measuring machine Zeiss Contura G2 and GOM Inspect software. The ES allows for obtaining the castings derived roughness grade number N7. The dimensional deviation between the simulation model of the metal substructure and the manufactured cast is 0.018mm. The arithmetic mean roughness values measured on the casting substructure are from 1.935µm to 2.778µm. The realized developed expert system with the integrated database is fully applicable for the observed hardware and software. Values of the arithmetic mean roughness and dimensional deviation indicate that casting substructures are surface quality, which is more than enough and useful for direct porcelain veneering. The

  8. Clinical effect of the CAD/CAM all-ceramic crowns on the anterior tooth restoration%计算机辅助设计和制造全瓷冠在前牙修复的临床效果

    Institute of Scientific and Technical Information of China (English)

    马慕兰; 张俭

    2013-01-01

    目的 比较计算机辅助设计和制造全瓷冠与钴铬合金烤瓷冠在前牙修复的临床效果.方法 采用计算机辅助设计和制造技术制作89件前牙二氧化锆全瓷冠,采用钴铬合金烤瓷冠制作67件前牙修复体,修复后1年复查,对边缘着色、龈缘密合度、修复体颜色、修复体周围龋、修复体折裂、牙龈健康情况进行评价.结果 在边缘着色、龈缘密合性、修复体颜色、牙龈健康状况方面差异有统计学意义(P<0.05),全瓷冠的临床效果优于钴铬合金烤瓷冠.结论 计算机辅助设计和制造全瓷冠的临床修复效果良好,是前牙修复的理想选择.%Objective To observe and compare the clinical effect of CAD/CAM all-ceramic crowns with cobalt-chromium alloy porcelain crowns in the restoration of anterior teeth.Methods Eighty-nine anterior teeth were restored with zirconia all-ceramic crowns,and 67 anterior teeth were restored with conventional cobalt-chromium alloy porcelain crowns.One year after the restoration,the marginal discoloration,change of marginal fit,color,caries around the crown,collapse porcelain and periodontal tissue heath of the two crowns were compared.Results The differences of the marginal discoloration,change of marginal fit,color,periodontal tissue heath between zirconia all-ceramic crowns and cobaltchromium alloy porcelain crowns was statistically significant (P < 0.1).The clinical effect of all-ceramic crowns was better than cobalt-chromium alloy porcelain crowns.Conclusion The clinical effect of CAD/CAM all-ceramic crowns was favourable in restoring anterior teeth.

  9. In-Ceram 全瓷冠与金属烤瓷冠对成纤维细胞株 L929细胞活力及相关基因表达的影响%Effect of In-Ceram all-ceramic crown and metal-ceramic crown on cell viabil ity and related gene expression in fibroblast cell l ines L929

    Institute of Scientific and Technical Information of China (English)

    石磊; 杨亮; 黄捷淳; 何恩宝; 吴志辉

    2016-01-01

    [ABSTRACT]Objective:To study the effect of In-Ceram all-ceramic crown and metal-ceramic crown on cell viability and related gene expression in fibroblast cell lines L929.Methods:Fibroblast cell lines L929 were cultured and treated with extract solution of In-Ceram all-ceramic crown,Ni-Cr alloy porcelain crown and Co-Cr alloy porcelain crown respectively,and then cell viability,serum cytokine contents as well as mRNA contents of Fas,FasL,Apo-1,mTOR and P70S6k in cells were detected. Results:Cell OD values of Ni-Cr alloy group and Co-Cr alloy group were significantly lower than that of negative control group;cell OD value of In-Ceram group was significantly higher than those of Ni-Cr alloy group and Co-Cr alloy group;TNF-α,IL-6 and IL-8 contents in cell culture medium of Ni-Cr alloy group and Co-Cr alloy group were significantly higher than those of neg-ative control group,and TNF-α,IL-6 and IL-8 contents in cell culture medium of In-Ceram group were significantly lower than those of Ni-Cr alloy group and Co-Cr alloy group and not different from those of negative control group;mRNA contents of Fas,FasL and Apo-1 in cells of Ni-Cr alloy group and Co-Cr alloy group were higher than those of negative control group,mR-NA contents of mTOR and P70S6k were lower than those of negative control group,mRNA contents of Fas,FasL and Apo-1 in cells of In-Ceram group were lower than those of Ni-Cr alloy group and Co-Cr alloy group and not different from those of negative control group,and mRNA contents of mTOR and P70S6k were higher than those of Ni-Cr alloy group and Co-Cr alloy group and not different from those of negative control group.Conclusion:In-Ceram all-ceramic crown has good histocompati-bility and will not affect cell viability as well as generation of inflammatory factors and expression of apoptosis and proliferation-related genes in fibroblast cell lines L929.%目的::研究 In-Ceram 全瓷冠与金属烤瓷冠对成纤维细胞株 L929细胞活力及相关

  10. Influence of Different Framework Designs on the Fracture Properties of Ceria-Stabilized Tetragonal Zirconia/Alumina-Based All-Ceramic Crowns

    Directory of Open Access Journals (Sweden)

    Tomofumi Sawada

    2016-05-01

    Full Text Available The aim of this study was to evaluate the fracture load and failure mode of all-ceramic crowns with different ceria-stabilized tetragonal zirconia/alumina nanocomposite (Ce-TZP/A framework designs. Four frameworks (anatomical shape: AS, with a buccal or lingual supporting structure: BS and LS, or buccal and lingual supporting structures: BLS were fabricated. All frameworks were veneered with porcelain to fabricate all-ceramic crowns followed by cementation to tooth analogs. The fracture load of each crown either without or with pre-loading (1.2 million cycles, 49 N was measured. The failure mode was classified into partial or complete fracture. Differences were tested for significance (p < 0.05 by a two-way Analysis of Variance (ANOVA, followed by Tukey’s test and by Fisher’s exact test, respectively. Without pre-loading, supporting structures did not influence the fracture load or failure mode. Partial fractures were the most common failure mode. Pre-loading promoted the severity of the failure mode, although the fracture load among the framework designs was not influenced. In the AS group, prefailures were observed during pre-loading, and complete fractures were significantly increased after pre-loading. In contrast, the failure mode of the BLS group remained unchanged, showing only partial fracture even after pre-loading. This Ce-TZP/A framework design, comprised of an anatomical shape with additional buccal and lingual structures, has the potential to reduce the chipping of the veneering porcelain.

  11. Finite element analysis of residual stress in a bilayered all-ceramic crown%饰瓷与基底瓷双层结构全瓷冠残余应力的三维有限元分析

    Institute of Scientific and Technical Information of China (English)

    马新扬; 辛海涛; 侯兵; 吴张

    2011-01-01

    目的 探讨全瓷冠高温烧结后冷却过程中,冠内不同部位以及结合界面处残余应力的分布及影响因素.方法 三维光学面扫描仪对全瓷修复体基底冠与最终牙冠表面分别进行扫描,获取冠内外点云数据;Geomagic Studio8与UG NX5将扫描后的壳体模型转成三维实体模型;运用有限元分析软件ABAQUS6.7热位移偶合单元对模型进行网格划分,施加温度载荷,模拟全瓷冠高温烧结后冷却过程,分析全瓷冠残余应力分布,并以修饰瓷与基底瓷热膨胀系数相同模型进行对比.结果 建立起饰瓷与基底瓷双层结构的全瓷冠三维有限元模型.残余应力在全瓷冠颈缘处修饰-基底瓷结合界面分布最大,在修饰瓷较厚部位残余应力分布较小.随着烧结温度的降低,残余应力逐渐增大.结论 运用三维面扫描建立的双层全瓷冠三维有限元模型精确,方法简便;全瓷冠残余应力分布较高部位与临床修复体的易破坏部位一致,提示,在进行全瓷冠修复时要注意基底瓷与修饰瓷热膨胀系数的匹配并且要保证冠边缘保持足够的瓷层厚度.%Objective To investigate the residual stress distribution of a bilayered all-ceramic crown during the cooling process using the finite element method. Methods The 3D point picture of a bilayered all-ceramic crown was obtained through three dimentional sensing system (3DSS). G eomagic Studio8 and UG NX5 were employed to transform the 3D point picture of a bilayered all-ceramic crown into a 3D solid model. The residual stress of the model was analyzed. The results were compared when the coefficient values of the veneer and core were the same. Results A 3D finite element model of bilayered dental ceramic crown was established. The maximum residual stress was found at the interface between the core and veneer on the margin of all-ceramic crown. The residual stress was minimum where the veneer ceramic was thickest. The residual stress also

  12. Functional aspects of treatment with implant-supported single crowns: a quality control study in subjects with tooth agenesis

    DEFF Research Database (Denmark)

    Goshima, Kenichi; Lexner, Michala O; Thomsen, Carsten Eckhart

    2010-01-01

    after implant placement shortly before crown cementation, and again 1 month after cementation. It consisted of questionnaires [including Oral Health Impact Profile (OHIP-49)] and functional examination with plastic strips, the Dental Prescale Film and the Occluzer system, Xylitol color-changeable gum......BACKGROUND: No comprehensive patient-centered and clinical evaluations of the functional effect of treatment with implant-supported single crowns (ISSC) have been reported previously. OBJECTIVE: To investigate whether and how treatment with ISSC affects masticatory function and Oral Health...

  13. Impression evaluation and laboratory use for single-unit crowns: Findings from The National Dental Practice-Based Research Network.

    Science.gov (United States)

    McCracken, Michael S; Litaker, Mark S; George, Ashley J; Durand, Scott; Malekpour, Sepideh; Marshall, Don G; Meyerowitz, Cyril; Carter, Lauren; Gordan, Valeria V; Gilbert, Gregg H

    2017-08-16

    Objectives were to determine the likelihood that a clinician accepts an impression for a single-unit crown and document crown remake rates. The authors developed a questionnaire that asked dentists about techniques used to fabricate single-unit crowns. The authors showed dentists photographs of 4 impressions and asked them to accept or reject each impression. The authors correlated answers with dentist and practice characteristics. Other questions pertained to laboratory use and crown remake rates. The response rate was 83% (1,777 of 2,132 eligible dentists). Of the 4 impressions evaluated, 3 received consistent responses, with 85% agreement. One impression was more equivocal; 52% accepted the impression. The likelihood of accepting an impression was associated significantly with the clinician's sex, race, ethnicity, and practice busyness. Clinicians produced 18 crowns per month on average, and 9% used in-office milling. Most dentists (59%) reported a remake rate of less than 2%, whereas 17% reported a remake rate greater than 4%. Lower remake rates were associated significantly with more experienced clinicians, optical impressions, and not using dual-arch trays. Although dentists were largely consistent in their evaluation of impressions (> 85%), nonclinical factors were associated with whether an impression was accepted or rejected. Lower crown remake rates were associated with more experienced clinicians, optical impressions, and not using dual-arch trays. These results provide a snapshot of clinical care considerations among a diverse group of dentists. Clinicians can compare their own remake rates and impression evaluation techniques with those in this sample when developing best practice protocols. Copyright © 2017 American Dental Association. Published by Elsevier Inc. All rights reserved.

  14. Analysis of reliability of the strength of all-ceramic crown on mandibular first molar%下颌第一磨牙全瓷冠强度可靠性的三维有限元分析

    Institute of Scientific and Technical Information of China (English)

    李岩; 张少锋; 陈建军

    2010-01-01

    目的 对随机载荷作用下全瓷冠强度的可靠性进行三维有限元分析,探讨不同加载模式对全瓷冠强度可靠性的影响.方法 建立用于下颌第一磨牙全瓷冠可靠性分析的三维有限元模型,通过概率统计方法 处理获得3~300 N区间内的随机载荷,确定3种加载模式:异常(牙合)接触加载:随机载荷分别单独加载于颊尖尖部、颊尖舌斜面和中央窝,加载面积均为0.4 mm~2;咀嚼骀接触加载:随机载荷加载位置同异常(牙合)接触加载,加载面积为1.5 mm~2;广泛(牙合)接触加载:随机载荷广泛加载于牙尖交错位时的(牙合)接触面,加载面积为12.6 mm~2.根据可靠度计算公式计算全瓷冠强度的可靠度.结果异常(牙合)接触加载时,全瓷冠颊尖尖部、颊尖舌斜面、中央窝强度的可靠度分别为97%、99%、100%;咀嚼(牙合)接触加载时,全瓷冠颊尖尖部、颊尖舌斜面、中央窝强度的可靠度分别为99%、100%、100%;广泛(牙合)接触加载时,全瓷冠骀面强度的可靠度为100%.结论 随机载荷作用下,早接触、过锐牙尖及咀嚼过硬食物造成的局部小面积集中载荷可显著降低全瓷冠强度的可靠度.%Objective To analyze the reliability of all-ceramic crown on mandibular first molar under randomized biting force,and to explore the failure possibility of all-ceramic crown.Methods Finite element(FE)models of all-ceramic crown on mandibular first molar were established using the Algor FE software.All-ceramic crown was loaded at different occlusal areas and positions with random variables of biting force,and the reliability of all-ceramic crown was analyzed.Results The occlusal contact positions were located on the fossa,inclined surface and dental cusp.When the occlusal contact area was 0.4 mm~2,The reliability of all-ceramic crown on mandibular first molar were 100%(fossa),99%(inclined surfacee),and 97%(cusp)respectively.When the occlusal contact area was 1.5 mm~2,the

  15. A systematic review and meta analysis of the longevity of anterior and posterior all-ceramic crowns

    NARCIS (Netherlands)

    Kassardjian, V.; Varma, S.; Andiappan, M.; Creugers, N.H.J.; Bartlett, D.

    2016-01-01

    BACKGROUND: Clinical experience suggests that there is a difference in survival between anterior and posterior all ceramic restorations. OBJECTIVES: This systematic review compared the difference in survival for full coverage all-ceramic materials used in adults to restore anterior or posterior

  16. Finite element stress analysis of all-ceramic crown of the upper central incisor in differential thickness%不同厚度上颌中切牙全瓷冠应力分布的有限元研究

    Institute of Scientific and Technical Information of China (English)

    胡建; 章非敏; 戴宁; 李泷杲; 顾卫平; 马骏驰

    2012-01-01

    Objective To investigate the stress distributions under load in an all-ceramic crown of the upper central incisor in differential thickness. Methods The 3-dimensional finite element model of all-ceramic crown of the upper central incisor in differential thickness was applied with differential loads(100, 150, 200 N). The stress values and distributions of all-ceramic crown were calculated and expressed. Results The tendency of stress distributions in all-ceramic crown of differential thickness and loads was similar. The maximal stress intensity value was located in the loading site and the cervical region. As the thickness of all-ceramic crown increased, the stress concentration reduced. When the load increased, the stress values increased, especially in the loading site and the cervical region. Conclusion The increasing of the thickness of all-ceramic crown will decrease stress concentration. Because stress concentration is mainly in cervical region and loading site, these regions should be cared in fabrication of all-ceramic crown.%目的 研究不同厚度上颌中切牙全瓷冠受载时的应力分布特点.方法 利用上颌中切牙全瓷冠的三维有限元模型,对3种不同厚度的全瓷冠分别进行100、150、200 N载荷模拟加载,并进行力学分析.结果 不同厚度全瓷冠不同载荷下的应力分布趋势相似,应力集中于冠的颈缘及加载点.随着厚度增加,应力集中趋势明显减弱.随着载荷增加,各部位的等效应力相应增加,加载点及颈缘尤为明显.结论 全瓷冠厚度的增加可降低应力集中.颈缘和加载点为应力集中区,全冠制作时应注意加强该区域.

  17. 三种基底冠对牙龈缘组织影响的临床比较%Clinical comparoson of three different kinds of ceramic crowns on marginal gingivae

    Institute of Scientific and Technical Information of China (English)

    区韵婵; 温灵; 段昌华

    2012-01-01

    Objective To compare the impact of complete crowns made by three different materials on the gingival health and pigmentation. Methods Forty patients were selected randomly and divided into three gr,oups:metal-ceramic crowns of Ni-Cr alloy;metal -ceramic crowns of Pd-Ag alloy; and zirconia all-ceramic crowns.After1,2 and 3 years follow up, the marginal gingival bleeding index and pigmentation were examined. The data were analyzed by SPSS 13.0 software. Results Givngival inflammation or pigmentation was observed in 15 cases of Ni-Cr group.Two cases of Pd-Ag alloy metal-ceramic crowns with discolored gingivae were observed. No gingival inflammation or pigmentation was observed in zirconia all-ceramic group. Conclusion The metal-ceramic crowns of Pd-Ag alloy and zirconia all -ceramic crowns showed good biocompatibility. There were no adverse effects of all-ceramic crowns on gingival health. The Pd-Ag alloy metal ceramic crowns would not cause obvious harm to the marginal gingival, while the Ni-Cr alloy metal ceramic crowns may increase the risk of gingival bleeding and pigmentation.%目的:观察比较非责金属(镍铬合金)、贵金属(钯银合金)和全瓷(二氧化锆全瓷)内冠三种基底烤瓷冠对牙龈组织的影响.方法:选取3种基底烤瓷冠各40例从牙龈充血和色素沉着等方面进行统计学分析.结果:镍铬合金为基底烤瓷冠修复后出现牙龈异常或龈缘色素沉着15例,钯银合金为基底烤瓷冠修复后出现牙龈异常或龈缘色素沉着2例,全瓷(二氧化锆全瓷)内冠为基底烤瓷冠修复后无1例出现牙龈异常或龈缘色素沉着.结论:贵金属基底烤瓷冠和全瓷烤瓷内冠具有良好的生物相容性,不容易造成牙龈炎及过敏反应,对牙龈无不良影响,减少了龈缘色素沉着的发生,而镍铬合金为基底烤瓷冠可引起龈缘组织异常反应.

  18. Clinical observation of the metal-ceramic crowns with shoulder porcelain of anterior teeth%肩台瓷金瓷冠在前牙修复中的临床效果观察

    Institute of Scientific and Technical Information of China (English)

    唐颖; 袁剑鸣; 潘峰

    2013-01-01

      Objective To observe the prosthetic effects of the metal-ceramic crowns with shoulder porcelain of anterior teeth clinically. Methods Forty-two units of metal-ceramic crowns with shoulder porcelain, forty-four u-nits Ni-Cr based porcelain-fuse-metal crowns were observed after one year through clinical methods. Results There were some differences between the two groups in color match, contour, marginal integrity and health of gum. But the difference between the two groups had no statistic significance. The differences of marginal integrity and marginal discoloration between metal-ceramic crowns with shoulder porcelain and Ni-Cr based porcelain-fuse-metal crowns had high statistic significance. Conclusion Using metal-ceramic crowns with shoulder porcelain could progress the esthetics in anterior teeth.%  目的分析肩台瓷金瓷冠在前牙修复中的临床效果。方法根据纳入标准分别对42颗肩台瓷金瓷冠、44颗镍铬合金烤瓷冠修复1年后的临床效果进行观察对比,评价其结果。结果2组间在颜色、外形、边缘密合性、牙龈健康方面有差异但无统计学意义。在牙龈灰线、边缘变色方面有差异,且差异有统计学意义。结论肩台瓷金瓷冠在前牙修复中有较好的美观效果。

  19. 金属烤瓷冠修复技术的临床效果观察%Clinical effect observation of metal-ceramic crown remediation technique

    Institute of Scientific and Technical Information of China (English)

    崔秀萍

    2015-01-01

    Objective To explore the clinical effect of metal-ceramic crown remediation technique and sum up the op-timal remediation of varieties of metal-ceramic crown. Methods Clinical data of 120 patients who visited our depart-ment and agreed on metal-ceramic crown remediation technique from July 2012 to June 2013 were retrospectively ana-lyzed and studied.Based on different remediation material,they were divided into observation group and control group,60 cases in each group.In observation group,inner crown in gold alloy was adopted for dental rehabilitation,while in control group,nichrome was chosen.One year after remediation,clinical therapeutic effect,occurrence of complications,advantage and disadvantage of two methods between two groups was analyzed and compared respectively. Results The total clini-cal therapeutic effect in observation group was 96.67%,much higher than that in control group accounting for 81.67%, with statistical difference (P<0.05).In observation group,incidence of complications like gingivitis,swelling and aching of gum,gingival bleeding,gingival discoloration,bad breath,and full crown loose was remarkably lower than that in control group,with statistical difference(P<0.05). Conclusion In the technique of metal-ceramic crown remediation,inner crown in gold alloy and nichrome both obtain satisfying effects,but the effect in the former is better than that in latter.Inner crown in gold alloy,at advantages of small damage to periodontium,few complications such as gingivitis,swelling and aching of gum,gingival bleeding,gingival discoloration,bad breath,and full crown loose and so forth,and high aesthetic perception,is a relatively ideal remediation,which is worthy of adoption and expansion.%目的:探讨金属烤瓷冠修复技术临床效果,总结金属烤瓷冠的最佳修复方法。方法选取2012年7月~2013年6月在本院口腔科就诊并选择金属烤瓷冠修复技术的120例患者的临床资料进行回顾性分析研究,根据

  20. CAD/CAM玻璃陶瓷全冠在后牙义齿修复中的运用%Clinical application of CAD/CAM all ceramic crown in the restoration of the posterior teeth

    Institute of Scientific and Technical Information of China (English)

    胡媛媛; 许琼莉; 周娟; 冷卫东; 陈永吉; 牛玉明

    2015-01-01

    Objective:To investigate the clinical use of CAD/CAM all ceramic crown in the restoration of the poste-rior teeth. Method:Thirty-five patients with forty-seven teeth of residual crown were selected and restored with CAD/CAM all ceramic crown after completely root canal therapy. Result:With 3 to 18 months following study,The retention、marginal adaptation and periodontal tissue of the dental prosthetic restoration of forty-five teeth were satisfactory ,one crowns with occlusion flaws,one crown failed for crown loose. Conclusion:The CAD/CAM all ceramic crown in the restoration for the posterior teeth can provide better effect of retention and esthetics.%目的:研究CAD/CAM全瓷冠在后牙义齿修复中的应用。方法:35例患者47个后牙经完善根管治疗后,使用CAD/CAM氧化锆全冠修复。结果:随访3~18个月,45个牙冠修复体的固位、边缘密合度、牙周状况均良好,1个冠咬合面出现隐裂,1个牙冠修复体出现松动。结论:CAD/CAM氧化锆全冠在后牙义齿修复中能够提供较好的固位及美学效果。

  1. Measurement of the convergence angle in teeth prepared for single crown

    Directory of Open Access Journals (Sweden)

    NokarS

    2002-07-01

    Full Text Available Retention, resistance and marginal integrity mostly depend on tooth preparation. An appropriate convergence angle fulfil this purpose, to high extent. In this study, a new method was used to measure the convergence angle of the teeth prepared for single crowns in Genera! practitioners" offices in Tehran. In order to do this. 325 dyes, prepared by General dentists in Tehran, were collected from 10 laboratories. All dyes wore trimmed at the area below the finishing line and then were scanned (Genius Color page- FIR 6 buccoiingualiy and mesiodistaily. Convergence angle of dyes were also measured with Adobe Photoshop (5.0 software. Data were analyzed by variance analysis test and 1- student bv the help of SPSS software. Results showed that the average convergence angle ranged from 16.18+8.34 to 35.1 8~10.38 which belonged to maxillary canine and mandibular molars, respectively, and the measured convergence angle is more than the ideal value of 10-16 degrees. Dyes of the madibular molars were ma"illar" convergent. These conclusions are helpful for professors, dentistry students and dentists, and arc an indicative of the practice quality of General practitioners in Tehran. Due to the fact that a convergence angle, more than the allowed limitation, endangers retention, resistance and marginal integrity of the restoration, paying attention to the principles of tooth preparation and proper application of instruments and dental cements, can progress fwed restorations quality.

  2. Impact of Crown-Implant Ratio of Single Restorations Supported by 6-mm Implants : A Short-Term Case Series Study

    NARCIS (Netherlands)

    Guljé, Felix L; Raghoebar, Gerry M; Erkens, Ward Al; Meijer, Henny Ja

    2016-01-01

    PURPOSE: High crown-implant ratios might affect the biologic and technical performance of a reconstruction. The aim of this study was to assess whether a higher crown-implant ratio of single restorations on 6-mm implants resulted in more peri-implant bone loss and more prosthetic complications durin

  3. Positional changes of maxillary central incisors following orthodontic treatment using single-crown implants as fixed reference markers

    DEFF Research Database (Denmark)

    Brahem Ben, Elissa; Holm, Bente; Sonnesen, L

    2017-01-01

    . MATERIALS AND METHODS: Fifty-seven patients - thirty-seven with (test group) and twenty without pre-implant orthodontic treatment (control group) - were rehabilitated with 89 single-crown implants in the upper maxilla. Clinical and radiographic data, clinical photographs, and dental casts were collected......OBJECTIVES: This follow-up study (1) compares tooth displacement of central incisors in patients with and without pre-implant orthodontic treatment and (2) investigates whether sex, age, or orthodontic retention have an effect on tooth displacement after the insertion of single-crown implants...... during baseline examinations after prosthetic rehabilitation and at the final follow-up examination at least 5 years later. A total of 114 dental casts were digitalized and aligned using a software program to measure changes in the positions of the central incisors. RESULTS: After a follow-up period...

  4. Dental crowns

    Science.gov (United States)

    ... you. The different types of crowns include: Stainless steel crowns: Are pre-made Work well as temporary crowns, especially for young children. The crown falls off when the child loses the baby tooth. Metal crowns: Hold up to chewing and teeth ...

  5. Influence of finish line in the distribution of stress trough an all ceramic implant-supported crown.

    Science.gov (United States)

    SANNINO, G.; GLORIA, F.; OTTRIA, L.; BARLATTANI, A.

    2010-01-01

    SUMMARY Porpose. The aim of this study was to evaluate, by finite element analysis (FEA), the influence of finish line on stress distribution and resistance to the loads of a ZrO2 crown and porcelain in implant-supported. Material and methods. The object of this analysis consisted of a fxture, an abutment, a passing screw, a layer of cement, a framework crown, a feldspatic porcelain veneering. The abutment’s marginal design was used in 3 different types of preparation: feather edge, slight chamfer and 50°, each of them was of 1 mm depth over the entire circumference. The ZrO2Y-TZP coping was 0.6 mm thick. Two material matching for the abutment and the framework was used for the simulations: ZrO2 framework and ZrO2 abutment, ZrO2 framework and T abutment. A 600 N axial force distributed over the entire surface of the crown was applied. The numerical simulations with finite elements were used to verify the different distribution of equivalent von Mises stress for three different geometries of abutment and framework. Results Slight chamfer on the matching ZrO2 - ZrO2 is the geometry with minimum equivalent stress of von Mises. Even for T abutment and ZrO2 framework slight chamfer is the best configuration to minimize the localized stress. Geometry that has the highest average stress is one with abutment at 50°, we see a downward trend for all three configurations using only zirconium for both components. Conclusions Finite element analysis. performed for the manifacturing of implant-supported crown, gives exact geometric guide lines about the choice of chamfer preparation, while the analysis of other marginal geometries suggests a possible improved behavior of the mating between ZrO2 abutment and ZrO2 coping. for three different geometries of the abutment and the coping. PMID:23285359

  6. 金属烤瓷冠修复失败39例的原因分析%Cause analysis of metal ceramic crown restoration failure in 39 cases

    Institute of Scientific and Technical Information of China (English)

    石林

    2015-01-01

    Objective:To explore the reasons and preventive measures of metal ceramic crown restoration failure.Methods:The clinical data of 39 patients with metal ceramic crown restoration failure were retrospectively analyzed.Results:The failure reasons were 18 cases of gingivitis,7 cases of tooth color coordination,6 cases of gingival discoloration,4 cases of restoration exfliation,4 cases of porcelain.Conclusion:The failure reasons of metal ceramic crown restoration are mainly closely related to clinical design, cases selection and metal porcelain crown.Making metal ceramic crown restoration should be having appropriate tooth preparation, the thickness of the porcelain layer should be uniform when making,it avoid the early contact and bite hard objects,and correctly restore the adjacency relationship.%目的:探索金属烤瓷冠修复失败的原因以及预防措施。方法:对39例金属烤瓷冠修复失败患者的临床资料进行回顾性分析。结果:失败的原因:牙龈炎18例,牙冠颜色不协调7例,牙龈变色6例,修复体脱落4例,崩瓷4例。结论:金属烤瓷冠修复失败的原因主要和临床设计、病例的选择以及金属烤瓷冠制作密切相关,制作金属烤瓷修复体应进行适当的牙体预备,制作时瓷层厚度要均匀,避免早接触以及咬硬物,要正确恢复邻接关系。

  7. Changes of Dental Porcelain Fused to Metal Crown, Zirconia all Ceramic Crowns on the Periodontal Tissue%试论前牙金属烤瓷冠、氧化锆全瓷冠修复后牙周组织变化

    Institute of Scientific and Technical Information of China (English)

    谷克晓; 李宁; 刘党利

    2016-01-01

    Objective Changes of dental porcelain fused to metal crown, zirconia all ceramic crowns on the periodontal tissue of the former.Methods selected in our hospital in June 2014 to 2015 December for patients with anterior teeth with PFM crowns 100 cases as the research object,divided into observation and control group. Patients in the control group were treated by the cobalt chromium alloy porcelain crowns, the observation group with zirconia all ceramic crowns, comparative analysis of the clinical therapeutic effect of the two groups.Results observation group of gingival papilla color change, gingival grey line and black line occurred rate of gingivitis was signiifcantly lower than that of the control group. Conclusion zirconia all ceramic crown restoration has a strong aesthetic,can be used to repair the anterior teeth.%目的:研究前牙金属烤瓷冠、氧化锆全瓷冠修复后牙周组织的变化。方法选取我院2014年6月~2015年12月收治的进行前牙烤瓷冠修复患者100例为研究对象,将其分为观察与对照两组,对照组进行钴铬合金烤瓷冠修复,观察组采用氧化锆全瓷冠修复,对比分析两组临床治疗效果。结果观察组的龈乳头颜色改变、牙龈缘灰线、黑线发生率牙龈炎发生率显著低于对照组。结论氧化锆全瓷冠修复具有较强的美观性,临床上可以将其用来修复前牙。

  8. 不同咬合状态下上颌中切牙全瓷冠修复的有限元分析%Finite element analysis of maxillary central incisor all-ceramic crowns in different occlusal states

    Institute of Scientific and Technical Information of China (English)

    肖严; 熊康; 权菲菲

    2016-01-01

    BACKGROUND:The strength of al-ceramic crowns is affected by many factors. At present there are many studies concerning the neck edge shape, cutting thickness, binder and convergence angle, but little has been reported on the effects of different occlusions on al-ceramic crowns. OBJECTIVE:To explore the maxilary central incisor al-ceramic crowns in different occlusal states by finite element analysis. METHODS: Three-dimensional finite element models of the maxilary central incisor al-ceramic crowns were established. Empress II and In-Ceram Zirconia were selected. The normal overbite position and deep overbite position were applied to force a load of 230 N, with the long axis of the tooth at a 45° angle. Distribution of inner stress and edge stress was analyzed at different occlusal states. RESULTS AND CONCLUSION:(1) The stress distribution of al-ceramic crowns under different occlusion relationship was different. The stress peaks of cementum, alveolar bone and periodontium in the deep overbite were lower than those in the normal overbite. The stress peaks of al-ceramic crowns and binder were higher than in the deep overbite than the normal overbite. The stress peak of the dentin in the Empress II group was higher in the deep overbite than in the normal overbite. The stress peak of the dentin in the In-Ceram Zirconia group was lower in the deep overbite than in the normal overbite. Different al-ceramic crowns had no influence on the stress distribution, but in the deep overbite, the stress was mainly concentrated in the occlusal contact area, and in the normal overbite, the stress was mainly concentrated in the occlusal contact area and at the labial cervical margin. (2) The stress distribution of different al-ceramic crowns under the same occlusal state was different. In the normal overbite, different al-ceramic crowns had no evident influence on the stress peak, and in the deep overbite, there was a certain effect of different al-ceramic crowns on the stress peak

  9. Clinical therapeutic effect comparison between Sirona Cerec 3D all-ceramic crowns and porcelain fused to metal crown in anterior teeth restoration%Sirona Cerec3D全瓷冠与金属烤瓷冠修复前牙的临床对比

    Institute of Scientific and Technical Information of China (English)

    汤琼

    2012-01-01

    目的 评价Sirona Cerec 3D全瓷冠进行前牙修复的临床效果.方法 将81例(145颗前牙)患者进行随机分组,参照美国加利福尼亚牙科协会(CDA)评价标准,对使用1年的牙冠进行评价,并与同期治疗的金属烤瓷冠进行对比.结果 Sirona Cerec 3D全瓷冠修复组在边缘完整性、解剖外形、颜色和表面的成功率分别为97.5%、95%、100%、97.5%,而金属烤瓷冠对照组成功率为97.6%、92.6%、87.8%和95.1%.修复组在解剖外形和颜色方面明显优于对照组(P<0.05),且牙龈炎等副反应发生率小.结论Sirona Cerec 3D全瓷冠进行前牙修复效果良好,值得临床广泛推广.%Objective To evaluate the clinical therapeutic effect ofSirona Cerec 3D all-ceramic crowns in anterior teeth restoration.Methods 81 patients(145 anterior teeth) were divided randomly into two groups.The clinical evaluation criteria of CDA was performed 6 months to two years after wearing.And we compared the effects with porcelain fused to metal (PFM) crowns in the same period.Results On the integrity of crown margin,anatomical shape,color and surface,the succeed rate of all-ceramic crowns group were 97.5%,95%,100% and 97.5% respectively while PFM crowns group were 97.6%,92.6%,87.8% and 95.1% respectively.All-ceramic crowns group was better than PFM crowns group on the anatomical shape and color ( P < 0.05 ) and had less side effects.Conclusion Sirona Cerec 3D all-ceramic crowns has a good effect in anterior teeth restoration,worthy in expanded clinical use.

  10. Avaliação das condutas adotadas por profissionais na utilização de coroas metalo-cerâmicas Assessment of clinical proceedings adopted by dental professionals regarding the employment of ceramic fused to metal crowns

    Directory of Open Access Journals (Sweden)

    Carlos Neanes Santos

    2003-12-01

    Full Text Available A fim de avaliar a opinião da classe odontológica sobre a utilização das coroas metalo-cerâmicas na prática odontológica, aplicou-se um questionário de 20 questões a cirurgiões-dentistas da cidade de Aracaju - SE, e a cirurgiões-dentistas e estudantes de pós-graduação em odontologia, na área de prótese dental, da cidade de Bauru-SP. Concluiu-se que: 1. As coroas metalo-cerâmicas são o tipo de restauração protética mais empregado em Odontologia. 2. A maioria dos dentistas refere-se às coroas metalo-cerâmicas como restaurações bem sucedidas, indicando superfícies oclusais metálicas para a maioria dos pacientes. 3. Apesar da maior parte dos profissionais utilizar as ligas de níquel-cromo nas coroas metalo-cerâmicas de seus pacientes, os mesmos prefeririam que ligas nobres ou semi-nobres fossem empregadas em suas próprias restaurações. 4. A maioria dos entrevistados emprega as coroas metalo-cerâmicas na restauração de dentes anteriores (57,23%. Entretanto, esse valor se deve à preferência dos dentistas de Aracaju (78% por esse tipo de restauração, ao passo que, em Bauru, prevaleceu o número de respostas favoráveis às coroas de porcelana pura. 5. O cimento de fosfato de zinco foi o cimento de escolha da maioria dos profissionais. 6. A preferência da maior parte dos entrevistados, com relação à porcelana utilizada foi pela porcelana Vita (34,34%, em comparação às porcelanas Noritake e Dulceram Plus (13,86%. 6. Ficou evidente o desejo dos entrevistados quanto ao desenvolvimento de mecanismos que facilitem o reparo das coroas metalo-cerâmicas.The current features of ceramic fused to metal crowns were evaluated by means of a questionnaire composed by 20 questions concerning the use of this type of restoration in the daily dental practice of professionals from Aracaju, Bauru and post-graduation students in the area of dental prosthesis. The conclusions were as follows: 1. Ceramic fused to metal crowns are

  11. Manufacturing and characterization of a ceramic single-use microvalve

    Science.gov (United States)

    Khaji, Z.; Klintberg, L.; Thornell, G.

    2016-09-01

    We present the manufacturing and characterization of a ceramic single-use microvalve with the potential to be integrated in lab-on-a-chip devices, and forsee its utilization in space and other demanding applications. A 3 mm diameter membrane was used as the flow barrier, and the opening mechanism was based on cracking the membrane by inducing thermal stresses on it with fast and localized resistive heating. Four manufacturing schemes based on high-temperature co-fired ceramic technology were studied. Three designs for the integrated heaters and two thicknesses of 40 and 120 μm for the membranes were considered, and the heat distribution over their membranes, the required heating energies, their opening mode, and the flows admitted through were compared. Furthermore, the effect of applying  +1 and  -1 bar pressure difference on the membrane during cracking was investigated. Thick membranes demonstrated unpromising results for low-pressure applications since the heating either resulted in microcracks or cracking of the whole chip. Because of the higher pressure tolerance of the thick membranes, the design with microcracks can be considered for high-pressure applications where flow is facilitated anyway. Thin membranes, on the other hand, showed different opening sizes depending on heater design and, consequently, heat distribution over the membranes, from microcracks to holes with sizes of 3-100% of the membrane area. For all the designs, applying  +1 bar over pressure contributed to bigger openings, whereas  -1 bar pressure difference only did so for one of the designs, resulting in smaller openings for the other two. The energy required for breaking these membranes was a few hundred mJ with no significant dependence on design and applied pressure. The maximum sustainable pressure of the valve for the current design and thin membranes was 7 bar.

  12. 种植后CEREC Ⅲ全瓷单冠修复的临床研究%Clinical study of CEREC Ⅲ all ceramic crown restorations for implant

    Institute of Scientific and Technical Information of China (English)

    张建英; 赵晓华; 贾丽红; 马艳美

    2012-01-01

    目的:评价种植术后CEREC Ⅲ全瓷单冠修复1年的临床效果.方法:选取2010年1月~ 2010年6月来解放军第264医院数字口腔中心就诊采用CEREC Ⅲ全瓷单冠修复的患者22例.修复后追踪观察1年,按照改良的USPHS标准进行临床评价.结果:各项指标均达到了B标准或以上,其中颜色匹配令人满意,达到A标准者为95.45%.结论:种植后CEREC Ⅲ全瓷单冠修复具有较好的临床效果,值得推广.%Objective To evaluate the practicality and performance of CEREC III all ceramic crown restorations for implant after one year of clinical service. Methods Twenty-two patients with 22 all ceramic crown restorations were involved in the study.These crowns were made from 2010.1 ~2010.6.After one year, the clinical performance of the restorations evaluated by examiners using modified USPHS criteria. Results Crown restorations scored B using modified USPHS criteria. Most satisfactory was color match problem that achieve 95.45% of A criteria. Conclusion It was satisfactory for CEREC III all ceramic crown restorations for implant.

  13. Single crystal and optical ceramic multicomponent garnet scintillators: A comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Yuntao, E-mail: ywu52@utk.edu [Scintillation Materials Research Center, University of Tennessee, Knoxville, TN 37996 (United States); Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Luo, Zhaohua; Jiang, Haochuan [Ningbo Institution of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Meng, Fang [Scintillation Materials Research Center, University of Tennessee, Knoxville, TN 37996 (United States); Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Koschan, Merry [Scintillation Materials Research Center, University of Tennessee, Knoxville, TN 37996 (United States); Melcher, Charles L. [Scintillation Materials Research Center, University of Tennessee, Knoxville, TN 37996 (United States); Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States)

    2015-04-21

    Multicomponent garnet materials can be made in optical ceramic as well as single crystal form due to their cubic crystal structure. In this work, high-quality Gd{sub 3}Ga{sub 3}Al{sub 2}O{sub 12}:0.2 at% Ce (GGAG:Ce) single crystal and (Gd,Lu){sub 3}Ga{sub 3}Al{sub 2}O{sub 12}:1 at% Ce (GLuGAG:Ce) optical ceramics were fabricated by the Czochralski method and a combination of hot isostatic pressing (HIPing) and annealing treatment, respectively. Under optical and X-ray excitation, the GLuGAG:Ce optical ceramic exhibits a broad Ce{sup 3+} transition emission centered at 550 nm, while the emission peak of the GGAG:Ce single crystal is centered at 540 nm. A self-absorption effect in GLuGAG:Ce optical ceramic results in this red-shift of the Ce{sup 3+} emission peak compared to that in the GGAG:Ce single crystal. The light yield under 662 keV γ-ray excitation was 45,000±2500 photons/MeV and 48,200±2410 photons/MeV for the GGAG:Ce single crystal and GLuGAG:Ce optical ceramic, respectively. An energy resolution of 7.1% for 662 keV γ-rays was achieved in the GLuGAG:Ce optical ceramic with a Hamamatsu R6231 PMT, which is superior to the value of 7.6% for a GGAG:Ce single crystal. Scintillation decay time measurements under {sup 137}Cs irradiation show two exponential decay components of 58 ns (47%) and 504 ns (53%) for the GGAG:Ce single crystal, and 84 ns (76%) and 148 ns (24%) for the GLuGAG:Ce optical ceramic. The afterglow level after X-ray cutoff in the GLuGAG:Ce optical ceramic is at least one order of magnitude lower than in the GGAG:Ce single crystal. - Highlights: • GGAG:Ce single crystal and GLuGAG:Ce optical ceramics were fabricated. • The light yield of both ceramic and crystal G(Lu)GAG:Ce reached the level of 45,000 photons/MeV. • GLuGAG:Ce optical ceramic showed a better energy resolution of 7.1% for 662 keV. • GLuGAG:Ce ceramics exhibited lower afterglow level than that of GGAG:Ce single crystals. • The possible optimization strategies for

  14. Complicated Crown-Root Fracture Treated Using Reattachment Procedure: A Single Visit Technique

    Directory of Open Access Journals (Sweden)

    Akhil Rajput

    2011-01-01

    Full Text Available Complicated crown-root fracture of maxillary central and lateral incisors is common in case of severe trauma or sports-related injury. It happens because of their anterior positioning in oral cavity and protrusive eruptive pattern. On their first dental visit, these patients are in pain and need emergency care. Because of impaired function, esthetics, and phonetics, such patients are quite apprehensive during their emergency visit. Successful pain management with immediate restoration of function, esthetics and phonetics should be the prime objective while handling such cases. This paper describes immediate treatment of oblique crown root fracture of maxillary right lateral incisor with reattachment procedure using light transmitting fiber post. After two and half years, the reattached fragment still has satisfying esthetics and excellent function.

  15. Inlab MC XL系统3种全瓷冠边缘和内部适合性的实验研究%Marginal and Internal Fit of Three All-ceramic Crowns in Inlab MC XL System

    Institute of Scientific and Technical Information of China (English)

    谭发兵; 王璐; 金萍; 付钢; 吴树洪

    2011-01-01

    Objective To investigate marginal and internal fit of three types of all the porcelain crowns in Inlab MC XL system and provide experimental evidences for its clinical application. Methods A lower right first molar in the standard model was prepared with 48 models also duplicated. Among them, 24 models were randomly selected to bind crowns and the other 24 models were used to bind Cerec Blocs, Incoris AL and In-ceram YZ crowns at the same numbers respectively. The fit of all-ceramic crowns were evaluated with modified United States Public Health Service(USPHS) criteria and scanning electron microscop image (SEM). Results All the marginal fit values were less than 120μm and there was statistical significance between Incoris AL and Cerec Blocs groups,Incoris AL and In-ceram YZ groups (P < 0.01).The occlucal surface's fit value (>200 μm)was the poorest in all three groups,while Cerec Blocs showed better internal fit than Incoris AL and In-ceram YZ in terms of mesial surface, lingual surface, buccal surface, and internal overall ( P < 0.05 ). However, there was no statistical significance(P > 0.05 )between Incoris AL and In-ceramYZ groups in terms of that of above observation projects. Conclusion The crowns' marginal fit of Cerec Blocs and In-ceram YZ was better than Incoris AL with the best internal fit of Cerec Blocs. Three types of all-ceramic crowns appear to have clinically acceptable marginal fit.%目的 研究Inlab MC XL系统3种瓷材料全冠的边缘和内部适合性,为临床应用提供参考.方法 制备-右下第一磨牙全冠预备体模型,复制48个代型.采用随机抽样法,24个用于采集光学印模,分别制作8个Cerec Blocs、Incoris AL、In-ceram YZ全冠,剩余24个代型用于冠的粘结.采用修正USPHS标准和SEM法评价冠的适合性.结果 修正USPHS法显示87.5%的边缘测试点临床可接受,3种瓷材料冠的边缘适合性比较无统计学意义(P>0.05);SEM法显示Incoris AL

  16. Controlling outbreaks of the coral-eating crown-of-thorns starfish using a single injection of common household vinegar

    Science.gov (United States)

    Boström-Einarsson, Lisa; Rivera-Posada, Jairo

    2016-03-01

    Outbreaks of the destructive coral-eating crown-of-thorns starfish, Acanthaster planci, present a considerable threat to coral reefs worldwide, and mitigating their impact has proven challenging. The most effective methods to control A. planci require injecting individual starfish with lethal chemicals. While some of these are highly effective, their administration often requires permits, training and access to specialised equipment. We aimed to identify a widely available and highly efficient alternative. We discovered that common household vinegar is lethal to A. planci individuals when injected at the base of one their arms. A single injection of 25 ml vinegar induced functional mortality in coral reefs.

  17. 氧化锆全瓷与金属烤瓷冠修复牙体缺损:8个月后牙周状况随访%Zirconia all-ceramic crown and porcelain fused to metal crown for dental defects: an 8-month follow-up of periodontal conditions

    Institute of Scientific and Technical Information of China (English)

    胡芳

    2015-01-01

    BACKGROUND:Zirconia al-ceramic crown restoration has good biocompatibility and corrosion resistance, and has little irritation to the human periodontal tissue. OBJECTIVE:To compare the clinical curative effects of zirconia al-ceramic and porcelain fused to metal crowns in the repair of dental defects. METHODS: Twenty patients (120 teeth) scheduled for crown lengthening+crown repair were enroled, including 7 males and 13 females, aged 19-60 years, and then randomly divided into observation group and control group. In the observation group, zirconia al-ceramic crown was used; and in the control group, porcelain fused to metal crown was used. Periodontal conditions, coordination of gingival margin height, and crown edge concealment were compared between the two groups at 8 months after restoration. RESULTS AND CONCLUSION: At 8 months after restoration, the observation group had better periodontal conditions and crown edge concealment than the control group (P < 0.05), and the time of wearing a temporary crown and recovery time were also shorter in the observation group than the control group (P < 0.05). There was no significant difference in the gingival margin height between the two groups at 1, 3 and 8 months after restoration. These findings indicate that after crown lengthening, the zirconia al-ceramic restoration for dental defect repair has better therapeutic effects than the porcelain fused to metal restoration, which can have better marginal adaptation, improve crown edge concealment, reduce gingivitis, decrease plaque adhesion ability, and preferably maintain the periodontal health.%背景:氧化锆全瓷冠修复体具有良好的生物相容性及耐腐蚀性,并且对人体牙周组织刺激较小.目的:对比氧化锆全瓷和金属烤瓷冠两种材料修复牙体缺损的临床疗效.方法:纳入20例(120颗牙)拟行牙冠延长联合牙冠修复患者,其中男7例,女13例,年龄19-60岁,采用随机数字表法均分为观察组和对照组,观

  18. The effect of ferrule presence and type of dowel on fracture resistance of endodontically treated teeth restored with metal-ceramic crowns

    Directory of Open Access Journals (Sweden)

    Vivek Aggarwal

    2014-01-01

    Full Text Available Aim: The purpose of the present study was to comparatively evaluate the effect of presence of a 2 mm ferrule and different type of dowels on fracture resistance of mandibular premolars. Materials and Methods: Fifty uniradicular mandibular premolars were divided into five groups (n = 10. Ten teeth received no treatment (group I. Samples in group II & III were decoronated 2 mm above cemento-enamel junction and received custom cast dowel-core and fiber dowel-composite core respectively, with 2 mm ferrule. Samples in group IV & V were decoronated at CEJ and were restored using cast dowels and fiber dowel-composite cores, without any ferrule. The restored teeth received metal ceramic crowns and were mechanically loaded. The specimens were subjected to a static load, until fracture, to determine the fracture resistance and fracture mode. Results: The samples with 2 mm ferrule had a higher fracture resistance than non ferrule groups. Within non ferrule groups, there were no significant differences in the fracture resistance. Specimen restored with cast dowel had more incidence of non-repairable fracture. Conclusions: Presence of ferrule increased the fracture resistance of endodontically treated teeth. In case of absence of ferrule, fiber dowels had similar fracture resistance as that of cast dowels and showed increased incidence of repairable fracture.

  19. A 3-year prospective study of implant-supported, single-tooth restorations of all-ceramic and metal-ceramic materials in patients with tooth agenesis

    DEFF Research Database (Denmark)

    Hosseini, Mandana; Worsaae, Nils; Schiødt, Morten

    2013-01-01

    OBJECTIVES: The purpose of this clinical study was to describe outcome variables of all-ceramic and metal-ceramic implant-supported, single-tooth restorations. MATERIALS AND METHODS: A total of 59 patients (mean age: 27.9 years) with tooth agenesis and treated with 98 implant-supported single...

  20. Randomized controlled within-subject evaluation of digital and conventional workflows for the fabrication of lithium disilicate single crowns. Part II: CAD-CAM versus conventional laboratory procedures.

    Science.gov (United States)

    Sailer, Irena; Benic, Goran I; Fehmer, Vincent; Hämmerle, Christoph H F; Mühlemann, Sven

    2017-07-01

    Clinical studies are needed to evaluate the entire digital and conventional workflows in prosthetic dentistry. The purpose of the second part of this clinical study was to compare the laboratory production time for tooth-supported single crowns made with 4 different digital workflows and 1 conventional workflow and to compare these crowns clinically. For each of 10 participants, a monolithic crown was fabricated in lithium disilicate-reinforced glass ceramic (IPS e.max CAD). The computer-aided design and computer-aided manufacturing (CAD-CAM) systems were Lava C.O.S. CAD software and centralized CAM (group L), Cares CAD software and centralized CAM (group iT), Cerec Connect CAD software and lab side CAM (group CiL), and Cerec Connect CAD software with centralized CAM (group CiD). The conventional fabrication (group K) included a wax pattern of the crown and heat pressing according to the lost-wax technique (IPS e.max Press). The time for the fabrication of the casts and the crowns was recorded. Subsequently, the crowns were clinically evaluated and the corresponding treatment times were recorded. The Paired Wilcoxon test with the Bonferroni correction was applied to detect differences among treatment groups (α=.05). The total mean (±standard deviation) active working time for the dental technician was 88 ±6 minutes in group L, 74 ±12 minutes in group iT, 74 ±5 minutes in group CiL, 92 ±8 minutes in group CiD, and 148 ±11 minutes in group K. The dental technician spent significantly more working time for the conventional workflow than for the digital workflows (P.05). Irrespective of the CAD-CAM system, the overall laboratory working time for a digital workflow was significantly shorter than for the conventional workflow, since the dental technician needed less active working time. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  1. Analysis of the Application of Porcelain Veneer and All Ceramic Crown O-fanterior Teeth Restoration%前牙美容修复中烤瓷贴面和全瓷冠的应用分析

    Institute of Scientific and Technical Information of China (English)

    何迎; 曲义

    2015-01-01

    Objective To analyze the effect of porcelain veneer and all ceramic crown restoration of anterior teeth in, provide the basis for clinical application. Methods 142 (352 teeth) patients in department of stomatology of our hospital from February 2008 to 2013 ,who needed for front teeth cosmetic, were divided into porcelain veneer group 66 cases (126 teeth) and all ceramic crown group of 76 cases (226 teeth) in accordance with different methods . All refractory the production technology were used in the re-pair of all ceramic crowns using. Application effect of the two groups was compared between the two groups. Results After treat-ment of patients with subjective satisfaction were 100%, of porcelain veneer patients subjective satisfaction was 90.6%, of porce-lain veneer group subjective satisfaction was 96.1%, there are no statistical differences between the two groups, P>0.05, followed up for one year, porcelain veneer group patients 9 teeth appear collapse, 5 teeth fall off, the intact rate was 88.9%, all ceramic crown group of patients with 0 teeth appear collapse, 0 teeth fall off, the intact rate was 100%, all ceramic crown group of intact rate was significantly higher than the control group, P0.05,随访一年,烤瓷贴面组患者9颗牙齿出现崩折,5颗牙齿出现脱落,完好率为88.9豫,全瓷冠组患者0颗牙齿出现崩折,0颗牙齿出现脱落,完好率为100豫,全瓷冠组完好率明显高于对照组,P<0.05。结论烤瓷贴面与全瓷冠在前牙美容修复中均有很好的美容效果,全瓷冠远期效果更加,在使用中可以根据患者的情况选择应用。

  2. 前牙龈下残根改良牙冠延长术后纤维桩联合全瓷冠修复的临床疗效评估%Evaluation of the clinical ef ect of fiber post combined with al ceramic crown after modified crown lengthening on subgingival residual root

    Institute of Scientific and Technical Information of China (English)

    陈燕芳; 班建东; 李军科; 孙红蕾; 梁建华; 吴晓宇

    2015-01-01

    目的:评价前牙龈下残根改良牙冠延长术后纤维桩联合全瓷冠修复的应用效果。方法:选择24例33颗上前牙因外伤、重度龋坏等造成只剩龈下残根的患者,行完善的根管治疗后,采用改良牙冠延长术延长临床牙冠长度后再应用纤维桩系统进行桩核及全瓷冠修复。通过临床检查和 x 线检查,评估纤维桩联合全瓷冠修复的临床应用效果。结果:随访12个月,24例患者的基牙无松动,未发生根折,纤维桩树脂核桩冠完好,无松动,无脱落,牙龈组织健康,牙槽骨无吸收,骨硬板连续一致。结论:对于因外伤、重度龋坏等造成只剩龈下残根的病例,采用改良牙冠延长术后纤维桩核联合全瓷冠进行桩冠修复有较好的治疗效果。%Objective:To evaluate the clinical ef ect of fiber post combined with al ceramic crown in the subgingival residual root of anterior teeth after modified crown lengthening sur-gery.Methods:24 patients whose maxil ary anterior teeth were fractured under gingiva because of trauma or odontonecrosis were repaired.After completely root canal therapy,the teeth were treated by modified crown lengthening surgery to increase the height of crown.Then,the teeth were treated with fiber post system and al ceramic crown.Periodontal condition,radiographic signs and pros-thodontic results were recorded.Results:According to the 12 months’clinical observation,the restoration was stable,the posts and roots had no movement or fracture,and the periodontal tissue was healthy.Conclusion:The fiber post system combined with al ceramic crown after modified crown lengthening are ef ective to treat the subgingival residual roots .

  3. The study of cyclic fatigue and lifetime for all-ceramic crown after cementation%前牙全瓷冠的循环疲劳特性及寿命分析

    Institute of Scientific and Technical Information of China (English)

    辛海涛; 郭伟国; 李玉龙

    2009-01-01

    Objective To study mechanical and cyclic fatigue behavior of IPS Empress2 under cyclic loading, and to establish guidelines for the use and design of all-ceramic crowns. Methods A 3-D finit element method model of tooth and crown were established. The strength and lifetime of all-ceramic crowns under cyclic loading in centric occlusion were investigated using computational techniques of the Abaqus and MSC Fatigue software. Results Most of the fatigue and fracture of all-ceramic crown occurred within the veneering material at cervical marginal of the crown. The number of loading cycles before failure occurred varied within specified limits 2 506 109-6 950 243. The lifetime of the crown decreased significantly as loading increased and decreased gradually as loading time increased as well. Conclusions The mechanical and fatigue behavior of ceramic materials and restorations need to be improved before clinical use in order to guarantee clinical long-term success of all-ceramic crown. The occlusal force should be adjusted properly in order to increase the longevity of all-ceramic crowns.%目的 分析全瓷冠(IPS Empres2)循环疲劳特性及寿命,为全瓷冠的临床设计、制作以及使用寿命的评估提供依据.方法 建立上中切牙及其全瓷冠的有限元模型,模拟牙尖交错(牙合)时前牙正常骀关系,在90~130 N静态载荷加载下,分析全瓷冠受力状况.根据有限元获得的应力、应变结果,使用MSC Fatigue疲劳分析软件在90~130 N循环载荷下研究全瓷冠的循环疲劳特性及寿命.结果全瓷冠唇舌侧颈部肩台为疲劳寿命最短的区域,可承受的疲劳循环次数为2 506 109~6 950 243次.前牙承担的载荷逐渐增加时,全瓷冠疲劳寿命明显降低.前牙咬合接触时间增加时,全瓷冠疲劳寿命也逐渐降低.结论全瓷冠修复对全瓷材料循环疲劳性能有较高的要求,(牙合)力对全瓷冠疲劳寿命的影响大于咬合接触时间的影响,临床应

  4. Luminescence and scintillation properties of YAG:Ce single crystal and optical ceramics

    CERN Document Server

    Mihóková, E; Mareš, J A; Beitlerová, A; Vedda, A; Nejezchleb, K; Blažek, K; D’Ambrosio, C

    2007-01-01

    We use various techniques to study optical and scintillation properties of Ce-doped yttrium aluminum garnet, Y3Al5O12 (YAG:Ce), in the form of a high-quality industrial single crystal. This was compared to optical ceramics prepared from YAG:Ce nanopowders. We present experimental data in the areas of optical absorption, radioluminescence, scintillation decay, photoelectron yield, thermally stimulated luminescence and radiation-induced absorption. The results point to an interesting feature—the absence of antisite (YAl, i.e. Y at the Al site) defects in optical ceramics. The scintillation decay of the ceramics is faster than that of the single crystal, but its photoelectron yield (measured with 1 μs integration time) is about 30–40% lower. Apart from the photoelectron yield value the YAG:Ce optical ceramic is fully comparable to a high quality industrial YAG:Ce single crystal and can become a competitive scintillator material.

  5. Impression Techniques Used for Single-Unit Crowns: Findings from the National Dental Practice-Based Research Network.

    Science.gov (United States)

    McCracken, Michael S; Louis, David R; Litaker, Mark S; Minyé, Helena M; Oates, Thomas; Gordan, Valeria V; Marshall, Don G; Meyerowitz, Cyril; Gilbert, Gregg H

    2017-01-11

    To: (1) determine which impression and gingival displacement techniques practitioners use for single-unit crowns on natural teeth; and (2) test whether certain dentist and practice characteristics are significantly associated with the use of these techniques. Dentists participating in the National Dental Practice-Based Research Network were eligible for this survey study. The study used a questionnaire developed by clinicians, statisticians, laboratory technicians, and survey experts. The questionnaire was pretested via cognitive interviewing with a regionally diverse group of practitioners. The survey included questions regarding gingival displacement and impression techniques. Survey responses were compared by dentist and practice characteristics using ANOVA. The response rate was 1777 of 2132 eligible dentists (83%). Regarding gingival displacement, most clinicians reported using either a single cord (35%) or dual cord (35%) technique. About 16% of respondents preferred an injectable retraction technique. For making impressions, the most frequently used techniques and materials are: poly(vinyl siloxane), 77%; polyether, 12%; optical/digital, 9%. A dental auxiliary or assistant made the final impression 2% of the time. Regarding dual-arch impression trays, 23% of practitioners report they typically use a metal frame tray, 60% use a plastic frame, and 16% do not use a dual-arch tray. Clinicians using optical impression techniques were more likely to be private practice owners or associates. This study documents current techniques for gingival displacement and making impressions for crowns. Certain dentist and practice characteristics are significantly associated with these techniques. © 2017 by the American College of Prosthodontists.

  6. Clinical research of long-term aesthetic results of the anterior region of zirconia all-ceramic crown%氧化锆全瓷冠在前牙美学修复中的临床应用研究

    Institute of Scientific and Technical Information of China (English)

    王红梅; 杨永进; 蔡兴伟; 郭军; 吕晓宁

    2012-01-01

    目的:探讨氧化锆全瓷冠在前牙美学修复中的应用效果和美学效果的稳定性及其相关影响因素.方法:应用CAD/CAM技术,对20例前牙要求美学修复的患者,共44颗前牙进行氧化锆全瓷冠修复,修复后定期随访2年,通过观察患者对全瓷冠颜色的满意程度,全瓷冠颜色的口内适应情况,颜色的改变情况及牙龈组织的健康状况等,来综合评价氧化锆全瓷冠在前牙美学修复中的应用效果.结果:氧化锆的比色效果在口内的适应性较好,自然美观;两年内患者对其美学效果的评价一致,满意程度高;两年随访观察中只有2例吸烟的男性患者发生颜色改变,其余患者颜色均未发生明显改变,牙龈健康状况良好.结论:氧化锆全瓷冠的前牙美学修复效果良好且稳定,患者满意,具有广阔的应用前景.%Objective To study the repair effect, stability of aesthetic effect and its related factors of zirconia all-ceramic crowns in the anterior dental esthetics restoration. Methods 20 patients who with requirements of anterior teeth aesthetics restoration, a total of 44 anterior teeth of zirconia all-ceramic crown restoration using the CAD/CAM tecnolory, and regular follow-up of 2 years after repair. Then compare the patients' satisfactions on all-ceramic crown color, all-ceramic crown color intraoral adaptation, color changes and the gum tissue health to evaluate the application effect of zirconia all-ceramic crowns in the anterior dental esthetics repair comprehensively. Results The colorimetric effect of zirconia is natural appearance in the mouth; all the patients show high levels of satisfaction during two years follow-up observation on the aesthetic evaluation of the effect of consistent.Only two smoking male patients with color change and the remaining patients had no obvious color change.and the gingival health is good. Conclusion The repair effect of zirconia all-ceramic crown of anterior dental esthetics is

  7. Technical Progress Report on Single Pass Flow Through Tests of Ceramic Waste Forms for Plutonium Immobilization

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, P; Roberts, S; Bourcier, W

    2000-12-01

    This report updates work on measurements of the dissolution rates of single-phase and multi-phase ceramic waste forms in flow-through reactors at Lawrence Livermore National Laboratory. Previous results were reported in Bourcier (1999). Two types of tests are in progress: (1) tests of baseline pyrochlore-based multiphase ceramics; and (2) tests of single-phase pyrochlore, zirconolite, and brannerite (the three phases that will contain most of the actinides). Tests of the multi-phase material are all being run at 25 C. The single-phase tests are being run at 25, 50, and 75 C. All tests are being performed at ambient pressure. The as-made bulk compositions of the ceramics are given in Table 1. The single pass flow-through test procedure [Knauss, 1986 No.140] allows the powdered ceramic to react with pH buffer solutions traveling upward vertically through the powder. Gentle rocking during the course of the experiment keeps the powder suspended and avoids clumping, and allows the system to behave as a continuously stirred reactor. For each test, a cell is loaded with approximately one gram of the appropriate size fraction of powdered ceramic and reacted with a buffer solution of the desired pH. The buffer solution compositions are given in Table 2. All the ceramics tested were cold pressed and sintered at 1350 C in air, except brannerite, which was sintered at 1350 C in a CO/CO{sub 2} gas mixture. They were then crushed, sieved, rinsed repeatedly in alcohol and distilled water, and the desired particle size fraction collected for the single pass flow-through tests (SPFT). The surface area of the ceramics measured by BET ranged from 0.1-0.35 m{sup 2}/g. The measured surface area values, average particle size, and sample weights for each ceramic test are given in the Appendices.

  8. 实验玻璃陶瓷冠边缘和内部适合性的研究%An in vitro study on the marginal and internal fit of crowns made with an experimental lithium disilicate glass-ceramic.

    Institute of Scientific and Technical Information of China (English)

    时嘉; 高婧; 王富; 邓再喜; 陈吉华; 李玲

    2013-01-01

    Objective: To evaluate the marginal and internal fit of Experimental lithium disilicate glass-ceramic (EL-DC) crowns and compare them with IPS e.max lithium disilicate pressable crowns. Method: Eight crowns were produced from each framework ceramic (ELDC and IPS e.max) according to the manufacturer's instructions. Each crown was seated on the orginal model and scanned using Micro-CT. Files and processed using software. The data were calculated and statistically analyzed using one-way ANOVA (a=0.05). Result: ELDC crowns showed clinically acceptable marginal and internal fit. The ANOVA revealed no significant difference in marginal and internal fit compared with IPS e.max crowns. Conclusion: With the limits of this vitro study, it could be concluded that the marginal and internal fit of ELDC crowns was clinically acceptable.%目的:对实验玻璃陶瓷冠的边缘和内部适合性进行研究,并与商品瓷IPS e.max比较,为临床应用提供参考.方法:分别制作实验玻璃陶瓷冠和IPS e.max冠各8个,就位于制备好的有机玻璃代型上,指压5N,维持10 min,通过Micro-CT对试件进行断层扫描和三维重建.用CT自带软件测量边缘和内部适合性,将所得数据使用SPSS 17.0软件进行单因素方差分析.结果:实验玻璃陶瓷冠能满足临床上对边缘和内部适合性的要求,与对照组IPS e.max冠无统计学差异(P >0.05).结论:实验玻璃陶瓷冠适合性良好,可以满足临床需求.

  9. Self-adhesive Luting of Partial Ceramic Crowns: Selective Enamel Etching Leads to Higher Survival after 6.5 Years In Vivo.

    Science.gov (United States)

    Baader, Katharina; Hiller, Karl-Anton; Buchalla, Wolfgang; Schmalz, Gottfried; Federlin, Marianne

    2016-01-01

    To investigate the influence of selective enamel etching on long-term clinical performance of partial ceramic crowns (PCCs) luted with a self-adhesive luting material (RXU: RelyX Unicem). At baseline, 34 patients received the intended treatment: two PCCs (Vita Mark II; Cerec 3D) for the restoration of extended lesions with multiple-cusp coverage were placed in a split-mouth design with a self-adhesive luting material, one without (RXU) and one with selective enamel etching (RXU+E). Patients were evaluated clinically (modified USPHS criteria) at baseline and up to 6.5 years (70 to 88 months). The chi-square test was used for statistical analyses (α=0.05). Clinical survival of all restorations (n=68) after 6.5 years was evaluated by Kaplan-Meier analysis. After 6.5 years, 18 patients (9 male, 9 female; median age 41, range 25 to 59 years) with 36 RXU and RXU+E restorations were available for clinical assessment (patient recall rate: 53%), with 13 RXU and 14 RXU+E PCCs placed in molars and 5 RXU and 4 RXU+E PCCs in premolars. Clinically, no statistically significant differences between the luting procedures were detected. Both RXU and RXU+E revealed significant changes over time with respect to marginal adaptation (significant deterioration) and marginal discoloration (significant increase). RXU revealed no cases of postoperative hypersensitivity and RXU+E only did so at baseline (n=5). Kaplan-Meier analysis showed a cumulative survival for RXU of 60% and for RXU+E of 82%, indicating a significantly higher survival rate for RXU+E. Clinically, RXU and RXU+E perform similarly. In PCC restorations with multiple-cusp coverage, lack of retention due to adhesive preparation, and little dentin available for adhesion caused by extensive core buildups or cavity linings, selective enamel etching is recommended.

  10. Comparative study of ceramic and single crystal Ce:GAGG scintillator

    Science.gov (United States)

    Yanagida, Takayuki; Kamada, Kei; Fujimoto, Yutaka; Yagi, Hideki; Yanagitani, Takagimi

    2013-10-01

    Recent study revealed that single crystal Ce:Gd3(Al,Ga)5O12 (Ce:GAGG) showed good scintillation response under γ-ray exposure. We discover here that ceramic Ce:GAGG scintillator exhibited better performance than the single crystal counterpart. We developed Ce 1% doped ceramic and single crystal GAGG scintillators with 1 mm thick and compared their properties. In radioluminescence spectra, they showed intense emission peaking at 530 nm due to Ce3+ 5d-4f transition. The 137Cs γ-ray induced light yields of ceramic and single crystal resulted 70 000 ph/MeV and 46 000 ph/MeV with primary decay times of 165 and 143 ns, respectively. At present, the observed light yield was the brightest in oxide scintillators.

  11. Effect of production method on surface roughness, marginal and internal fit, and retention of cobalt-chromium single crowns.

    Science.gov (United States)

    Lövgren, Nils; Roxner, Rikard; Klemendz, Susanne; Larsson, Christel

    2017-07-01

    New production methods have been developed for metal-ceramic restorations. Different production methods may show different surface roughness and fit, which may affect retention and long-term success. The purpose of this in vitro study was to examine 3 different production methods with regard to surface roughness, marginal and internal fit, and retention of cobalt-chromium alloy single-crown copings. A master abutment of a premolar mandibular tooth preparation with 4-mm height and a 0.6-mm deep 120-degree chamfer finish line with a 12-degree angle of convergence was replicated in die stone and scanned. Thirty-six cobalt-chromium alloy copings were produced using 3 different production techniques. Twelve copings were produced by laser-sintering, 12 by milling, and 12 by milled wax/lost wax. The surface microstructure of 2 copings in each group was analyzed using interferometry. The remaining 10 copings in each group were used to evaluate marginal and internal fit by using an impression material replica method, and retention was evaluated by using a uniaxial tensile force pull-off test. The copings from each test group were cemented with zinc phosphate cement onto resin abutments. Statistical analyses of differences in marginal and internal fit were performed using 1-way ANOVA and the Mann-Whitney U test. Differences in surface topography were analyzed with the Kruskal-Wallis and Mann-Whitney U tests for nonparametric data. Differences in retentive values were analyzed using the Mann-Whitney U test for nonparametric data (all α=.05). Differences in surface microstructure were seen. The laser-sintered copings showed increased surface roughness compared with milled and milled wax/lost wax copings. Differences in marginal and internal fit were noted. Laser-sintered showed significantly smaller spaces between coping and abutment than milled wax/lost wax copings (P=.003). At the margins, laser-sintered copings showed significantly smaller spaces than either the milled

  12. Observation on clinical application value of all-ceramic crown of glass ifber post and resin core for residual crown and residual root repair of anterior teeth%玻璃纤维桩树脂核全瓷冠在前牙残冠及残根修复中的临床应用价值探讨

    Institute of Scientific and Technical Information of China (English)

    李伟; 赵国廷; 徐革英

    2014-01-01

    Objective To observe the clinical application value and effect of all-ceramic crown of glass fiber post and resin core for residual crown and residual root repair of anterior teeth. Method 106 cases with residual crown and residual root of anterior teeth treated in our hospital from April 2010 to March 2012 were selected, and the patients received repair after root canal therapy. The patients were divided into two groups according to repair modes, observation group and control group. Observation group received repair of all-ceramic crown of glass ifber post and resin core, and control group received repair of cast metal post-core and baked porcelain crown. The repair effect of two groups was compared and observed. Result After following up for two years, the success rate and satisfactory degree of observation group was evidently higher than that of control group, and the expulsion rate and odontagma rate of restoration was lower than that of control group (P<0.05), which had statical signiifcance. Conclusion Applying all-ceramic crown of glass ifber post and resin core to all-ceramic crown of glass ifber post and resin core for residual crown and residual root repair of anterior teeth not only has good retention, good color and appearance maintenance, and has little stimulation on the surrounding tissues, but also can effectively reduce detachment and fracture of restoration, which evidently improves the success rate of repair and satisfactory degree of patients, which has ideal clinical application value.%目的:探讨在前牙残冠、残根修复中使用玻璃纤维桩树脂核与全瓷冠的临床应用效果及价值。方法选取本院2010年4月至2012年3月收治的前牙残冠、残根患者106例,根管治疗后修复,并根据修复方式分为观察组与对照组,观察组患者使用玻璃纤维桩树脂核与全瓷冠修复,对照组患者使用铸造金属桩核与烤瓷冠或全瓷冠修复,对比观察两

  13. Clinical Observation on CAD/CAM Zirconia Ceramic Crowns in 50 Cases of the Implant Prosthesis%CAD/CAM氧化锆全瓷冠在50例种植修复中的临床观察

    Institute of Scientific and Technical Information of China (English)

    康振中; 唐吉飞

    2013-01-01

    目的 探讨CAD/CAM氧化锆全瓷冠在50例种植修复中的临床效果.方法 选取种植术后患者50例,共72颗缺失牙.采用CAD/CAM氧化锆全瓷冠修复,随访3a,了解患者全瓷冠完整情况和冠周情况.结果 经3a随访观察发现,50例患者72颗修复体中,2颗修复体周围有轻微炎症,治疗后痊愈.3颗后牙修复体瓷面破损,其余修复体均正常,失败率为4.2%.结论 采用CAD/CAM氧化锆全瓷冠进行种植修复可取得良好效果.%Objective To evaluate the clinical effect of CAD/CAM zirconia ceramic crowns in 50 cases of prosthesis.Method 50 cases with 72 missing teeth after planting operation were fixed with CAD/CAM allceramic crowns.There were 72 missing teeth.All patients were followed up 3 years,in which the intactness of zirconium porcelain crown and the status of gingival prosthesis were checked.Results 72 Missing teeth were fixed among 50 cases.It was found after the follow-up for 3 years that peripheral surfaces of 2 teeth were slightly inflammatory and recovered after treatment.The surfaces of 3 prostheses were damaged and the others were normal.The failure rate was 4.2%.Conclusion Adopting CAD/CAM zirconia ceramic crowns to repair implants teeth can achieve a better therapeutic effect.

  14. Comparison of adaptation of crowns of different lithium disilicate glass-ceramic%三种二硅酸锂玻璃陶瓷冠密合性的比较

    Institute of Scientific and Technical Information of China (English)

    李柯檬; 艾红军; 伊哲

    2016-01-01

    Objective To evaluate the adaptation of different lithium disilicate glass-ceramic crown and whether different fabrication processes affect the adaptation of crowns.Methods Thirty epoxy dies crowns were divided into 3 groups.They were cemented to domestic lithium disilicate glass-ceramic crowns in Group A,to IPS e.max CAD crowns in Group B and to IPS e.max Press crowns in Group C respectively.All crowns were cut by cutting machine.A confocal laser scanning microscope was used to measure the gap between crown tissue surface and die.Results There were significant differences in the three groups of measurement points(P<0.05).Within the groups,specimens in group A showed in the lowest marginal fit([46.8±9.1] μm).Those in group B showed the lowest shoulder suitability([59.3±7.9] μm),axial plane([50.5±3.6] μm) and occlusal surface([87.6± 11.6 μm].Those in group C demonstrated the lowest axial plane angle[(84.4± 10.1) μm].In addition to the axial plane angle,the CAD/CAM system exhibited good accuracy of fit.Conclusions The three groups of lithium disilicate glass-ceramic crowns appeared to have clinically acceptable fit.%目的 探讨3种二硅酸锂玻璃陶瓷冠的密合性及不同制备工艺对二硅酸锂玻璃陶瓷冠密合性的影响,以期为临床提供参考.方法 30颗下颌第一磨牙标准预备体代型均分为A、B、C3组(每组10颗),分别制作国产二硅酸锂玻璃陶瓷冠、IPS e.max CAD冠、IPS e.maxPress冠.3组全瓷冠粘接、包埋、切割后,利用激光扫描共聚焦显微镜观察冠边缘、肩台、轴面、(牙合)面、轴面角处各测量点粘接剂厚度,即修复体密合性.结果 3组各测量点粘接剂厚度总体差异均有统计学意义(P<0.05).A组边缘密合性最好[(46.8±9.1)μm];B组肩台[(59.3±7.9)μm]、轴面[(50.5±3.6)μm)]和(牙合)面[(87.6±11.6)μm]密合性最好;C组轴面角[(84.4±10.1)μm]密合性最好.除轴面角外,A、B组各测量点粘接

  15. 玻璃纤维桩与氧化锆全瓷冠修复磨牙临床分析%Clinical analysis of glass fiber piles and Zirconium all-ceramic crowns repair molar cases

    Institute of Scientific and Technical Information of China (English)

    刘红; 宋志红

    2012-01-01

    Objective To evaluate the clinical application of glass fiber post and resin core combined with zirconia all -ceramic crowns in the restoration of the molar. Methods Totally 70 teeth from 58 patients were restored by glass fiber post and resin core. All the patients were observed, examined and evaluated after 3 months to 2 years of the restoration. Results Totally 2 restoration of the residual root fell off, the failure rate is 3. 4%. One of the two was restored by glass fiber post and the other was restored by implant. Other fiber post have no fell off or broken. Zirconia all - ceramic crowns was preserved perfectly with good marginal adaption. Conclusions Molar restoration with fiber post and resin core combined with zirconia all - ceramic crowns is an ideal clinical method.%目的 探讨玻璃纤维桩树脂核联合氧化锆全瓷冠修复磨牙的临床效果.方法 玻璃纤维桩树脂核联合氧化锆全瓷冠修复磨牙58例,共70颗牙.修复完成3个月至2年,对全部病例进行随访,检查和评估.结果 2颗残根修复后纤维桩脱落,失败率为3.4%,其中1颗再次桩冠修复,一颗拔除后种植修复.其余病例氧化锆全瓷冠保持完整,边缘密合,纤维桩无脱落、折断.结论 纤维桩树脂核联合氧化锆全瓷冠修复磨牙,临床效果好,是一种较理想的修复方法.

  16. Restoration of Endodontically Treated Molars Using All Ceramic Endocrowns

    Directory of Open Access Journals (Sweden)

    Roopak Bose Carlos

    2013-01-01

    Full Text Available Clinical success of endodontically treated posterior teeth is determined by the postendodontic restoration. Several options have been proposed to restore endodontically treated teeth. Endocrowns represent a conservative and esthetic restorative alternative to full coverage crowns. The preparation consists of a circular equigingival butt-joint margin and central retention cavity into the entire pulp chamber constructing both the crown and the core as a single unit. The case reports discussed here are moderately damaged endodontically treated molars restored using all ceramic endocrowns fabricated using two different systems, namely, CAD/CAM and pressed ceramic.

  17. Marginal fit of Cercon all-ceramic CAD/CAM crowns with different finish line curvature and margin%不同颈缘弯曲度和肩台形态的泽康全瓷冠的精度

    Institute of Scientific and Technical Information of China (English)

    陶建祥; 陈建荣; 依田正信

    2009-01-01

    Objective To evaluate the marginal fit of Cercon all-ceramic CAD/CAM crowns with different finish line curvature and margin in vitro.Methods Six groups of abutments (finish line curvature: 1mm, 3mm and 5mm, margin shape: chamfer and shoulder) were prepared. Thirty all-ceramic crowns were fabricated (five for each group). The marginal gaps of copings and veneered crowns were measured respectively. The data were calculated and analyzed with two-way ANOVA and Tukey HSD test (α=0.05).Results The mean marginal gaps and their standard difference (SD) of veneered crowns for 1mm, 3mm and 5mm-curvature-chamfer were 51 and 21μm, 53 and 22μm, 54 and 20μm respectively. The mean marginal gaps and their SD of veneered crowns for 1mm, 3mm and 5mm-curvature-shoulder were 49 and 18μm, 51 and 19μm, and 50 and 22μm respectively. There was no significant difference on the marginal gaps among six groups of abutments.Conclusion The marginal gaps of Cercon all-ceramic crowns were within the range of clinically acceptable values. The abutment finish line curvature and shape had no significant influence on the marginal fit of Cercon all-ceramic crowns.%目的 调查不同颈缘弯曲度和肩台形态的泽康CAD/CAM全瓷冠的边缘精度.方法 准备6种不同形态的基牙(弯曲度:1mm,3mm,5mm;肩台外形:圆弧肩台,直角肩台).制作30个泽康CAD/CAM全瓷冠(每种肩台各5个),测定陶瓷基底冠和全瓷冠的边缘缝隙.采用双因子ANOVA分析后用T检验测定有无统计学差异.结果 弯曲度1mm,3mm,5mm圆弧肩台的泽康全瓷冠的边缘缝隙分别为51(21)μm,53(22)μm,54(20)μm.弯曲度1mm,3mm,5mm直角肩台的泽康全瓷冠的边缘缝隙分别为49(18)μm,51(19)μm,50(22)μm.统计结果显示6种基牙之间没有显著性差异.结论 泽康全瓷冠有良好的边缘精度,颈缘弯曲度和肩台形态对泽康全瓷冠的边缘精度没有显著影响.

  18. The rehabilitation of an edentulous mandible with a CAD/CAM zirconia framework and heat-pressed lithium disilicate ceramic crowns: a clinical report.

    Science.gov (United States)

    Cho, Youngwook; Raigrodski, Ariel J

    2014-06-01

    This clinical report describes a complete arch, implant-supported prosthesis with a zirconia framework and monolithic lithium disilicate crowns. The design of the computer-aided design/computer-aided manufacturing zirconia framework with cemented crowns with screw access is useful in facilitating retrievability and adequate fit, and may reduce the likelihood of porcelain chipping.

  19. 玻璃纤维桩联合氧化锆全瓷冠在残冠残根修复中的临床分析%Clinical application of glass fiber post in combination with a zirconia-ceramic crown in the restoration of residual roots and crowns

    Institute of Scientific and Technical Information of China (English)

    裘松波; 卢礼; 徐昌会; 张萍; 周燕; 张纲

    2011-01-01

    Objective To study the clinical effect of glass fiber post and resin core in combination with a zirconia-ceramic crown in the restoration of residual roots and crowns. Methods Forty-eight patients were enrolled in the study. A total of 65 teeth (26 anterior and 39 posterior with 22 abutment teeth; 18 residual roots and 47 residual crowns) were restored with glass fiber post and resin core in combination with a zirconia ceramic crown. After 6 months to 2 years, all patients were examined and the restoration effect was evaluated. Rtestults In all cases, 3 post debondings occurred after the restoration of residual roots (failure rate 4.62% ), in which 2 cases were restored after re-treatment and 1 case was withdrawn. No fracture of zirconia-ceramic crown was observed. No root or post fracture was observed clinically or on radiographs. No apical or periodontal shadow was observed on radiographs, and no secondary dental caries of tooth neck was found. Conclusion The application of glass fiber post in combination with a zirconia-ceramic crown is feasible in metal-free restora tion of residual roots and crowns.%目的 探讨玻璃纤维桩和树脂核联合氧化锆全瓷冠在残冠残根修复中的临床效果.方法 以玻璃纤维桩和树脂核联合氧化锆全瓷冠修复残冠残根病例48例,共65颗牙(前牙26颗,后牙39颗,其中作为桥基牙的有22颗;残根18颗,残冠47颗).于修复完成6个月至2年,对全部临床病例进行随访、检查和评估.结果 3颗残根修复后纤维桩脱落,失败率为4.62%,其中2颗经再治疗后有效,另1颗被放弃;其余病例氧化锆全瓷冠保持完整,纤维桩无脱落、折断;X线片示牙根和纤维桩无折断,无牙周和根尖的阴影,牙颈部无继发龋.结论 应用玻璃纤维桩树脂核联合氧化锆全瓷冠修复残冠残根,达到了无金属修复的临床要求,是一种较理想的修复方法.

  20. 桩核材料对全瓷冠半透性和颜色的影响%Influence of different posts and cores on the translucency and color of all-ceramic crown

    Institute of Scientific and Technical Information of China (English)

    李东方; 万乾炳; 杨瑛

    2011-01-01

    目的:研究不同材料桩核对全瓷冠不同部位半透性和颜色的影响.方法:制作全瓷桩核、氧化锆桩树脂核、抛光金合金桩核、抛光钯银合金桩核、钴铬合金烤瓷桩核各3 个,测量不同桩核背景下IPS-Empress2全瓷冠唇面颈1/3、中1/3和切1/3的透射率和颜色参数,计算色差(ΔE).结果:在全瓷桩核和氧化锆桩树脂核背景下,全瓷冠的颈1/3和中1/3的透射率最高;不同桩核下全瓷冠切1/3的透射率无差别.全瓷桩核背景的全瓷冠的L*值最高,抛光钯银合金桩核背景的L*值最低;在全瓷冠的颈1/3,抛光钯银合金桩核的L*、a*、b*值最低;在全瓷冠的中1/3,抛光钯银合金桩核的L*、a*值最低.结论:应用IPS-Empress 2全瓷冠修复根管治疗后的上前牙时,推荐使用全瓷桩核和氧化锆桩树脂核,可以考虑使用钴铬合金烤瓷桩核或抛光金合金桩核,不推荐使用抛光钯银合金桩核.%Objective: To study influence of different types of posts and cores on the translucency and color of all-ceramic crown.Methods: Five types of posts and cores ( Cerapost with Empress cosmo, Cerapost with composite resin, polished gold alloy, polished PaAg alloy and ceramized Co-Cr alloy)were made. Three surface zones surface( cervical, middle and incisal) of IPS-Empress 2 crowns with different posts and cores were measured for the shifts of translucency and color with a spectroradiometer (PR-650). Results: The transmittance increased obviously from cervical part to incisal part of the crowns and the transmittance of the crowns with zirconium oxide post and core was the highest. The L * values of the crowns with Cerapost and Empress cosmo were the highest while that of polished PaAg alloy were the lowest. In the cervical zone, The L * a * b * values of the crowns with polished Pa-Ag alloy post and core were the lowest. In the middle zone, the L * a * values of the crowns with polished Pa- Ag alloy post and core were the lowest

  1. [Prosthetic rehabilitation of partially edentulous patients: fixed - removable - combined? Metal - ceramics - all - ceramics? Implants? Anything goes! Part 2: two case studies represent the fixed, respectively the combined fixed-removable prosthetic restoration by utilization of implants].

    Science.gov (United States)

    Schnabl, Dagmar

    2015-01-01

    The prosthetic rehabilitation of two partially edentulous patients is presented: one Patient was restored by permanent crowns and bridges attached to natural teeth and to implants, the second was treated by crowns attached to natural teeth and removable implant- supported prostheses. Depending on esthetic requirements and the localization of preparation margins all- or metal-ceramics were used for single crowns, metal-ceramics was used for bridges. In general, a well coordinated cooperation of dentist, surgeon and dental technician in treatment planning and realization is required for a successful prosthetic rehabilitation.

  2. Did we push dental ceramics too far? A brief history of ceramic dental implants.

    Science.gov (United States)

    Haubenreich, James E; Robinson, Fonda G; West, Karen P; Frazer, Robert Q

    2005-01-01

    Humankind has developed and used ceramics throughout history. It currently has widespread industrial applications. Dental ceramics are used for fabricating highly esthetic prosthetic denture teeth, crowns, and inlays. However, ceramic's biocompatibility and compressive strength are offset by its hardness and brittleness. Nonetheless, a single crystal sapphire aluminum oxide endosseous implant was developed in 1972 as an alternative to metal. It was more esthetic than its metallic counterparts and was eventually produced in a variety of shapes and sizes. Clinical studies demonstrated its excellent soft and hard tissue biocompatibility, yet the range of problems included fractures during surgery, fractures after loading, mobility, infection, pain, bone loss, and lack of osseointegration. Ultimately, single crystal sapphire implants fell into irredeemable disfavor because of its poor impact strength, and dentists and surgeons eventually turned to other implant materials. However, bioactive ceramic coatings on metal implants have kept ceramics as a key component in dental implantology.

  3. CROWN LENGTHENING

    OpenAIRE

    2014-01-01

    2014 Latar Belakang: Penampilan jaringan gingiva disekitar gigi memegang peranan penting secara estetis. Abnormalitas dalam simetris dan kontur akan memiliki efek harmonisasi penampilan gigi-geligi. Prosedur yang dapat memberikan solusi untuk masalah estetik, periodontal dan restoratif ini adalah crown lengthening. Crown lengthening adalah prosedur bedah yang bertujuan dalam pengambilan dari jaringan periodontal untuk peningkatan panjang klinis ma...

  4. Influence of veneer application on failure behavior and reliability of lithium disilicate glass-ceramic molar crowns%饰瓷对磨牙二硅酸锂玻璃陶瓷冠疲劳失效与结构可靠性的影响

    Institute of Scientific and Technical Information of China (English)

    魏雅茹; 潘娱; 曹姗姗; 张新平; 赵克

    2013-01-01

    Objective To evaluate the influence of veneer application on failure behavior and reliability of lithium disilicate glass-ceramic (LDG) crowns of maxillary first molar,and thus to reveal the failure mechanism of bilayered LDG crowns.Methods Twenty-six LDG maxillary first molar crowns were fabricated in a dental laboratory using IPS e.max Press or IPS e.max Press/Ceram.The crowns were randomly assigned into two groups (with or without veneer application) with thirteen in each group.The crowns were cemented on composite resin dies.After storage in water for one week,the sliding-contact fatigue test was performed by sliding the steatite ceramic ball indenter (6 mm in diameter) from central fossa up to the lingual surface of disto-buccal cusp,cyclic loaded 1 200 000 times with a weight of 100 N at 2 Hz with a fatigue chewing simulator.Survived specimens were subjected to single-load-to-fracture testing using a steatite ceramic ball of 6 mm in diameter at a cross-head speed of 0.5 mm/min in a universal testing machine.Fracture load values were recorded and analyzed with t test.Weibull modulus was calculated to evaluate structure reliability.Fractographic analysis was carried out to determine fracture modes of the failed specimens by a stereomicroscope and a scanning electron microscope (SEM).Results Statistical analysis results indicated a significant difference of the fracture load values between monolithic group [(2071.23 ± 397.05) N] and bilayered group [(1483.41 ± 327.87) N] (P < 0.001).Monolithic and bilayered groups present similar Weibull modulus (95% confidence interval) as 6.15 (5.15 ~7.15) and 5.54 (4.01 ~7.08) respectively,with no significant difference (the confidence bounds overlapped with each other).Bulk fracture initiating from the middle of oblique ridge of the first maxilla molar was the primary failure mode of monolithic/bilayered LDG crowns.Crack propagation initiated from core-veneer interfacial defects was another major failure mode of

  5. 218 例残冠用金属烤瓷冠修复效果的临床评价%Evaluation on clinical effect of ceramic alloy crown on treating residual tooth in 218 patients

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Objective: To evaluate the forward clinical effect of ceramic alloy crown on treating residual tooth. Methods: After the treating residual teeth of 218 patients by ceramic alloy crown, to observed the clinical effect for two to seven years after treatment. Results: The rate of forward success was 98% in all of the 218 patients. Conclusion: It is suggest that many different factors that influence forward successful treatment to avoid failing.%目的:评价用金属烤瓷冠修复残冠的临床效果。方法:对 218 例残冠病人用金属烤瓷冠修复治疗后,经过 2~7a 的随访复查,以观察该项治疗的效果。结果:本组病例修复成功率为 98%。讨论:分析了影响修复成功的各种因素,以便进一步完善该项修复治疗。

  6. CAD/CAM锆瓷冠在后牙种植修复中的临床应用%Clinical application of CAD/CAM zirconia ceramic crowns in the implants repair of back teeth

    Institute of Scientific and Technical Information of China (English)

    郭敏; 刘林

    2012-01-01

    目的 探讨CAD/CAM锆瓷冠在后牙种植体修复中的临床应用.方法 选取种植术后患者30例,采用CAD/CAM 全瓷冠修复,随访2年,检查患者锆瓷冠完整情况及修复体情况.结果 30例患者共修复缺失牙43颗,经2年随访观察发现,1颗磨牙面瓷破损,其余修复体均正常,失败率为2.3%,修复体形态、表面质地,边缘适合性能、修复体颜色等级等修复效果满意.结论 采用CAD/CAM锆瓷冠进行后牙种植修复,种植体周围无不良刺激,咀嚼效果良好,稳定不脱落,舒适美观,患者可取得良好的修复效果.%Objective To investigate the clinical application of CAD/CAM zirconia ceramic crowns in the implants repair of back teeth. Methods 30 cases of patients after planting operation were repaired with CAD/CAM all-ceramic crowns. All patients were followed up 2 years, and the intactness of zirconium porcelain crown and the status of gingival prosthesis were checked. Results 43 missing tooth were repaired among 30 cases of patients, after 2 years of follow-up, porcelain damage of molar surface in one case was observed and the rest prosthesis were normal, the failure rate was 2.3%; repairing effect of shape, surface texture, marginal adaptation, performance and color grade were satisfactory. Conclusion Adopting CAD/CAM zirconia ceramic crowns to repair back teeth implants shows no negative stimulus around the implants, which has good chewing function and stability and is comfortable and beautiful, thus achieves good repair outcomes.

  7. Retrospective Analysis of 200 Anterior All-ceramic Crown Long-term Clinical Effects%200个前牙全瓷冠远期临床效果的回顾性分析

    Institute of Scientific and Technical Information of China (English)

    衡超; 乔梦婷

    2014-01-01

    Objective This study evaluated the long -term clinical effects of 200 feldspathic all-ceramic crown res-toration after 1 to 5 years, in order to provide clinical reference.Methods According to the United States Public Health include 8 indices, such as completeness, abrasion, color satisfaction, edge staining, marginal adaption, secondary caries, dentine hypersensitivity symptoms and gingival index (GI).We used the lifetime table to collect the statistics of the survival rate of porcelain crowns from 1 to 5 years.Results All-ceramic crowns from 1 to 5 years survival rate were 99.5%, 98.0%, 96.4%, 95.2%and 93.9%.Conclusions The long-term clinical effect of all -ceramic crowns is good.%目的:评价完成修复1~5年的200个长石质全瓷冠的远期临床效果,以期为临床效果仅为参考。方法对完成修复1~5年的200个前牙全瓷冠进行修复,参照改良美国公共健康协会( United States Public Health Society ,USPHS)评价标准对全瓷冠的修复体完整度、修复体磨耗、颜色满意度、边缘染色、边缘适合性、继发龋、牙本质敏感症状及牙龈指数(gingival index, GI)8项指标进行评估,寿命表统计烤瓷全冠1~5年存留率。结果全瓷冠1~5年存留率分别为99.5%、98.0%、96.4%、95.2%、93.9%。结论全瓷冠修复技术的远期临床效果良好。

  8. Three years in vivo wear: core-ceramic, veneers, and enamel antagonists.

    Science.gov (United States)

    Esquivel-Upshaw, Josephine F; Rose, William F; Barrett, Allyson A; Oliveira, Erica R; Yang, Mark C K; Clark, Arthur E; Anusavice, Kenneth J

    2012-06-01

    Test the hypotheses that there are equivalent wear rates for enamel-versus-enamel and ceramic-versus-enamel, analyzing the in vivo wear of crown ceramics, their natural enamel antagonists, and the corresponding two contralateral teeth; and, that bite force does not correlate with the wear. A controlled, clinical trial was conducted involving patients needing full coverage crowns opposing enamel antagonists. Bite forces were measured using a bilateral gnathodynamometer. Single-unit restorations of metal/ceramic (Argedent 62, Argen Corp/IPS d.SIGN veneer); or, core-ceramic/veneer from either, Empress2/Eris, or e.max Press core/e.max Ceram glaze (ceramics: Ivoclar Vivadent, USA) were randomly assigned, fabricated and cemented. Impressions were made of the ceramic crowns, as well as each maxillary and mandibular quadrant at one week (baseline) and one, two and three years. Resulting models were scanned (3D laser scanner). Maximum wear was calculated by superimposing baseline with annual images. There were a total of thirty-six crowns required for thirty-one patients. Each restoration had three associated enamel teeth: crown, (1) antagonist, (2) contralateral and (3) contralateral-antagonist. SAS PROC MIXED (α=0.05) indicated no statistical significance for mean maximum wear among crown ceramics, enamel antagonists and contralaterals. However, enamel wear was statistically significant in relation to intraoral location (p=0.04) and among years (p<0.02). Analyzed alone, the enamel contralateral-antagonist exhibited significantly greater wear (p<0.001). Considering all wear sites, there was no correlation with bite force (p=0.15). The ceramics and their antagonists exhibited in vivo wear rates within the range of normal enamel. Future studies should examine the wear implications of the contralateral-antagonist enamel. Copyright © 2012 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  9. 饰瓷对磨牙e.max双层全瓷冠断裂类型的影响%Influence of Veneering on Failure Behavior of e. max Bi- layered All- ceramic Molar Crowns. P

    Institute of Scientific and Technical Information of China (English)

    潘娱; Michael V Swain; 马骁; 张新平; 赵克

    2011-01-01

    目的:通过抗折破坏实验研究饰瓷对磨牙e.max双层全瓷冠断裂强度和断裂类型的影响,为减少临床双层全瓷修复体崩瓷提供实验依据.方法:制作单层全瓷冠(IPS e.max Press)和双层全瓷冠(IPS e.max Press/Ceram)共40个(每组20个),粘接于树脂代型后进行抗折破坏实验并记录断裂强度值;体视显微镜和扫描电子显微镜下观察断裂类型;能谱分析饰瓷-核瓷界面化学元素构成.结果:单层全瓷冠断裂强度值[(2665.4±759.2)N]与双层全瓷冠[(1431.1±404.3)N]间差异有统计学意义(P=0.000).饰瓷内部及饰瓷-核瓷界面缺陷催生裂纹造成饰瓷崩裂是双层全瓷冠断裂的主要模式.结论:饰瓷对磨牙e.max双层全瓷冠断裂强度和断裂类型均有影响;饰瓷内部及饰瓷-核瓷界面缺陷是全瓷冠断裂的主要原因,提高饰瓷断裂强度及减少界面缺陷可减少因崩瓷造成的修复体失败.%Objective: To evaluate the effect of veneering on fracture strength and failure mode of e. max bi-layered all-ceramic molar crowns, so as to provide an experimental basis for reducing veneer chipping and delamination in clinical situations. Methods: Forty all-ceramic molar crowns (IPSe. max Press) were fabricated in two groups (with and without veneering) and each group consists of twenty identical crowns. The crowns were seated on composite resin dies by adhesion and then the specimens were loaded to failure by using a universal mechanical testing machine under compressive load. Fractographic morphology and fracture mode of the failed specimens were observed by a stereomicroscope and a scanning electron microscope (SEM), and the compositions of the veneer-core interface were analyzed by energy dispersive spectroscopy (EDS). Result: Statistical analysis results indicated a significant difference of the mean fracture strength between mono-layered group (2665.4±759.2 N) and bi-layered group (1431.1±404.3 N, P=0.000). The bi-layered crowns

  10. IPSe.max CAD全瓷冠修复的短期临床评价%Clinical study of short-term restorative effects of IPS e. max CAD ceramic crown

    Institute of Scientific and Technical Information of China (English)

    翟家彬; 黄丽娟; 俞青

    2015-01-01

    目的:对IPS e. max CAD 全瓷冠近期修复效果进行观察和评价。方法共选取469例542颗前、后牙IPS e. max CAD 全瓷冠修复体,修复3~12个月后,按照美国加州牙科协会(CDA)制定的全瓷修复临床评定标准进行修复体评估。结果97.2%的修复体保持完整,未出现破裂、崩瓷、脱落、基牙冠折等并发症,患者满意度较高。结论 IPS e. max CAD 全瓷修复体的近期修复效果良好。%Objective To study and evaluate the short-term restorative effects of IPS e. max CAD ceramic crown. Methods 469 patients with 542 restorations were selected and the satisfactory degree of the patients was investigated. The restorative effect was evalua-ted after 3-12 months. Result The satisfactory rate of IPS e. max CAD full ceramic restorations was 97. 2%,without porcelain frac-ture,loss of crown or abutment broken. Conclusion The short-term clinical behavior of IPS e. max CAD all ceramic restorations is en-couraging.

  11. Implant-Supported Single Crowns Replacing Congenitally Missing Maxillary Lateral Incisors: A 5-Year Follow-Up.

    Science.gov (United States)

    Branzén, Marie; Eliasson, Alf; Arnrup, Kristina; Bazargani, Farhan

    2015-12-01

    Knowledge of the long-term survival of single implants in cases of congenitally missing lateral incisors in the maxilla is limited. This retrospective study aimed to evaluate the 5-year survival of implants and implant-supported crowns (ISCs) and to assess the functional and aesthetic outcomes from the professional and patient perspectives. From a total of 46 patients with congenitally missing upper lateral incisors, 36 patients treated with 54 Brånemark® (Nobel Biocare AB, Göteborg, Sweden) implants and ISCs participated in the study. A clinical examination, California Dental Association (CDA) evaluation, and patient questionnaire were used to rate and compare the objective and subjective evaluations of the ISCs. The survival of implants and ISCs was 100%. The CDA ratings were satisfactory for all ISCs, with 70% being rated excellent. The patient rating was also high for the overall satisfaction item, with 21 being completely satisfied and 14 fairly satisfied. However, 12 patients wished for the replacement of their ISCs. Logistic regression analysis indicated that a less optimal embrasure fill was the most discriminating factor though not statistically significant (p = .082). One-third of the patients wished for the replacement of their ISCs. Soft tissue adaptation seems to be an important factor for overall satisfaction. © 2014 Wiley Periodicals, Inc.

  12. Method of manufacture of single phase ceramic superconductors

    Science.gov (United States)

    Singh, Jitrenda P.; Poeppel, Roger B.; Goretta, Kenneth C.; Chen, Nan

    1995-01-01

    A ceramic superconductor is produced by close control of oxygen partial pressure during sintering of the material. The resulting microstructure of YBa.sub.2 Cu.sub.3 O.sub.x indicates that sintering kinetics are enhanced at reduced p(O.sub.2) and that because of second phase precipitates, grain growth is prevented. The density of specimens sintered at 910.degree. C. increased from 79 to 94% theoretical when p(O.sub.2) was decreased from 0.1 to 0.0001 MPa. The increase in density with decrease in p(O.sub.2) derives from enhanced sintering kinetics, due to increased defect concentration and decreased activation energy of the rate-controlling species undergoing diffusion. Sintering at 910.degree. C resulted in a fine-grain microstructure, with an average grain size of about 4 .mu.m. Post sintering annealing in a region of stability for the desired phase converts the second phases and limits grain growth. The method of pinning grain boundaries by small scale decompositive products and then annealing to convert its product to the desired phase can be used for other complex asides. Such a microstructure results in reduced microcracking, strengths as high as 230 MPa and high critical current density capacity.

  13. 瓷贴面和全瓷冠牙科材料修复前牙的效果比较%Esthetic effects of porcelain laminate veneerversus all-ceramic crown in anterior tooth restoration

    Institute of Scientific and Technical Information of China (English)

    聂廷洪; 孙迎春; 郑琳; 高平

    2015-01-01

    背景:瓷贴面和全瓷冠是现阶段较好的前牙美学修复方式。目的:比较瓷贴面和全瓷冠在前牙修复中的效果。方法:收集63例(267颗)行前牙美学修复患者的临床治疗资料,其中采用IPS e.max铸瓷贴面修复者26例(138颗),采用氧化锆全瓷冠修复者37例(129颗),修复后采用目测类比评分法评价患者满意度;由修复专业医师对修复体颜色、形态、半透明度、边缘美观效果进行美学效果评价;于修复后1,3,6,12,24个月复诊,对修复体颜色匹配、修复体完整度、边缘适合度及牙龈反应进行临床效果评价,2年后评价两种修复方式成功率。结果与结论:两组修复后均有较高的患者满意度及医师评价。随访2年内,瓷贴面组有2例出现色彩偏差、2例瓷贴面脱落、1例冠折裂、2例出现明显牙龈红肿,全瓷冠组有1例全瓷冠折裂、4例明显牙龈红肿;2年后两组修复成功率比较差异无显著性意义(P >0.05)。结果表明瓷贴面和全瓷冠均具有较好的前牙美学修复效果。%BACKGROUND:Both porcelain laminate veneer and al-ceramic crowns are good choices for aesthetic restorations of anterior teeth at present. OBJECTIVE:To compare the effects of porcelain laminate veneer and al-ceramic crown in aesthetic restorations of anterior teeth. METHODS:Totaly 267 teeth of 63 patients with esthetic defect were included in this study, among which, 138 incisors were restored with IPS e.max porcelain laminate veneer and 129 incisors were restored with zirconia al-ceramic crowns. The final appearance of each restoration was evaluated by patient’s satisfaction on visual analogue scales and the esthetic effect was evaluated by professional prosthodontists. Evaluation criteria included color, shape, translucency and margin effects. Al restorations were evaluated at 1, 3, 6, 12 and 24 months after restoration in terms of the color match, the integrity of

  14. 有限元方法模拟不同全瓷冠破坏过程初探%Analysis of the fracture processes in all-ceramic crowns by finite element analysis

    Institute of Scientific and Technical Information of China (English)

    刘亦洪; 冯海兰; 包亦望; 邱岩

    2008-01-01

    目的 用有限元方法模拟不同材料和形态的基底冠全瓷冠破坏过程,分析材料和形态对全瓷冠破坏机制的影响.方法 分别建立均匀厚度、不均匀厚度、带颈环3种基底冠形态的氧化铝和氧化锆全瓷冠模型,用BFPA'2D有限元分析软件模拟加载后全瓷冠的破坏过程.结果 6种模型均由拉应力引发破坏,裂纹始于牙尖顶的饰瓷表面,并沿基底冠与饰瓷的界面扩展.在本项研究加载条件下,仅饰瓷破坏,无基底瓷破坏,加载压强5 MPa时氧化锆模型破坏,加载6 MPa时氧化铝模型破坏.加载开始时有颈环模型呈现颈环处最小主应力集中,不均匀厚度基底冠模型呈现颈部最大主应力集中.结论 氧化锫模型的基底瓷与饰瓷界面存在更大的应力.不均匀厚度基底冠设计未增加全瓷冠破坏的风险,有颈环基底冠模型的颈部是拉应力集中的薄弱环节.%Objective To analyze the effects of core material and design on the fracture mechanism of veneered all-ceramic crowns. Methods The fracture process of 6 veneered alumina or zirconia crowns with different core design (well-distributed core, not well distributed core, and core with cervical ring) under load was analyzed by RFPA'2D finite element analysis software. Results All the six tested crowns fractured due to tension failure, and the crack started at the porcelain in the cusp and spread along the interface between core and porcelain. Under the conditions of this test, the break was only related to the porcelain and not the core, and the crack of porcelain took place earlier in zirconia crowns than in alumina crowns. Minimum stress distribution in cervical ring core design crown and maximum stress distribution in not well distributed core design crown could be seen at the neck area. Conclusions Zircania crowns presented greater stress at the interface between core and porcelain than alumina crowns. The not well distributed core design did not

  15. 3种全瓷系统冠边缘适合性的比较%A comparison of three-dimensional marginal adaptation among three all-ceramic crown systems

    Institute of Scientific and Technical Information of China (English)

    张艳; 李江; 薛小琴; 陈振宇; 李小菊

    2011-01-01

    目的:比较临床常用3种全瓷系统(Kavo Everest、IPS e.max、In-Ceram alumina)冠的边缘适合性,为临床应用提供理论依据.方法:选取1颗无龋的离体前磨牙行牙体预备,其中(牙合)面预备2mm,颈部凹槽肩台,宽度为0.8mm,(牙合)聚合度为6°.双重印模法取模,每种系统分别制作10个冠修复体.然后采用双色硅橡胶印模法复制间隙模型,应用光学显微镜采集间隙图像及使用Auto CAD2006软件对其水平边缘间隙、垂直边缘间隙和绝对边缘间隙进行测量,将所得数据使用SPSS13.0软件包进行单因素方差分析.结果:3种全瓷系统制作的上颌前磨牙冠的水平边缘间隙的平均值在41.1~44.9μm,垂直边缘间隙的平均值在51.4~71.7μm,绝对边缘间隙的平均值在66.2~85.1μm.结论:本研究中,3种全瓷系统冠的绝对边缘间隙、垂直边缘间隙和水平边缘间隙均在临床可接受范围;然而,与In-Ceram alumina系统相比,IPS e.max和Kavo Everest系统制作的全瓷冠显示出较好的边缘适合性.%PURPOSE: This study was to compare the marginal adaptation of ingle crown made of 3 different allceramic systems (IPS e.max, In-Ceram alumina, Kavo Everest) in vitro using a light-body silicone supported by a heavybody silicone material. METHODS: The crowns were made for 1 extracted maxillary premolar prepared with a 0.8-ram chamfer margin and 6-degree tapered walls by milling. Ten crowns per system were fabricated. The horizontal marginal discrepancies, vertical marginal discrepancies and absolute marginal discrepancies were measured under an optical microscope at 39.2 magnification. The data were analyzed with one-way analysis of variance (ANOVA) using SPSS 13.0 software package. RESULTS: The results showed the mean values for horizontal marginal discrepancies were between 41.1μm and 44.9μm, for vertical marginal discrepancies were between 51.4μm and 71.7μm, and for absolute marginal discrepancies were between 66.2

  16. Effect of different luting spaces on marginal fit of all-ceramic crowns%不同隙料厚度对全瓷冠适合性的影响

    Institute of Scientific and Technical Information of China (English)

    申丹凤; 王小林; 王璐; 吴恙; 徐凌

    2012-01-01

    目的 研究InLab MC XL系统不同隙料厚度对Cerec Blocs全瓷冠边缘和内部适合性的影响.方法 制备右上颌第一磨牙全冠预备体模型并翻制硅橡胶阴模,分别灌制全瓷石膏、超硬石膏预备体模型各30个.30个全瓷石膏预备体用于光学印模采集,获得30个数字化代型并完全随机分为6组分别设置不同隙料厚度值:0(A组)、10(B组)、20(C组)、30(D组)、40 μm(E组)和50 μm(F组),每组5个.30个超硬石膏预备体用于全瓷冠黏结,经包埋、剖开后,体式显微镜扫描试件剖面.结果 C、D组边缘适合性均介于30~ 120 μm,内部适合性均介于30 ~ 300 μm.C组与D组冠边缘适合性比较有统计学差异(P<0.05).C、D组冠内部适合性不均匀,(牙合)面适合性相对较大.结论 当隙料厚度为20、30 μm时,全瓷冠的边缘和内部适合性均在临床可接受范围内;30 μm的冠边缘适合性优于20 μm,但20、30 μm的冠(牙合)面适合性较差.%Objective To determine the effect of different luting spaces on marginal and internal fit of Cerec Blocs all-ceramic crowns in InLab MC XL system. Methods A right maxillary first molar in the standard model was prepared and subsequently replicated into silicone rubber negative mold. Respectively, 30 preparations of all-ceramic plaster and die stone were irrigated. Thirty all-ceramic plasters were used for optical impression, and then 30 three-dimensional digital images were obtained and randomly and equally divided into 6 groups, with their luting spaces were set to 0 (group A) , 10 (group B) , 20 (group C) , 30 (group D) , 40 (group E) and 50 um (group F) respectively by computer software. In addition, 30 die stones were prepared for bonding of the all-ceramic crowns. After being bonded, embedded and slitted, these specimens were scanned by stereo microscopy. Results The marginal fit was ranging from 30 to 120 um and the internal one from 30 to 300 um in groups C and D. There were

  17. 玻璃纤维桩和氧化锆全瓷冠在前牙美学修复中的应用%Zirconia All-ceramic Crowns And Glass Fiber Posts On Aesthetic Restoration Of Anterior Teeth

    Institute of Scientific and Technical Information of China (English)

    宋应博

    2014-01-01

    Objective:To investigate clinical effects of zirconia all-ceramic crowns and glass fiber postson on aesthetic restoration of anterior teeth. Methods:Computer Aided Design and Computer Aided Manufacture(CAD/CAM)technicals were used to make zirconia all-ceramic crowns and glass fiber posts restoration in 162 teeth in 78 patients. In the 2 years,satisfactory degree of patients was evaluated by examining oral adaptability of restoration and gingival health condition. Results:Oral adaptability was accepted by patients with high satisfactory degree. The fall of glass fiber post was found in 2 teeth and gingivitis was found in 1 tooth. The rest were all good. Conclusion:Zirconia all-ceramic crowns and glass fiber posts technical obtained wonderful effects,which was worthy of popularization in clinical practice.%目的:探讨玻璃纤维桩和氧化锆全瓷冠在前牙美学修复中的临床应用效果。方法:应用计算机辅助设计(Computer Aided Design,CAD)和计算机辅助制作(Computer Aided Manufacture,CAM)技术,对78例前牙美学修复的患者,共162颗患牙行玻璃纤维桩和氧化锆全瓷冠修复,随访2年,调查患者满意度,观察修复体在口内适应情况和牙龈的健康状况等,综合评价其应用效果。结果:玻璃纤维桩和氧化锆全瓷冠在口内的适应性良好,患者满意程度高;随访观察中有2颗玻璃纤维桩脱落,1颗牙冠边缘出现牙龈炎,其余修复体均良好。结论:玻璃纤维桩和氧化锆全瓷冠的前牙美学修复效果良好,应用前景广阔。

  18. Effects of single pulse energy on the properties of ceramic coating prepared by micro-arc oxidation on Ti alloy

    Science.gov (United States)

    Wang, Jun-Hua; Wang, Jin; Lu, Yan; Du, Mao-Hua; Han, Fu-Zhu

    2015-01-01

    The effects of single pulse energy on the properties of ceramic coating fabricated on a Ti-6Al-4V alloy via micro-arc oxidation (MAO) in aqueous solutions containing aluminate, phosphate, and some additives are investigated. The thickness, micro-hardness, surface and cross-sectional morphology, surface roughness, and compositions of the ceramic coating are studied using eddy current thickness meter, micro-hardness tester, JB-4C Precision Surface roughness meter, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Single pulse energy remarkably influences the ceramic coating properties. The accumulative time of impulse width is an important parameter in the scientific and rational measurement of the film forming law of ceramic coating. The ceramic coating thickness approximately linearly increases with the cumulative time of impulse width. Larger impulse width resulted in higher single pulse energy, film forming rates and thicker ceramic coating thickness. The sizes of oxide particles, micro-pores and micro-cracks slightly increase with impulse width and single pulse energy. The main surface conversion products generated during MAO process in aqueous solutions containing aluminate are rutile TiO2, anatase TiO2, and a large amount of Al2TiO5. The effects of single pulse energy on the micro-hardness and phase composition of ceramic coating are not as evident as those of frequency and duty cycle.

  19. Faradaic current in different mullite materials. Single crystal, ceramic and cermets

    Energy Technology Data Exchange (ETDEWEB)

    Mata-Osoro, Gustavo; Moya, Jose S.; Pecharroman, Carlos [Instituto de Ciencia de Materiales de Madrid (CSIC) (Spain); Morales, Miguel [Universidad de Santiago de Compostela (Spain). LabCaF; Diaz, L. Antonio [Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN-CSIC), Llanera (Spain); Schneider, Hartmut [Koeln Univ. (Germany). Inst. fuer Kristallographie

    2012-04-15

    Faradaic current measurements have been carried out on three different types of mullite: 2: 1 mullite single crystals (E perpendicular to c), 3: 2 ceramics and 11 % mullite/Mo composites. Measurements were carried out on very thin samples (60 {mu}m) at high voltages (500 to 1 000 V). Under these conditions, measurable currents were recorded even at room temperature. Results indicate notable differences between these three samples, which suggest that, although they share the same name and similar crystalline structure, binding energies and defect distributions seem to be very different. Finally, it has been seen that the excellent behaviour against dielectric breakdown of ceramic mullite does not hold for single crystals or mullite based cermets. (orig.)

  20. Comparison the fitness of zirconia ceramic crown sintered by microwave sintering method and conventional sintering method%微波烧结和常规烧结氧化锆全瓷冠适合性的比较

    Institute of Scientific and Technical Information of China (English)

    吴丽艳; 苏晓晖; 王磊; 韦赞军

    2014-01-01

    Objective:To study the effect of different sintering method on the marginal and internal adaptation of Cercon zirconia crowns. Method:A first premolar teeth was prepared and replicated in to ten resin castes. The units were randomly assigned to two groups and the crowns were made by CAD/CAM system. Group one was sintered by manufacturers recommend conventional second-time sintering process. Group two was sintered by microwave second-time sintering process. All crowns adhered to the corresponding dies and compare their adaption through statistical analysis. Result:Marginal fit and axial plane of zirconia ceramic crowns sintered by two methods have no significant differences (P>0.05). Shoulder suitability and occlusal surface have significant differences (P <0.05).Conclusion:Microwave sintered Cercon zirconia crowns appeared to have clinically acceptable marginal fit.%目的:研究微波烧结工艺制作的Cercon氧化锆全瓷冠适合性。方法:选取1颗完好的离体前磨牙行全瓷冠牙体预备,双重印模法取模,翻制10个相同的环氧树脂代型,将代型随机分为2组,利用CAD/CAM制作Cercon全瓷冠后,分别用微波二次烧结和常规二次烧结,将制得的全瓷冠粘接、包埋、切割后利用扫描电镜(SEM)测量冠适合性。结果:两种烧结方法制作的冠的边缘间隙和轴面间隙差异均无统计学意义(P>0.05),肩台间隙和牙合面间隙差异均有统计学意义(P<0.05)。结论:利用微波二次烧结制作的Cercon全瓷冠具有与常规烧结氧化锆相似的冠边缘适合性,在临床的接受范围内。

  1. 前牙缺损应用纤维桩联合全瓷冠修复临床效果%Tooth defect of application of fiber pile with all ceramic crown repair clinicaleffect

    Institute of Scientific and Technical Information of China (English)

    于艳

    2014-01-01

    Objective:To study the clinical application effect of the fiber pile and crown restoration of anterior teeth defect clinical analysis. Methods:From 2012 February to 2013 February in our hospital treatment of front teeth defect,90 cases with residual roots or crowns of patients(112 teeth),Give out of glass fiber post in restoration of teeth shape after the combined application of all ceramic crowns,In the 6 months after the whole treatment and 12 months for patients with tooth color change Wacom is loose,broken pile,shedding were observed and analyzed. Results:90 patients with 112 teeth with 3 crown pile shedding,occurred in 1 patients with periapical periodontitis teeth in combination therapy,All patients of 112 teeth after treatment no root,no discoloration. Conclusion:Clinical application of anterior tooth defect using the fiber pile combined with clinical crown restoration method significantly,Have favorable aesthetic effect and significant biological compatibility.%目的:研究分析前牙缺损临床采用纤维桩联合全瓷冠修复法的临床应用效果。方法:选取2012年2月至2013年2月来我院治疗的前牙缺损,残根或残冠的90例患者(112颗牙),给予进行玻璃纤维桩修复牙齿外形后联合应用全瓷冠修复,在整体治疗后的6个月及12个月对患者牙齿的色泽变化和冠桩是否出现松动、断折、脱落等情况进行观察和分析。结果:90例患者的112颗牙齿在联合治疗后有3颗冠桩脱落、1例出现牙齿跟尖周炎,全部患者112颗牙齿治疗后无断根、无变色。结论:前牙缺损临床采用纤维桩联合全瓷冠修复法的临床应用效果显著,具有良好的美学效果以及显著的生物相容特性。

  2. Self-focusing in chromium-doped potassium niobate single ceramic crystal

    Energy Technology Data Exchange (ETDEWEB)

    Castillo T, J.; Gonzalez M, S.; Aguirre L, A.; Hernandez, M.B.; Aguilar M, J.A. [Instituto de Fisica y Matematicas, Universidad Tecnologica de la Mixteca, 69000, Huajuapan de Leon, Oaxaca (Mexico); Hernandez A, J. [lFUNAM, PO Box 20-364, 01000 Mexico, DF (Mexico)]. e-mail: jaimec@mixteco.utm.mx

    2006-07-01

    The self-focusing and nonlinear optical absorption in a chromium-doped potassium niobate single ceramic crystal have been investigated. The third-order electric susceptibility X{sup (3)} at continuous 532 nm radiation is estimated based on a band transport model describing photo refractive properties for this electro-optic material. An anisotropic behavior on its nonlinear optical absorption properties has also been observed due to the presence of chromium ions. (Author)

  3. Tests for ultrasonic vibration assisted grinding of sintered zirconia ceramics crowns%超声振动辅助磨削完全烧结氧化锆陶瓷牙冠的实验研究

    Institute of Scientific and Technical Information of China (English)

    郑侃; 肖行志; 廖文和

    2014-01-01

    针对现有全锆牙在制作过程中存在二次烧结、收缩精度难以控制等问题,提出了采用超声振动辅助磨削完全烧结氧化锆陶瓷牙冠的方法。从理论分析的角度对其运动学特性进行了研究,并通过超声振动辅助磨削和普通金刚石磨削实验,对该方法的可行性进行了分析。结合牙冠的加工特点,重点研究了主轴转速对材料去除率、表面粗糙度以及最大边缘碎裂的影响规律。实验结果表明,超声振动辅助磨削不仅能提升材料的去除率,有效抑制出口边缘碎裂,同时降低了工件表面的粗糙度,是实现完全烧结氧化锆陶瓷牙冠高效低损伤加工的新方法。%Aiming at machining problems of zirconia ceramics dental prosthesis,such as,complexly processing, difficult to control shrinkage and so on,a new method using ultrasonic vibration assisted grinding presintered zirconia ceramics crowns was proposed.Firstly,its macro kinematic characteristics were investigated with theoretical analysis. Then,tests for machining presintered zirconia ceramics with ultrasonic vibration assisted grinding and diamond grinding were conducted to analyze the feasibility of the new method.Effects of spindle speed on material removal rate,surface roughness and edge chipping size were studied,combined with the machining characteristics of dental prosthesis.The test results demonstrated that the ultrasonic vibration assisted grinding not only raises the material removal rate,but also reduces the surface roughness and restrains the edge chipping effectively,therefore,the ultrasonic vibration assisted grinding is a new method with higher efficiency and lower damage for machining presintered zirconia ceramics crowns.

  4. Clinical application of ceramic restorations Ⅰ.Technique of layered ceramic crown and bridge%瓷修复技术的临床应用Ⅰ.瓷沉积冠桥修复技术

    Institute of Scientific and Technical Information of China (English)

    刘洪臣; 王燕一

    2008-01-01

    @@ 瓷沉积系统(electro layerecl ceramic system,ELC system)是一种陶瓷电泳沉积技术系统,其以氧化铝全瓷(In-Ceram alumina)、氧化锆全瓷(In-Ceram zireonia)或尖晶石全瓷(In-Ceram Spinell)为材料,用电泳沉积的方法形成渗透陶瓷内冠,在其上完成冠桥修复.

  5. Marginal microleakage of different In-ceram alumina crowns using differet cements%不同制作技术及粘接剂对氧化铝全瓷冠边缘微渗漏的影响

    Institute of Scientific and Technical Information of China (English)

    李东方; 姚心韵

    2015-01-01

    目的:评价不同制作技术及粘接剂对In-Ceram氧化铝全瓷冠边缘微渗漏的影响。方法3种技术制作氧化铝全瓷冠各15个,分别采用3种粘接剂粘固于离体牙,温度循环实验后,将样本放入质量分数为2%的亚甲蓝溶液48h,体式显微镜观察牙与粘接剂界面的微渗漏状况,记录观察结果,对实验数据进行统计分析。结果自粘结树脂型粘接剂微渗漏最小,其次是树脂加强型玻璃离子,玻璃离子微渗漏最大(P<0.05);采用树脂加强型玻璃离子和玻璃离子粘固不同全瓷冠时,粉浆涂塑氧化铝冠的微渗漏最大(P<0.05)。结论 Cerec inLab system制作的全瓷冠边缘微渗漏小。自粘结树脂型粘接剂抗边缘微渗漏能力强,是粘固In-Ceram氧化铝全瓷冠的理想粘接剂。%Objective To evaluate the marginal microleakage of different In-Ceram alumina crowns using different cements. Methods 45 extracted maxillary first premolars were prepared for a complete coverage restoration and were fabricated on the models using the following systems:Group SL,the slip-cast technique (In-Ceram system);Group CR,a CAD/CAM system (Cerec inLab system) and Group WO,the electro-deposition dipping technique (Wol-Ceram). Luted onto standard prepared teeth using different cements,after temperature cycling test,all the crowns were then immersed in 2%methylene blue dye for a period of 48h. The marginal microleakage at tooth interfaces was observed using stereomictoscopy and evaluated in classification index. The data were subjected to statistical analysis using Kruskal-Wallis U test and Mann-Whitney test. Results The difference in microleakage between three crowns using different cements was statistically significant(P<0.05). Conclusion The copings fabricated using Cerec inLab system had an observable decrease in mircoleakage. RelyXTM Unicem adhensive resin luting system which was the first se-lection in clinical was better than

  6. Thin Single Crystal Silicon Solar Cells on Ceramic Substrates: November 2009 - November 2010

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, A.; Ravi, K. V.

    2011-06-01

    In this program we have been developing a technology for fabricating thin (< 50 micrometres) single crystal silicon wafers on foreign substrates. We reverse the conventional approach of depositing or forming silicon on foreign substrates by depositing or forming thick (200 to 400 micrometres) ceramic materials on high quality single crystal silicon films ~ 50 micrometres thick. Our key innovation is the fabrication of thin, refractory, and self-adhering 'handling layers or substrates' on thin epitaxial silicon films in-situ, from powder precursors obtained from low cost raw materials. This 'handling layer' has sufficient strength for device and module processing and fabrication. Successful production of full sized (125 mm X 125 mm) silicon on ceramic wafers with 50 micrometre thick single crystal silicon has been achieved and device process flow developed for solar cell fabrication. Impurity transfer from the ceramic to the silicon during the elevated temperature consolidation process has resulted in very low minority carrier lifetimes and resulting low cell efficiencies. Detailed analysis of minority carrier lifetime, metals analysis and device characterization have been done. A full sized solar cell efficiency of 8% has been demonstrated.

  7. Fracture resistance and failure patterns of endodontically treated mandibular molars with and without glass fiber post in combination with a zirconia-ceramic crown

    NARCIS (Netherlands)

    Salameh, Z.; Ounsi, H.F.; Abou Shelib, M.N.M.; Sadig, W.; Ferrari, M.

    2008-01-01

    Objective: The aim of this study was to investigate the influence of a fiber post on the fracture mechanics of zirconia crowns inserted over endodontically treated teeth with different extent of coronal damage. Methods: Endodontically treated human molars with three types of coronal damage received

  8. Mechanisms of Class II correction induced by the crown Herbst appliance as a single-phase Class II therapy: 1 year follow-up.

    Science.gov (United States)

    Jakobsone, Gundega; Latkauskiene, Dalia; McNamara, James A

    2013-09-11

    The objective of this study is to evaluate the skeletal and dentoalveolar effects of the crown Herbst appliance used alone for a single phase of therapy followed by a 1-year observation period. Forty patients (mean age 13.6±1.3 years) with a stable Class I occlusion 1 year following the treatment with the crown Herbst appliance were selected from a prospective sample of 180 consecutively treated Class II patients. No other appliances were used during treatment or during the follow-up period. The dentoskeletal changes were compared with a matched sample of untreated Class II subjects (mean age 13.9±1.6 years). Lateral cephalograms were taken before treatment, after Herbst treatment (1 year), and after 1-year follow-up. Overcorrection was avoided intentionally. Treatment produced an increase in mandibular length, a decrease in ANB angle, and a restriction in the vertical growth of posterior maxilla. The maxillary molars moved backward and tipped distally. The lower incisors proclined markedly, and the upper incisors became retroclined. During the follow-up period, the changes primarily were dentoalveolar in nature, with marked rebound of the upper molars and lower incisors, resulting in some increases in overbite and overjet. The occlusal correction of Class II malocclusion observed 1 year after the crown Herbst appliance as a single-phase therapy was achieved primary due to the dentoalveolar changes and only limited skeletal change occurred.

  9. Effects of single pulse energy on the properties of ceramic coating prepared by micro-arc oxidation on Ti alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jun-Hua [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023 (China); Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming 650500 (China); Wang, Jin [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control, Beijing 100084 (China); Lu, Yan [School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023 (China); Du, Mao-Hua [Faculty of Mechanical and Electrical Engineering, Kunming University of Science and Technology, Kunming 650500 (China); Han, Fu-Zhu, E-mail: hanfuzhu@mail.tsinghua.edu.cn [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Beijing Key Lab of Precision/Ultra-precision Manufacturing Equipments and Control, Beijing 100084 (China)

    2015-01-01

    Highlights: • Single pulse energy remarkably influences the properties of ceramic coating prepared by MAO on Ti alloy. • The accumulative time of impulse width is an important parameter in the scientific and rational measurement of the film forming law of ceramic coating. • The ceramic coating thickness approximately linearly increases with the cumulative time of impulse width. • Larger impulse width resulted in higher single pulse energy, film forming rates and thicker ceramic coating thickness. • The effects of single pulse energy on the micro-hardness and phase composition of ceramic coating are not as evident as those of frequency and duty cycle. - Abstract: The effects of single pulse energy on the properties of ceramic coating fabricated on a Ti–6Al–4V alloy via micro-arc oxidation (MAO) in aqueous solutions containing aluminate, phosphate, and some additives are investigated. The thickness, micro-hardness, surface and cross-sectional morphology, surface roughness, and compositions of the ceramic coating are studied using eddy current thickness meter, micro-hardness tester, JB-4C Precision Surface roughness meter, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Single pulse energy remarkably influences the ceramic coating properties. The accumulative time of impulse width is an important parameter in the scientific and rational measurement of the film forming law of ceramic coating. The ceramic coating thickness approximately linearly increases with the cumulative time of impulse width. Larger impulse width resulted in higher single pulse energy, film forming rates and thicker ceramic coating thickness. The sizes of oxide particles, micro-pores and micro-cracks slightly increase with impulse width and single pulse energy. The main surface conversion products generated during MAO process in aqueous solutions containing aluminate are rutile TiO{sub 2}, anatase TiO{sub 2}, and a large amount of Al{sub 2}TiO{sub 5}. The effects of

  10. Ceramic Films via Organometallic Complex as Single Source Precursor

    Institute of Scientific and Technical Information of China (English)

    Shyu Shin-Guang; Wu Juan-Seng; Wu Chi-Chin; Chi Kal-Ming

    2004-01-01

    Fe2(CO)6(μ-S2) was used as a single source precursor in attempt to produce FeS film via MOCVD. Pyrolysis of Fe2(CO)6(μ-S2) at temperature below 500℃ produced Fe1-xS or Fe7S8 powder as indicated by its powder X-ray spectra. At 750 ℃, polycrystalline FeS powder was obtained. In film deposition, polycrystalline Fe1-xS or Fe7Ss films were obtained on Si(100) and Ag/Si(100) substrates below 500 ℃. SEM micrographs showed the film on Si(100) substrate containing whisker like grains. However, pillar like grains were obtained on Ag/Si(100) substrate.Deposition rates are also different for different substrates as evaluated by the thickness of the films, which were obtained by SEM micrographs of the cross section of the films. At 750℃, similar polycrystalline Fe1-xS or Fe7S8 film was obtained.

  11. A hybrid phenomenological model for ferroelectroelastic ceramics. Part I: Single phased materials

    Science.gov (United States)

    Stark, S.; Neumeister, P.; Balke, H.

    2016-10-01

    In this part I of a two part series, a rate-independent hybrid phenomenological constitutive model applicable for single phased polycrystalline ferroelectroelastic ceramics is presented. The term "hybrid" refers to the fact that features from macroscopic phenomenological models and micro-electromechanical phenomenological models are combined. In particular, functional forms for a switching function and the Helmholtz free energy are assumed as in many macroscopic phenomenological models; and the volume fractions of domain variants are used to describe the internal material state, which is a key feature of micro-electromechanical phenomenological models. The approach described in this paper is an attempt to combine the advantages of macroscopic and micro-electromechanical material models. Its potential is demonstrated by comparison with experimental data for barium titanate. Finally, it is shown that the model for single phased materials cannot reproduce the material behavior of morphotropic PZT ceramics based on a realistic choice for the material parameters. This serves as a motivation for part II of the series, which deals with the modeling of morphotropic PZT ceramics taking into account the micro-structural specifics of these materials.

  12. Specific-heat measurement of single metallic, carbon, and ceramic fibers at very high temperature

    Science.gov (United States)

    Pradère, C.; Goyhénèche, J. M.; Batsale, J. C.; Dilhaire, S.; Pailler, R.

    2005-06-01

    The main objective of this work is to present a method for measuring the specific heat of single metallic, carbon, and ceramic fibers at very high temperature. The difficulty of the measurement is due to the microscale of the fiber (≈10μm) and the important range of temperature (700-2700K). An experimental device, a modelization of the thermal behavior, and an analytic model have been developed. A discussion on the measurement accuracy yields a global uncertainty lower than 10%. The characterization of a tungsten filament with thermal properties identical to those of the bulk allows the validation of the device and the thermal estimation method. Finally, measurements on carbon and ceramic fibers have been done at very high temperature.

  13. Peri-implant biomechanical responses to standard, short-wide, and mini implants supporting single crowns under axial and off-axial loading (an in vitro study).

    Science.gov (United States)

    Kheiralla, Lamia Sayed; Younis, Jihan Farouk

    2014-02-01

    This study compared the biomechanical responses of 3 single crowns supported by 3 different implants under axial and off-axial loading. A standard implant (3.75 mm diameter, 13 mm length), a mini implant (3 mm diameter, 13 mm length), and a short-wide implant (5.7 mm diameter, 8 mm length) were embedded in epoxy resin by the aid of a surveyor to ensure their parallelism. Each implant supported a full metal crown made of Ni-Cr alloy with standardized dimensions. Strain gauges and finite element analysis (FEA) were used to measure the strain induced under axial and off-axial functional loads of 300 N. Results showed that mini implants recorded the highest microstrains, under both axial and off-axial loading. All implants showed a considerable increase in strain values under off-axial loading. Standard and short-wide implants proved to be preferable in supporting crowns, as the standard implant showed the lowest strains under axial and off-axial loading using FEA simulation, while the short-wide implant showed the lowest strains under nonaxial loading using strain gauge analysis.

  14. Thermal/mechanical simulation and laboratory fatigue testing of an alternative yttria tetragonal zirconia polycrystal core-veneer all-ceramic layered crown design.

    Science.gov (United States)

    Bonfante, Estevam A; Rafferty, Brian; Zavanelli, Ricardo A; Silva, Nelson R F A; Rekow, Elizabeth D; Thompson, Van P; Coelho, Paulo G

    2010-04-01

    This study evaluated the stress levels at the core layer and the veneer layer of zirconia crowns (comprising an alternative core design vs. a standard core design) under mechanical/thermal simulation, and subjected simulated models to laboratory mouth-motion fatigue. The dimensions of a mandibular first molar were imported into computer-aided design (CAD) software and a tooth preparation was modeled. A crown was designed using the space between the original tooth and the prepared tooth. The alternative core presented an additional lingual shoulder that lowered the veneer bulk of the cusps. Finite element analyses evaluated the residual maximum principal stresses fields at the core and veneer of both designs under loading and when cooled from 900 degrees C to 25 degrees C. Crowns were fabricated and mouth-motion fatigued, generating master Weibull curves and reliability data. Thermal modeling showed low residual stress fields throughout the bulk of the cusps for both groups. Mechanical simulation depicted a shift in stress levels to the core of the alternative design compared with the standard design. Significantly higher reliability was found for the alternative core. Regardless of the alternative configuration, thermal and mechanical computer simulations showed stress in the alternative core design comparable and higher to that of the standard configuration, respectively. Such a mechanical scenario probably led to the higher reliability of the alternative design under fatigue.

  15. 齿科常见修复材料微观结构与氧化锆磨损量之间的关系%The Wear of Different Dental Crown Restorative Materials Opposed to Zirconia Ceramic

    Institute of Scientific and Technical Information of China (English)

    刘晶莹; 郭长军; 刘晓明

    2012-01-01

    [Objective]The purpose of this study was to evaluate the effects of microstructure to the wear of different kinds of restorative crown materials used in clinical and zirconia ceramic. [Methods] Specimens were evaluated at a xSO and x500 magnification by a scanning electron microscope. The weight loss of opposing zirconia ceramic was measured to compare the wear properties. [Results] The results of scanning electron micrograph (SEM) of different materials were different. The weight loss of zirconia ceramic caused by four materials from small to large were gold alloy, nanoceramic, hydrothermal low-fusing ceramic, and D.SIGN (P<0.05). [Conclusion] The microstructure of the restorative material is one of the important factors that influences the zirconia ceramic wear properties.%[目的]通过体外实验,探讨齿科不同牙冠修复材料微观结构与氧化锆磨损量的关系.[方法]采用针-盘式二体磨耗机,以氧化锆为对磨物,电镜观察义获嘉陶瓷、低温水热陶瓷、纳米陶瓷和金钯合金4种牙科常用冠修复材料磨耗面的微观结构,以及称量测定氧化锆的质量损失.[结果]电镜下金钯合金磨耗面呈均质状结构,低温水热陶瓷磨耗后气孔少见,形状规则,无大的裂纹存在,纳米陶瓷磨耗后可见细小裂隙,偶见小气孔,形状规则,义获嘉陶磨耗面粗糙,可见磨损凹陷沟窝及细裂纹,形状不规则.氧化锆与各种材料对磨后质量损失由大到小分别为义获嘉陶瓷组、低温水热陶瓷组、纳米陶瓷组、金钯合金组,且各组间均有显著差异(P<0.05).[结论]修复材料的微观结构是影响氧化锆耐磨性能的重要因素之一.

  16. Modelling of the measured longitudinal piezoelectric coefficient of single ceramic fibres with annular electrodes

    Science.gov (United States)

    Pientschke, Christoph; Steinhausen, Ralf; Kern, Sabine; Beige, Horst

    2011-05-01

    A method for the measurement of the longitudinal piezoelectric coefficient d33 of single ceramic fibres with diameters 100-500 µm was recently developed. The voltage was applied using annular electrodes and the resulting displacement was measured by a capacitive method. In this paper, a number of calculations regarding the field distribution and the resulting piezoelectric displacement are presented for a typical lead zirconate titanate (PZT) ceramic. Provided that the fibres are ideally poled in the longitudinal direction, they can be modelled using the finite element method taking into account linear constitutive equations. The deviation of the measured and the actual d33 was modelled for a broad range of heights and diameters of the fibres and different electrode dimensions. The electric field distribution was analysed for typical examples and the influence of the mechanical stress on the measured d33 was studied. For sufficiently long and thin fibres the field distribution of the electric field is quite uniform and the d33 can be measured with high accuracy. Moreover, it was shown that for such fibres the measured piezoelectric coefficient d33 is determined by no other material parameter of the ceramics. The found trends of preferable geometries for the measurement can apparently be transferred to other piezoceramics.

  17. FEM evaluation of cemented-retained versus screw-retained dental implant single-tooth crown prosthesis.

    Science.gov (United States)

    Cicciu, Marco; Bramanti, Ennio; Matacena, Giada; Guglielmino, Eugenio; Risitano, Giacomo

    2014-01-01

    Prosthetic rehabilitation of partial or total edentulous patients is today a challenge for clinicians and dental practitioners. The application of dental implants in order to recover areas of missing teeth is going to be a predictable technique, however some important points about the implant angulation, the stress distribution over the bone tissue and prosthetic components should be well investigated for having final long term clinical results. Two different system of the prosthesis fixation are commonly used. The screw retained crown and the cemented retained one. All of the two restoration techniques give to the clinicians several advantages and some disadvantages. Aim of this work is to evaluate all the mechanical features of each system, through engineering systems of investigations like FEM and Von Mises analyses. The FEM is today a useful tool for the prediction of stress effect upon material and biomaterial under load or strengths. Specifically three different area has been evaluated through this study: the dental crown with the bone interface; the passant screw connection area; the occlusal surface of the two different type of crown. The elastic features of the materials used in the study have been taken from recent literature data. Results revealed an adequate response for both type of prostheses, although cemented retained one showed better results over the occlusal area.

  18. FEM evaluation of cemented-retained versus screw-retained dental implant single-tooth crown prosthesis

    Science.gov (United States)

    Cicciu, Marco; Bramanti, Ennio; Matacena, Giada; Guglielmino, Eugenio; Risitano, Giacomo

    2014-01-01

    Prosthetic rehabilitation of partial or total edentulous patients is today a challenge for clinicians and dental practitioners. The application of dental implants in order to recover areas of missing teeth is going to be a predictable technique, however some important points about the implant angulation, the stress distribution over the bone tissue and prosthetic components should be well investigated for having final long term clinical results. Two different system of the prosthesis fixation are commonly used. The screw retained crown and the cemented retained one. All of the two restoration techniques give to the clinicians several advantages and some disadvantages. Aim of this work is to evaluate all the mechanical features of each system, through engineering systems of investigations like FEM and Von Mises analyses. The FEM is today a useful tool for the prediction of stress effect upon material and biomaterial under load or strengths. Specifically three different area has been evaluated through this study: the dental crown with the bone interface; the passant screw connection area; the occlusal surface of the two different type of crown. The elastic features of the materials used in the study have been taken from recent literature data. Results revealed an adequate response for both type of prostheses, although cemented retained one showed better results over the occlusal area. PMID:24955150

  19. 氧化锆全瓷冠修复单个后牙的临床观察%Clinical evaluation of zirconia crowns for single posterior teeth

    Institute of Scientific and Technical Information of China (English)

    陈渊华; 孟翔峰; 俞青

    2014-01-01

    目的:观察CERECinLab计算机辅助设计和制造(CAD/CAM)的氧化锆全瓷冠修复复杂后牙的临床效果。方法对于242名需行单个后牙冠修复的患者,采用CERECinLabCAD/CAM设计制作二氧化锆全瓷修复体,共242件。分别在粘接完成时、6个月、12个月、24个月和36个月进行临床观察,采用改良的美国公共卫生署标准评估。结果采用χ2检验分析。结果观察期间有5名患者失访,对于剩余修复体观察发现,随着时间推移,修复体的成功率下降,在36个月时A级成功率在85%以上。结论CERECinLab制作的单个后牙的二氧化锆全瓷修复体,短期成功率良好。%Objective To observe and evaluate the clinical performance of zirconia crowns made by CEREC inLab com-puter aided design/computer aided manufacturing(CAD/CAM) for posterior teeth. Methods A total of 242 patients were implanted with zirconia crowns fabricated by CEREC inLab CAD/CAM. The crowns were evaluated by Modified US Public Health Service criteria at baseline, 6, 12, 24, and 36 months. The chi-square test was used to analyze the survival rate. Results All but five crowns were evaluated by an independent evaluator at baseline, 6, 12, 24, and 36 months. The survival rate de-clined with time. The A score percentage was above 85% at 36 months. Conclusion The single zirconia crowns fabricated by CEREC inLab CAD/CAM demonstrate satisfactory clinical performance during a short period.

  20. Efficacy and Long-term Prognosis of Zirconia All-ceramic Crown Plus Fiber Post for Repair of Ante-rior Teeth Complex Crown Root Fracture%氧化锆全瓷冠加纤维桩修复前牙复杂冠根折的疗效及远期预后分析

    Institute of Scientific and Technical Information of China (English)

    周凌燕; 毛艳; 苏宗佑; 陈俊文; 罗家威; 吕夏

    2016-01-01

    Objective To analyze the efficacy and long-term prognosis zirconia all-ceramic crown plus fiber post to repair anterior teeth complex crown root fracture.Methods From Feb.2008 to Jan.2010 in Affiliated Stomatology Hospital of Guangxi Medical University 110 patients for treatment of anterior teeth crown root fracture were included as research objects,and were divided into observation group and control group according to random number table method,55 cases each.The observation group adopted zirconia all-ceramic crown plus fiber post restoration treatment,an the control group adopted conventional orthodontic traction plus crown lengthening surgery for treatment.The tooth mobility,periodontal probing depth,gingival sulcus bleeding index of the two groups before and after treatment were compared,and 5 years of follow-up was done to compare the long-term prognosis.Results After treatment the tooth mobility,the sulcus bleeding index of the observation group were significantly lower than the control group [ ( 0.19 ±0.04 ) vs ( 0.40 ± 0.11),(0.78 ±0.16) vs (2.01 ±0.27),P <0.01],probing depth of the observation group was signifi-cantly higher than the control group[(5.99 ±0.14) mm vs (3.97 ±0.10) mm,P<0.01],the difference was statistically significant ( P <0.05 );the repair success rate of the observation group was significantly higher than the control group [92.73% (51/55) vs 54.55% (30/55)],the difference was statistically sig-nificant ( P <0.05 ) .Root fracture, secondary caries and periodontal disease incidence of the observation group were significantly lower than the control group [1.82%(1/55) vs 14.55%(8/55),1.82%(1/55) vs 9.09%(7/55),3.64%(2/55) vs 18.18%(10/55)],the differences were statistically significant(P<0.05).Conclusion Zirconia all-ceramic crowns plus fiber post has good clinical efficacy for anterior teeth complex crown root fracture,which can promote tooth mobility,probing depth,and improve sulcus bleeding index,with good long-term prognosis,thus is

  1. Clinical evaluation of selective double gingival retraction technique for anterior all-ceramic crown prosthesis%选择性双线排龈技术在前牙全瓷冠修复中的应用研究

    Institute of Scientific and Technical Information of China (English)

    刘思言; 牟雁东

    2016-01-01

    目的:评价选择性双线排龈技术在前牙全瓷冠修复中的临床应用效果。方法选择126例门诊患者258颗前牙行全瓷冠修复,简单随机法分为两组各63例,试验组130颗基牙采用选择性双线排龈技术排龈,对照组128颗采用单线排龈技术排龈,评价牙龈止血效果满意率、预备体边缘和肩台暴露、游离龈与牙面分离满意率。结果选择性双线排龈技术的牙龈止血效果满意率、预备体边缘和肩台暴露、游离龈与牙面分离满意率分别为96.92%、96.15%及95.38%,明显高于单线排龈技术的83.59%、82.03%及81.25%。差异有统计学意义( P<0.05)。结论在前牙全瓷冠修复中,选择性双线排龈技术有很好的临床应用效果。%Objective To evaluate the clinical application effect of selective double gingival retraction technique for anterior all-ceramic crown prosthesis .Methods Two hundred and fifty-eight anterior all-ceramic crowns from 126 patients were randomly divid-ed into experimental or control groups ,63 cases in each group.Selective gingival retraction technique was used in the experimental group (130 teeth) while singlet gingival retraction technique was used in the control group (128 teeth).The effect on satisfaction rates of gingival hemostasis ,prepared teeth margins and shoulder exposure ,and satisfaction rates of separation of free gingiva and tooth sur-face were evaluated .Results The rates of satisfaction of gingival hemostasis ,prepared teeth margins and shoulder exposure and separa-tion of free gingiva and tooth surface in the selective double gingival retraction group were 96.92%,96.15%and 95.38%,respective-ly,that were significantly higher than that with singlet gingival retraction technique (83.59%,82.03%and 81.25%,respectively) (P<0.05 ) .Conclusion Selective double gingival retraction technique is an effective method for anterior all -ceramic crown prosthesis .

  2. The durability of single, dual, and multiphase titanate ceramic waste forms for nuclear waste immobilization

    Science.gov (United States)

    Harkins, Devin J. H.

    A significant amount of the energy used in the United States comes from nuclear power, which produces a large amount of waste materials. Recycling nuclear waste is possible, but requires a way to permanently fix the unusable radionuclides remaining from the recycling process in a stable, leach resistant structure. Multiphase titanate ceramic waste forms are one promising option under consideration. However, there is insufficient work on the long term corrosion of the individual phases, as well as the multiphase systems of these ceramics. These multiphase titanate ceramic waste forms have three targeted phases: hollandite, pyrochlore, and zirconolite. Hollandite is a promising candidate for the incorporation of Cs, while pyrochlore is readily formed with lanthanides, such as Nd, the most prevalent lanthanide in the waste stream. The third targeted phase, zirconolite, is for the incorporation of zirconium and the actinides. This work looks into the formation of single phase systems of lanthanide titanates, formation of dual phase systems of Ga doped Ba hollandites and Nd titanate, durability of single phase hollandites and multiphase model systems using Vapor Hydration Testing (ASTM C 1663-09), dissolution of dual phase systems of Ga doped Ba hollandites and Nd titanate using Product Consistency Testing (ASTM C 1285-02), as well investigating how grain size affects amount of alterative phases formed using Vapor Hydration Testing. The dual phase systems of hollandites and Nd titanate show significant amounts of secondary phases forming, heavily influenced by the composition of hollandite used in the systems. The most significant phase present was BaNd2Ti5O14. This phase proves to be problematic due to the degradation to the hollandite structure. Using Vapor Hydration Testing to investigate single and multiphase systems presented many some possible alteration phases that could occur in the long term aging of these ceramics. Most notably, Cs rich phases were found in

  3. Clinical evaluation of the fiber post and direct composite resin restoration for fixed single crowns on endodontically treated teeth

    Science.gov (United States)

    Murali Mohan, S.; Mahesh Gowda, E.; Shashidhar, M.P.

    2015-01-01

    Background The restoration of an endodontically treated fractured tooth has been a challenge for restorative dentists for decades. The performance of fiber posts when used in conjunction with direct composite resin restorations have been largely unreported. This study was conducted with the aim of evaluating the survival rate of endodontically treated teeth restored with adhesive bonded fiber reinforced resin posts and direct composite core with additional crown coverage. Methods Sixty patients who required endodontic treatment with post core crown were selected from outpatient department of Air Force Institute of Dental Sciences, Bangalore. Sixty-four teeth were endodontically treated and restored with fiber post and direct resin composite core restoration. Patients were evaluated immediately after restoration and reevaluated at the end of first, second and third months. After 3 months of clinical evaluation, if teeth were asymptomatic they were restored with complete coverage porcelain fused to metal restorations and evaluated immediately, and again reevaluated at the end of first, third, and sixth months. Results After 3 months of clinical evaluation, only two teeth exhibited periapical lesion with clinical symptoms and three teeth without any clinical symptoms. Five teeth exhibited slight marginal staining, three teeth showed partial loss of restoration, and two teeth exhibited complete loss of restoration with the fracture of the post. At the end of sixth month after restoration with full coverage crown, two teeth had dislodged restoration due to fracture of post and two teeth exhibited displacement of the post. Conclusion Fiber posts are the best alternative for restoration of fractured endodontically treated teeth. Fiber posts and direct composite resin core materials are strongly recommended for restoration of endodontically treated mutilated teeth among the dental establishments of Armed Forces. PMID:26288494

  4. A feasible, aesthetic quality evaluation of implant-supported single crowns: an analysis of validity and reliability

    DEFF Research Database (Denmark)

    Hosseini, Mandana; Gotfredsen, Klaus

    2012-01-01

    OBJECTIVES: To test the reliability and validity of six aesthetic parameters and to compare the professional- and patient-reported aesthetic outcomes. MATERIAL AND METHODS: Thirty-four patients with 66 implant-supported premolar crowns were included. Two prosthodontists and 11 dental students......,24) were found between patient and professional evaluations. CONCLUSIONS: The feasibility, reliability and validity of the CIS make the parameters useful for quality control of implant-supported restorations. The professional- and patient-reported aesthetic outcomes had no significant correlation....

  5. A feasible, aesthetic quality evaluation of implant-supported single crowns: an analysis of validity and reliability

    DEFF Research Database (Denmark)

    Hosseini, Mandana; Gotfredsen, Klaus

    2012-01-01

    OBJECTIVES: To test the reliability and validity of six aesthetic parameters and to compare the professional- and patient-reported aesthetic outcomes. MATERIAL AND METHODS: Thirty-four patients with 66 implant-supported premolar crowns were included. Two prosthodontists and 11 dental students......,24) were found between patient and professional evaluations. CONCLUSIONS: The feasibility, reliability and validity of the CIS make the parameters useful for quality control of implant-supported restorations. The professional- and patient-reported aesthetic outcomes had no significant correlation....

  6. In-ceram氧化锆基全瓷冠的适合性评价%Marginal and international gaps of In-ceram zirconia-based crowns

    Institute of Scientific and Technical Information of China (English)

    李东方; 王夏衡; 刘小丽

    2014-01-01

    目的 评价3种In-ceram氧化锆基全瓷冠的边缘和内部间隙.方法 制作In-Ceram YZ全瓷冠、In-Ceram Zirconia全瓷冠和Wolceram全瓷冠各12个,采用树脂粘接剂粘固于人工预备的离体上颌前磨牙上,经过温度循环试验后,沿近远中向和颊舌向片切试件,用扫描电镜观察并测量全瓷冠组织面与牙体组织之间的间隙,3组试件的数据用SPSS12.0软件进行统计学分析.结果 3种全瓷冠的间隙宽度中,均是边缘间隙宽度最小,(牙合)面间隙宽度最大.In-Ceram YZ全瓷冠的边缘间隙宽度为(19.86±1.81)μm,肩台间隙宽度为(92.66±0.64) μm,(牙合)面间隙宽度为(128.06±1.38) μm,在3种全瓷冠中最小;Wolceram全瓷冠的边缘间隙宽度为(29.43±0.84) μm,肩台间隙宽度为(117.89±1.73) μm,轴壁间隙宽度为(112.50±1.71) μm,(牙合)面间隙宽度(168.11±1.33) μm,在3种全瓷冠中最大.结论 3种In-Ceram氧化锆基全瓷冠的间隙宽度均在临床可接受范围内,其中In-Ceram YZ和In-Ceram Zirconia全瓷冠的边缘和内部间隙较Wolceram全瓷冠小.

  7. Fatigue resistance of CAD/CAM resin composite molar crowns.

    Science.gov (United States)

    Shembish, Fatma A; Tong, Hui; Kaizer, Marina; Janal, Malvin N; Thompson, Van P; Opdam, Niek J; Zhang, Yu

    2016-04-01

    To demonstrate the fatigue behavior of CAD/CAM resin composite molar crowns using a mouth-motion step-stress fatigue test. Monolithic leucite-reinforced glass-ceramic crowns were used as a reference. Fully anatomically shaped monolithic resin composite molar crowns (Lava Ultimate, n=24) and leucite reinforced glass-ceramic crowns (IPS Empress CAD, n=24) were fabricated using CAD/CAM systems. Crowns were cemented on aged dentin-like resin composite tooth replicas (Filtek Z100) with resin-based cements (RelyX Ultimate for Lava Ultimate or Multilink Automix for IPS Empress). Three step-stress profiles (aggressive, moderate and mild) were employed for the accelerated sliding-contact mouth-motion fatigue test. Twenty one crowns from each group were randomly distributed among these three profiles (1:2:4). Failure was designated as chip-off or bulk fracture. Optical and electron microscopes were used to examine the occlusal surface and subsurface damages, as well as the material microstructures. The resin composite crowns showed only minor occlusal damage during mouth-motion step-stress fatigue loading up to 1700N. Cross-sectional views revealed contact-induced cone cracks in all specimens, and flexural radial cracks in 2 crowns. Both cone and radial cracks were relatively small compared to the crown thickness. Extending these cracks to the threshold for catastrophic failure would require much higher indentation loads or more loading cycles. In contrast, all of the glass-ceramic crowns fractured, starting at loads of approximately 450N. Monolithic CAD/CAM resin composite crowns endure, with only superficial damage, fatigue loads 3-4 times higher than those causing catastrophic failure in glass-ceramic CAD crowns. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  8. The influence of metal ceramic crown restoration on periodontal health of restored tooth%金属烤瓷全冠对患牙牙周可疑致病菌的影响

    Institute of Scientific and Technical Information of China (English)

    邱燕; 陈军; 龚媛媛; 余璐

    2012-01-01

    Objectives: To explore the influence of three metal ceramic crown restoration on the subgingival plaque in Pg and Aa positive rate of restored tooth and the effect of periodontal index. Methods:Collect each of the 30 patients who was placed the Ni - Cr alloy porcelain ,the Pd - Ag alloy porcelain crown, and the Gold alloy porcelain erown, Through the comparison of the changes of all periodontal index between patient's first visit and 6 months' later, and restored teeth's subgingival plaque were collected for detecting the changes of the positive rates of Pg and Aa. Results:six months after Ni - Cr alloy porcelain crowns were. placed,PD and SBI were higher ( P〈 0.05) ,PLI were the same as the first visit, subgingival plaque in Pg positive rate increased, the positive rate of Aa without change;while to the Pd - Ag alloy and the Gold alloy,PD were higher, SBI and PLI had no difference from the first visit, subgingival plaque in Pg positive rate and the positive rate of Aa without change. Conclusion: After 6 months the placement of the Pd- Ag alloy porcelain crowns restoration and the Gold alloy porcelain crowns restoration, they had little influence on the periodontal index of restored tooth and the detection frequency of the restored teeth' s subgingival plaque.%目的;探讨三种不同金属烤瓷全冠修复体对患牙龈下菌斑中魄、Aa检出率及牙周指数的影响。方法:收集进行镍铬合金烤瓷全冠、钯银合金烤瓷全冠,金合金烤瓷全冠修复的患者各30例,修复后6个月复诊,比较修复前、后患牙龈下菌斑中瞻、Aa检出率及各项牙周指数的差别。结果:镍铬合金烤瓷全冠修复6个月后患牙PD、SBI增大(P〈0.05),PLI与修复前无差别(P〉0.05)。钯银合金烤瓷全冠、金合金烤瓷全冠修复6个月后PD增大(P〈0.05),PLI、SBI均与修复前无差别(P〉0.05)。镍铬合金烤瓷全冠修复后患牙龈下菌斑中如检

  9. Evaluation of soft tissues around single tooth implants in the anterior maxilla restored with cemented and screw-retained crowns.

    Science.gov (United States)

    Cutrim, Emerson Souza; Peruzzo, Daiane Cristina; Benatti, Bruno

    2012-12-01

    Implant-supported restorations can be attached as screw-retained or cemented prostheses. In both situations, the characteristics of the soft tissues around the implants are crucial for oral rehabilitation and patient satisfaction. Therefore, this study uses the Pink Esthetic Score (PES), which allows evaluation of gingival esthetics around implants, to evaluate the soft tissues around implants in the anterior maxilla rehabilitated with cemented prostheses (CP) and screw-retained prostheses (SP). Forty implants placed in the anterior maxilla were evaluated, and these had been rehabilitated with prosthetic crowns for a minimum of 1 year. Periodontal examination was performed to evaluate probing depth (PD) and bleeding on probing (BOP) of the implant and the corresponding natural tooth. The total mean (±SD) PES for SP was 10.73 (±1.98) and 10.41 (±2.67) for CP, which was not statistically significant (P ≥ .05). Periodontal examination revealed that CP and SP showed no difference for BOP (P ≥ .05). Differences were only detected in PD when comparing the reference teeth of both groups to CP and SP (P ≤ .05). The present study demonstrates that the PES proved to be an efficient index to assess peri-implant tissues, and that the type of crown retention does not influence the health and quality of the soft tissues around implants.

  10. Sintered silicon carbide: a new ceramic vessel material for microwave chemistry in single-mode reactors.

    Science.gov (United States)

    Gutmann, Bernhard; Obermayer, David; Reichart, Benedikt; Prekodravac, Bojana; Irfan, Muhammad; Kremsner, Jennifer M; Kappe, C Oliver

    2010-10-25

    Silicon carbide (SiC) is a strongly microwave absorbing chemically inert ceramic material that can be utilized at extremely high temperatures due to its high melting point and very low thermal expansion coefficient. Microwave irradiation induces a flow of electrons in the semiconducting ceramic that heats the material very efficiently through resistance heating mechanisms. The use of SiC carbide reaction vessels in combination with a single-mode microwave reactor provides an almost complete shielding of the contents inside from the electromagnetic field. Therefore, such experiments do not involve electromagnetic field effects on the chemistry, since the semiconducting ceramic vial effectively prevents microwave irradiation from penetrating the reaction mixture. The involvement of electromagnetic field effects (specific/nonthermal microwave effects) on 21 selected chemical transformations was evaluated by comparing the results obtained in microwave-transparent Pyrex vials with experiments performed in SiC vials at the same reaction temperature. For most of the 21 reactions, the outcome in terms of conversion/purity/product yields using the two different vial types was virtually identical, indicating that the electromagnetic field had no direct influence on the reaction pathway. Due to the high chemical resistance of SiC, reactions involving corrosive reagents can be performed without degradation of the vessel material. Examples include high-temperature fluorine-chlorine exchange reactions using triethylamine trihydrofluoride, and the hydrolysis of nitriles with aqueous potassium hydroxide. The unique combination of high microwave absorptivity, thermal conductivity, and effusivity on the one hand, and excellent temperature, pressure and corrosion resistance on the other hand, makes this material ideal for the fabrication of reaction vessels for use in microwave reactors.

  11. Failure modes and fracture origins of porcelain veneers on bilayer dental crowns.

    Science.gov (United States)

    Liu, Yihong; Liu, Guanghua; Wang, Yong; Shen, James Zhijian; Feng, Hailan

    2014-01-01

    The aims of this study were to determine the fracture origins and crack paths in the porcelain of clinically failed bilayer ceramic restorations and to reveal the correlation between the porcelain failures and material properties. Three clinically failed crowns of each material (bilayer zirconia crowns, galvano-ceramic crowns, and porcelain-fused-to-metal crowns) were collected and underwent failure analysis. The fractures found in porcelain veneers showed several characteristics including wear, Hertzian cone crack, chipping off, and delamination. The results indicated that the fracture origins and features of the porcelain in bilayer ceramic restorations might be affected by the rigidity of core materials and thickness of copings.

  12. [Sunrise gold foil jacket crown].

    Science.gov (United States)

    Lecardonnel, A

    1989-09-01

    This technique permits the preparation of ceramic jacket crowns made on Sunrise laminated precious metal alloy. The Sunrise foil is gold-colored, made of 99% of precious metals and is 50 microns thick. The die is prepared in order to display a moderate and regular undercut beyond the cervical limit. The margin will be underlined with a red pencil. The Sunrise foil is cut according to predetermined templates. Then the foil is applied without burnishing, according to the technique of jacket crowns on platinum foil only by finger pressure. The double folding on closure is preferably done distally or mesially. Then, the metal base is disinserted, sandblasted with 100 microns aluminum oxide, replaced on its die, and placed in a rubber casing before being placed in the isostatic press, to be subjected to a pressure of 2,000 TSI (14 kg par cm2). Sunrise's orange color reinforces rather subtetly the overall color, making these reconstructions particularly esthetic. The color of the Sunrise metal does not require, therefore a too thick opaque. Any ceramic intended to be fired on a metal base, may be used in respecting its firing protocol. Sunrise, as any other technique of this type, require a careful preparation with a shoulder that has a rounded gingivoaxial line angle. Bridges may be built on the "thimbles" crowns, fitted on Sunrise cores, the pontics being made as a ceramo-metal framework.

  13. Preconcentration of thallium (I) by single drop microextraction with electrothermal atomic absorption spectroscopy detection using dicyclohexano-18-crown-6 as extractant system.

    Science.gov (United States)

    Chamsaz, Mahmoud; Arbab-Zavar, Mohammad Hossien; Darroudi, Abolfazl; Salehi, Thiery

    2009-08-15

    A simple single drop liquid-phase microextraction (SDME) technique, combined with electrothermal atomic absorption spectroscopy (ETAAS) is developed both to preconcentrate and determine thallium (I) ions in aqueous solutions. The ions were transferred from 10.0 ml of aqueous sample (donor phase) containing 0.5 ml of 1% picric acid as the ion-pair agent into a 3 microl microdrop of nitrobenzene (acceptor phase) containing dicyclohexano-18-crown-6 as the complexing agent. The latter will help to improve the extraction efficiency of the analyte. After the ions have been extracted, the acceptor drop was directly injected into a graphite furnace for thallium (I) determination. Several parameters such as the extracting solvent, extraction time, temperature, concentration of picric acid and crown ether, drop volume and stirring rate were examined. Under the optimized experimental conditions, the detection limit (L.O.D.) was 0.7 ng ml(-1). The relative standard deviation for five replicate analysis of 10 ng ml(-1) of thallium (I) was 5.1%. The calibration curve was linear in the range of 3-22 ng ml(-1). The results for determination of thallium in reference material, spiked tap water and seawater demonstrated the accuracy, recovery and applicability of the presented method. The enrichment factor was 50.

  14. Bending strength of piezoelectric ceramics and single crystals for multifunctional load-bearing applications.

    Science.gov (United States)

    Anton, Steven R; Erturk, Alper; Inman, Daniel

    2012-06-01

    The topic of multifunctional material systems using active or smart materials has recently gained attention in the research community. Multifunctional piezoelectric systems present the ability to combine multiple functions into a single active piezoelectric element, namely, combining sensing, actuation, or energy conversion ability with load-bearing capacity. Quantification of the bending strength of various piezoelectric materials is, therefore, critical in the development of load-bearing piezoelectric systems. Three-point bend tests are carried out on a variety of piezoelectric ceramics including soft monolithic piezoceramics (PZT-5A and PZT-5H), hard monolithic ceramics (PZT-4 and PZT-8), single-crystal piezoelectrics (PMN-PT and PMN-PZT), and commercially packaged composite devices (which contain active PZT-5A layers). A common 3-point bend test procedure is used throughout the experimental tests. The bending strengths of these materials are found using Euler-Bernoulli beam theory to be 44.9 MPa for PMN-PZT, 60.6 MPa for PMN-PT, 114.8 MPa for PZT- 5H, 123.2 MPa for PZT-4, 127.5 MPa for PZT-8, 140.4 MPa for PZT-5A, and 186.6 MPa for the commercial composite. The high strength of the commercial configuration is a result of the composite structure that allows for shear stresses on the surfaces of the piezoelectric layers, whereas the low strength of the single-crystal materials is due to their unique crystal structure, which allows for rapid propagation of cracks initiating at flaw sites. The experimental bending strength results reported, which are linear estimates without nonlinear ferroelastic considerations, are intended for use in the design of multifunctional piezoelectric systems in which the active device is subjected to bending loads.

  15. Recent advances in materials for all-ceramic restorations.

    Science.gov (United States)

    Griggs, Jason A

    2007-07-01

    The past 3 years of research on materials for all-ceramic veneers, inlays, onlays, single-unit crowns, and multi-unit restorations are reviewed in this article. The primary changes in the field were the proliferation of zirconia-based frameworks and computer-aided fabrication of prostheses, and a trend toward more clinically relevant in vitro test methods. This article includes an overview of ceramic fabrication methods, suggestions for critical assessment of material property data, and a summary of clinical longevity for prostheses constructed of various materials.

  16. Fast single firing applied to clay ceramics; Monoqueima rapida aplicada a ceramica vermelha

    Energy Technology Data Exchange (ETDEWEB)

    Zanelatto, F.C.; Uggioni, E. [Universidade do Extremo Sul Catarinense (UNESC), Criciuma, SC (Brazil). Dept. de Engenharia de Materiais; Botega, J. [Universidade do Extremo Sul Catarinense (UNESC), Criciuma, SC (Brazil). Dept. de Tecnologia em Ceramica; Luckmann, G.; Bernardin, A.M., E-mail: amb@unesc.ne [Servico Nacional de Aprendizagem Industrial (SENAI), Tijucas, SC (Brazil). Dept. de Tecnologia em Ceramica

    2009-07-01

    This work aimed to obtain clay ceramics using fast single firing by dry processing. Four clay samples were characterized by chemical (FRX) and mineralogical (XRD) analyses and mixture design was used for the formulation of eight compositions. The compositions were dried and homogenized to 15% moisture and processed in a laboratory extruder. After drying (110 deg C, 24h), the formulations were fired in a laboratory roller kiln (900 deg C, 2h) and then characterized (water absorption and resistance to compression). The temperature of maximum sintering rate of each formulation was determined by optical dilatometry (10 deg C/min). The results show the effect of chemical and mineralogical composition of clays on the properties of the final compositions. (author)

  17. Performance comparison between ceramic Ce:GAGG and single crystal Ce:GAGG with digital-SiPM

    Science.gov (United States)

    Park, C.; Kim, C.; Kim, J.; Lee, Y.; Na, Y.; Lee, K.; Yeom, J. Y.

    2017-01-01

    The Gd3Al2Ga3O12 (Ce:GAGG) is a new inorganic scintillator known for its attractive properties such as high light yield, stopping power and relatively fast decay time. In this study, we fabricated a ceramic Ce:GAGG scintillator as a cost-effective alternative to single crystal Ce:GAGG and, for the first time, investigated their performances when coupled to the digital silicon photomultiplier (dSiPM)—a new type of photosensor designed for applications in medical imaging, high energy and astrophysics. Compared to 3 × 3 × 2 mm3 sized single crystal Ce:GAGG, the translucent ceramic Ce:GAGG, which has a much lower transmittance than the single crystal, was determined to give an output signal amplitude that is approximately 61% of single crystal Ce:GAGG. The energy resolution of the 511 keV annihilation peak of a 22Na source was measured to be 9.9 ± 0.2% and 13.0 ± 0.3% for the single and ceramic scintillators respectively. On the other hand, the coincidence resolving time (CRT) of ceramic Ce:GAGG was 307 ± 23 ps, better than the 465 ± 37 ps acquired with single crystals—probably attributed to its slightly faster decay time and higher proportion of the fast decay component. The ceramic Ce:GAGG may be a promising cost-effective candidate for applications that do not require thick scintillators such as x-ray detectors and charged particle detectors, and those that require time-of-flight capabilities.

  18. Evaluating residual dentin thickness following various mandibular anterior tooth preparations for zirconia full-coverage single crowns: an in vitro analysis.

    Science.gov (United States)

    Borelli, Bruna; Sorrentino, Roberto; Goracci, Cecilia; Amato, Massimo; Zarone, Fernando; Ferrari, Marco

    2015-01-01

    The objective of this study was to evaluate the residual dentin thickness (RDT) after different tooth preparations. Ninety mandibular anterior teeth were divided into three groups: central incisors, lateral incisors, and canines. Specimens were prepared for single-crown coverage with shoulder, slight chamfer, and knife-edge finish lines. Specimens were sectioned and divided into four subgroups according to measurement areas: (1) buccal, (2) distal, (3) lingual, and (4) mesial. The RDT was analyzed statistically by means of one-way analysis of variance and Tukey post hoc test (P = .05). Significant differences were found for shoulder but not for slight chamfer and knife-edge finish lines. The interproximal areas wound up being critical due to thin RDT, potentially interfering with the structural and biologic integrity of teeth.

  19. Influence of coping material selection and porcelain firing on marginal and internal fit of computer-aided design/computer-aided manufacturing of zirconia and titanium ceramic implant-supported crowns%氧化锆和纯钛基底冠材料及饰瓷烧结对种植全冠适合性的影响

    Institute of Scientific and Technical Information of China (English)

    刘翠玲; 杨丽媛; 高旭; 商红

    2016-01-01

    Objective This study aimed to investigate the influence of coping material and porcelain firing on the marginal and internal fit of computer-aided design/computer-aided manufacturing (CAD/CAM) of zirconia ceramic implant- and titanium ceramic implant-supported crowns. Methods Zirconia ceramic implant (group A, n=8) and titanium metal ceramic implantsupported crowns (group B, n=8) were produced from copings using the CAD/CAM system. The marginal and internal gaps of the copings and crowns were measured by using a light-body silicone replica technique combined with micro-computed tomog-raphy scanning to obtain a three-dimensional image. Marginal gap (MG), horizontal marginal discrepancy (HMD), and axial wall (AW) were measured. Statistical analyses were performed using SPSS 17.0. Results Prior to porcelain firing, the measurements for MG, HMD, and AW of copings in group A were significantly larger than those in group B (P0.05). Porcelain firing significantly reduced MG (P0.05). Conclusion The marginal fits of CAD/CAM zirconia ceramic implant-supported crowns were superior to those of CAD/CAM titanium ceramic-supported crowns. The fits of both the CAD/CAM zirconia ceramic implant- and titanium ceramic implant-supported crowns were obviously influenced by porcelain firing.%目的:研究氧化锆和纯钛基底冠材料及饰瓷烧结对种植全冠内部和边缘适合性的影响。方法制作计算机辅助设计/计算机辅助制作(CAD/CAM)氧化锆烤瓷种植全冠(A组)和纯钛烤瓷种植全冠(B组)各8个(n=8)。分别用硅橡胶轻体复制饰瓷烧结前基底冠和饰瓷烧结后全冠的内部和边缘间隙,采用Micro-CT扫描硅橡胶,建立三维图像,测量冠边缘垂直间隙(MG)、冠边缘水平间隙(HMD)和冠内部轴面中点间隙(AW)。采用SPSS 17.0软件对测量结果进行统计学分析。结果饰瓷烧结前,A组基底冠MG、HMD和AW均大于B组(P0.05)。

  20. Predictors of peri-implant bone loss during long-term maintenance of patients treated with 10-mm implants and single crown restorations.

    Science.gov (United States)

    De la Rosa, Manuel; Rodríguez, Angel; Sierra, Katia; Mendoza, Gerardo; Chambrone, Leandro

    2013-01-01

    The aim of this retrospective study was to evaluate the predictors of peri-implant bone loss in a sample of patients treated with 10-mm implants and single crowns who underwent periodontal/peri-implant maintenance (PM) in a Mexican private periodontal practice. Outcomes of a group of systemically healthy, partially edentulous patients attended up to July 2012 were assessed. Patient data were considered for inclusion if they involved treatment of partially edentulous sites with 10-mm-long implants and single crown restorations, as well as at least 3 years of regular PM following implant placement. Peri-implant bone loss was evaluated from data recorded at the most recent examination. Logistic regression analysis was performed to investigate associations between peri-implant bone loss and sex, duration of PM, location and number of implants placed per patient, region of the mouth, smoking status, type of implant, and retention of restoration. A sample of 104 subjects who had been treated with four different types of dental implants and maintained for at least 3 years was selected. Of the 148 implants placed and followed for an average period of continuing PM of 6 years (range, 3 to 15 years), only one implant (1.8%) was lost. The outcomes of logistic regression analysis showed that the independent variables smoking, retention of restoration (cemented vs screw-retained), and type of implant (internal- or external-hex) were found to be correlated with peri-implant bone loss, with odds ratios of 39.64, 4.85, and 0.04, respectively. Peri-implant bone loss was significantly associated with smoking status, the type of implant (ie, externally hexed), and type of retention (ie, cemented). Overall, all patients maintained low rates of bone loss.

  1. Changes in the periodontal condition after replacement of swaged crowns by metal.

    Science.gov (United States)

    Plotniece-Baranovska, Anita; Soboleva, Una; Rogovska, Irena; Apse, Peteris

    2006-01-01

    Evidence based clinical studies have shown exact recommended design for artificial crown reconstruction with acceptable long-term results taking into an account the biological price. Previous histological and clinical studies proved that fixed prostheses might influence the periodontal condition of crowned teeth, if not all biological criteria have been considered. The aim of the present study was to assess the periodontal condition of the crowned teeth after stainless steel swaged crowns were replaced by cast metal ceramic crowns. Participants were selected at the Institute of Stomatology, Stradin's University. Selection criteria included need to replace existing swaged crowns by metal ceramic crowns for patients with absence of any systemic disease. Following symptoms of periodontal condition were examined - presence of inflammation (clinical signs, probing) and pocket depth. Assessments were carried out at four different points of time (first appointment after replacement existing swaged crowns by temporary crowns; two weeks after cementation of permanent metal ceramic restoration; after three month; after six month). Overall bleeding score "2" and "3" at the first measurement was observed in majority of study population. Bleeding scores between the 1st and the 4th measurement was significantly lower (pcrowns by metal ceramic improves gingival health and leads to better long-term prognosis for restored teeth. It is recommended that swaged crowns be replaced with more biologically friendly crowns.

  2. Comparison of the marginal fit of two kinds of all-ceramic and Au-Pt based porcelain-fused-metal crown systems%两种全瓷系统与金铂合金PFM冠边缘适合性的实验研究

    Institute of Scientific and Technical Information of China (English)

    李永斌; 孙迎春; 韦荣智; 包玮玮

    2012-01-01

    Objective: This study was performed to evaluate two ceramic and PFM crown systems for their accuracy of marginal fit. Methods: A total of 30 experimental crowns, the first molar of mandibular, were fabricated from two all-ceramic systems (IPS e.max and VITA In-Ceram Zirconia) and Au-Pt PFM systems (n=10). All restorations were delivered to prefabricated stone dies with composite resin cement. Gap widths were measured by light microscopy (magnificationx200). Intergroup differences were analyzed by one-way ANOVA. Results: The results showed there were significant differences for the marginal gap widths (F=2488.6, P<0.05). IPS e.max system seemed to have the smallest gap width, even better than Au-Pt PFM, while VITA In-Ceram Zirconia had the largest. Conclusion: IPS e.max system combined with composite resin cement has excellent marginal fit, which indicated that all-ceramic restorations were acceptable for clinical use regarding to marginal fit.%目的:比较两种全瓷系统与金-铂合金烤瓷熔附金属全冠(Porcelain-fused-to-metal Crown,PFM)的边缘适合性,为临床修复材料的选择提供参考依据.方法:30个右下第一磨牙的标准预备体石膏模型随机分为3组(n=10),分别制作IPSe.max,VITA In-Ceram Zirconia和金-铂合金PFM全冠修复体,树脂粘接剂粘固后,200倍光学显微镜下测量冠边缘间隙大小.结果:三组材料制作的修复体边缘间隙大小差异有统计学意义(F=2488.6,P<0.05),边缘间隙由小到大依次为IPSe.max,金-铂合金PFM,VITA In-Ceram Zirconia.并且各组间差异均有统计学意义(P<0.05).结论:IPS e.max全瓷修复体用树脂水门汀粘接后,边缘适合性良好,优于传统的PFM修复.全瓷修复体的边缘适合性符合临床应用要求.

  3. Comparison of laser performance of electro-optic Q-switched Nd:YAG ceramic/single crystal laser

    Institute of Scientific and Technical Information of China (English)

    Jianghua Ji; Xiaolei Zhu; Chunyu Wang; Yongwei Feng; Qihong Lou

    2006-01-01

    @@ An electro-optic Q-switched Nd:YAG ceramic laser operating at kHz repetition rate was demonstrated.Thermal induced lens' focus of ceramic rod was measured and compensated by plano-convex cavity structure. Depolarization loss at different output powers was measured in Nd:YAG single crystal and ceramic lasers. High-energy high-beam-quality laser pulse output was obtained in both laser structures. Pulse energy of about 20 mJ and pulse width of less than 12 ns were achieved, and the average power reached 20 W. The divergence of output laser beam was less than 1.2 mrad, and the beam propagation factor M2was about 1.4.

  4. Crack-free cutting of thick and dense ceramics with CO 2 laser by single-pass process

    Science.gov (United States)

    Ji, Lingfei; Yan, Yinzhou; Bao, Yong; Jiang, Yijian

    2008-10-01

    This paper presents a laser crack-free cutting method of Al 2O 3 ceramics by single-pass process in internal straight and curve profiles. The thickness and theoretical density of the ceramics are up to 10 mm and about 99%, respectively. The effective cutting speed is about 0.23-0.42 mm/s corresponding to the laser head moving speed of 3 mm/s. The cutting process based on close-piercing lapping of piercing time of 0.1-0.5 s and piercing pitch of 0.03-0.05 mm is divided into two continuous stages. Appropriate time slot for each piercing, high peak power of 3500 W and low cycle duty (laser crack-free cutting method is a promising method to achieve complex profiles of ceramic cuts.

  5. Clinical outcomes of three different crown systems with CAD/CAM technology.

    Science.gov (United States)

    Batson, Emily R; Cooper, Lyndon F; Duqum, Ibrahim; Mendonça, Gustavo

    2014-10-01

    Computer-aided design and computer-aided manufacturing (CAD/CAM) generated restorations are gaining popularity. However, limited clinical evidence is available for single-unit posterior CAD/CAM restorations fabricated with established and newer crown materials. The purpose of this clinical study was to assess the restoration quality of and gingival response to CAD/CAM fabricated posterior single-tooth restorations with different processing technologies. Twenty-two individuals in need of posterior complete coverage crowns were recruited under an institutional review board approved protocol. Teeth were randomized to 1 of 3 groups: metal ceramic, lithium disilicate, and monolithic zirconia. An unprepared or minimally restored tooth on the contralateral side was chosen as a control tooth for gingival measurements with each participant. Teeth were prepared and scanned intraorally by 1 of 3 experienced practitioners. A total of 32 restorations were digitally designed and fabricated with either milling technology or rapid-prototype printing and casting with conventional porcelain application. Restorations were evaluated with modified United States Public Health Service criteria for contour, marginal adaptation, occlusion, and shade. Gingival crevicular fluid volume and bleeding on probing were recorded preoperatively, at 1-month and 6-month postcementation visits. Polyvinyl siloxane impressions were made of the buccal margin of cemented restorations and evaluated with microcomputed tomography to assess marginal adaptation (horizontal discrepancy). The Mantel Haenszel row mean score was used to assess whether the crown systems differed with respect to the modified United States Public Health Service criteria. Linear mixed models were used to assess whether the average gingival volumes were affected by the explanatory variables (crown system, tooth status [treated vs control], or visit). A generalized estimating equation approach was used to assess whether bleeding on

  6. Dental composite resins containing silica-fused ceramic single-crystalline whiskers with various filler levels.

    Science.gov (United States)

    Xu, H H

    1999-07-01

    Currently available direct-filling composite resins are susceptible to fracture and hence are not recommended for use in large stress-bearing posterior restorations involving cusps. The glass fillers in composites provide only limited reinforcement because of the brittleness and low strength of glass. The aim of the present study was to use ceramic single-crystalline whiskers as fillers to reinforce composites, and to investigate the effect of whisker filler level on composite properties. Silica particles were fused onto the whiskers to facilitate silanization and to roughen the whiskers, thereby improving retention in the matrix. The composite flexural strength, elastic modulus, hardness, and degree of polymerization conversion were measured as a function of whisker filler mass fraction, which ranged from 0% to 70%. Selected composites were polished simulating clinical procedures, and the surface roughness was measured with profilometry. The whisker composite with a filler mass fraction of 55% had a flexural strength (mean +/- SD; n = 6) of 196+/-10 MPa, significantly higher than 83+/-14 MPa of a microfill and 120+/-16 MPa of a hybrid composite control (family confidence coefficient = 0.95; Tukey's multiple comparison). The composite modulus and hardness increased monotonically with filler level. The flexural strength first increased, then plateaued with increasing filler level. The degree of conversion decreased with increasing filler level. The whisker composite had a polished surface roughness similar to that of a conventional hybrid composite (p>0.1; Student's t). To conclude, ceramic whisker reinforcement can significantly improve the mechanical properties of composite resins; the whisker filler level plays a key role in determining composite properties; and the reinforcement mechanisms appear to be crack pinning by whiskers and friction from whisker pullout resisting crack propagation.

  7. Single crowns in the resorbed posterior maxilla supported by either 6-mm implants or by 11-mm implants combined with sinus floor elevation surgery : A 1-year randomised controlled trial

    NARCIS (Netherlands)

    Guljé, Felix L; Raghoebar, Gerry M; Vissink, Arjan; Meijer, Henny J A

    2014-01-01

    Purpose: The aim of this randomised controlled trial was to assess the clinical performance of single crowns in the posterior maxilla supported by either 6-mm or 11-mm implants combined with maxillary sinus floor elevation. Materials and methods: 41 consecutive patients with one missing premolar or

  8. Recent developments in restorative dental ceramics.

    Science.gov (United States)

    Anusavice, K J

    1993-02-01

    Since the introduction of porcelain jacket crowns in the early 1900s, dental ceramics have been praised for their esthetic appearance. But there's more to consider: other benefits, longevity, limitations. This review addresses major developments in modern dental ceramics and metal-ceramics.

  9. Comparison of the clinical value of porcelain veneer and all ceramic crowns in the restoration of anterior teeth%烤瓷贴面和全瓷冠在前牙美容修复中的临床应用价值比较

    Institute of Scientific and Technical Information of China (English)

    刘卫锋; 刘继华; 闫慧鑫; 王生党; 王垚

    2015-01-01

    目的:旨在比较烤瓷贴面和全瓷冠在前牙美容修复中的临床效果。方法选择2012年1月至2013年1月在我院接受烤瓷贴面和全瓷冠前牙美容修复的患者127例(320颗),根据患者的牙齿情况选择修复材料,其中接受烤瓷贴面修复患者70例(144颗),全瓷冠修复患者57例(176颗),320颗前牙均采用耐火代型技术进行修复,对所有患者随访2年。为了评价2种修复方式在前牙美容中的效果,分别在修复后3个月和24月后比较近期的美容效果和远期的完整性效果。结果经烤瓷贴面和全瓷冠修复后,患者均达到较好的近期美容效果,其主观满意度均达到100%,2种修复方式差异无统计学意义(P=0.51);全瓷冠修复的客观满意度为94.7%,高于烤瓷贴面(90.0%),表明全瓷冠的遮色效果优于烤瓷贴面。修复2年后全瓷冠的完好率仍为100%,烤瓷贴面的完好率为96.0%,二者差异有统计学意义(P=0.04),全瓷冠修复的远期完整性效果更佳。结论烤瓷贴面和全瓷冠对于前牙修复均能收到较好的美容效果,全瓷冠修复的远期完整性效果优于烤瓷贴面修复。%Objective To compare the clinical effects of porcelain veneer and all ceramic crowns in the cosmetic restoration of anterior teeth .Methods One hundred and twenty-seven patients ( 320 teeth ) , who received porcelain veneer and all ceramic crowns in the cosmetic restoration of anterior teeth from January , 2012 to January, 2013 in our hospital were chosen for our study .The repair materials for the patients′teeth were selected in accordance with the patient conditions of the teeth .All the 320 anterior teeth were repaired with refractory generation technology , of which 70 cases (144 teeth) were repaired with porcelain veneer and 57 cases (176 teeth) were repaired with all ceramic crowns , and all the patients had medical follow-ups for 2

  10. Complication rate of molar crowns: a practice-based clinical evaluation.

    Science.gov (United States)

    Rinke, S; Schäfer, S; Roediger, M

    2011-01-01

    This practice-based study evaluates the initial clinical performance of conventionally luted metal-ceramic and zirconia molar crowns fabricated with a prolonged cooling period of the veneering porcelain. Forty-nine patients were treated (group A: high precious alloy + low fusing porcelain; group B: zirconia crowns). All zirconia crowns were veneered with a modified porcelain firing cycle including a 6-minute cooling period. Ninety-two restorations (74 vital abutments/18 nonvital abutments) were evaluated after a mean observation period of 18.2 +/- 4.6 months. No complete failures or loss of vitality were recorded in either group. Two events were recorded in group A (1 loss of retention/1 minor ceramic chipping zirconia crowns fabricated with a modified porcelain firing. The modified firing of the zirconia porcelain seems to decrease the risk for early ceramic chipping in the molar area, leading to a technical complication rate comparable to that of metal-ceramic crowns.

  11. A Novel Technique for Immediate Loading Single Root Form Implants With an Interim CAD/CAM Milled Screw-Retained Crown.

    Science.gov (United States)

    Proussaefs, Periklis

    2016-08-01

    A technique is described where an interim abutment and crown are fabricated in the laboratory by utilizing computer-aided design/computer-aided manufacturing (CAD/CAM) technology and placed the day of dental implant surgery. The design and contours of the interim crown are designed by the computer software to be identical to the contours of the tentatively designed definitive prosthesis. The interim crown satisfies esthetics immediately after dental implant surgery while allowing the tissue to heal and obtain contours similar to the contours of the definitive prosthesis. The interim crown can be either cement retained or screw retained. The presented technique describes fabrication of a screw-retentive interim crown. After osseointegration is confirmed, a definitive impression is made with a CAD/CAM impression coping. The definitive prosthesis is then fabricated.

  12. Longevity of silicate ceramic restorations.

    Science.gov (United States)

    Beier, Ulrike Stephanie; Dumfahrt, Herbert

    2014-09-01

    The demand for esthetic restorations has resulted in an increased use of dental ceramics as a biocompatible and functionally sufficient alternative to conventional restorative materials. Silicate ceramic restorations are widely used for veneers, inlays, onlays, and crowns in dentistry. Long-term data are of crucial importance to optimize clinical practice. The purpose of the present article is to summarize data of the Innsbruck ceramic evaluation up to 261 months with the focus on longevity and failure characteristics.

  13. Effect of IPS e.max Press Ceramic Crown on the Level of MMP-2 in Gingival Crevicular Fluid%IPS e.max Press铸瓷全冠对龈沟液中MMP-2水平的影响

    Institute of Scientific and Technical Information of China (English)

    董蕾; 孙振学; 朱海燕

    2015-01-01

    Objective To observe the ef ects of IPS e.max press ceramic crown on the periodontal tissue of the restored teeth. Methods 79 clinical patients (107 anterior teeth)were selected to be placed by IPS e.max press ceramic crown ,and before and 6 months after rehab,the weight of gingival crevicular fluid (GCF)was mensurated and the level of MMP-2 in GCF was checked by way of enzyme-linked immuno sorbent assay,the result was analyzed. Results The weight of GCF,the level of MMP-2 in GCF after rehab had no significantly statistical dif erence with those before rehab(﹥0.05). Conclusion IPS e.max press ceramic crown has no significantly negative influence on gingival health of the restored teeth. And it is a kind of restoration with favorable biocompatibility.%目的:探讨IPS e.max Pres 铸瓷全冠修复对牙周组织的影响。方法选择IPS e.max Pres 铸瓷全冠修复患者79例107颗患牙,在修复前和修复后6个月,测定龈沟液(GCF)量,并运用采用酶联免疫吸附试验(ELISA)对龈沟液中基质金属蛋白酶-2(MMP-2)水平进行分析。结果修复后GCF量、MMP-2水平与修复前比较差异无统计学意义(﹥0.05)。结论 IPS e.max Pres 铸瓷全冠对牙周组织无明显影响,是一种生物相容性良好的修复方式。

  14. CERCON- SMART CERAMICS, FROM THEORY TO PRACTICE

    Directory of Open Access Journals (Sweden)

    Daniela POPA

    2015-03-01

    Full Text Available Introduction of the CAD/CAM systems in dentistry has resulted in highly accurate and quality dentures, meeting the needs of both dental technician and dentist. The present study aims at illustrating the benefits and peculiarities of using CAD/CAM systems in current practice. To this aim, the case of a 29 year-old patient who wanted to have a 2.1 coverage crown replaced, being dissatisfied with its aesthetics, was considered. The fixed single tooth prosthesis was restored with the CAD/CAM CERCON (DeguDent - Smart Ceramics.

  15. Clinical evaluation of quartz fiber post and zirconia all-ceramic crowns in restoring extensively damaged molar%纤维桩联合氧化锆全冠修复磨牙大面积缺损的临床评价

    Institute of Scientific and Technical Information of China (English)

    张海燕; 彭利伟; 郭东晓

    2012-01-01

    目的:评价石英纤维桩联合氧化锆全瓷冠在磨牙大面积缺损修复活疗中的短期临床效果.方法:对28例患者32颗已完善的根管治疗的磨牙残根、残冠,采用石英纤维桩联合氧化锆全瓷冠进行修复.修复后1、6、12个月随访检查,包括修复体完整性、边缘适合性、解剖外形、颜色及牙龈.结果:修复体的完整性好(93.75%),有2例因咬过硬食物崩瓷,边缘适合性及解剖外形良好,修复体颜色与邻牙协调一致(84.37%),纤维桩核及冠均无松动、脱落,X线牙片示纤维桩与根管壁密贴,未见折裂等.结论:石英纤维桩联合氧化锆全瓷冠在磨牙大面积缺损修复治疗中可取得良好的近期临床效果.%Objective To evaluate the clinical effect of quartz fiber post and zirconia all-ceramic crowns in restoring extensively damaged molar. Methods A total of 32 molars of 28 patients were included.After complete root canal therapy,the teeth were restored with quartz fiber posts and zirconia all -ceramic crowns. Follow -up survey were conducted 1month,6 months and 12 months later,including the intactness,marginal adaptation,anatomical contour and color of prostheses and gingival health. Results 93.75% of prostheses were found to be intact;little wane was found in two all -ceramic crowns due to hard food biting.Marginal adaptation and anatomical contour was good,color of prostheses in harmony with adjacent teeth (84.37%).No loosening or exfoliation was found among quartz fiber posts and composite resin core.Roentgen diagnosis revealed posts' adaptation to root canal without fracture of posts and cores in any prostheses. Conclusion Quartz fiber posts and zirconia all-ceramic crowns are reliable and ideal materials in the restoration of extensively damaged molar.

  16. In-ceram全瓷冠前牙修复的临床研究%Clinical Approach of the In-ceram All Ceramic Crown in Restoration of Anterior Teeth

    Institute of Scientific and Technical Information of China (English)

    马练; 刘学恒

    2005-01-01

    目的:探讨和评价In-ceram全瓷冠在前牙修复中的应用及其临床牙科美学特征.方法:用金刚砂车针进行常规的全瓷冠牙体预备,取印模、灌制模型,自然光线下用Vita比色板比色、选色,用Vita In-ceram Alumina系列烤瓷粉制作修复体,临床试戴、调改、粘结.结果:94%的病人对In-ceram全瓷冠修复非常满意,6%满意.结论:In-ceram全瓷冠修复前牙无论从维护牙龈组织的健康还是从临床牙科美学的角度都不失为一种满意的修复手段.

  17. 饰面瓷厚度对氧化锆全瓷冠抗压缩破坏力的影响%Influence of veneering porcelain thickness on the compressive strength of zirconia all-ceramic crown

    Institute of Scientific and Technical Information of China (English)

    王晓雪; 仇亚非; 袁硕; 张钊; 郭长军

    2016-01-01

    目的:研究饰面瓷厚度对氧化锆全瓷冠抗压缩破坏力的影响。方法:常规 CAD-CAM制作氧化锆筒状基底冠25个,厚度均为0.5 mm,随机分为 A、B、C、D、E 5组,饰面瓷厚度依次为0.5、1.0、1.5、2.0、2.5 mm。万能材料试验机测试各组试件抗压缩破坏力值。采用 SPSS13.0统计软件对测试结果进行统计分析。用扫描电镜(SEM)观察试件断裂面微观结构。结果:A ~E 组试件抗压缩破坏力值依次为:(1279.96±42.85)N、(2235.44±50.14)N、(2216.38±48.97)N、(2169.22±60.40)N、(2028.70±47.37)N。A 组、E 组氧化锆全瓷修复体的抗压缩破坏力值均低于其他3组(P <0.01);其余组间抗压缩破坏力值无统计学差异(P >0.05)。扫描电子显微镜观察发现,A 组、E 组氧化锆全瓷修复体基底瓷-饰面瓷结合界面处不平坦,较为疏松;饰瓷层出现气孔及微裂纹增多、增大。结论:饰面瓷厚度低于1.0 mm 及高于2.0 mm 时,修复体的微观结构可能会受到影响,从而氧化锆全瓷冠整体抗压缩破坏力的性能受影响,建议临床应用时严格控制饰面瓷厚度。%Objective:To explore the influence of the veneering porcelain thickness on the compressive strength of zirconia all-ceramic crown.Methods:25 zirconia basement crowns with the thickness of 0.5 mm were made by CAD-CAMsystem,and then were divided into 5 groups randomly with the veneering porcelain thickness of 0.5(A),1.0(B),1.5(C),2.0(D)and 2.5 mm(E)respectively. The compressive strength of the samples was measured by a testing machine.Statistical analysis was conducted by SPSS13.0 software. The microstructure of the fractured bonding interface of the specimens was observed by scanning electron microscope(SEM).Results:The compressive strength in group A,B,C,D and E were:(1 279.96 ±42.85)N,(2 235.44 ±50.14)N,(2 216.38 ±48.97)N, (2 169.22 ±60

  18. Orthodontic crown lengthening.

    Science.gov (United States)

    Hohlt, W F

    1992-01-01

    As comprehensive dentistry becomes more complex, procedures must be developed to save teeth once considered unsuitable for crown restoration due to inaccessible finishing lines. Orthodontic crown lengthening is less invasive than a flap procedure and does not result in crestal bone reduction. The crown lengthening procedure is a simple and time-saving remedy for a difficult restorative problem.

  19. In vitro analysis of residual tooth structure of maxillary anterior teeth after different prosthetic finish line preparations for full-coverage single crowns.

    Science.gov (United States)

    Borelli, Bruna; Sorrentino, Roberto; Goracci, Cecilia; Zarone, Fernando; Ferrari, Marco

    2013-03-01

    To evaluate residual dentin thickness (RDT) after different tooth preparations, 90 sound maxillary anterior teeth were selected and divided into 3 groups according to tooth type (n = 30), namely, maxillary central incisors, maxillary lateral incisors, and maxillary canines. In each group, specimens were randomly divided and prepared for single-crown coverage with shoulder (SHO, n = 10, control), slight chamfer (CHA, n = 10), and knife-edge (KNE, n = 10) finish lines. After tooth preparation, specimens were sectioned and divided into 4 subgroups (buccal, distal, palatal, and mesial) according to measurement area. RDT values were compared by using one-way ANOVA and Tukey's post hoc test (P = 0.05). Significant differences were found between SHO and the other two groups (P 0.05). SHO was significantly more aggressive than CHA and KNE, which were comparable. Interproximal areas became critical due to thin RDT, which could potentially compromise the structural and biological integrity of teeth. The choice of finish line should be guided by careful clinical evaluation.

  20. Crystal structure and single crystal EPR of (NH4)2(15-crown-5)3[Cu(mnt)2] and (NH4)2(benzo-15-crown-5)4[Cu(mnt)2]·0.5H2O

    Institute of Scientific and Technical Information of China (English)

    SUI; YunXia; WEN; LiLi; ZHANG; Huan; MENG; QingJin

    2007-01-01

    The X-ray crystal structures of (NH4)2(15-crown-5)3[Cu(mnt)2] (1) and (NH4)2(benzo-15-crown-5)4- [Cu(mnt)2]·0.5H2O (2) were determined. Two single crystals are composed of distinct structures of ammonium-crown ether supramolecular cation and [Cu(mnt)2]2- anion. The triple-decker dication in complex 1 and a sandwich dimmer in complex 2 were observed. X-Band EPR studies on the single crystals of both complex 1 and complex 2 have been carried out at room temperature, which revealed that complex 2 showed a perfect hyperfine structure of Cu whereas that of complex 1 could not be observed. The principal values and direction cosines of the principal axes of the g and A tensors were computed by a least-squares fitting procedure. The spin density of Cu(Ⅱ) was estimated according to the principal values of the A tensors and compared well with the results calculated based on DFT method.

  1. Multi-susceptibile single-phased ceramics with both considerable magnetic and dielectric properties by selectively doping.

    Science.gov (United States)

    Liu, Chuyang; Zhang, Yujing; Jia, Jingguo; Sui, Qiang; Ma, Ning; Du, Piyi

    2015-04-02

    Multiferroic ceramics with extraordinary susceptibilities coexisting are vitally important for the multi-functionality and integration of electronic devices. However, multiferroic composites, as the most potential candidates, will introduce inevitable interface deficiencies and thus dielectric loss from dissimilar phases. In this study, single-phased ferrite ceramics with considerable magnetic and dielectric performances appearing simultaneously were fabricated by doping target ions in higher valence than that of Fe(3+), such as Ti(4+), Nb(5+) and Zr(4+), into BaFe12O19. In terms of charge balance, Fe(3+)/Fe(2+) pair dipoles are produced through the substitution of Fe(3+) by high-valenced ions. The electron hopping between Fe(3+) and Fe(2+) ions results in colossal permittivity. Whilst the single-phased ceramics doped by target ions exhibit low dielectric loss naturally due to the diminishment of interfacial polarization and still maintain typical magnetic properties. This study provides a convenient method to attain practicable materials with both outstanding magnetic and dielectric properties, which may be of interest to integration and multi-functionality of electronic devices.

  2. Study on Tooth Crown Wear Resistance of the Single-roll Crusher for 120m2 Sintering Machine%120烧结单辊破碎机齿冠抗磨研究

    Institute of Scientific and Technical Information of China (English)

    谢福利; 马敬勋; 许强

    2011-01-01

    The tooth crown of the single-roll crusher at the end of the sintering machine has a very short service life. It is one of the technical difficulties to restrict the sintering process. Owing to poor working conditions, the tooth crown has less than 5 months in average of service life. By analyzing the tooth crown load, failure effect and the factor affecting the wear resistance of high chromium cast iron, it puts forward the roll tooth structure optimization and tooth profile improvement to prolong the service life of the tooth crown.%烧结机尾部的单辊破碎机齿冠使用寿命过短是制约烧结工艺的技术难题之一。由于工作环境恶劣破碎机齿冠平均使用寿命不到5个月。通过分析齿冠受力情况、失效特征及影响高铬铸铁抗磨性能的各方面原因,提出了优化辊齿结构和改进齿形的方法,实施后提高了破碎机齿辊使用寿命。

  3. Urban Crowns: crown analysis software to assist in quantifying urban tree benefits

    Science.gov (United States)

    Matthew F. Winn; Sang-Mook Lee Bradley; Philip A. Araman

    2010-01-01

    UrbanCrowns is a Microsoft® Windows®-based computer program developed by the U.S. Forest Service Southern Research Station. The software assists urban forestry professionals, arborists, and community volunteers in assessing and monitoring the crown characteristics of urban trees (both deciduous and coniferous) using a single side-view digital photograph. Program output...

  4. RELATIONSHIP BETWEEN POWDER COMPOSITION AND SINGLE SCREW EXTRUSION FOR MANUFACTURING RELIABLE RANDOM CERAMIC PACKED BED ACCORDING STATISTICAL APPROACH

    Directory of Open Access Journals (Sweden)

    Amin Salem

    2016-03-01

    Full Text Available The present investigation provides a detailed relationship between the powder composition and reliability of random ceramic beds. This evaluation is important due to standing in the liquid-gas contactors as well as predicting lifetime. It is still unclear whether the normal distribution is the most suitable function for estimation of failure. By developing the application of ceramic beds in the chemical plants, a special attention has been paid in screening strength distributions. To achieve this goal, an experimental-theoretical study was presented on compressive strength distribution. The powder compositions were prepared according to the statistical response surface methodology and then were formed by a single screw extrusion as Raschig rings. The compressive strength of specimens was measured to evaluate the strength data sets by normal and Weibull distributions. The results were analyzed by the Akaike information criterion and the Anderson-Darling test. The accuracy of distributions in prediction fracture was discussed.

  5. Fiber post, resin core with all-ceramic crown big dentinal body defect of the applied research%纤维桩、树脂核结合全瓷冠修复牙体大面积缺损应用研究

    Institute of Scientific and Technical Information of China (English)

    苏丽英; 方鸿满

    2012-01-01

    [目的]探讨纤维桩、树脂核结合全瓷冠修复体的临床应用及其优、劣势.[方法]161例患者的190颗残根、残冠经完善的根管治疗后,采用制作玻璃纤维桩、双固化树脂核恢复基牙外形并行氧化锫全瓷冠修复.[结果]纤维桩组95颗修复体经24个月的临床随访观察,2颗桩核折断(其中12的桩核在9个月折断,34桩核于19个月时折断),1颗桩核松动(7个月),2颗边缘可探及微小缝隙,所有修复体颜色匹配度均完好,修复效果满意,成功率为96.9%.与金属桩组比较(成功率为84.2%),差异具有统计学意义(P<0.05).[结论]玻璃纤维桩、双固化复合树脂、氧化锆全瓷冠是目前修复牙体大面积缺损的临床较理想的修复体.%[Objective] To study the fiber post and resin core combined with clinical application of all-ceramic crown restorations and their advantages and disadvantages. [Methods] In 161 patients 190 residual roots and crowns,after perfect root-pipe treatment, the production of glass fiber post, dual curing resin core recovery of abutment teeth shape parallel zirconia all-ceramic crown restoration. [Results]Fiber post 95 restorations after 24 months of clinical follow-up observation, 2 broken post and core (12, post and core in the nine month break, 34 nuclear in the 19 months to break), 1 teeth post-core loosening (7 months), 2 edge detection and tiny gap, all restorations color matching degree are in good condition, satisfactory repair, the success rate for 96.9%. And the metal pile group ( 84.2% success rate ), the difference was statistically significant ( P < 0.05 ). [ Conclusion ] Glass fiber post, dual curing composite resin, zirconia all-ceramic crown is the repair of big dentinal body defect the more ideal clinical restoration.

  6. 两种粘结剂粘结CAD/CAM氧化锆全瓷冠边缘微渗漏的研究%A comparative study of marginal microleakage using two kinds of cements in CAD/CAM zirconia all ceramic crown

    Institute of Scientific and Technical Information of China (English)

    梁天文; 王珏; 李英

    2012-01-01

    目的 评价两种不同粘结剂在CAD/CAM氧化锆全瓷冠修复中的边缘微渗漏情况.方法 制作10个CAD/CAM氧化锆全瓷冠,随机分成2组,分别采用磷酸锌水门汀粘结剂和Panavia F树脂粘结剂粘固于前磨牙,经温度循环试验后,将样本浸入2%品红溶液中24h,用体视显微镜观察牙-粘结剂界面边缘微渗漏状况,并进行分级评估.结果 采用SPSS 17.0软件对2组的微渗漏程度进行统计分析,得出Panavia F树脂粘结剂微渗漏小于磷酸锌水门汀粘结剂(x2=81.142,P<0.05).结论 Panavia F树脂粘结剂具有较优越的抗边缘微渗漏性能.%Objective To evaluate the marginal microleakage of CAD/CAM zirconia all ceramic crown using two different cements. Methods Ten CAD/CAM zirconia all ceramic crowns were built and randomly divided into two groups, cohered onto standard prepared human forward molars using two different cements (zinc phosphate cement and Panavia F resin cement). After temperature cycling test, all the crowns were then submerged in 2% fuchsin for 24h. The marginal microleakage at tooth cement interfaces was observed using light stereomicroscopy and evaluated in classification index. Results The marginal microleakage grade of two groups were analyzed by SPSS 17.0. The result showed that the marginal microleakage of Panavia F was less than zinc phosphate cement (x2=81.142,P<0.05). Conclusion Panavia F resin cement was suited to cement CAD/CAM zireonia all ceramic crown.

  7. A comparison between the effect of All-Ceramic and metal-ceramic restorations on the plaque accumulation

    Directory of Open Access Journals (Sweden)

    Ezatollah Jalalian

    2015-07-01

    Full Text Available Background and Aims: Tooth crowning often leads to changes in periodontal index through changes in emergence profile zone. The purpose of this study was to compare the effect of metal-ceramic with that ofAll-Ceramic restorations on the plaque a accumulation.   Materials and Methods: In this clinical trial, we used 102 teeth covered with metal-ceramic and all-ceramic restorations. Before and after crowning, plaque index (PI and gingival indexes (MGl were measured. Data were analyzed using covariance (ANCOVA test.   Results: Measured PI and MGI (Mean±SD in PFM Group prior to crowning were (1.96±0.38 and (1.45±0.48, respectively. In metal-ceramic restorations group, six months after crowning, measured PI and MGI (Mean±SD were (1.22±0.49 and (1.82±0.61, respectively. Measured PI and MGI (Mean±SD in All-Ceramic Group prior to crowning were (1.22±0.52 and (1.25±0.29, respectively. In All-Ceramic, six months after crowning, measured PI and MGI (Mean±SD were (0.88±0.51 and (1.43±0.50, respectively. ANOVA test showed statistical significance difference between metal-ceramic and All-Ceramic Groups in Indexes (P<0.001.   Conclusion: Metal-ceramic and All-Ceramic crowns were associated with inflammatory changes in gingival. Metal-ceramic restorations were associated with higher inflammatory indexes compared with All-Ceramic crowns.

  8. Failure analysis of various monolithic posterior aesthetic dental crowns using finite element method

    Science.gov (United States)

    Porojan, Liliana; Topală, Florin

    2017-08-01

    The aim of the study was to assess the effect of material stiffness and load on the biomechanical performance of the monolithic full-coverage posterior aesthetic dental crowns using finite element analysis. Three restorative materials for monolithic dental crowns were selected for the study: zirconia; lithium disilicate glass-ceramic, and resin-based composite. Stresses were calculated in the crowns for all materials and in the teeth structures, under different load values. The experiments show that dental crowns made from all this new aesthetic materials processed by CAD/CAM technologies would be indicated as monolithic dental crowns for posterior areas.

  9. Aesthetic effect of zirconia crown on the anterior tooth%二氧化锆全瓷冠在前牙美容修复中的应用

    Institute of Scientific and Technical Information of China (English)

    邓薇; 杨永进; 蔡兴伟; 张娜; 李颖华; 郑创益

    2011-01-01

    Objective: To investigate the clinical results ofzirconia crown on the anterior tooth. Methods: All 58 patients treated with porcelain-veneered zirconia single crowns for 86 anterior teeth. After 12 months follow up. Results: The clinical outcome of the 86 all-ceramic zirconia crowns at a rank A in all five aspects between 0-6 months (100%), only one zirconia single crowns in marginal fitness (97.6%) and the situation ofgingival (97.6%) at rank B and C after 12 months follow up. Conclusion: Porcelain-veneered zirconia single crown contribute to the aesthetic effect of the anterior teeth.%目的:探讨二氧化锆全瓷冠在前牙美容修复的应用.方法:选择58例患者的86颗前牙,二氧化锆全瓷冠修复,观察1年.结果:86颗二氧化锆全瓷冠在修复完成第1天及6个月五项评价指标均达到A级(100%),12个月边缘完整性(97.6%)和牙龈状况 (97.6%)达到B、C级各1例.结论:二氧化锆全瓷冠在前牙美学修复中的临床效果较理想.

  10. Raman scattering of light in YBa2Cu3O(7-delta) single-phase ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Limonov, M.F.; Markov, IU.F.; Pollert, E.; Triska, A.

    1988-07-01

    Results of an experimental study of Raman spectra are reported for specimens of YBa/sub 2/Cu/sub 3/O(7-delta) ceramics (delta=0.37) produced by the sintering of Y/sub 2/O/sub 3/, CuO, and BaCO/sub 3/. The characteristics of the Raman spectra of the specimens are discussed, and it is shown that the specimens of superconducting ceramics investigated are characterized by high homogeneity, with no traces of the 'parasitic' Y/sub 2/O/sub 3/ and Y/sub 2/Cu/sub 2/O/sub 5/ phases. 7 references.

  11. 磨牙全瓷冠断裂类型的力学实验与三维有限元分析研究%A comparative study of mechanical experiment and three-dimensional finite element analysis on fracture mode of all-ceramic molar crowns

    Institute of Scientific and Technical Information of China (English)

    王勤琴; 张骏; 赵克; 张新平

    2008-01-01

    Objective To investigate the influence of indenter diameter on fracture strength and fracture mode of IPS e. max all-ceramic crowns using mechanical experiments and three-dimensional finite element (3-DFE) method, to validate the 3-DFE model using mechanical experiments, and to provide a guideline for occlnsal surface design for IPS e. max all-ceramic crowns. Methods A 3-DFE model of an all-ceramic crown on a molar was established using ANSYS10.0 software. The 3-DFE crown was loaded occlusally at three points to simulate the contact points of a hemispherical indenter loading on the crown. Two indenter diameters (4 mm and 10 mm) were designed by changing loading point, load level and its direction. The stress distribution and the principal stress in the 3-DFE model were calculated. Meanwhile, IPS e. max ceramic crowns were made on a laboratory model and loaded with indenters. The diameters of the indenters were also 4 mm and 10 mm respectively. Fracture mode and fracture-resistance of the crowns were recorded. Results The principal stress increased as load increases for both small and large indenters. Stress concentrated in the central fossa of the 3-DFE crown when loaded with the small indenter. Stress concentration appeared in the middle area of the occlusal surface mesio-distally when 3-DFE crown was loaded with large indenter. The fracture-resistance load was 600 N to 700 N for 4 mm diameter indenter, and 2500 N to 2750 N for 10 mm diameter indenter. Mechanical experiments indicated the same results as those from 3-DFE analysis. Conclusions Both the three-dimensional finite element analysis and the mechanical experiment showed the same results. When loaded with 4 mm diameter indenter, fracture occured in the central fossa of the crown, however, 10 mm diameter indenter usually caused extensive crown damage.%通过力学实验和三维有限元研究不同直径半球形压头对全瓷冠断裂强度、断裂类型的影响,以期为临床全瓷冠(牙合)面形

  12. Fractographic features of glass-ceramic and zirconia-based dental restorations fractured during clinical function.

    Science.gov (United States)

    Oilo, Marit; Hardang, Anne D; Ulsund, Amanda H; Gjerdet, Nils R

    2014-06-01

    Fractures during clinical function have been reported as the major concern associated with all-ceramic dental restorations. The aim of this study was to analyze the fracture features of glass-ceramic and zirconia-based restorations fractured during clinical use. Twenty-seven crowns and onlays were supplied by dentists and dental technicians with information about type of cement and time in function, if available. Fourteen lithium disilicate glass-ceramic restorations and 13 zirconia-based restorations were retrieved and analyzed. Fractographic features were examined using optical microscopy to determine crack initiation and crack propagation of the restorations. The material comprised fractured restorations from one canine, 10 incisors, four premolars, and 11 molars. One crown was not categorized because of difficulty in orientation of the fragments. The results revealed that all core and veneer fractures initiated in the cervical margin and usually from the approximal area close to the most coronally placed curvature of the margin. Three cases of occlusal chipping were found. The margin of dental all-ceramic single-tooth restorations was the area of fracture origin. The fracture features were similar for zirconia, glass-ceramic, and alumina single-tooth restorations. Design features seem to be of great importance for fracture initiation.

  13. Comparison of Clinical Effects of Au-Pt Based and Ni-Cr Based Porcelain Crowns

    Institute of Scientific and Technical Information of China (English)

    Li-chun Wu; Ye Shi; Teng Ma

    2012-01-01

    Objective To compare the long-term clinical effects of two kinds of crowns and bridges made of porcelain fused to Au-Pt alloy and Ni-Cr alloy.Methods A total of 131 teeth (64 patients) were rehabilitated using porcelain-fused-to-metal crowns,among which 59 were rehabilitated with Au-Pt alloy metal ceramic crown and 72 with Ni-Cr alloy metal ceramic crown.The porcelain fracture,shade,marginal adaptation,gingival discoloration,and gingival status after finishing restoration and 36 months of follow-up were evaluated.Results After 36 months of restoration,porcelain fused to Au-Pt alloy crown showed better clinical effects than porcelain fused to Ni-Cr alloy crown in shade,marginal adaptation,gingival discoloration,as well as gingival status (all P<0.05).Conclusion The Au-Pt alloy ceramic crown is superior to Ni-Cr alloy ceramic crown in long-term clinical effects.

  14. Digital restorative dentistry and prosthodontics(18)---The fit of all-ceramic crowns and custom abutments%数字化口腔修复(18)--CAD/CAM全瓷冠与个性化基台的适合性

    Institute of Scientific and Technical Information of China (English)

    强翔; 姚江武

    2016-01-01

    目的:比较不同计算机辅助设计和制造( computer aided design/manufacture,CAD/CAM)全瓷冠与氧化锆个性化基台的边缘和内部适合性。方法:用CAD/CAM分别设计和加工氧化锆个性化基台和全瓷冠3组( IPS e. max、Enamic和Suprinity),每组各5个全瓷冠。通过微机断层扫描( micro computed tomography,micro⁃CT)测量全瓷冠与氧化锆个性化基台的绝对边缘差异( absolute marginal discrepancy,AMD)、轴面间隙( axial gap,AG)、咬合间隙( oc⁃clusal gap,OG),比较不同材料全瓷冠与氧化锆个性化基台的边缘和内部适合性。结果:Enamic组分别与IPS e. max组和Suprinity组AMD之间的比较差异均具有统计学意义(P<0.05);而IPS e. max组与Suprinity组AMD之间的差异则无统计学意义(P>0.05)。 Suprinity组分别与IPS e. max组和Enamic组AG之间的比较差异均具有统计学意义(P<0.05);IPS e. max组与Enamic组AG之间的差异不具有统计学意义(P>0.05)。 Suprinity组、IPS e. max组和Enamic组3组OG之间的比较差异具有统计学意义(P<0.05)。结论:不同的CAD/CAM全瓷冠材料影响其边缘和内部适合性。 Suprinity和IPS e. max陶瓷材料的边缘适合性优于Enamic材料,Suprinity材料全瓷冠的轴面间隙和咬合间隙最小。%Objective:To compare the marginal and internal fits of different computer aided design/manufacture ( CAD/CAM) all⁃ceramic crowns seated on zirconia custom abutments. Methods:CAD/CAM systems were used to fabricate a zirconia custom abutment and three groups( IPS e. max,Enamic and Suprinity) of all⁃ceramic crowns for five samples,respec⁃tively. The absolute marginal discrepancy( AMD) ,axial gap( AG) ,and occlusal gap( OG) were evaluated by micro computed tomography( micro⁃CT) for comparing the marginal and internal fits of all⁃ceramic crowns and zirconia custom abutments. Re

  15. CAD/CAM氧化锆全瓷冠修复对牙周组织的影响%Effect of the CAD/CAM zirconia all-ceramic crown restoration on periodontal tissue

    Institute of Scientific and Technical Information of China (English)

    商丽娟; 吴岩; 徐永军

    2014-01-01

    背景:全冠修复体远期疗效的维持很大程度上取决于牙周组织的健康状况。目的:探讨CAD/CAM氧化锆全瓷冠修复体对牙周组织健康状况的影响。方法:随机选择需行全冠修复的55例患者64颗基牙作为研究对象,实验组为CAD/CAM氧化锆全瓷冠修复的29例患者32颗基牙,对照组为进行镍铬合金烤瓷冠修复的26例患者32颗基牙。检测两组修复前和修复后12个月的龈沟液含量、肿瘤坏死因子α和白细胞介素6水平,以及牙龈出血指数、牙周探诊深度、菌斑指数及附着丧失。结果与结论:实验组修复前后各指标比较差异均无显著性意义(P >0.05)。对照组修复12个月后的龈沟液含量、肿瘤坏死因子α、白细胞介素6、牙龈出血指数、牙周探诊深度及菌斑指数均高于修复前(P >0.05)。修复12个月后,实验组龈沟液含量、肿瘤坏死因子α、白细胞介素6、牙龈出血指数、牙周探诊深度及菌斑指数均低于对照组(P0.05). At 12 months after restoration, in the control group, the volume of gingival crevicular fluid, the levels of interleukin-6 and tumor necrosis factor-α, sulcus bleeding index, probing depth, and plaque index were al increased (P>0.05);meanwhile, these indexes in the experimental group were significantly lower than those in the control group (P<0.05). Experimental findings suggest that the CAD/CAM zirconia al-ceramic crown restoration is more favorable to the health of periodontal tissues.

  16. Single Tooth Replacement Using InCeram Resin Bonded Fixed Partial Denture: A Clinical Report.

    Directory of Open Access Journals (Sweden)

    Elnaz Moslehifard

    2014-02-01

    Full Text Available This clinical report describes a treatment option for replacement of a missing mandibular anterior tooth using InCeram resin bonded fixed partial denture (RBFPD. The conventional approach for replacing mandibular incisors dictates the placement of either a conventional porcelain-fused-to-metal (PFM bridge, Maryland bridge, or fiber-reinforced composite veneer bridge and several appearance-related disadvantages have been reported in the use of a prosthesis that incorporates a metal substructure. The InCeram bridge is a minimally invasive restoration and eliminates undesirable incisal graying frequently observed in metal RBFPDs. This method was successfully clinically applied to overcome shortcomings of other approaches that may require a minimal invasive technique to preserve lasting sound tooth structure.

  17. Ceramic design concepts based on stress distribution analysis.

    Science.gov (United States)

    Esquivel-Upshaw, J F; Anusavice, K J

    2000-08-01

    This article discusses general design concepts involved in fabricating ceramic and metal-ceramic restorations based on scientific stress distribution data. These include the effects of ceramic layer thickness, modulus of elasticity of supporting substrates, direction of applied loads, intraoral stress, and crown geometry on the susceptibility of certain restoration designs to fracture.

  18. Longevity of Single-Tooth All-Ceramic CAD/CAM Restorations: A Meta-Analysis

    Science.gov (United States)

    2013-07-01

    from 3 to 11 years. Medicina Oral Patologia Oral Cirugia Bucal, 15 (3), e531-e537. Griggs J. (2007). Recent advances in materials for all-ceramic...University of the Health Sciences in partial fulfillment of the requirements of the degree of Master of Science in Oral Biology June 2013...the thesis requirement for the Master of Science degree in Oral Biology at the June 2013 graduation. Thesis Committee: Kim E. Diefenderfe CAPT

  19. A 3-year prospective study of implant-supported, single-tooth restorations of all-ceramic and metal-ceramic materials in patients with tooth agenesis

    DEFF Research Database (Denmark)

    Hosseini, Mandana; Worsaae, Nils; Schiødt, Morten

    2013-01-01

    of crowns, cement excess and technical complications. The aesthetic outcome was assessed by using the Copenhagen Index Score, and the patient-reported outcomes were recorded using the OHIP-49 questionnaire. The statistical analyses were mainly performed by using mixed model of ANOVA for quantitative data...... and PROC NLMIXED for ordinal categorical data. RESULTS: The 3-year survival rate was 100% for implants and 97% for abutments and crowns. Significantly more marginal bone loss was registered at gold-alloy compared to zirconia abutments (P = 0.040). The mPlI and mBI were not significantly different at three......-up examinations, the biological outcome variables such as survival rate of implants, marginal bone level, modified Plaque Index (mPlI), modified Sulcus Bleeding Index (mBI) and biological complications were registered. The technical outcome variables included abutment and crown survival rate, marginal adaptation...

  20. Ceramics as biomaterials for dental restoration.

    Science.gov (United States)

    Höland, Wolfram; Schweiger, Marcel; Watzke, Ronny; Peschke, Arnd; Kappert, Heinrich

    2008-11-01

    Sintered ceramics and glass-ceramics are widely used as biomaterials for dental restoration, especially as dental inlays, onlays, veneers, crowns or bridges. Biomaterials were developed either to veneer metal frameworks or to produce metal-free dental restorations. Different types of glass-ceramics and ceramics are available and necessary today to fulfill customers' needs (patients, dentists and dental technicians) regarding the properties of the biomaterials and the processing of the products. All of these different types of biomaterials already cover the entire range of indications of dental restorations. Today, patients are increasingly interested in metal-free restoration. Glass-ceramics are particularly suitable for fabricating inlays, crowns and small bridges, as these materials achieve very strong, esthetic results. High-strength ceramics are preferred in situations where the material is exposed to high masticatory forces.

  1. Ceramic Laser Materials

    Directory of Open Access Journals (Sweden)

    Guillermo Villalobos

    2012-02-01

    Full Text Available Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers, ultrashort pulse lasers, novel materials such as sesquioxides, fluoride ceramic lasers, selenide ceramic lasers in the 2 to 3 μm region, composite ceramic lasers for better thermal management, and single crystal lasers derived from polycrystalline ceramics. This paper highlights some of these notable achievements.

  2. Ceramic Laser Materials

    Science.gov (United States)

    Sanghera, Jasbinder; Kim, Woohong; Villalobos, Guillermo; Shaw, Brandon; Baker, Colin; Frantz, Jesse; Sadowski, Bryan; Aggarwal, Ishwar

    2012-01-01

    Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG) ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers, ultrashort pulse lasers, novel materials such as sesquioxides, fluoride ceramic lasers, selenide ceramic lasers in the 2 to 3 μm region, composite ceramic lasers for better thermal management, and single crystal lasers derived from polycrystalline ceramics. This paper highlights some of these notable achievements. PMID:28817044

  3. Comparison of the properties of tonpilz transducers fabricated with 001 fiber-textured lead magnesium niobate-lead titanate ceramic and single crystals.

    Science.gov (United States)

    Brosnan, Kristen H; Messing, Gary L; Markley, Douglas C; Meyer, Richard J

    2009-11-01

    Tonpilz transducers are fabricated from 001 fiber-textured 0.72Pb(Mg(1/3)Nb(2/3))O(3)-0.28PbTiO(3) (PMN-28PT) ceramics, obtained by the templated grain growth process, and PMN-28PT ceramic and Bridgman grown single crystals of the same composition. In-water characterization of single element transducers shows higher source levels, higher in-water coupling, and more usable bandwidth for the 81 vol % textured PMN-28PT device than for the ceramic PMN-28PT element. The 81 vol % textured PMN-28PT tonpilz element measured under large signals shows linearity in sound pressure levels up to 0.23 MV/m drive field but undergoes a phase transition due to a lowered transition temperature from the SrTiO(3) template particles. Although the textured ceramic performs well in this application, it could be further improved with compositional tailoring to raise the transition temperature and better processing to improve the texture quality. With these improvements textured piezoelectric ceramics will be viable options for medical ultrasound, actuators, and sonar applications because of their ease of processing, compositional homogeneity, and potentially lower cost than single crystal.

  4. Final restoration of implants with a hybrid ceramic superstructure.

    Science.gov (United States)

    Kurbad, Andreas

    The use of materials with elastic properties for the fabrication of dental implant superstructures seems to be a promising way to reduce the functional occlusal forces on implants. Vita Enamic (Vita Zahnfabrik, Bad Säckingen), a hybrid ceramic material for CAD/CAM technology, is available in a special form that can be relatively easily combined with titanium (Ti) base connectors for the fabrication of abutment crowns and mesostructures. Thus, an easily manageable method is available for reducing peak loads on dental implant fixtures. Representative cases are presented to demonstrate the clinical workflows for a single- element solution (Ti base) and two-element solution (Ti base with mesostructure) for implant-supported crowns.

  5. ZrC Ceramics Prepared by Self-propagating High-temperature Synthesis/Single Action Pressing

    Directory of Open Access Journals (Sweden)

    CHENG Yong

    2017-01-01

    Full Text Available ZrC ceramics were prepared by mechanical axial compression of self-propagating high-temperature synthesis/single action pressing (SHS/SAP.The effects of pressure on microstructure and densification of the products,as well as the relationship between displacement/variation of the load curve and SHS reaction,were studied.The structure and properties of the products were investigated by XRD and SEM.In addition,the density was measured by the drain away liquid method.Meanwhile,universal testing machine was used to record the displacement and load curve alternations.The results indicate that products are mainly composed of ZrC phase,the process of exhaust are accelerated as the increasing of pressure as well,leading to the smaller size of porosity and crystal particles.Density manifested as an increasing pattern by the elevated pressure with no longer change at 80MPa.Due to the strong attenuation of pressure at the peak of temperature,the density of the production is only 65.7% in 120MPa.The end point of the SHS reaction and the plastic time of the products can be monitored by displacement and load curve.The results provide evidence for the application of self-propagating high-temperature synthesis/pseudo-hot isostatic pressing to further improve the density of ceramics.

  6. Crown Fire Potential

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — Crown fire potential was modeled using FlamMap, an interagency fire behavior mapping and analysis program that computes potential fire behavior characteristics. The...

  7. Shear Bond Strength of Orthodontic Brackets Bonded to Zirconium Crowns

    Science.gov (United States)

    Mehmeti, Blerim; Azizi, Bleron; Kelmendi, Jeta; Iljazi-Shahiqi, Donika; Alar, Željko

    2017-01-01

    Background An increasing demand for esthetic restorations has resulted in an increased use of all-ceramic restorations, such as zirconium. However, one of the challenges the orthodontist must be willing to face is how to increase bond strength between the brackets and various ceramic restorations.Bond strength can beaffected bybracket type, by the material that bracketsaremade of, and their base surface design or retention mode. ​ Aim: of this study was to perform a comparative analysis of the shear bond strength (SBS) of metallic and ceramic orthodontic brackets bonded to all-zirconium ceramic surfaces used for prosthetic restorations, and also to evaluate the fracture mode of these two types of orthodontic brackets. Material and methods Twenty samples/semi-crowns of all-zirconium ceramic, on which orthodontic brackets were bonded, 10 metallic and 10 ceramic polycrystalline brackets, were prepared for this research. SBS has been testedby Universal Testing Machine, with a load applied using a knife edged rod moving at a fixed rate of 1 mm/min, until failure occurred. The force required to debond the brackets was recorded in Newton, then SBS was calculated to MPa. In addition, the samples were analyzed using a digital camera magnifier to determine Adhesive Remnant Index (ARI). Statistical data were processed using t-test, and the level of significance was set at α = 0.05. Results Higher shear bond strength values were observed in metallic brackets bonded to zirconium crowns compared tothoseof ceramic brackets, with a significant difference. During the test, two of the ceramic brackets were partially or totally damaged. Conclusion Metallic brackets, compared to ceramic polycrystalline brackets, seemed tocreate stronger adhesion with all-zirconium surfaces due to their better retention mode. Also, ceramic brackets showed higher fragility during debonding. PMID:28827846

  8. IPSe.max Press铸瓷全冠修复效果的临床观察%A short term clinical evaluation of IPS e.max Press all-ceramic crowns

    Institute of Scientific and Technical Information of China (English)

    吴文生; 徐培成; 周曼莉

    2011-01-01

    目的:评价IPS e.max Press铸瓷全冠的临床修复效果.方法:对41例患者127颗前牙和前磨牙进行IPS e.maxPress热压铸瓷全冠修复,修复后12~42个月(平均28个月),参照美国公共卫生服务修正标准对修复体的颜色匹配、边缘着色、修复体折裂、继发龋、边缘适合度以及牙龈健康情况进行评价.结果:在颜色匹配方面,94.49%的修复体表现为A级,5.51%表现为B级;1.57%的全冠出现边缘着色;1颗(0.79%)修复体出现饰面瓷折裂;未发现继发龋;94.49%的修复体边缘适合度表现为A级,5.51%表现为B级;在牙龈健康方面,93.70%的修复体表现为A级,4.72%表现为B级,1.58%表现为C级.结论:在平均28个月的临床观察中,IPS e.max Press铸瓷全冠临床修复效果优良.%PURPOSE: The aim of this study was to evaluate the clinical effect of IPS e.max Press crowns. METHODS: A total of 127 IPS e.max Press crowns was placed in forty-one patients from 2007 to 2009. The crowns were evaluated with a modified USPHS criteria for color match, marginal discoloration, fracture, secondary caries, marginal adaptation and gingival health for a period of 12 to 42 months, with a mean of 28 months after insertion. A,B,C and D ratings were assigned. RESULTS: 94.49% of the crowns were rated as A and 5.51% rated as B for color match and marginal adaptation. 1.57% of the crowns was detected with marginal discoloration and one crown (0.79%) was detected with veneer chipping. No secondary caries was detected, and 93.70% of the crowns were rated as A, 4.72% rated as B and 1.58% rated as C for gingival health. CONCLUSION: IPS e.max Press crowns exhibit excellent clinical performance over a mean evaluation period of 28 months.

  9. Complexes of Diquat with Dibenzo-24-Crown-8

    Institute of Scientific and Technical Information of China (English)

    LI Shijun; HUANG Feihe; SLEBODNICK Carla; ASHRAF-KHORASSANI Mehdi; GIBSON Harry W.

    2009-01-01

    The complexation between dibenzo-24-crown-8(1)and diquat(2)was investigated in detail by NMR,MS andlated,in which a single molecule of diquat is enclosed in the concave cavity provided by two dibenzo-24-crown-8 host molecules.Both results are different from the previously assumed stoichiometry of the complexation between dibenzo-24-crown-8 and diquat.This result enriches the range of host-guest complexes based on dibenzo-24crown-8 and provides new opportunities for developing more complicated structures and chemosensors for diquat.

  10. Clinical retrospective analysis of All-ceramic crowns and bridges with CAD/CAM Zirconia-base: A Four-year Follow up%CAD/CAM氧化锆全瓷冠桥随访4年的临床分析

    Institute of Scientific and Technical Information of China (English)

    孙凤; 张相皡; 晁春良; 杜阳; 李祎

    2011-01-01

    Objective: To evaluate the clinical performance of CAD/CAM zirconia all-ceramic crowns and fixed partial dentures (FPDs). Methods: 681 all-ceramic crowns or FPDs were fabricated for 267 patients. 562 restorations of 205 patients were clinically followed for 2-6 years. Recalls were made 3 months after cementation. Porcelain fracture performance was compared between restorations in anterior and premolar and molar. Using modified US Public Health Service criteria, judgments were made on marginal integrity and shade and color. Loose or dislodgement, fracture and breakage were reviewed in the annually follow up. Results: Chipping rate is 3.3 l%,Chipping of restorations in molars were higher than the restorations in premolars and in anterior teeth (x2 test, P< 0.01). Different technicians had significant influence (x2 test, P< 0.001) on color match of crowns, while different color of abutments did not (x2 test, P> 0.05). The authors rated 90.8% as good or better in regard to color match, 99.2% of the restorations were ranked as good or better on marginal integrity, Loose or dislodgement0.35%, 0% for fracture of Zirconia-based. Conclusion: Zirconia-based all-ceramic crowns with CAD/CAM show good marginal integrity and shade compatibility with nature teeth, with a clinically acceptable chipping rate, This material can be used in conventional and esthetic prosthetic dentistry and especially is the preferred esthetic restorations in case of abutment teeth discoloration. Further studies are needed to reduce the chipping in molars and to improve the marginal integrity of long bridges.%目的:回顾分析评价CAD/CAM氧化锆全瓷冠桥的修复效果.方法:为267位患者制做CAD/CAM氧化锆全瓷冠或桥681件,随访了205例患者的562件全瓷冠桥,随访时间2-6年.对修复体的崩瓷、全瓷冠的颜色与修复体的边缘密合度进行评价.结果:CAD/CAM氧化锆全瓷冠的崩瓷率3.31%,与修复体部位有明显相关性(P<0.01),不

  11. The optical property of four different all-ceramic crowns on the light color core ND1 substructure%高明度 ND1代型材料表面4种全瓷冠光学特性比较

    Institute of Scientific and Technical Information of China (English)

    陈奕帆; 张琳; 刘长虹; 王剑

    2015-01-01

    目的:评估高明度 ND1代型材料表面4种全瓷底冠光学参数 CIE L*a*b*值、透射比,烧结 A2体瓷后与 A2色片色差ΔE。方法:制作 ND1色基牙,分别戴入 Procera 氧化铝、Procera 氧化锆、Lava 氧化锆、IPS E.max 低透铸瓷底冠,分光光度比色仪拍摄并在颈1/3、体1/3、切1/3随机选点测色。4组底冠烧结 A2体瓷粉后再戴入 ND1色基牙(总瓷层厚度控制1.5 mm),分光光度比色仪测色,数据进行单因素方差分析、Bonferroni 多重均数比较。结果:4组底冠均提高基牙的 L*值,彩度a*值下降、b*值变化不一致,多数组间 L*a*b*值有统计学差异。烧结体瓷后各组冠 L*值明显下降,彩度 a*、b*值上升。各部分与 A2总体色差减小(ΔE =1.27~4.17)。4组底冠透光率均值依次为 E.max-LT A2>Pro-Alu >Lava-Zir >Pro-Zir。结论:ND1基牙戴入 4组全瓷底冠后明度、彩度差异大。底冠烧结体瓷后明度差异减少,彩度差异较大。Lava-Zir 和IPS E.max 体瓷组色差超过临床可接受度。铸造陶瓷和氧化铝底冠通透性高于2种氧化锆底冠。%Objective:To evaluate the optical property of the light color core substructure ND1 overlaid by 4 different all-ceramic crowns respectively and to study the color difference between the crowns and target tab.Methods:Light color(ND1)substructures were made and were respectively tried in 4 groups of all-ceramic crowns (Procera alumina,Procera zirconia,Lava zirconia and IPS E.max glass-ceramic lithium disilicate-reinforced monolithic,n =10).The CIE L*,a*,b* values of the cervical part,body and incisal site of the samples were recorded and analyzed by a spectrophotometer before and after veneer.The color difference between the all-ceramic crowns and target A2 dentin tab was evaluated.The spectral integral transmittance of the 4 copings was measured by a spectrophotometer.Results:The L* values of the abutments was

  12. Synthesis and Cation Complexation of Lariat Calix[4 ] crowns

    Institute of Scientific and Technical Information of China (English)

    SHI Zheng-Wei; JIN Chuan-Ming; LU Guo-Yuan

    2003-01-01

    @@ Calixcrowns carrying bridging polyethyleneoxy moieties on the lower rim, which combine calixarene and crown ether in a single molecule, are a novel class of host compounds which have attracted increasing attention because of their increased ability for selective complexation of cations and neutral molecules compared with crown ethers or cal ixarenes.

  13. 单个上前牙即刻种植即刻非功能修复的临床疗效观察%The clinic effect of immediate single-tooth implants and non-functional provisional crowns in the anterior maxilla

    Institute of Scientific and Technical Information of China (English)

    罗智斌; 曾融生; 罗志宾; 林丽婷; 徐佳丽

    2009-01-01

    Objective To observe the clinical effect of the restoration of a single upper missing tooth with immediate implant placement and non-functional prosthesis in the aesthetic area. Methods Seven consecutive patients with un-savable single teeth in the aesthetic zone were included. Teeth were extracted and replaced with immediate implant and non-functional provisional crowns. Suitable permanent abutments were chosen and porcelain-fused-metal or all-ceramic restorations were made on the abutments after 6 months. Patients were followed up 1 year after crown insertion. The marginal bone level around the implant and Pink Esthetic Score (PES) value immediately after crown insertion and 1 year later were measured for comparison. Results The success rate of implant was 100%, mesial and distal peri-implant bone changes were (0.79 ± 0.48)mm and (0.71 ± 0.46)mm respectively. The average PES value was (8.6 ± 1.3) and (11.1 ± 1.8), respectively. Significant difference was found by Walcoxon analysis (P=0.027). Conclusions For strictly selected cases, single-tooth immediate implant and immediate non-functional prosthetsis is an effective method. Good appearance can be achieved and the esthetics of peri-implant soft tissue can be improved over time.%目的 探讨美学区单个上前牙即刻种植即刻非功能修复临床疗效.方法 7例上颌单个无法保留患牙,拔除后即刻植入种植体,当日制作并戴入临时树脂冠,6个月后复诊取模,选择合适基台制作永久金属烤瓷或全瓷修复体,最终修复体戴入后1年复诊,比较刚戴入修复体与1年后随诊时种植体周骨组织水平以及红色美学指数(PES)的变化情况.结果 种植体成功率为100%,种植体近、远中周牙槽骨变化分别为(0.79 ± 0.48)mm、(0.71 ± 0.46)mm;刚戴入修复体与1年后随诊时PES值分别为(8.6 ± 1.3)和(11.1 ± 1.8),Walcoxon统计学分析,两者差异有统计学意义(P=0.027).结论 在严格选择病例的情况下,单牙即

  14. A comparison between the effect of All-Ceramic and metal-ceramic restorations on the plaque accumulation

    OpenAIRE

    Ezatollah Jalalian; Fatemeh Rajaei; Marzieh Bavaisi; Niloofar Moghaddam; Fereshte Keykha; Rezvaneh Cheraghi

    2015-01-01

    Background and Aims: Tooth crowning often leads to changes in periodontal index through changes in emergence profile zone. The purpose of this study was to compare the effect of metal-ceramic with that ofAll-Ceramic restorations on the plaque a accumulation.   Materials and Methods: In this clinical trial, we used 102 teeth covered with metal-ceramic and all-ceramic restorations. Before and after crowning, plaque index (PI) and gingival indexes (MGl) were measured. Data were analyzed using co...

  15. IN-SITU FORMATION AND DENSIFICATION OF MgAl2O4-SmAlO3 CERAMICS BY A SINGLE-STAGE REACTION SINTERING PROCESS

    Directory of Open Access Journals (Sweden)

    Beiyue Ma

    2015-06-01

    Full Text Available Stoichiometric magnesium aluminate spinel (MgAl2O4, MA-samarium aluminate (SmAlO3, SA ceramics have been prepared at 1580oC for 4 h from calcined magnesia (MgO, commercial alumina (Al2O3 and samarium oxide (Sm2O3 by a single-stage in-situ reaction sintering (SIRS method. The phase compositions, microstructures, shrinkage ratio, bulk density and cold compressive strength of the MA-SA ceramics have been investigated. The ceramics with 2.5 - 7.5 wt. % Sm2O3 are composed of MA and SA phases. The microstructures of the ceramics are dense. MA particles exist as angular shape, and their grain size varies between 2 and 10 μm but the average grain size is about 5 μm. SmAlO3 particles form due to the reaction of Sm2O3 and Al2O3, and they distribute in the intergranular space of MA grains. The diameter shrinkage ratio, volume shrinkage ratio, bulk density and cold compressive strength of MA-SA ceramics are greatly improved due to the addition of Sm2O3

  16. Clinical assessment of enamel wear caused by monolithic zirconia crowns.

    Science.gov (United States)

    Stober, T; Bermejo, J L; Schwindling, F S; Schmitter, M

    2016-08-01

    The purpose of this study was to measure enamel wear caused by antagonistic monolithic zirconia crowns and to compare this with enamel wear caused by contralateral natural antagonists. Twenty monolithic zirconia full molar crowns were placed in 20 patients. Patients with high activity of the masseter muscle at night (bruxism) were excluded. For analysis of wear, vinylpolysiloxane impressions were prepared after crown incorporation and at 6-, 12-, and 24-month follow-up. Wear of the occlusal contact areas of the crowns, of their natural antagonists, and of two contralateral natural antagonists (control teeth) was measured by use of plaster replicas and a 3D laser-scanning device. Differences of wear between the zirconia crown antagonists and the control teeth were investigated by means of two-sided paired Student's t-tests and linear regression analysis. After 2 years, mean vertical loss was 46 μm for enamel opposed to zirconia, 19-26 μm for contralateral control teeth and 14 μm for zirconia crowns. Maximum vertical loss was 151 μm for enamel opposed to zirconia, 75-115 μm for control teeth and 60 μm for zirconia crowns. Statistical analysis revealed significant differences between wear of enamel by zirconia-opposed teeth and by control teeth. Gender, which significantly affected wear, was identified as a possible confounder. Monolithic zirconia crowns generated more wear of opposed enamel than did natural teeth. Because of the greater wear caused by other dental ceramics, the use of monolithic zirconia crowns may be justified.

  17. Characterization of High-Velocity Single Particle Impacts on Plasma-Sprayed Ceramic Coatings

    Science.gov (United States)

    Kiilakoski, Jarkko; Lindroos, Matti; Apostol, Marian; Koivuluoto, Heli; Kuokkala, Veli-Tapani; Vuoristo, Petri

    2016-08-01

    High-velocity impact wear can have a significant effect on the lifetime of thermally sprayed coatings in multiple applications, e.g., in the process and paper industries. Plasma-sprayed oxide coatings, such as Cr2O3- and TiO2-based coatings, are often used in these industries in wear and corrosion applications. An experimental impact study was performed on thermally sprayed ceramic coatings using the High-Velocity Particle Impactor (HVPI) at oblique angles to investigate the damage, failure, and deformation of the coated structures. The impact site was characterized by profilometry, optical microscopy, and scanning electron microscopy (SEM). Furthermore, the connection between the microstructural details and impact behavior was studied in order to reveal the damage and failure characteristics at a more comprehensive level. Differences in the fracture behavior were found between the thermally sprayed Cr2O3 and TiO2 coatings, and a concept of critical impact energy is presented here. The superior cohesion of the TiO2 coating inhibited interlamellar cracking while the Cr2O3 coating suffered greater damage at high impact energies. The HVPI experiment has proven to be able to produce valuable information about the deformation behavior of coatings under high strain rates and could be utilized further in the development of wear-resistant coatings.

  18. Crown lengthening revisited.

    Science.gov (United States)

    Rosenberg, E S; Cho, S C; Garber, D A

    1999-06-01

    Over the last 37 years, crown-lengthening procedures have been used predictably to restore teeth broken down from caries, trauma, and extensive wear. With crown lengthening, the dentogingival junction is "re-created" at a more apical level on the root to accommodate the junctional epithelium and the connective tissue attachment. Forced eruption can be used in addition, or as an alternative, to tooth lengthening. The authors discuss the indications for tooth lengthening, forced eruption, and orthodontic extrusion, as well as the treatment planning for these procedures.

  19. Restoration of the Severely Decayed Tooth Using Crown Lengthening with Simultaneous Tooth-Preparation

    OpenAIRE

    2010-01-01

    This clinical case describes a treatment approach that combines, in a single appointment, a crown lengthening procedure and the final crown preparation for the restoration of a severely decayed tooth. This approach allows for a more accurate placement of the crown margin in relation to the bone crest while reducing treatment time.

  20. Restoration of the severely decayed tooth using crown lengthening with simultaneous tooth-preparation.

    Science.gov (United States)

    Park, Jun-Beom

    2010-04-01

    This clinical case describes a treatment approach that combines, in a single appointment, a crown lengthening procedure and the final crown preparation for the restoration of a severely decayed tooth. This approach allows for a more accurate placement of the crown margin in relation to the bone crest while reducing treatment time.

  1. The Evaluation of the Use of Single Cast Metal Post-core Retained Com-plete Crown in the Treatment of Posterior Teeth%单根管桩核修复磨牙残冠的临床观察

    Institute of Scientific and Technical Information of China (English)

    张朔

    2009-01-01

    目的 评价单根管桩核修复磨牙残冠的效果.方法 2007年2月~2008年2月在本院就诊的磨牙残冠缺损患者40例,随机分成观察组(单根管桩核修复)和对照组(多根管分体桩核修复)两组.修复结束后评价比较两组的治疗效果.结果 观察组随访1年,仅1个(5.00%)单根管桩核冠出现桩核松动,其余单根管桩核X线片显示桩核与根管结合紧密,患者咀嚼功能恢复良好.对照组无桩核松动.观察组修复后1年咬合力测试结果为(29.89±7.42)kg,与对照组咬合力测试结果(30.65±6.94)kg比较差异不显著(t=0.3345,P>0.05).结论 单根管桩核修复磨牙残冠效果尚佳,克服了多根桩制作的复杂程序,建议临床进一步推广.%Objective To evaluate the effects of single cast metal post-core retained complete crown in the treatment of posterior teeth. Methods February 2007 ~ 2008 in our hospital for treatment of patients with molar residual crown and 40 cases of defects,were randomly divided into observation group(a single dowel-core repair) and the control group(more than root canal post and core restoration split) groups. After the repair, the evaluation results were compared between two groups. Results 1-year follow-up of the observation group, only 1 (5.00%) a single dowel-core crown core appeared relaxed,and the remaining single dowel-core X-ray fdm and the root canal post and core combination of close, masticatory function in patients with good recovery. The control group without post-core loosening. Observer Group after one year to repair the test results for bite force(29.89 ± 7.42)kg with the control group to test the results of bite force(30.65 ± 6.94)kg compared with no sig-nificant difference(t=0.3345,P>0.05). Conclusion Single cast metal post-core retained complete crown in the treatment of posterior teeth better results,also overcome many root pile of the complicated process of production,may make recommendations to further promote the

  2. Aesthetic Surgical Crown Lengthening Procedure.

    Science.gov (United States)

    de Oliveira, Pablo Santos; Chiarelli, Fabio; Rodrigues, José A; Shibli, Jamil A; Zizzari, Vincenzo Luca; Piattelli, Adriano; Iezzi, Giovanna; Perrotti, Vittoria

    2015-01-01

    The aim of this case report was to describe the surgical sequence of crown lengthening to apically reposition the dentogingival complex, in addition to an esthetic restorative procedure. Many different causes can be responsible for short clinical crown. In these cases, the correct execution of a restorative or prosthetic rehabilitation requires an increasing of the crown length. According to the 2003 American Academy of Periodontology (Practice Profile Survey), crown lengthening is the most habitual surgical periodontal treatment.

  3. Aesthetic Surgical Crown Lengthening Procedure

    OpenAIRE

    2015-01-01

    The aim of this case report was to describe the surgical sequence of crown lengthening to apically reposition the dentogingival complex, in addition to an esthetic restorative procedure. Many different causes can be responsible for short clinical crown. In these cases, the correct execution of a restorative or prosthetic rehabilitation requires an increasing of the crown length. According to the 2003 American Academy of Periodontology (Practice Profile Survey), crown lengthening is the most h...

  4. Aesthetic Surgical Crown Lengthening Procedure

    Science.gov (United States)

    de Oliveira, Pablo Santos; Chiarelli, Fabio; Rodrigues, José A.; Shibli, Jamil A.; Zizzari, Vincenzo Luca; Piattelli, Adriano; Iezzi, Giovanna; Perrotti, Vittoria

    2015-01-01

    The aim of this case report was to describe the surgical sequence of crown lengthening to apically reposition the dentogingival complex, in addition to an esthetic restorative procedure. Many different causes can be responsible for short clinical crown. In these cases, the correct execution of a restorative or prosthetic rehabilitation requires an increasing of the crown length. According to the 2003 American Academy of Periodontology (Practice Profile Survey), crown lengthening is the most habitual surgical periodontal treatment. PMID:26609452

  5. Aesthetic Surgical Crown Lengthening Procedure

    Directory of Open Access Journals (Sweden)

    Pablo Santos de Oliveira

    2015-01-01

    Full Text Available The aim of this case report was to describe the surgical sequence of crown lengthening to apically reposition the dentogingival complex, in addition to an esthetic restorative procedure. Many different causes can be responsible for short clinical crown. In these cases, the correct execution of a restorative or prosthetic rehabilitation requires an increasing of the crown length. According to the 2003 American Academy of Periodontology (Practice Profile Survey, crown lengthening is the most habitual surgical periodontal treatment.

  6. Conservative restorative treatment using a single-visit, all-ceramic CAD/CAM system.

    Science.gov (United States)

    Benk, Joel

    2007-01-01

    Computer-aided design/computer-aided manufacturing (CAD/CAM) continues to radically change the way in which the dental team plans, prepares, and fabricates a patient's restoration. This advancing technology offers the clinician the ability to scan the patient's failing dentition and then designs a long-lasting, reliable restoration based on this data. CAD/CAM systems also permit efficient, single-visit placement of the restoration while preserving much of the natural tooth structure. This article discusses how a chairside CAD/CAM system can be used to provide such a restoration in the posterior region in a single-visit.

  7. Crown lengthening procedures

    Directory of Open Access Journals (Sweden)

    AA. Khoshkhonejad

    1994-06-01

    Full Text Available Nowadays, due to recent developments and researches in dental science, it is possible to preserve and restore previously extracted cases such as teeth with extensive caries, fractured or less appropriate cases for crown coverage as well as teeth with external perforation caused by restorative pins. In order to restore the teeth with preservation of periodontium, we should know thoroughly physiological aspects of periodontium and protection of Biologic Width which is formed by epithelial and supracrestal connective tissue connections. Considering biologic width is one of the principal rules of teeth restoration, otherwise we may destruct periodontal tissues. Several factors are involved in placing a restoration and one of the most important ones is where the restoration margin is terminated. Many studies have been conducted on the possible effects of restoration margin on the gingiva and due to the results of these studies it was concluded that restoration margin should be finished supragingivally. However, when we have to end the restoration under Gingival Crest, First a healthy gingival sulcus is required. Also, we should not invade the biological width. Since a normal biologic with is reported 2 mm and sound tooth tissue should be placed at least 2 mm coronal to the epithelial tissue, the distance between sound tooth tissue and crown margin should be at least 4mm. Thus, performing crown lengthening is essential to increase the clinical crown length. Basically, two objectives are considered: 1 restorative 2 esthetic (gummy smile Surgical procedure includes gingivectomy and flap procedure. Orthodontic procedure involves orthodontic extrusion or force eruption technique which is controlled vertical movements of teeth into occlusion. Besides, this procedure can also used to extrude teeth defects from the gingival tissue. By crown lengthening, tooth extraction is not required and furthermore, adjacent teeth preparation for placing a fixed

  8. Three- to nine-year survival estimates and fracture mechanisms of zirconia- and alumina-based restorations using standardized criteria to distinguish the severity of ceramic fractures.

    Science.gov (United States)

    Moráguez, Osvaldo D; Wiskott, H W Anselm; Scherrer, Susanne S

    2015-12-01

    The aims of this study were set as follows: 1. To provide verifiable criteria to categorize the ceramic fractures into non-critical (i.e., amenable to polishing) or critical (i.e., in need of replacement) 2. To establish the corresponding survival rates for alumina and zirconia restorations 3. To establish the mechanism of fracture using fractography Fifty-eight patients restored with 115 alumina-/zirconia-based crowns and 26 zirconia-based fixed dental prostheses (FDPs) were included. Ceramic fractures were classified into four types and further subclassified into "critical" or "non-critical." Kaplan-Meier survival estimates were calculated for "critical fractures only" and "all fractures." Intra-oral replicas were taken for fractographic analyses. Kaplan-Meier survival estimates for "critical fractures only" and "all fractures" were respectively: Alumina single crowns: 90.9 and 68.3 % after 9.5 years (mean 5.71 ± 2.6 years). Zirconia single crowns: 89.4 and 80.9 % after 6.3 years (mean 3.88 ± 1.2 years). Zirconia FDPs: 68.6 % (critical fractures) and 24.6 % (all fractures) after 7.2 and 4.6 years respectively (FDP mean observation time 3.02 ± 1.4 years). No core/framework fractures were detected. Survival estimates varied significantly depending on whether "all" fractures were considered as failures or only those deemed as "critical". For all restorations, fractographic analyses of failed veneering ceramics systematically demonstrated heavy occlusal wear at the failure origin. Therefore, the relief of local contact pressures on unsupported ceramic is recommended. Occlusal contacts on mesial or distal ridges should systematically be eliminated. A classification standard for ceramic fractures into four categories with subtypes "critical" and "non-critical" provides a differentiated view of the survival of ceramic restorations.

  9. Portfolio: Ceramics.

    Science.gov (United States)

    Hardy, Jane; And Others

    1982-01-01

    Describes eight art activities using ceramics. Elementary students created ceramic tiles to depict ancient Egyptian and medieval European art, made ceramic cookie stamps, traced bisque plates on sketch paper, constructed clay room-tableaus, and designed clay relief masks. Secondary students pit-fired ceramic pots and designed ceramic Victorian…

  10. Portfolio: Ceramics.

    Science.gov (United States)

    Hardy, Jane; And Others

    1982-01-01

    Describes eight art activities using ceramics. Elementary students created ceramic tiles to depict ancient Egyptian and medieval European art, made ceramic cookie stamps, traced bisque plates on sketch paper, constructed clay room-tableaus, and designed clay relief masks. Secondary students pit-fired ceramic pots and designed ceramic Victorian…

  11. Ceramic laser materials

    Science.gov (United States)

    Ikesue, Akio; Aung, Yan Lin

    2008-12-01

    The word 'ceramics' is derived from the Greek keramos, meaning pottery and porcelain. The opaque and translucent cement and clay often used in tableware are not appropriate for optical applications because of the high content of optical scattering sources, that is, defects. Recently, scientists have shown that by eliminating the defects, a new, refined ceramic material - polycrystalline ceramic - can be produced. This advanced ceramic material offers practical laser generation and is anticipated to be a highly attractive alternative to conventional glass and single-crystal laser technologies in the future. Here we review the history of the development of ceramic lasers, the principle of laser generation based on this material, some typical results achieved with ceramic lasers so far, and discuss the potential future outlook for the field.

  12. Probing the Nanodomain Origin and Phase Transition Mechanisms in (UnPoled PMN-PT Single Crystals and Textured Ceramics

    Directory of Open Access Journals (Sweden)

    Aneta Slodczyk

    2010-11-01

    Full Text Available Outstanding electrical properties of solids are often due to the composition heterogeneity and/or the competition between two or more sublattices. This is true for superionic and superprotonic conductors and supraconductors, as well as for many ferroelectric materials. As in PLZT ferroelectric materials, the exceptional ferro- and piezoelectric properties of the PMN-PT ((1−xPbMg1/3Nb2/3O3−xPbTiO3 solid solutions arise from the coexistence of different symmetries with long and short scales in the morphotropic phase boundary (MPB region. This complex physical behavior requires the use of experimental techniques able to probe the local structure at the nanoregion scale. Since both Raman signature and thermal expansion behavior depend on the chemical bond anharmonicity, these techniques are very efficient to detect and then to analyze the subtitle structural modifications with an efficiency comparable to neutron scattering. Using the example of poled (field cooling or room temperature and unpoled PMN-PT single crystal and textured ceramic, we show how the competition between the different sublattices with competing degrees of freedom, namely the Pb-Pb dominated by the Coulombian interactions and those built of covalent bonded entities (NbO6 and TiO6, determine the short range arrangement and the outstanding ferro- and piezoelectric properties.

  13. Monolithic zirconia dental crowns. Internal fit, margin quality, fracture mode and load at fracture.

    Science.gov (United States)

    Schriwer, Christian; Skjold, Anneli; Gjerdet, Nils Roar; Øilo, Marit

    2017-09-01

    Dental all-ceramic restorations of zirconia, with and without an aesthetic veneering layer, have become a viable alternative to conventional metal-ceramic restorations. The aim of this study was to evaluate whether factors of the production methods or the material compositions affect load at fracture, fracture modes, internal fit or crown margins of monolithic zirconia crowns. Sixty crowns made from six different commercially available dental zirconias were produced to a model tooth with a shallow circumferential chamfer preparation. Internal fit was assessed by the replica method. The crown margin quality was assessed by light microscopy on an ordinal scale. The cemented crowns were loaded centrally in the occlusal fossa with a horizontal steel cylinder with a diameter of 13mm at 0.5mm/min until fracture. Fractographic analysis was performed on the fractured crowns. There were statistically significant differences among the groups regarding crown margins, internal fit and load at fracture (p<0.05, Kruskall Wallis). Fracture analyses revealed that all fractures started cervically and propagated to the occlusal surface similar to clinically observed fractures. There was statistically significant correlation between margin quality and load at fracture (Spearman's rank correlation, p<0,05). Production method and material composition of monolithic zirconia crowns affect internal fit, crown margin quality and the load at fracture. The hard-machined Y-TZP zirconia crowns had the best margin quality and the highest load at fracture. Reduction of margin flaws will improve fracture strength of monolithic zirconia crowns and thereby increase clinical success. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  14. Marginal Assessment of Crowns by the Aid of Parallel Radiography

    Directory of Open Access Journals (Sweden)

    Farnaz Fattahi

    2015-03-01

    Full Text Available Introduction: Marginal adaptation is the most critical item in long-term prognosis of single crowns. This study aimed to assess the marginal quality as well asthe discrepancies in marginal integrity of some PFM single crowns of posterior teeth by employing parallel radiography in Shiraz Dental School, Shiraz, Iran. Methods: In this descriptive study, parallel radiographies were taken from 200 fabricated PFM single crowns of posterior teeth after cementation and before discharging the patient. To calculate the magnification of the images, a metallic sphere with the thickness of 4 mm was placed in the direction of the crown margin on the occlusal surface. Thereafter, the horizontal and vertical space between the crown margins, the margin of preparations and also the vertical space between the crown margin and the bone crest were measured by using digital radiological software. Results: Analysis of data by descriptive statistics revealed that 75.5% and 60% of the cases had more than the acceptable space (50µm in the vertical (130±20µm and horizontal (90±15µm dimensions, respectively. Moreover, 85% of patients were found to have either horizontal or vertical gap. In 77% of cases, the margins of crowns invaded the biologic width in the mesial and 70% in distal surfaces. Conclusion: Parallel radiography can be expedient in the stage of framework try-in to yield some important information that cannot be obtained by routine clinical evaluations and may improve the treatment prognosis

  15. Analysis of the stress-strain state in single overlap joints using piezo-ceramic actuators

    Science.gov (United States)

    Pǎltânea, Veronica; Pǎltânea, Gheorghe; Popovici, Dorina; Jiga, Gabriel; Papanicolaou, George

    2014-05-01

    In this paper is presented a 2D approach to finite element modeling and an analytical calculus of a single lap bonded joint. As adherent material were selected a sheet of wood, aluminum and titanium. For adhesive part were selected Bison Super Wood D3 in case of the wood single lap joint and an epoxy resin type DGEBA-TETA for gluing together aluminum and titanium parts. In the article is described a combined method, which consists in the placement of the piezoelectric actuator inside of the adhesive part, in order to determine the tensile stress in the overlap joint. A comparison between the analytical and numerical results has been achieved through a multiphysics modeling - electrical and mechanical coupled problem. The technique used to calculate the mechanical parameters (First Principal Stress, displacements) was the three-point bending test, where different forces were applied in the mid-span of the structure, in order to maintain a constant displacement rate. The length of the overlap joint was modified from 20 to 50 mm.

  16. 有限元法分析不同粘接剂对全瓷冠应力分布的影响%Effect of different bonding agents on the stress distribution of all-ceramic crown by three-dimension finite element analysis

    Institute of Scientific and Technical Information of China (English)

    李冰; 张晔; 武秀萍; 邓菁菁; 吴婷婷; 张并生

    2014-01-01

    目的:探讨不同种类粘接剂对双层结构的全瓷冠及粘接剂应力分布的影响,为临床修复设计提供依据。方法利用螺旋CT断层图像,构建双层结构的全瓷冠(核瓷层和饰瓷层)、粘接剂层、牙体组织、牙根、牙周膜和牙槽骨6部分的三维有限元模型,设计垂直集中载荷600N的加载方式,分析全瓷冠经3种不同粘接剂(Panavia,3M RelyX Unicem,3M RelyX Luting)粘固后,粘接剂层、核瓷层和饰瓷层的最大主应力分布。结果粘接层应力集中部位为近中颊侧肩台和腭侧面近牙合面部分。核瓷层应力主要集中在核瓷内部,饰瓷层应力主要集中在加载点附近。随着粘接材料弹性模量的增加,位于饰瓷层的最大主应力呈现出下降的趋势,而位于核瓷层和粘接层的最大主应力出现上升的趋势。结论全瓷冠在不同粘接材料粘固后受到力的作用时,最大主应力分布区域相对固定,但分布范围有向加载侧分布的趋势。在某些条件下,高弹性模量的粘接剂可能会降低全瓷冠崩瓷的发生,并在一定程度上降低核瓷层的抗折能力。%Objective To investigate the relationship between the bonding agents and the stress distribu-tion of all-ceramic crown and then provide the basis for clinical restoration design. Methods The tomography im-ages of spiral CT were used to construct the finite element analysis mode, which was composed of six parts:double layer structure of all-ceramic crown(include the core layer and the veneer layer), adhesive layer, tooth tissues, tooth root, periodontal ligament, and alveolar bone. The loading way was designed as follows:600N load was verti-cally concentrated, and ANSYS software was used to analyze the stress values of the core layer、the veneer layer and the adhesive layer with three bonding agents including the Panavia,the 3M RelyX Unicem and the3M RelyX Luting cement. Results The distribution

  17. PES and WES evaluation of CAD/CAM custom abutments and all ceramic crowns in the anterior teeth area%红、白美学评价 CAD/CAM 个性化基台与全瓷冠在前牙区的应用

    Institute of Scientific and Technical Information of China (English)

    张晓真; 周国兴; 戴文雍; 赵毅; 邱憬; 王洁; 汤春波

    2013-01-01

    Objective:To investigate the clinic application of computer aided design&computer aided manufacturing ( CAD/CAM) custom abutments and all ceramic crowns and evaluate their esthetic effect in the anterior teeth area according to the assessment criteria Pink Esthetic Score ( PES ) and White Esthetic Score ( WES ) .Methods:Totally 73 CAD/CAM custom abutments and all ceramic crowns were used in 51 implant-supported prosthesis cases .The esthetic prosthetic effect was evaluated according to the assessment cri-teria PES and WES.Results:The 3-month-follow-up results of totally 73 CAD/CAM custom abutments and all ceramic crowns of 51 pa-tients:the percentage of the PES scores of 10,8-9,6-7 and≤5 was 9.59%,71.23%,17.81%,and 1.37%,respectively;the percent-age of the WES scores of 10,8-9,6-7 and ≤5 was 39.73%,60.27%,0%,and 0%,respectively.The 6-month-follow-up results: the percentage of the PES scores of 10,8-9,6-7 and≤5 was 8.22%,69.86%,17.81%,and 4.11%,respectively;the percentage of the WES scores of 10,8-9,6-7 and≤5 was 36.99%,61.64%,1.37%,and 0%,respectively.The 1-year-follow-up results:the percentage of the PES scores of 10,8-9,6-7 and≤5 was 5.48%,68.49%,20.55%,and 5.48%,respectively;the percentage of the WES scores of 10,8-9,6-7 and ≤5 was 31.51%,64.38%,4.11%,and 0%,respectively.During the follow-up of 1 to 3 years,there was only one abutment got fractured when the torque control was installed ,and one loosened during observation .In all cases,the gingivae were in healthy condition ,and no further obvious gingival retreat or periimplantitis occurred .Conclusions:PES and WES are objective ,integrat-ed and comparable .CAD/CAM custom abutments and all ceramic crowns have good biocompatibility and chemical stability ,and can be more widely used in the anterior teeth area .However,their long term effects need to be confirmed by further follow-up.%目的:研究计算机辅助设计及计算机辅助制作( CAD/CAM )个性化基台及全瓷冠的临床

  18. Fracture resistance of computer-aided design/computer-aided manufacturing-generated composite resin-based molar crowns.

    Science.gov (United States)

    Harada, Akio; Nakamura, Keisuke; Kanno, Taro; Inagaki, Ryoichi; Örtengren, Ulf; Niwano, Yoshimi; Sasaki, Keiichi; Egusa, Hiroshi

    2015-04-01

    The aim of this study was to investigate whether different fabrication processes, such as the computer-aided design/computer-aided manufacturing (CAD/CAM) system or the manual build-up technique, affect the fracture resistance of composite resin-based crowns. Lava Ultimate (LU), Estenia C&B (EC&B), and lithium disilicate glass-ceramic IPS e.max press (EMP) were used. Four types of molar crowns were fabricated: CAD/CAM-generated composite resin-based crowns (LU crowns); manually built-up monolayer composite resin-based crowns (EC&B-monolayer crowns); manually built-up layered composite resin-based crowns (EC&B-layered crowns); and EMP crowns. Each type of crown was cemented to dies and the fracture resistance was tested. EC&B-layered crowns showed significantly lower fracture resistance compared with LU and EMP crowns, although there was no significant difference in flexural strength or fracture toughness between LU and EC&B materials. Micro-computed tomography and fractographic analysis showed that decreased strength probably resulted from internal voids in the EC&B-layered crowns introduced by the layering process. There was no significant difference in fracture resistance among LU, EC&B-monolayer, and EMP crowns. Both types of composite resin-based crowns showed fracture loads of >2000 N, which is higher than the molar bite force. Therefore, CAD/CAM-generated crowns, without internal defects, may be applied to molar regions with sufficient fracture resistance. © 2015 Eur J Oral Sci.

  19. Multidisciplinary and esthetic approach to clinical crown lengthening: report of a case.

    Science.gov (United States)

    Ngan, P; Knobloch, L

    1993-12-01

    This paper describes the combined efforts of an orthodontist, periodontist, and a restorative dentist to save an unrestorable tooth by clinical crown lengthening. A maxillary lateral incisor, originally treatment planned for extraction, was treated with orthodontic extrusion, circumferential fiberotomy, and metal-ceramic crown restoration. To maximize the esthetic appearance of the tooth during orthodontic treatment, an acrylic resin facing was designed together with the orthodontic appliance used to facilitate vertical extrusion. Clinical crown lengthening may be used as an alternative approach to the treatment of severely broken down anterior teeth.

  20. Aestheric effect of zirconia crown on the anterior tooth%前牙二氧化锆全瓷冠美容修复疗效的临床观察

    Institute of Scientific and Technical Information of China (English)

    毕鹏; 刘宝娟; 张红

    2012-01-01

    目的:探讨二氧化锆全瓷冠在前牙美容修复的临床综合修复效果.方法:选择64例患者的122颗前牙,二氧化锆全瓷冠修复,参照美国公共健康协会的修正标准,对临床结果进行追踪观察1年.结果:122颗二氧化锆全瓷冠在修复完成第1天6项评价指标均达到A级(100%),3个月边缘着色(96.7%)和修复体颜色(96.7%),6个月边缘着色(93.2%)和边缘密合度(98.3%),1年边缘着色(91.4%)和边缘密合度(96.6%).结论:二氧化锆全瓷冠在前牙美学修复中的临床效果较理想.%Objective To investigate the clinical results of zirconia crown on the anterior tooth. Methods All 64 patients treated with zirconia single crowns for 122 anterior teeth,r followed up and after 1 yea. Results The clinical outcome of the 122 all-ceramic zirconia crowns at a rank A in all six aspects betweenO-3months (100%),only four zirconia crowns in marginal color (96.7%) and the color of zirconia crowns (96.7%)in 3 months,eight zirconia crowns in marginal color (93.2%)and two zirconia crowns in marginal fitness (98.3% )in 6 months.ten zirconia crowns in marginal cofor (91.4%)and four zirconia crowns in marginal fitness (96.6%)in 1 year. Conclusion Porcelain-veneered zirconia single crown contribute to the aesthetic effect of the anterior teeth.

  1. Three-dimensional finite element stress analysis of all-ceramic crowns of the first mandibular molar%下颌第一磨牙全瓷冠的三维有限元分析

    Institute of Scientific and Technical Information of China (English)

    贾骏; 段嫄嫄; 周建学; 吴舜; 张少锋

    2006-01-01

    目的:研究下颌第一磨牙进行全瓷冠修复后的应力分布情况,为全瓷冠的临床修复设计提供理论依据.方法:建立下颌第一磨牙的三维有限元模型,分别生成EmpressⅠ、EmpressⅡ、In-Ceram Alumina 以及In-Ceram Zirconia 4种材料的全瓷冠模型.模拟最大咬合力600 N垂直加载于全瓷冠模型咬合面.结果:4种材料的应力分布规律相似,并且其压应力、张应力以及剪切应力极值之间无显著性差异.压应力集中在全瓷冠表面,而张应力、剪切应力则主要集中在牙冠边缘和牙冠内表面部分.结论:静态载荷下全瓷冠的有限元分析仅能反映应力的分布规律,不同全瓷冠材料的抗疲劳性能和寿命分析应当在循环载荷下通过有限元疲劳分析来进行.

  2. Dissolution Kinetics of Titanium Pyrochlore Ceramics at 90?C by Single-Pass Flow-Through Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Icenhower, Jonathan P.; McGrail, B. Peter; Schaef, Herbert T.; Cordova, Elsa A.

    2000-12-01

    Corrosion resistances of titanium-based ceramics are quantified using single-pass flow-through (SPFT) experiments. The materials tested include simple pyrochlore group (B2Ti2O7, where B=Lu^3+ or Gd^3+) and complex multiphase materials that are either pyrochlore- (PY12) or zirconolite-dominated (BSL3). Experiments are conducted at 90?C over a range of pH-buffered conditions with typical duration of experiments in excess of 120 days. Apparent steady-state dissolution rates at pH=2 determined on the Gd2Ti2O7 and Lu2Ti2O7 samples indicate congruent dissolution, with rates of the former (1.3x10^-3 to 4.3x10^-3) slightly faster than the latter (4.4x10^-4 to 7.0x10^-4 g m^-2 d^-1). Rates for PY12 materials into pH=2 solutions are 5.9x10^-5 to 8.6x10^-5 g m^-2 d^-1. In contrast, experiments with BSL3 material do not reach steady-state conditions, and appear to undergo rapid physical and chemical corrosion into solution. At faster flow-through rates, dissolution rates display a shallow amphoteric behavior, with a minimum (4.6x10^-5 to 5.8x10^-5 g m^-2 d^-1) near pH values of 7. Dissolution rates display a measurable increase (~10X) with increasing flow-through rate indicating the strong influence that chemical affinity asserts on the system. These results step towards an evaluation of the corrosion mechanism and an evaluation of the long-term performance of Pu-bearing titanite engineered materials in the subsurface.

  3. The fit of crowns produced using digital impression systems.

    Science.gov (United States)

    Vennerstrom, Micael; Fakhary, Mobin; Von Steyern, Per Vult

    2014-01-01

    Compare the marginal and internal fit of crowns manufactured using four different digital impression systems with crowns manufactured using conventional impression technique, that served as a control group. Fifty all-ceramic crowns were fabricated using 50 standardized dies divided into five groups, each group representing one impression system. Each crown was cemented onto its respective model and sectioned into four segments.The marginal and internal fit were measured at 8 predefined points. A total of 1567 measurements were made, statistically analyzed and compared with crowns fabricated using the five systems. The following was found: (1) No significant difference was found with regard to mar ginal gap when comparing the control group to any of the digital systems. (2) Lava™ had smaller marginal gaps than CEREC® and iTero®, (3) CEREC and Lava had smaller gaps in the chamfer compared to iTero and the control, (4) E4D® showed smaller gaps than CEREC at measuring points 4-8 and CEREC a smaller gap at point 2, (5) Lava showed smaller gaps than CEREC at measuring points 1,3 and 5-8. (6) Lava had smaller gaps than iTero at measuring points 1-4,7 and 8. All differences presented were significant. In conclusions, crowns manufactured using digital impressions present a marginal and internal fit equal to, or better than, crowns made using a conventional impression method.The marginal and internal fit of reconstructions made using digital impression techniques could improve with a lower initial setting of the spacer.

  4. Single-tooth implant reconstructions: esthetic factors influencing the decision between titanium and zirconia abutments in anterior regions.

    Science.gov (United States)

    Sailer, Irena; Zembic, Anja; Jung, Ronald Ernst; Hämmerle, Christoph Hans Franz; Mattiola, Alessandro

    2007-01-01

    Implant-supported single crowns have become a valid alternative to conventional fixed dental prostheses due to their excellent clinical long-term results. However, along with good survival rates, esthetic factors are important for success in anterior regions. Today, several kinds of implant abutments are offered by implant manufacturers. A choice must be made between standardized and customized abutments; further, different abutment materials such as titanium or various ceramics (alumina, zirconia) are available. Finally, the reconstruction can be cemented on the abutment or screw-retained directly on the implant. When choosing an abutment for an anterior single-unit case, several factors should be considered: visibility of the region (eg, high vs low smile line); biotype of the gingiva; color of the neighboring teeth; and finally, esthetic expectations of the patient. In esthetically demanding situations, customized ceramic abutments are indicated. In patient situations with thin peri-implant soft tissues, zirconia abutments and all-ceramic crowns should be used in combination. In cases with thick mucosa, titanium can be used as the abutment material, combined with metal-ceramic crowns. In order to avoid difficulties removing excess cement, screw-retained reconstructions may be preferred; however, the screw access hole should be positioned palatal to the incisal edge.

  5. Crown lengthening: a clinical review.

    Science.gov (United States)

    Talbot, T R; Briggs, P F; Gibson, M T

    1993-09-01

    The use of crown lengthening surgery as an adjunct to restorative therapy was first suggested by Rosen and Gitnick. This technique is designed to increase the clinical crown heights of teeth requiring restoration following extensive wear through attrition, abrasion and erosion. This loss of tooth tissue and resulting clinical crown height may be localized to a few teeth or affect the entire dentition. This clinical problem is reflected by the increasing number of reports of treatment of the worn dentition.

  6. Effect of framework design on crown failure.

    Science.gov (United States)

    Bonfante, Estevam A; da Silva, Nelson R F A; Coelho, Paulo G; Bayardo-González, Daniel E; Thompson, Van P; Bonfante, Gerson

    2009-04-01

    This study evaluated the effect of core-design modification on the characteristic strength and failure modes of glass-infiltrated alumina (In-Ceram) (ICA) compared with porcelain fused to metal (PFM). Premolar crowns of a standard design (PFMs and ICAs) or with a modified framework design (PFMm and ICAm) were fabricated, cemented on dies, and loaded until failure. The crowns were loaded at 0.5 mm min(-1) using a 6.25 mm tungsten-carbide ball at the central fossa. Fracture load values were recorded and fracture analysis of representative samples were evaluated using scanning electron microscopy. Probability Weibull curves with two-sided 90% confidence limits were calculated for each group and a contour plot of the characteristic strength was obtained. Design modification showed an increase in the characteristic strength of the PFMm and ICAm groups, with PFM groups showing higher characteristic strength than ICA groups. The PFMm group showed the highest characteristic strength among all groups. Fracture modes of PFMs and of PFMm frequently reached the core interface at the lingual cusp, whereas ICA exhibited bulk fracture through the alumina core. Core-design modification significantly improved the characteristic strength for PFM and for ICA. The PFM groups demonstrated higher characteristic strength than both ICA groups combined.

  7. EPR and optical study of Yb3+-doped β-PbF2 single crystals and nanocrystals of glass-ceramics

    Science.gov (United States)

    Dantelle, G.; Mortier, M.; Goldner, Ph; Vivien, D.

    2006-08-01

    β-PbF2 single crystals doped with YbF3 (0.2% and 2%) were studied by x-ray diffraction (XRD), electron paramagnetic resonance (EPR) and optical spectroscopy. EPR revealed the presence of only one kind of paramagnetic ion Yb3+, in a cubic symmetry site. The optical absorption, emission and excitation spectra enabled us to identify the transitions attributed to Yb3+ in the cubic site and to determine its energy level diagram. Site-selective laser spectroscopy also evidenced the presence of another type of Yb3+ ions, undetectable by classical EPR. This second type, which dominates in the 2%-doped crystal and exhibits cooperative luminescence, was attributed to Yb3+ ions forming clusters. Transparent oxyfluoride glass-ceramics, containing β-Pb1-yYbyF2+y nanocrystallites, were also synthesized and studied by XRD, EPR and optical spectroscopy. Two types of Yb3+ ions were found, as in β-PbF2 single crystals. The optical properties of the oxyfluoride glass-ceramics turn out to be similar to those of ytterbium activated β-PbF2 single crystals. Moreover, the Yb environments found in PbF2 single crystals seem to already occur in the parent glass. Therefore, these materials are expected to be good laser media, like the rare-earth doped fluorite crystals, either in bulk or fibre form.

  8. Orientation control of (K,Na)NbO3 ceramics using platelike NaNbO3 templates prepared by single-step molten salt synthesis with mixed salt

    Science.gov (United States)

    Ishii, Keisuke; Tashiro, Shinjiro

    2016-10-01

    In order to shorten the firing time for sintering textured (K,Na)NbO3 system ceramics, the fabrication method of the single-step molten salt synthesis for preparing platelike NaNbO3 single-crystal particles was improved. An uneven shape was formed on the surfaces of platelike NaNbO3 single-crystal particles obtained by single-step molten salt synthesis in the mixed salts of KCl and NaCl. Using these single-crystal particles as the templates, textured (K,Na)NbO3 ceramics were fabricated. The sinterability of the textured ceramics and their piezoelectricity were compared between two kinds of templates synthesized in the mixed salt and in the conventional NaCl salt. The diffusivity of K atoms into these templates from the matrix powder of (K,Na)NbO3 during firing was also compared.

  9. Properties and Clinical Application of Three Types of Dental Glass-Ceramics and Ceramics for CAD-CAM Technologies

    Science.gov (United States)

    Ritzberger, Christian; Apel, Elke; Höland, Wolfram; Peschke, Arnd; Rheinberger, Volker M.

    2010-01-01

    The main properties (mechanical, thermal and chemical) and clinical application for dental restoration are demonstrated for three types of glass-ceramics and sintered polycrystalline ceramic produced by Ivoclar Vivadent AG. Two types of glass-ceramics are derived from the leucite-type and the lithium disilicate-type. The third type of dental materials represents a ZrO2 ceramic. CAD/CAM technology is a procedure to manufacture dental ceramic restoration. Leucite-type glass-ceramics demonstrate high translucency, preferable optical/mechanical properties and an application as dental inlays, onlays and crowns. Based on an improvement of the mechanical parameters, specially the strength and toughness, the lithium disilicate glass-ceramics are used as crowns; applying a procedure to machine an intermediate product and producing the final glass-ceramic by an additional heat treatment. Small dental bridges of lithium disilicate glass-ceramic were fabricated using a molding technology. ZrO2 ceramics show high toughness and strength and were veneered with fluoroapatite glass-ceramic. Machining is possible with a porous intermediate product.

  10. [A primary study of color tolerance of anterior tooth crown prosthesis].

    Science.gov (United States)

    Ge, Qi-min; Zhang, Fu-qiang

    2008-12-01

    To study the color tolerance of anterior ceramic crown and seek an effective approach for color-matching of oral prostheses. 30 single maxillary incisor ceramic prostheses and the corresponding nature teeth were measured by a digital camera in a steady environment for image taking and color measurement, which based on the standard recommended by CIE. The color tolerance was analyzed in two groups based on satisfaction and dissatisfaction of prostheses color-matching. The deltaE of satisfaction group was 2.5503, while the deltaE of dissatisfaction group was 4.0772. There was significant difference between chromatic aberration of satisfaction group and dissatisfaction group (P0.05). When the lightness and saturation of prosthesis were smaller than nature teeth, there was significant difference between deltaL*, deltab*, deltaC* of satisfaction group and dissatisfaction group (PControl of color difference is the key for shade matching of anterior tooth prosthesis. Applying the color tolerance is beneficial to improving the prosthesis quality.

  11. Fracture performance of computer-aided manufactured zirconia and alloy crowns

    NARCIS (Netherlands)

    Rosentritt, M.; Behr, M.; Thaller, C.; Rudolph, H.; Feilzer, A.J.

    2009-01-01

    Objective: To compare the fracture resistance and fracture performance of CAD/CAM zirconia and alloy crowns. Method and Materials: One electrophoretic deposition alumina ceramic (Wolceram, Wolceram) and 4 zirconia-based systems (ce.novation, ce.novation; Cercon, DeguDent; Digizon, Amann Girrbach; an

  12. Preformed posterior stainless steel crowns: an update.

    Science.gov (United States)

    Croll, T P

    1999-02-01

    For almost 50 years, dentists have used stainless steel crowns for primary and permanent posterior teeth. No other type of restoration offers the convenience, low cost, durability, and reliability of such crowns when interim full-coronal coverage is required. Preformed stainless steel crowns have improved over the years. Better luting cements have been developed and different methods of crown manipulation have evolved. This article reviews stainless steel crown procedures for primary and permanent posterior teeth. Step-by-step placement of a primary molar stainless steel crown is documented and permanent molar stainless steel crown restoration is described. A method for repairing a worn-through crown also is reviewed.

  13. In vitro failure of crowns produced by two CAD/CAM systems.

    Science.gov (United States)

    Donnelly, Thomas J; Burke, F J Trevor

    2011-09-01

    Previous laboratory studies have demonstrated satisfactory fracture resistance of all-ceramic crowns placed using a resin-composite luting material and a dentine bonding system. This study investigated the fracture resistance of teeth restored using CAD/CAM technology, namely, Zirconia Based crowns and Cerec produced feldspathic porcelain crowns, both luted with a self adhesive resin luting material (RelyX Unicem Clicker 3M ESPE). Standardized preparations were carried out on two groups often sound, unrestored, maxillary premolar teeth. Ceramic crowns were constructed to have a thickness of 2mm at their midline fissure. Compressive fracture resistance was determined for each group using a Universal Testing Machine. The failure modes were also examined visually and interpreted according to a chosen scale. Mean Compressive fracture resistance of 746 (147)N and 1630 (175)N were recorded for the Cerec and Lava groups respectively; differences were statistically significant (p < 0.001). The fracture resistance of teeth restored with Lava crowns is significantly greater than a similar group of teeth restored with Cerec crowns.

  14. Study on the effect of different impression methods on the marginal fit of all-ceramic crowns%不同数字印模方式影响全瓷冠边缘适合性的研究

    Institute of Scientific and Technical Information of China (English)

    占莉琳; 曾利伟; 陈萍; 廖岚; 李十月; 刘仁英

    2015-01-01

    目的:  研究硅橡胶印模扫描、直接光学印模和传统的物理印模对计算机义齿辅助设计与制作全瓷冠边缘适合性的影响。方法  用数控车床制备聚甲基丙烯酸甲酯材质下颌第一磨牙标准全冠预备体16个,采用硅橡胶制取精细印模,超硬石膏灌注翻制成石膏模型。分别采用扫描全冠预备体、硅橡胶印模和石膏模型获取数字化模型,制作48个氧化锆全瓷冠。采用间隙印模测量法评价3组冠的边缘间隙,应用SPSS 17.0软件对实验数据进行统计分析。结果 直接扫描组、硅橡胶印模组、超硬石膏组的全瓷冠边缘间隙测量结果分别为(69.18±9.47)、(81.04±10.88)、(84.42±9.96)μm。直接扫描组与硅橡胶印模组、超硬石膏组差异有统计学意义(P0.05)。结论  直接扫描、硅橡胶印模扫描、石膏模型扫描法全瓷冠的边缘适合性均在临床可接受范围之内,硅橡胶印模扫描可作为临床上获取数字模型的方式之一。%Objective  To investigate the effect of three different impression methods on the marginal fit of all-ceramic crowns. The three methods include scanning silicone rubber impression, cast models, and direct optical impression. Methods The polymethyl methacrylate (PMMA) material of a mandibular first molar in standard model was prepared with 16 models duplicated. The all-ceramic crowns were prepared using three different impression methods. Accurate impressions were made using silicone rubber, and the cast models were obtained. The PMMA models, silicone rubber impressions, and cast models were scanned, and digital models of three groups were obtained to produce 48 zirconia all-ceramic crowns with computer aided design

  15. Ready to crown

    LENUS (Irish Health Repository)

    McReynolds, David

    2017-04-01

    When multiple teeth or localised segments of the mouth require crowns, the restorative interventions involved can be psychologically and physically demanding for the operator, patient and dental technician alike.1,2 It is important that all parties involved in restorations of this nature hold a shared understanding of the expected outcome of treatment, with a realistic, common end goal in mind right from the very beginning. Such clarity of thought and communication is key to avoiding biological, mechanical and aesthetic failures in the planning and execution of advanced restorative treatments. Biomechanically stable and aesthetically pleasing provisional restorations are an essential aspect of treatment, which allow teeth to be prepared and provisionalised over multiple appointments within the comfort zone of the operator and patient.3

  16. Novel glass-ceramics for dental restorations.

    Science.gov (United States)

    Pollington, Sarah

    2011-01-01

    There are many different ceramic systems available on the market for dental restorations. Glass-ceramics are a popular choice due to their excellent esthetics and ability to bond to tooth structure allowing a more conservative approach. However, at present, these materials have insufficient strength to be used reliably in posterior regions of the mouth. The aim of this review article is to discuss the types of novel glass-ceramic currently be investigated including composition, microstructure and properties. Current research in glass-ceramics focuses on the quest for a highly esthetic material along with sufficient strength to enable crowns and bridgework to be reliably placed in these areas. There is a gap in the market for a machinable resin bonded glass-ceramic with sufficient strength as well as excellent esthetics.

  17. 个别牙位全瓷冠的美学仿真修复%Application of Aesthetic Principles in Single-unit all Ceramic Restorations

    Institute of Scientific and Technical Information of China (English)

    陈晨; 章非敏; 谢海峰

    2012-01-01

    Objective: To evaluate effects of applications of aesthetic principle in all - ceramic single-unit restorations. Method; Shade guide was used in color matching. In addition, portraying tooth shade pictures or recording the digital tooth images were performed to make technicians comprehend the aims of doctors and patients completely. Result: All the all-ceramic restorations achieved good aesthetic results. Conclusion: Applying aesthetic principles correctly and comunicating with technicians well would contribute to improving clinic success of single-unit all ceramic restorations aesthetically.%目的:探讨个别牙位全瓷冠的美学仿真修复要点和临床注意事项.方法:在明确患者要求的前提下,对拟进行个别牙位全瓷冠修复的病例综合采用比色板比色、绘制比色图、记录个性特征、拍摄数码照片等方式,制作全瓷修复体.拍摄修复前后的数码照片进行美学评价.结果:所有患者的全瓷冠临床美学修复效果良好.结论:灵活运用美学原理,综合借助多种方式进行有效的医技沟通,有助于重建出美观、富有个性特征的全瓷修复体.

  18. Clinical evaluation of fractured metal-ceramic fixed dental prostheses repaired with indirect technique.

    Science.gov (United States)

    Galiatsatos, Aristidis A; Galiatsatos, Panagiotis A

    2015-03-01

    Metal ceramic restorations continue to be widely used in dental practice, as they combine esthetics with superior mechanical properties. However, ceramic materials have the potential to fracture due to their brittle nature. The purpose of this study was to evaluate the clinical survival of fractured metal-ceramic restorations repaired with an indirect technique which uses a new "overlay" metal-ceramic crown that is luted to the existing restoration. The study population consisted of 92 patients. Only patients with one or more fractured retainers of multipleunit metal-ceramic fixed partial dentures were involved in this study. In all cases there were a bulk fracture of the overlaying ceramic material and exposure of the underlying metal substructure. The remaining retainers of the fixed partial dentures were intact. The total number of fractured retainers was 106. All clinical procedures of the indirect repairs were carried out by a single investigator, according the previously published technique. The patients were examined clinically at 1, 2, 4, 6, and 8 years after placement of the new restorations. The repaired restorations were examined for debonding, fracture rate, and esthetics. Patient acceptance was also recorded. Of the 92 patients re-examined, all were satisfied with the function and the esthetic appearance of their restorations. None of the repaired restorations fractured after 8 years of service, and there were no gingival margin problems of significance. Four restorations debonded during the evaluation period. The overall survival rate was 96.2% after 8 years. Repair methodology and materials employed in this study resulted in satisfactory longevity for metal-ceramic dental prostheses. The success rate was 96.2% after 8 years. The retention rate was very good, patient satisfaction was very encouraging, and maintenance of the esthetics was good.

  19. CAD/CAM systems available for the fabrication of crown and bridge restorations.

    Science.gov (United States)

    Miyazaki, T; Hotta, Y

    2011-06-01

    Dental biomaterials are widely used in all areas of routine dental practice. There are mainly two methods for their application. Firstly, dental biomaterials are placed into living tissues, such as teeth, to fill the space. Secondly, dental devices such as crown and bridge restorations and dentures are fabricated using various materials to restore the morphology and function of the dentition. Crown and bridge restorations are one of the main treatment methods used by general practitioners to achieve lifelike restoration of form and function. The recent introduction of osseointegrated implants has expanded the application of crown and bridge restorations for partially edentulous patients. Mechanical durability and precision fit are mandatory requirements for crowns and bridges. The development of various casting alloys and precise casting systems has contributed to the successful use of metal-based restorations. However, patient requests for more aesthetic and biologically 'safe' materials has led to an increased demand for metal-free restorations. There is also a growing demand to provide all-ceramic restorations more routinely. New materials such as highly sintered glass, polycrystalline alumina, zirconia based materials and adhesive monomers, will assist dentists to meet this demand. In addition, new fabrication systems combined with computer-assisted fabrication systems (dental CAD/CAM) and various networks are now available. Dental technology was centred on lost-wax casting technology but we now face a revolution in crown and bridge fabrication. This article reviews the history and recent status of dental CAD/CAM, the application of CAD/CAM fabricated tooth-coloured glass ceramic crowns, and the application of all-ceramic crowns and bridges using CAD/CAM fabricated zirconia based frameworks.

  20. On Ceramics.

    Science.gov (United States)

    School Arts, 1982

    1982-01-01

    Presents four ceramics activities for secondary-level art classes. Included are directions for primitive kiln construction and glaze making. Two ceramics design activities are described in which students make bizarrely-shaped lidded jars, feet, and footwear. (AM)

  1. Challenges in reconstructing an isolated anterior tooth with a metal-free crown

    Directory of Open Access Journals (Sweden)

    Max Doria Costa

    2013-01-01

    Full Text Available Introduction: Currently, new esthetic treatments are available to the dentist due to the advent of ceramic-ceramic prostheses. A new option has become part of daily clinical practice, with the promise of esthetic optimization through the elimination of metal in prosthetic crowns. The translucence of these new systems allows the transmission of light through the tooth structure, minimizing gingival darkness and producing a vibrant and natural appearance. Case Report: The patient, 30 years old, female, showed with a fractured tooth crown at the cervical level in the right lateral incisive. It was observed that the tooth had prior adequate endodontic treatment. A metal-free restorative system was selected. A plaster model was obtained for subsequent tooth preparative scanning and manufacture of ceramic framework. After receiving the framework, adjustments were made and the color choice of covering ceramic, following the protocol of choice for a chroma suboptimal aiming further characterization. After the ceramics application, adjustments in shape, texture, and occlusion were made. The crown was characterized by exterior paint, getting a favorable result, restoring esthetics and function. Discussion : The metal-free systems are a viable alternative to the restorative treatment when esthetics is desired, allowing a natural and harmonious smile, combined with the reliability of the restorative material.

  2. Synthesis of ZrB{sub 2}-SiC ceramic composites from a single-source precursor

    Energy Technology Data Exchange (ETDEWEB)

    Arish, Dasan, E-mail: arishd@rediffmail.com [Université of Limoges, SPCTS-CNRS, UMR 7315, Centre Européen de la Céramique (CEC), 12 Rue Atlantis, F-87068, Limoges Cedex (France); Shiju, Chellan [Synthetic Products Division, Corporate R & D Center (CRDC), HLL Lifecare Limited, Thiruvananthapuram, Kerala (India); Joseyphus, Raphael Selwin, E-mail: rsjoseyphus@gmail.com [PG & Research, Department of Chemistry, Mar Ivanios College (Autonomous), Thiruvananthapuram, 695015, Kerala (India); Pushparajan, Joseph [Travancore Titanium Products Ltd., Kochuveli, Thiruvananthapuram, 695021, Kerala (India)

    2017-06-15

    Preceramic polymer zirconoborosiloxane was synthesized from the reaction with boric acid, diphenyldiethoxysilane and zirconium (IV) propoxide via solventless process. The thermogravimetric analysis of the polymer showed that ceramic yield as decomposition product at 900 °C was 71%. The pyrolysis of zirconoborosiloxane in an argon gas environment was investigated as standard pyrolytic process up to 1650 °C. Microstructure evolution of ceramic phases was made by means of Fourier transform infrared, Raman spectroscopy, X-ray diffraction and scanning electron microscope analysis. The results clearly demonstrated the pyrolysis products at 1650 °C consist of totally non-oxide ceramic phases of β-SiC, ZrB{sub 2} and free carbon. - Highlights: • Preceramic polymer zirconoborosiloxane was synthesized by non-aqueous solventless process. • Non-oxide ZrB{sub 2}-SiC composites could be obtained from the pyrolysed products at 1650 °C. • Free carbon content was identified by Raman spectroscopy.

  3. Tailored Ceramics for Laser Applications

    Energy Technology Data Exchange (ETDEWEB)

    Hollingsworth, Joel [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2007-12-10

    Transparent ceramics match or exceed the performance of single-crystal materials in laser applications, with a more-robust fabrication process. Controlling the distribution of optical dopants in transparent ceramics would allow qualitative improvements in amplifier slab design by allowing gain and loss to be varied within the material. My work aims to achieve a controlled pattern or gradient of dopant prior to sintering, in order to produce tailored ceramics.

  4. Fracture resistance of teeth restored with dentin-bonded crowns.

    Science.gov (United States)

    Burke, F J; Watts, D C

    1994-05-01

    While dentin-bonded crowns may hold esthetic advantages over metal-ceramic restorations, and minimal tooth preparation may also be appropriate, resistance to fracture of the restored unit is an important consideration. Dentin-bonded crowns were placed on standardized preparations in two groups of 10 maxillary premolar teeth in vitro. The preparations differed only in degree of taper. The restored specimens were subjected to compressive loading at 1 mm/min from a steel bar placed along the midline fissure. Mean fracture loads of 0.77 kN (6-degree taper) and 0.71 kN (8-degree taper) were recorded for the groups of prepared teeth, and a mean fracture load of 0.97 kN was obtained for a group of unprepared controls. Statistical analysis indicated that there was no significant difference between the fracture load of the 6-degree taper group and that of the sound control teeth.

  5. The effect of thermal barrier coated piston crown on engine characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Chan, S.H.; Khor, K.A.

    2000-02-01

    While there have been numerous research papers in recent years describing the theoretical benefits obtained from the use of ceramic components in reciprocating engines, the amount of literature that describes practical results is very limited. Although successes have been reported and ceramic components are now in service in production engines, mainly for reduced in-cylinder heat rejection, many researchers have experienced failures or a drop in engine performance. This article presents the work completed on a low heat rejection engine. Extensive experiments were conducted on a three-cylinder SI Daihatsu engine with piston crowns coated with a layer of ceramic, which consisted of yttria-stabilized zirconia (YSZ). Measurement and comparison of engine performance, in particular fuel consumption, were made before and after the application of YSZ coatings deposited onto the piston crowns. The details of the cylinder pressures during the combustion process were also investigated.

  6. Cu{sub 2}ZnSnSb(S,Se,Te){sub 4} film formation from selenization of sputtered self-prepared single ceramic target

    Energy Technology Data Exchange (ETDEWEB)

    Tsega, Moges, E-mail: mogestsega@yahoo.com [Department of Physics, University of the Free State (Qwaqwa campus), Private Bag X13, Phuthaditjhaba 9866 (South Africa); Kuo, Dong-Hau [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan (China); Dejene, F.B. [Department of Physics, University of the Free State (Qwaqwa campus), Private Bag X13, Phuthaditjhaba 9866 (South Africa)

    2015-08-31

    Single-layered Cu{sub 2}ZnSnSb(S,Se,Te){sub 4}(CZTASSeTe) thin films were prepared on Mo/glass substrate by radio frequency magnetron sputtering of a self-prepared single ceramic target. Successive selenization for the as-deposited film at a substrate temperature of 200 °C in Se-atmosphere was performed at various temperatures between 400 °C and 600 °C for 1 h. Structural investigation of the grown films revealed single-phase tetragonal structure corresponding to kesterite CZTSSe. All measured samples were found to exhibit p-type conductivity. An improved grain size and crystal quality with suitable atomic ratio [Cu/(Zn + Sb + Sn) = 0.89, Zn/Sn = 1.15, and metal/(S + Se + Te) = 1.02] obtained for CZTASSeTe film selenized at 600 °C. The Hall concentration increased from 1.06 to 5.8 × 10{sup 17} cm{sup −3}, mobility increased from 2.82 to 44.3 cm{sup 2} V{sup −1} s{sup −1}, and resistivity decreased from 20.92 to 0.24 Ω cm as the precursor film is selenized to 600 °C. An enhanced Hall mobility can be ascribed to the larger grains with better crystallinity and composition in the selenized film at 600 °C. Our large grain size and maximized mobility for CZTASSeTe film at the selenization temperature of 600 °C from single ceramic target can be useful for the fabrication of the CZTASSeTe absorber layer. - Highlights: • Cu{sub 2}ZnSnSb(S,Se,Te){sub 4} thin films were deposited by sputtering single ceramic target. • Structural and electrical properties of the films are presented. • Properties of CZTASSeTe thin films were related to Se vaporization temperature. • Selenized film at 600 °C presents the best crystal quality and enhanced Hall mobility.

  7. Single-source-precursor synthesis of dense SiC/HfCxN1-x-based ultrahigh-temperature ceramic nanocomposites

    Science.gov (United States)

    Wen, Qingbo; Xu, Yeping; Xu, Binbin; Fasel, Claudia; GuillonPresent Address: Forschungszentrum Jülich, Institut Für Energie-Und Klimaforschung 1: Werkstoffsynthese Und Herstellungsverfahren, Wilhelm-Johnen-Straße, D.-52425 Jülich., Olivier; Buntkowsky, Gerd; Yu, Zhaoju; Riedel, Ralf; Ionescu, Emanuel

    2014-10-01

    A novel single-source precursor was synthesized by the reaction of an allyl hydrido polycarbosilane (SMP10) and tetrakis(dimethylamido)hafnium(iv) (TDMAH) for the purpose of preparing dense monolithic SiC/HfCxN1-x-based ultrahigh temperature ceramic nanocomposites. The materials obtained at different stages of the synthesis process were characterized via Fourier transform infrared (FT-IR) as well as nuclear magnetic resonance (NMR) spectroscopy. The polymer-to-ceramic transformation was investigated by means of MAS NMR and FT-IR spectroscopy as well as thermogravimetric analysis (TGA) coupled with in situ mass spectrometry. Moreover, the microstructural evolution of the synthesized SiHfCN-based ceramics annealed at different temperatures ranging from 1300 °C to 1800 °C was characterized by elemental analysis, X-ray diffraction, Raman spectroscopy and transmission electron microscopy (TEM). Based on its high temperature behavior, the amorphous SiHfCN-based ceramic powder was used to prepare monolithic SiC/HfCxN1-x-based nanocomposites using the spark plasma sintering (SPS) technique. The results showed that dense monolithic SiC/HfCxN1-x-based nanocomposites with low open porosity (0.74 vol%) can be prepared successfully from single-source precursors. The average grain size of both HfC0.83N0.17 and SiC phases was found to be less than 100 nm after SPS processing owing to a unique microstructure: HfC0.83N0.17 grains were embedded homogeneously in a β-SiC matrix and encapsulated by in situ formed carbon layers which acted as a diffusion barrier to suppress grain growth. The segregated Hf-carbonitride grains significantly influenced the electrical conductivity of the SPS processed monolithic samples. While Hf-free polymer-derived SiC showed an electrical conductivity of ca. 1.8 S cm-1, the electrical conductivity of the Hf-containing material was analyzed to be ca. 136.2 S cm-1.A novel single-source precursor was synthesized by the reaction of an allyl hydrido

  8. Fracture mode during cyclic loading of implant-supported single-tooth restorations

    DEFF Research Database (Denmark)

    Hosseini, Mandana; Kleven, Erik; Gotfredsen, Klaus

    2012-01-01

    restorations of zirconia abutment-retained crowns with zirconia copings veneered with glass-ceramics (n=8) and feldspathic ceramics (n=8). The control group was composed of 16 metal ceramic restorations of titanium abutment-retained crowns with gold alloy copings veneered with glass (n=8) and feldspathic...... ceramics (n=8). The palatal surfaces of the crowns were exposed to cyclic loading of 800 N with a frequency of 2 Hz, which continued to 4.2 million cycles or until fracture of the copings, abutments, or implants. The number of cycles and the fracture modes were recorded. The fracture modes were analyzed...... and resisted more cyclic loads than the ceramic restorations, particularly when the metal ceramic crowns were veneered with glass-ceramics....

  9. Overdenture dengan Pegangan Telescopic Crown

    Directory of Open Access Journals (Sweden)

    Pambudi Santoso

    2014-06-01

    Full Text Available Kaitan presisi merupakan alat retensi mekanis yang menghubungkan antara satu atau lebih pegangan gigi tiruan, yang bertujuan untuk menambah retensi dan/atau stabilisasi. Kaitan presisi dapat digunakan secara luas pada gigi tiruan cekat, gigi tiruan sebagian lepasan, overdenture, implant untuk retensi overdenture, dan protesa maksilo fasial. Overdenture dengan kaitan presisi dapat membantu dalam pembagian beban kunyah, meminimalkan trauma pada gigi pegangan dan jaringan lunak, meminimalkan resorbsi tulang, dan meningkatkan estetik dan pengucapan suara. Salah satu jenis dari kaitan presisi adalah telescopic crown, terdiri dari 2 macam mahkota, yaitu mahkota primer yang melekat secara permanen pada gigi penyangga, dan mahkota sekunder yang melekat pada gigi tiruan. Tujuan pemaparan kasus ini adalah untuk memberikan informasi tentang rehabilitasi pasien edentulous sebagian rahang atas dengan telescopic crown..  Pasien wanita berusia 45 tahun datang ke klinik prostodonsia RSGM Prof.Soedomo dengan keluhan ingin dibuatkan gigi tiruan. Pasien kehilangan gigi 11 12 15 16 17 21 22 24 25 26 dan 27 yang diindikasikan untuk pembuatan overdenture gigi tiruan sebagian lepasan (GTS kerangka logam dengan pegangan telescopic crown pada gigi 13 dan 14 dengan sistem parallel-sided crown. Tahap-tahap pembuatan telescopic crown yaitu mencetak model study dengan catatan gigit pendahuluan. Perawatan saluran dilakukan pada akar gigi 13, dilanjutkan pemasangan pasak fiber serta rewalling dinding bukal. Gigi 13 dan 14 dilakukan preparasi mahkota penuh, dilanjutkan dengan pencetakan model kerja untuk coping primer dan kerangka logam dengan metode double impression. Coping primer disementasi pada gigi penyangga, dilanjutkan pasang coba coping sekunder beserta kerangka logam. Selanjutnya dilakukan pencatatan gigit, pencetakan model kerja, penyusunan gigi dan pasang coba penyusunan gigi pada pasien. Prosedur dilanjutkan dengan proses di laboratorium, serta insersi pada

  10. Raspberry Crown Borer [Pennisetia marginata

    OpenAIRE

    Alston, Diane

    2015-01-01

    This fact sheet described raspberry crown borer, a pest that attacks raspberry plants in northern Utah, causing cane-wilt and death. It includes life history, host injury, monitoring and thresholds, and management techniques.

  11. Horizontal Roll Vortices and Crown Fires.

    Science.gov (United States)

    Haines, Donald A.

    1982-06-01

    Observational evidence from nine crown fires suggests that horizontal roll vortices are a major mechanism in crown-fire spread. Post-burn aerial photography indicates that unburned tree-crown streets are common with crown fire. Investigation of the understory of these crown streets after two fires showed uncharred tree trunks along a center line. This evidence supports a hypothesis of vortex action causing strong downward motion of air along the streets. Additionally, photographs of two ongoing crown fires show apparent horizontal roll vortices. Discussion also includes laboratory and numerical studies in fluid dynamics that may apply to crown fires.

  12. 不同外冠材料套筒冠固位力的比较研究%Comparison of the retention between different outer crown materials of telescopic crown

    Institute of Scientific and Technical Information of China (English)

    李文婕

    2012-01-01

    Objective To compare the telescope crown retention by two kinds of outer crown materials. Methods All ceramic inter crowns were made on the standard abutment,and Co-Cr alloy and pure titanium were used as the materials of outer crowns,respectively. The retention was measured after insertion/separation process. Results The retention of pure titanium outer crown was bigger than that of Co-Cr alloy outer crown(P < 0. 05 ) . Conclusion The property of outer crown materials is related to the telescope crown retention , and pure titanium outer crown could provide the longer lasting retention.%目的 探讨两种外冠材料对套筒冠固位力的影响. 方法 在标准代型上制作全瓷内冠,外冠分别采用钴铬合金和纯钛制作,经循环摘戴后测试其固位力值.使用SPSS13.0软件包对数据进行£检验. 结果 纯钛外冠组固位力大于钴铬合金外冠组,差异具有显著性(P<0.05). 结论 外冠材料性能与套筒冠固位力相关,纯钛外冠更能提供长期持久的固位力.

  13. A Radiographic Comparison of Progressive and Conventional Loading on Crestal Bone Loss and Density in Single Implants

    Directory of Open Access Journals (Sweden)

    Majid Sorouri

    2013-01-01

    Full Text Available Objectives: Crestal bone loss is a biologic complication in implant dentistry. The aim of this study was to compare the effect of progressive and conventional loading on crestal bone height and bone density around single osseointegrated implants in posterior maxilla by a longitudinal radiographic assessment technique.Materials and methods: Twenty micro thread implants were placed in 10 patients (two implants per patient. One of the two implants of each patient was assigned to progressive and the other to conventional loading groups. Eight weeks after surgery, conventional implants were restored with a metal ceramic crown and progressive group underwent a progressive loading protocol. The progressive loading group takes different temporary acrylic crowns at 2, 4 and 6 months. After eight months, acrylic crowns were replaced with metal ceramic crown. Computer radiography of both progressive and conventional implants was taken at 2, 4, 6, and 12 months. Image analysis was performed to measure height of crestal bone loss and bone density.Results: The mean values of crestal bone loss at month 12 were 0.11 (0.19 mm for progressively and 0.36 (0.36 mm for conventionally loaded implants, with a statistically significant difference (P 0.05.Conclusion: Progressive group showed less crestal bone loss in single osseointegrated implant than conventional group. Bone density around progressively loaded implants showed increase in crestal, middle and apica

  14. Comparative in vitro evaluation of CAD/CAM vs conventional provisional crowns

    Directory of Open Access Journals (Sweden)

    Adil Othman ABDULLAH

    Full Text Available ABSTRACT Objective This study compared the marginal gap, internal fit, fracture strength, and mode of fracture of CAD/CAM provisional crowns with that of direct provisional crowns. Material and Methods An upper right first premolar phantom tooth was prepared for full ceramic crown following tooth preparation guidelines. The materials tested were: VITA CAD-Temp®, Polyetheretherketone “PEEK”, Telio CAD-Temp, and Protemp™4 (control group. The crowns were divided into four groups (n=10, Group1: VITA CAD-Temp®, Group 2: PEEK, Group 3: Telio CAD-Temp, and Group 4: Protemp™4. Each crown was investigated for marginal and internal fit, fracture strength, and mode of fracture. Statistical analysis was performed using GraphPad Prism software version 6.0. Results The average marginal gap was: VITA CAD-Temp® 60.61 (±9.99 µm, PEEK 46.75 (±8.26 µm, Telio CAD-Temp 56.10 (±5.65 µm, and Protemp™4 193.07(±35.96 µm (P0.05. Conclusions CAD/CAM fabricated provisional crowns demonstrated superior fit and better strength than direct provisional crowns.

  15. Comparative in vitro evaluation of CAD/CAM vs conventional provisional crowns

    Science.gov (United States)

    ABDULLAH, Adil Othman; TSITROU, Effrosyni A; POLLINGTON, Sarah

    2016-01-01

    ABSTRACT Objective This study compared the marginal gap, internal fit, fracture strength, and mode of fracture of CAD/CAM provisional crowns with that of direct provisional crowns. Material and Methods An upper right first premolar phantom tooth was prepared for full ceramic crown following tooth preparation guidelines. The materials tested were: VITA CAD-Temp®, Polyetheretherketone “PEEK”, Telio CAD-Temp, and Protemp™4 (control group). The crowns were divided into four groups (n=10), Group1: VITA CAD-Temp®, Group 2: PEEK, Group 3: Telio CAD-Temp, and Group 4: Protemp™4. Each crown was investigated for marginal and internal fit, fracture strength, and mode of fracture. Statistical analysis was performed using GraphPad Prism software version 6.0. Results The average marginal gap was: VITA CAD-Temp® 60.61 (±9.99) µm, PEEK 46.75 (±8.26) µm, Telio CAD-Temp 56.10 (±5.65) µm, and Protemp™4 193.07(±35.96) µm (P0.05). Conclusions CAD/CAM fabricated provisional crowns demonstrated superior fit and better strength than direct provisional crowns. PMID:27383707

  16. Characterization of ceramic powders used in the inCeram systems to fixed dental Prosthesis

    Directory of Open Access Journals (Sweden)

    Alexandra Almeida Diego

    2007-03-01

    Full Text Available InCeram (Vita Zahnfabrik- Germany is known as a high strength ceramic being used for core crowns and for fixed partial denture frameworks. InCeram system consists of slip-casting technique which is used for to build the framework, which is then pre-sintered obtaining an open-pore microstructure. The material gains its strength by infiltration of the lanthanum glass into the porous microstructure. In this work, commercial alumina (Al2O3, alumina-zirconia (Al2O3-ZrO2 and glasses lanthanum oxide-rich powders, used in InCeram system, were characterized, using x ray diffraction, dilatometry and scanning electron microscopy. The characteristics of these powders were related aiming to consider their substitution for new ceramic materials.

  17. Crown color match of implant-supported zirconia and Porcelain-Fused-to-Metal restorations:

    DEFF Research Database (Denmark)

    Peng, Min; Fei, Wei; Hosseini, Mandana

    2014-01-01

    Objectives: The aim of the present study was to compare the crown color match of implant supported zirconia restorations and Porcelain-Fused-to-Metal (PFM) restorations in anterior maxillary region by spectrophotometric evaluation. Materials and Methods: Eighteen patients with 29 implant......-supported single crowns in anterior maxillary area were recruited, 11 of the implant crowns were zirconia restorations and 18 were PFM restorations. Color match of the implant crown with contra-lateral/neighboring tooth at the position of body 1/3 of the crown were assessed using spectrophotometer (Spectro......ShadeTM, Micro Dental) in CIEL¿a¿b¿ coordinates. Subjective crown color match scores were evaluated. Independent sample t test of SPSS17.0 was used to compare the difference between zirconia restoration and PFM restoration. Spearman correlation was used to analyze the relationship between the spectrophotometric...

  18. Crown color match of implant-supported zirconia and Porcelain-Fused-to-Metal restorations:

    DEFF Research Database (Denmark)

    Peng, Min; Fei, Wei; Hosseini, Mandana

    2014-01-01

    Objectives: The aim of the present study was to compare the crown color match of implant supported zirconia restorations and Porcelain-Fused-to-Metal (PFM) restorations in anterior maxillary region by spectrophotometric evaluation. Materials and Methods: Eighteen patients with 29 implant......-supported single crowns in anterior maxillary area were recruited, 11 of the implant crowns were zirconia restorations and 18 were PFM restorations. Color match of the implant crown with contra-lateral/neighboring tooth at the position of body 1/3 of the crown were assessed using spectrophotometer (Spectro......ShadeTM, Micro Dental) in CIEL¿a¿b¿ coordinates. Subjective crown color match scores were evaluated. Independent sample t test of SPSS17.0 was used to compare the difference between zirconia restoration and PFM restoration. Spearman correlation was used to analyze the relationship between the spectrophotometric...

  19. Forest Crown Cover Estimation in Northern Boreal and Temperate European Forest

    Science.gov (United States)

    Sirro, Laura; Hame, Tuomas; Ahola, Heikki; Lonnqvist, Anne

    2012-04-01

    A method for forest crown cover estimation using high resolution optical earth observation data was developed and tested at four study sites in Europe. Crown cover was estimated using the probability estimation method of VTT and Image2006 data. The accuracy of the crown cover predictions was assessed using reference data that were collected by visual interpretation of very high resolution aerial and space borne imagery. The average crown cover values in the reference data varied from 17 % to 86 % and in the predictions from 18 % to 80 %. The absolute root mean square error of the crown cover predictions varied between 14 % and 33 %. The results of the study showed that it is possible to map forest crown cover with twenty to thirty meter spatial resolution optical earth observation data using the single pixel values. However, understanding the variable results at different sites requires further investigation.

  20. Preparation of LuAG Powders with Single Phase and Good Dispersion for Transparent Ceramics Using Co-Precipitation Method

    Directory of Open Access Journals (Sweden)

    Liangjie Pan

    2015-08-01

    Full Text Available The synthesis of pure and well dispersed lutetium aluminum garnet (LuAG powder is crucial and important for the preparation of LuAG transparent ceramics. In this paper, high purity and well dispersed LuAG powders have been synthesized via co-precipitation method with lutetium nitrate and aluminum nitrate as raw materials. Ammonium hydrogen carbonate (AHC was used as the precipitant. The influence of aging time, pH value, and dripping speed on the prepared LuAG powders were investigated. It showed that long aging duration (>15 h with high terminal pH value (>7.80 resulted in segregation of rhombus Lu precipitate and Al precipitate. By decreasing the initial pH value or accelerating the dripping speed, rhombus Lu precipitate was eliminated and pure LuAG nano powders were synthesized. High quality LuAG transparent ceramics with transmission >75% at 1064 nm were fabricated using these well dispersed nano LuAG powders.

  1. CAD/CAM generated all-ceramic primary telescopic prostheses.

    Science.gov (United States)

    Kurbad, A; Ganz, S; Kurbad, S

    2012-01-01

    Computer-aided design and manufacturing (CAD/CAM) systems have proven effective not only for the manufacture of crown and bridge frameworks, inlays, onlays and veneers, but also for the generation of all-ceramic primary telescopic prostheses in more than 10 years of use in dental technology. The new InLab 4.0 software generation makes it possible to design and mill primary telescopic prostheses with CAD/CAM technology. The computer-generated raw crowns for these restorations require very little manual adaptation. The secondary crowns are manufactured by electroforming and bonded onto the tertiary structure or framework.

  2. Structures of dioxobipyridil-12-crown-4 and its complexes with silver (I) and copper (II) cations

    Science.gov (United States)

    Starova, Galina L.; Denisova, Anna S.; Dem'yanchuk, Evgeniya M.

    2008-02-01

    The structures of dioxobipyridil-12-crown-4 ( bpy-CO-crown) and its complexes with copper (II) and silver (I) cations have been determined using single crystal X-ray-diffraction. The results have been compared with the literature data on the complexes of dcmbpy and its complex with silver (I) and copper (II) cations.

  3. Preparation and properties of dental zirconia ceramics

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Y2O3-stabilized tetragonal zireonia polyerystalline (Y-TZP) ceramics with high-performance were prepared for dental application by use of the micro-emulsion and two-step sintering method.The crystal phase,morphology,and microstructure of the reaction products were characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM),and transmission electron microscopy (TEM).XRD results show that the ceramics mainly consist of tetragonal zirconia.Physical and mechanical properties test results show that the bending strength,fracture toughness,and the density of full sintered Y-TZP ceramics are llS0 MPa,5.53 crown machined with this material by CAD/CAM system exhibits a verisimilitude configuration and the material's expansion coefficient well matches that of the glaze.These results further indicate that the product can be used as a promising new ceramic material

  4. Ceramic joining

    Energy Technology Data Exchange (ETDEWEB)

    Loehman, R.E. [Sandia National Lab., Albuquerque, NM (United States)

    1996-04-01

    This paper describes the relation between reactions at ceramic-metal interfaces and the development of strong interfacial bonds in ceramic joining. Studies on a number of systems are described, including silicon nitrides, aluminium nitrides, mullite, and aluminium oxides. Joints can be weakened by stresses such as thermal expansion mismatch. Ceramic joining is used in a variety of applications such as solid oxide fuel cells.

  5. Ceramic Processing

    Energy Technology Data Exchange (ETDEWEB)

    EWSUK,KEVIN G.

    1999-11-24

    Ceramics represent a unique class of materials that are distinguished from common metals and plastics by their: (1) high hardness, stiffness, and good wear properties (i.e., abrasion resistance); (2) ability to withstand high temperatures (i.e., refractoriness); (3) chemical durability; and (4) electrical properties that allow them to be electrical insulators, semiconductors, or ionic conductors. Ceramics can be broken down into two general categories, traditional and advanced ceramics. Traditional ceramics include common household products such as clay pots, tiles, pipe, and bricks, porcelain china, sinks, and electrical insulators, and thermally insulating refractory bricks for ovens and fireplaces. Advanced ceramics, also referred to as ''high-tech'' ceramics, include products such as spark plug bodies, piston rings, catalyst supports, and water pump seals for automobiles, thermally insulating tiles for the space shuttle, sodium vapor lamp tubes in streetlights, and the capacitors, resistors, transducers, and varistors in the solid-state electronics we use daily. The major differences between traditional and advanced ceramics are in the processing tolerances and cost. Traditional ceramics are manufactured with inexpensive raw materials, are relatively tolerant of minor process deviations, and are relatively inexpensive. Advanced ceramics are typically made with more refined raw materials and processing to optimize a given property or combination of properties (e.g., mechanical, electrical, dielectric, optical, thermal, physical, and/or magnetic) for a given application. Advanced ceramics generally have improved performance and reliability over traditional ceramics, but are typically more expensive. Additionally, advanced ceramics are typically more sensitive to the chemical and physical defects present in the starting raw materials, or those that are introduced during manufacturing.

  6. Single-phase driven ultrasonic motor using two orthogonal bending modes of sandwiching piezo-ceramic plates

    Science.gov (United States)

    Ma, Yuting; Choi, Minkyu; Uchino, Kenji

    2016-11-01

    A compact ultrasonic motor using sandwiching piezo-ceramic plates was developed, having advantages of low manufacturing costs, simple driving circuit, and high scalability. The stator is composed of two piezoelectric plates attached to a T-shaped steel body. Two orthogonal bending modes can be excited by driving one piezoelectric plate and the reversed motion of the rotor can be obtained by driving the piezoelectric plate on the opposite side. The prototype stator with a size of 15 mm × 2.44 mm × 2 mm, operated at 44.8 kHz, was experimentally characterized, and a maximum torque of 2 mN m was obtained. Maximum power of 2.3 mW and efficiency of 9% were produced with a load of 0.8 mN m at a rotation speed of 27 rpm.

  7. Single-phase driven ultrasonic motor using two orthogonal bending modes of sandwiching piezo-ceramic plates.

    Science.gov (United States)

    Ma, Yuting; Choi, Minkyu; Uchino, Kenji

    2016-11-01

    A compact ultrasonic motor using sandwiching piezo-ceramic plates was developed, having advantages of low manufacturing costs, simple driving circuit, and high scalability. The stator is composed of two piezoelectric plates attached to a T-shaped steel body. Two orthogonal bending modes can be excited by driving one piezoelectric plate and the reversed motion of the rotor can be obtained by driving the piezoelectric plate on the opposite side. The prototype stator with a size of 15 mm × 2.44 mm × 2 mm, operated at 44.8 kHz, was experimentally characterized, and a maximum torque of 2 mN m was obtained. Maximum power of 2.3 mW and efficiency of 9% were produced with a load of 0.8 mN m at a rotation speed of 27 rpm.

  8. Enamel wear caused by monolithic zirconia crowns after 6 months of clinical use.

    Science.gov (United States)

    Stober, T; Bermejo, J L; Rammelsberg, P; Schmitter, M

    2014-04-01

    The purpose of this study was to evaluate enamel wear caused by monolithic zirconia crowns and to compare this with enamel wear caused by contralateral natural antagonists. Twenty monolithic zirconia crowns were placed in 20 patients requiring full molar crowns. For measurement of wear, impressions of both jaws were made at baseline after crown cementation and at 6-month follow-up. Mean and maximum wear of the occlusal contact areas of the crowns, of their natural antagonists and of the two contralateral natural antagonists were measured by the use of plaster replicas and 3D laser scanning methods. Wear differences were investigated by the use of two-sided paired Student's t-tests and by linear regression analysis. Mean vertical loss (maximum vertical loss in parentheses) was 10 (43) μm for the zirconia crowns, 33 (112) μm for the opposing enamel, 10 (58) μm for the contralateral teeth and 10 (46) μm for the contralateral antagonists. Both mean and maximum enamel wear were significantly different between the antagonists of the zirconia crowns and the contralateral antagonists. Gender and activity of the masseter muscle at night (bruxism) were identified as possible confounders which significantly affected wear. Under clinical conditions, monolithic zirconia crowns seem to be associated with more wear of opposed enamel than are natural teeth. With regard to wear behaviour, clinical application of monolithic zirconia crowns is justifiable because the amount of antagonistic enamel wear after 6 months is comparable with, or even lower than, that caused by other ceramic materials in previous studies.

  9. A preliminary study on the short-term efficacy of chairside computer-aided design/computer-assisted manufacturing- generated posterior lithium disilicate crowns.

    Science.gov (United States)

    Reich, Sven; Fischer, Sören; Sobotta, Bernhard; Klapper, Horst-Uwe; Gozdowski, Stephan

    2010-01-01

    The purpose of this preliminary study was to evaluate the clinical performance of chairside-generated crowns over a preliminary time period of 24 months. Forty-one posterior crowns made of a machinable lithium disilicate ceramic for full-contour crowns were inserted in 34 patients using a chairside computer-aided design/computer-assisted manufacturing technique. The crowns were evaluated at baseline and after 6, 12, and 24 months according to modified United States Public Health Service criteria. After 2 years, all reexamined crowns (n = 39) were in situ; one abutment exhibited secondary caries and two abutments received root canal treatment. Within the limited observation period, the crowns revealed clinically satisfying results.

  10. Integrally cored ceramic investment casting mold fabricated by ceramic stereolithography

    Science.gov (United States)

    Bae, Chang-Jun

    Superalloy airfoils are produced by investment casting (IC), which uses ceramic cores and wax patterns with ceramic shell molds. Hollow cored superalloy airfoils in a gas turbine engine are an example of complex IC parts. The complex internal hollow cavities of the airfoil are designed to conduct cooling air through one or more passageways. These complex internal passageways have been fabricated by a lost wax process requiring several processing steps; core preparation, injection molding for wax pattern, and dipping process for ceramic shell molds. Several steps generate problems such as high cost and decreased accuracy of the ceramic mold. For example, costly tooling and production delay are required to produce mold dies for complex cores and wax patterns used in injection molding, resulting in a big obstacle for prototypes and smaller production runs. Rather than using separate cores, patterns, and shell molds, it would be advantageous to directly produce a mold that has the casting cavity and the ceramic core by one process. Ceramic stereolithography (CerSLA) can be used to directly fabricate the integrally cored ceramic casting mold (ICCM). CerSLA builds ceramic green objects from CAD files from many thin liquid layers of powder in monomer, which are solidified by polymerization with a UV laser, thereby "writing" the design for each slice. This dissertation addresses the integrally cored casting ceramic mold (ICCM), the ceramic core with a ceramic mold shell in a single patternless construction, fabricated by ceramic stereolithography (CerSLA). CerSLA is considered as an alternative method to replace lost wax processes, for small production runs or designs too complex for conventional cores and patterns. The main topic is the development of methods to successfully fabricate an ICCM by CerSLA from refractory silica, as well as related issues. The related issues are the segregation of coarse fused silica powders in a layer, the degree of segregation parameter to

  11. Fractographic features of glass-ceramic and zirconia-based dental restorations fractured during clinical function

    OpenAIRE

    Øilo, Marit; Hardang, Anne Dybdahl; Ulsund, Amanda Hembre; Gjerdet,Nils Roar

    2014-01-01

    Fractures during clinical function have been reported as the major concern associated with all-ceramic dental restorations. The aim of this study was to analyze the fracture features of glass-ceramic and zirconia-based restorations fractured during clinical use. Twenty-seven crowns and onlays were supplied by dentists and dental technicians with information about type of cement and time in function, if available. Fourteen lithium disilicate glass-ceramic restorations and 13 zirconia-based res...

  12. Amended Delaunay Algorithm for Single Tree Factor Extraction Using 3-D Crown Modeling%基于改进Delaunay算法的树冠三维重构单木因子提取

    Institute of Scientific and Technical Information of China (English)

    巩垠熙; 何诚; 冯仲科; 李文钊; 闫飞

    2013-01-01

    针对树冠结构复杂和点云数据量大的特点,为了提高测算单木因子中树冠表面积和体积的精度和效率,通过改进Delaunay三角网的算法机制,提出一种基于空间分割的分块优先级机制的三角网表面重建算法,用于重构树冠表面,形成一种高精度高效率的树冠表面积和体积因子提取方法.利用地面三维激光扫描系统获取树冠点云数据,分别通过传统人工方法、点云量测法、数字高程模型算法与提出的改进SD Delaunay算法,计算实验区域研究对象的树冠表面积与体积,并进行对比分析,结果表明提出的算法完全满足计算精度,同时该计算方法的耗时只有传统人工法的41%,数字高程模型法的62%,大大提高了运算效率.%Crown structure is complex and has huge amount of point cloud data. In order to achieve more accurate and more efficient measurement of crown surface area and volume, the characteristics of existing algorithms were analyzed and an improved triangular mesh surface reconstruction algorithm which is based on spatial division block priority mechanism was proposed for the reconfiguration of the crown surface. A precise and efficient factor extraction method for crown surface area and volume was formed. Crown point cloud data obtained through ground 3-D laser scanning system was used. Through the traditional artificial method, cloud point measurement method, the classics digital elevation model algorithm and the proposed algorithm, the crown surface and volume of the experimental subjects was calculated respectively. The inter comparison of the algorithm results fully meets the calculation accuracy. The time consumption of the proposed algorithm only accounts for 41% of the traditional way and 62% of digital elevation model method, which appears to greatly improve the operation efficiency.

  13. [Ceramic posts].

    Science.gov (United States)

    Mainjot, Amélie; Legros, Caroline; Vanheusden, Alain

    2006-01-01

    As a result of ceramics and all-ceram technologies development esthetic inlay core and abutments flooded the market. Their tooth-colored appearance enhances restoration biomimetism principally on the marginal gingiva area. This article reviews indications and types of cores designed for natural teeth and implants.

  14. Influence of different designs and porcelain/glaze firing on the marginal and internal fit of implant-supported zirconia crowns crowns%不同设计和饰/釉瓷烧结对氧化锆种植全瓷冠内部和边缘适合性的影响

    Institute of Scientific and Technical Information of China (English)

    刘翠玲; 高旭; 齐玉萍; 杨丽媛

    2016-01-01

    Objective This study investigated the influence of different designs and porcelain/glaze firing on the marginal and internal fit of three kinds of computer aided design/computer aided manufacturing (CAD/CAM) zirconia ceramic implantsupported crowns. Methods Three groups of zirconia ceramic implant-supported crowns with different designs were produced from copings by using a Cercon CAD/CAM system (n=8). The first two groups comprised double-layer crowns (zirconia coping+veneer) with regular (Group A) and full circumferential zirconia-collar marginal designs (Group B). The third group was composed of anatomic single-layer zirconia crowns without cores (Group C). Initially, the marginal and internal gaps of the copings and crowns were individually replicated by light-body silicon and then measured by micro-computed tomography scanning before and after porcelain/glaze firing. Five measurements were employed: vertical marginal gap (MG); horizontal marginal discrepancy (HMD); chamfer area (CA); axial wall (AW); and axial-occlusal transition area (AOT). Statistical analyses were performed by SPSS 17.0. Results HMD measurements in Group A were statistically higher than those in Groups B and C (P0.05). Moreover, no differences were noted in MG, CA, AW, and AOT among the three groups (P>0.05). All the measurements in the three groups showed no significant change after porcelain/glaze firing (P>0.05), except for MG in Group A, which significantly decreased (P0.05),A、B、C三组间MG、CA、AW、AOT均无统计学差异(P>0.05)。饰/釉瓷烧结后,A组MG较烧结前明显减小(P0.05)。结论   360°氧化锆颈环烤瓷全冠和全解剖式氧化锆全冠的边缘适合性优于常规氧化锆烤瓷全冠,饰瓷烧结对常规氧化锆烤瓷全冠垂直间隙的影响最明显。

  15. Ceramic Methyltrioxorhenium

    CERN Document Server

    Herrmann, R; Eickerling, G; Helbig, C; Hauf, C; Miller, R; Mayr, F; Krug von Nidda, H A; Scheidt, E W; Scherer, W; Herrmann, Rudolf; Troester, Klaus; Eickerling, Georg; Helbig, Christian; Hauf, Christoph; Miller, Robert; Mayr, Franz; Nidda, Hans-Albrecht Krug von; Scheidt, Ernst-Wilhelm; Scherer, Wolfgang

    2006-01-01

    The metal oxide polymeric methyltrioxorhenium [(CH3)xReO3] is an unique epresentative of a layered inherent conducting organometallic polymer which adopts the structural motifs of classical perovskites in two dimensions (2D) in form of methyl-deficient, corner-sharing ReO5(CH3) octahedra. In order to improve the characteristics of polymeric methyltrioxorhenium with respect to its physical properties and potential usage as an inherentconducting polymer we tried to optimise the synthetic routes of polymeric modifications of 1 to obtain a sintered ceramic material, denoted ceramic MTO. Ceramic MTO formed in a solvent-free synthesis via auto-polymerisation and subsequent sintering processing displays clearly different mechanical and physical properties from polymeric MTO synthesised in aqueous solution. Ceramic MTO is shown to display activated Re-C and Re=O bonds relative to MTO. These electronic and structural characteristics of ceramic MTO are also reflected by a different chemical reactivity compared with its...

  16. The teaching of all-ceramic restorations in North American dental schools: materials and techniques employed.

    Science.gov (United States)

    Frazier, K B; Mjör, I A

    1997-01-01

    North American dental schools were surveyed to determine the types of clinical experiences and the extent of material use that predoctoral students encounter with restorative procedures that employ all-ceramic materials. The results were based on an overall response rate of 80% from the 64 surveyed schools. The majority (96%) of the 51 schools responding to the survey did offer an opportunity to become experienced with all-ceramic restorations. The selection of bases and liners for all-ceramic restorations included dentin adhesive agents, glass ionomer materials, and calcium hydroxide products, by a ratio of 5:4:1, respectively. The most commonly used impression material types were addition silicone and polyether. One or both of these materials were used by every school. Dicor glass ceramic and alumina core ceramic were the most commonly used materials by the responding schools for veneers, onlays, and crowns. Dicor glass ceramic and CAD/CAM ceramic were most commonly used for inlays. Crowns were made of more different all-ceramic material types than the other restoration classes. Fabrication of all-ceramic restorations was primarily by commercial laboratories and school technicians. Students have hands-on experience in the fabrication of all-ceramic restorations in 6% of the responding schools. Luting agents for all-ceramic restorations include dual-cured resin, in 96% of the responding schools, light-cured resin, 43%, and glass ionomer cement, 33%. Zinc phosphate, chemical-cured composite, and polycarboxylate were used by less than one fourth of the respondents. Only resin-based composite materials were used to lute ceramic veneers. Rubber dam was applied primarily during luting procedures involving all-ceramic inlays and onlays. Crowns and veneers were isolated by this method in less than 30% of the responding schools. Finishing procedures with all-ceramic restorations were accomplished with three or more instruments by 89% of the schools.

  17. Displacive Transformation in Ceramics

    Science.gov (United States)

    1994-02-28

    single cycle[21]. In zirconia , ferroelastic domains appeared during the cubic to tetragonal transformation at -2200’C, where [c] axes were elongated...Mechanism in Tetragonal Zirconia ( TZP ) Ceramics," Adv. in Ceramics 24 (1986) 653-662. 26. K. Mehta, J. F. Jue and A. V. Virkar, "Grinding-Liduced...barium copper oxide (YBa2Cu306+x) and dicalcium silicate (Ca 2 SiO4 ). The cubic to tetragonal transformation in PbTiO3 40 was proven to be

  18. Earth Pressure on Tunnel Crown

    DEFF Research Database (Denmark)

    Andersen, Lars

    Two different analyses have been carried out in order to find the vertical earth pressure, or overburden pressure, at the crown of a tunnel going through a dike. Firstly, a hand calculation is performed using a simple dispersion of the stresses over depth. Secondly, the finite‐element program...

  19. Earth Pressure on Tunnel Crown

    DEFF Research Database (Denmark)

    Andersen, Lars

    Two different analyses have been carried out in order to find the vertical earth pressure, or overburden pressure, at the crown of a tunnel going through a dike. Firstly, a hand calculation is performed using a simple dispersion of the stresses over depth. Secondly, the finite‐element program...

  20. Monolithic Lithium Disilicate Full-Contour Crowns Bonded on CAD/CAM Zirconia Complete-Arch Implant Bridges With 3 to 5 Years of Follow-Up.

    Science.gov (United States)

    Pozzi, Alessandro; Tallarico, Marco; Barlattani, Alberto

    2015-08-01

    This study was carried on to assess the clinical performance of a novel restorative concept consisting in single monolithic lithium disilicate full-contour crowns bonded on computer-aided design/computer-aided manufacturing (CAD/CAM) zirconia complete-arch implant bridges, to overcome the drawbacks related to the chipping of porcelain fused to zirconia restorations. Sixteen patients received 18 implant-supported hybrid screw-cement-retained complete-arch restorations, consisting of single monolithic lithium disilicate full-contour crowns bonded on CAD/CAM zirconia frameworks. The restorations were supported by 4-8 implants. All patients were followed up for at least 3 years on function (range 36 to 60 months, mean 49.3 months). Clinical controls were scheduled every 4 months. The outcomes were implant and prosthetic survival and success rates, any complications, patient satisfaction, and soft tissue parameters. No dropouts occurred. The overall implant and prosthesis survival rates were 100%. One of 18 restorations (1 of 236 dental units) showed a chip-off fracture of the veneering ceramic that was polished intraorally without any additional treatment, scoring a cumulative prosthetic success rate of 100%, according to the California Dental Association index. All patients were functionally and esthetically highly satisfied with their restorations. Successful soft tissue parameters were found around all implants. Single monolithic lithium disilicate full-contour crowns, bonded on CAD/CAM screw-retained complete-arch zirconia frameworks, showed favorable preliminary outcomes with medium-term follow-up. However, randomized controlled studies of this technique are required for further conclusive recommendations.

  1. Predicting tree crown defoliation using color-infrared orthophoto maps

    Directory of Open Access Journals (Sweden)

    Eigirdas M

    2013-01-01

    Full Text Available Orthophoto maps based on color-infrared aerial photography have been used by the Lithuanian forest inventory since 2001. This study aimed to investigate the opportunities for using these orthophoto maps to predict tree crown defoliation at the single tree and sample plot levels. The test area was located in the Aukstaitija National Park, eastern Lithuania, and it was photographed in the summer of 2008 using a Vexcel UltraCam D digital frame aerial camera to produce digital orthophoto maps with a 0.5 x 0.5 m ground sampling density. Some 1721 tree crowns (mainly pine, spruce and birch, located in 166 permanent sample plots, were identified and delineated on the orthophoto maps. Crown defoliation and other dendrometric characteristics were field-estimated for all of these trees in summer 2008. Judgments on the suitability of using color-infrared aerial photography based orthophotos to estimate tree crown defoliation were based on the accuracy of the defoliation prediction. Defoliation for each crown was predicted using the non-parametric k-Nearest Neighbor (k-NN method and characteristics extracted from the digital orthophoto maps as the auxiliary variables for prediction. Prediction accuracies were validated using the “Leave One Out” technique by comparing the predicted data with data from field-assessed crown defoliations. The lowest root mean square errors for the predicted tree crown defoliation values were 7.564 for pine trees, 9.166 for spruce and 7.712 for birch and the highest coefficients of correlation between field-estimated and predicted crown defoliations were 0.576, 0.600 and 0.386, respectively. However, there was no best performing solution for using the k-NN prediction found, as the best results were achieved using different approaches. Next, predicted and field estimated tree crown defoliation values were aggregated up to the sample plot level by taking an averaging of trees in the same sample plot. The root mean square error

  2. Individual lithium disilicate crowns in a full-arch, implant-supported rehabilitation: a clinical report.

    Science.gov (United States)

    Maló, Paulo; de Sousa, Sérgio Tavares; De Araújo Nobre, Miguel; Moura Guedes, Carlos; Almeida, Ricardo; Roma Torres, António; Legatheaux, João; Silva, António

    2014-08-01

    This clinical report presents the clinical outcome of a maxillary full-arch implant-supported fixed rehabilitation with lithium disilicate reinforced glass ceramic monolithic crowns opposing a mandibular metal-acrylic implant-supported fixed rehabilitation in a 62-year-old woman. Eight implants were successfully placed (four maxillary, four mandibular), and no complications occurred in the postoperative or maintenance periods. Six months after delivery, the maxillary and mandibular prostheses were found to be clinically, biologically, and mechanically stable, and the patient was satisfied with the esthetics and her ability to function. Although the present indications for the use of lithium disilicate are still restricted to tooth-borne restorations, it is possible to successfully rehabilitate edentulous patients through implant-supported fixed prostheses using lithium disilicate reinforced glass ceramic monolithic crowns.

  3. The Effects of New Design of Access Hole on Porcelain Fracture Resistance of Implant-Supported Crowns

    Directory of Open Access Journals (Sweden)

    Reza Derafshi

    2015-03-01

    Full Text Available Statement of the Problem: One disadvantage of cement-retained crowns is the lack of predictable irretrievability. This problem can be overcome through designing a screw access hole in the metal substructure of cement-retained restora-tion and using porcelain stain to define this area. Purpose: This study aimed to evaluate the influence of existence of screw access hole on porcelain fracture resistance of metal-ceramic implant-supported crowns. Materials and Method: Thirty six standardized metal-ceramic crowns were fabri-cated and divided into 3 groups (n=12; group 1 conventional cement-retained metal-ceramic crowns as control group, group 2 cement-retained MC crowns in which porcelain stain was used to define the location of screw access channel, and group 3 cement-retained metal-ceramic crowns in the metal substructure of which a hole and ledge was designed in the location of screw access channel. The specimens were cemented (TempBond, Kerr to their dedicated abutments. A hole was made in the location of screw access channel in group 2 and 3 and filled with photo-polymerized composite resin (3M; ESPE. All specimens were thermocycled and loaded in universal testing machine at crosshead speed of 2mm/min until fracture. Mean values of load at fracture were calculated in each group and compared with One-way ANOVA (α=0.05. Results: Mean value of the load required to fracture the restorations was 1947±487 N in group 1, 1927±539 N in group 2, and 2170±738 N in group 3. No statistically significant difference was found between the fracture resistance values of the three groups (p> 0.05 Conclusion: Presence of screw access channel in cement-retained implant restora-tions does not compromise fracture resistance.

  4. Complexation between Methyl Viologen (Paraquat) Bis(Hexafluorophosphate) and Dibenzo[24]Crown-8 Revisited

    DEFF Research Database (Denmark)

    Gasa, Travis B.; Spruell, Jason M.; Dichtel, William R.

    2009-01-01

    Paraquat bis(hexafluorophosphate) undergoes stepwise dissociation in acetone. All three species - the neutral molecule, and the mono- and dications - are represented significantly under the experimental conditions typically used in host-guest binding studies. Paraquat forms at least four host...... toward dibenzo[24]crown-8. Thus, the relative abundance of neutral, singly, and doubly charged pseudorotaxanes is identical to the relative abundance of neutral, singly, and doubly charged paraquat unbound with respect to the crown ether in acetone. In the specific case of paraquat/dibenzo[24]crown-8...

  5. Single-step fabrication of nanolamellar structured oxide ceramic coatings by metal-organic chemical vapor deposition.

    Science.gov (United States)

    Eils, Nadine K; Mechnich, Peter; Keune, Hartmut; Wahl, Georg; Klages, Claus-Peter

    2011-09-01

    Oxide ceramic coatings in the system Y2O3-Al2O3-ZrO2 were fabricated in laboratory scale by using a MOCVD unit. A hot wall reactor was used along with different precursor feeding systems. Most experiments were carried out by using powder flash evaporation including a screw feeder for precursor powder delivery. For comparison, further samples were fabricated by using band flash evaporation and continuous evaporation from a crucible. Oxygen was used in all cases as reactant gas. Aluminium-tris-2,4-pentanedione (Al(acac)3), yttrium-tris-2,2,6,6-tetramethyl-3,5-heptanedione (Y(thd)3) and zirconium-tetrakis-2,2,6,6-tetramethyl-3,5-heptanedione (Zr(thd)4) were applied as metal-organic precursors because of their similar vaporization behaviour under the given conditions. The coating stoichiometry was varied from pure alumina to complex ternary compositions in the system Y2O3-Al2O3-ZrO2. Both kinds of ternary coatings fabricated by using flash evaporation methods show a nanolamellar microstructure in the as deposited state. Heat treating experiments at 1200 degrees C for up to 5 days enhance the lamellar character of the coating deposited by using powder flash evaporation. The lamellar microstructure is due to alternating YSZ enriched layers and YAG enriched layers in this state. However, the coating fabricated by using band flash evaporation shows a dense interpenetrating network of YSZ and YAG after heat treating instead of a lamellar microstructure observed in the as deposited state.

  6. FATIGUE OF DENTAL CERAMICS

    Science.gov (United States)

    Zhang, Yu; Sailer, Irena; Lawn, Brian R

    2013-01-01

    Objectives Clinical data on survival rates reveal that all-ceramic dental prostheses are susceptible to fracture from repetitive occlusal loading. The objective of this review is to examine the underlying mechanisms of fatigue in current and future dental ceramics. Data/sources The nature of various fatigue modes is elucidated using fracture test data on ceramic layer specimens from the dental and biomechanics literature. Conclusions Failure modes can change over a lifetime, depending on restoration geometry, loading conditions and material properties. Modes that operate in single-cycle loading may be dominated by alternative modes in multi-cycle loading. While post-mortem examination of failed prostheses can determine the sources of certain fractures, the evolution of these fractures en route to failure remains poorly understood. Whereas it is commonly held that loss of load-bearing capacity of dental ceramics in repetitive loading is attributable to chemically-assisted 'slow crack growth' in the presence of water, we demonstrate the existence of more deleterious fatigue mechanisms, mechanical rather than chemical in nature. Neglecting to account for mechanical fatigue can lead to gross overestimates in predicted survival rates. Clinical significance Strategies for prolonging the clinical lifetimes of ceramic restorations are proposed based on a crack-containment philosophy. PMID:24135295

  7. Diffusion in ceramics

    CERN Document Server

    Pelleg, Joshua

    2016-01-01

    This textbook provides an introduction to changes that occur in solids such as ceramics, mainly at high temperatures, which are diffusion controlled, as well as presenting research data. Such changes are related to the kinetics of various reactions such as precipitation, oxidation and phase transformations, but are also related to some mechanical changes, such as creep. The book is composed of two parts, beginning with a look at the basics of diffusion according to Fick's Laws. Solutions of Fick’s second law for constant D, diffusion in grain boundaries and dislocations are presented along with a look at the atomistic approach for the random motion of atoms. In the second part, the author discusses diffusion in several technologically important ceramics. The ceramics selected are monolithic single phase ones, including: A12O3, SiC, MgO, ZrO2 and Si3N4. Of these, three refer to oxide ceramics (alumina, magnesia and zirconia). Carbide based ceramics are represented by the technologically very important Si-ca...

  8. Fatigue of dental ceramics.

    Science.gov (United States)

    Zhang, Yu; Sailer, Irena; Lawn, Brian R

    2013-12-01

    Clinical data on survival rates reveal that all-ceramic dental prostheses are susceptible to fracture from repetitive occlusal loading. The objective of this review is to examine the underlying mechanisms of fatigue in current and future dental ceramics. The nature of various fatigue modes is elucidated using fracture test data on ceramic layer specimens from the dental and biomechanics literature. Failure modes can change over a lifetime, depending on restoration geometry, loading conditions and material properties. Modes that operate in single-cycle loading may be dominated by alternative modes in multi-cycle loading. While post-mortem examination of failed prostheses can determine the sources of certain fractures, the evolution of these fractures en route to failure remains poorly understood. Whereas it is commonly held that loss of load-bearing capacity of dental ceramics in repetitive loading is attributable to chemically assisted 'slow crack growth' in the presence of water, we demonstrate the existence of more deleterious fatigue mechanisms, mechanical rather than chemical in nature. Neglecting to account for mechanical fatigue can lead to gross overestimates in predicted survival rates. Strategies for prolonging the clinical lifetimes of ceramic restorations are proposed based on a crack-containment philosophy. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Crowns to create esthetics for mal-aligned central incisors: a case report.

    Science.gov (United States)

    Savadi, Ravindra C; Savadi, Anupama R; Kumar, Preeti Satheesh

    2011-06-01

    This case report describes the smile design of crowded upper central anteriors in a female patient aged 25 years. The patient wanted the correction to be completed in a short period of time. A smile design schedule was drawn up involving root canal treatment of the central incisors and placing posts in both the teeth. All ceramic crowns were then fabricated to establish a very satisfactory and pleasing esthetics.

  10. Reflectance signature on sunlit crown of conifers

    Institute of Scientific and Technical Information of China (English)

    王锦地; 李小文; 项月琴

    1997-01-01

    Based on the field measurements of the reflected radiation distribution on sunlit crown surface and crown structure, the analytical approximation model of path-scattering of light in a homogeneous layer is applied to the calculation of the reflectance signature of sunlit crown. The reflectance on the sunlit crown surface is considered as the weighted sum of the direct-to-hemisphere reflectance and the hemisphere-to-hemisphere reflectance. The validation results show that the calculated reflectance signature fits the field measurement very well This paper presents details of the validation and the feasibility of the model application to nonuniform medium, such as tree crown canopies.

  11. Crown lengthening: the periodontal-restorative connection.

    Science.gov (United States)

    Becker, W; Ochsenbein, C; Becker, B E

    1998-03-01

    Crown lengthening procedures are based on biologic principles that can be determinants for successful treatment. These procedures are fixed on an understanding of the biologic width. A few of the indications for crown lengthening are caries beneath the gingival margin, fractured teeth with insufficient clinical crown exposure, and teeth with excessive occlusal or incisal wear. This article describes flap designs, the use of a new bur probe for precise measurement of clinical crown exposure, and suturing methods for flap stabilization. Clinical documentation of patients with various clinical situations requiring crown lengthening is presented.

  12. [Combined crown lengthening surgery with restorative therapy for inducing papilla growth: a case report].

    Science.gov (United States)

    Le, Di; Hu, Wen-jie; Zhang, Hao

    2013-04-18

    A young lady with unsatisfied restorations of upper anterior teeth and swollen gum wanted to improve aesthetics. Oral examination showed that 12-22 were provisional crowns with normal occlusion, poorly gingival contour and gummy smile. The gingiva was red, light swollen and bleeding on probing. X-ray showed the roots of 11, 21 were short and the alveolar bone absorbed. After the periodontal initial treatment, an ideal location of gingival margin was determined. Then, an esthetic periodontal surgery was performed to recover the biology width and the gingival margin was fitted with the anterior teeth. The temporary restorations were made twice to guide the gingiva growth by changing the shape of the restorations and moving up the contact points of the restorations. The ceramic crowns were completed 3 months after the operation. The gummy smile disappeared and the gingival margin was filled well with the upper anterior ceramic crowns. The 14-month follow-up presented a satisfied effect. Crown lengthening surgery combined restorative therapy could lead papilla to grow well. This process is beneficial for the future treatment plan and clinical esthetic evaluation.

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

    Science.gov (United States)

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

    2011-08-01

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

  14. Survival of resin infiltrated ceramics under influence of fatigue.

    Science.gov (United States)

    Aboushelib, Moustafa N; Elsafi, Mohamed H

    2016-04-01

    to evaluate influence of cyclic fatigue on two resin infiltrated ceramics and three all-ceramic crowns manufactured using CAD/CAM technology. CAD/CAM anatomically shaped crowns were manufactured using two resin infiltrated ceramics (Lava Ultimate and Vita Enamic), two reinforced glass ceramic milling blocks ((IPS)Empress CAD and (IPS)e.max CAD) and a veneered zirconia core ((IPS)Zir CAD). (IPS)e.max CAD and (IPS)Zir CAD were milled into 0.5mm thick anatomically shaped core structure which received standardized press-on veneer ceramic. The manufactured crowns were cemented on standardized resin dies using a resin adhesive (Panavia F2.0). Initial fracture strength of half of the specimens was calculated using one cycle load to failure in a universal testing machine. The remaining crowns were subjected to 3.7 million chewing cycles (load range 50-200N at 3s interval) in a custom made pneumatic fatigue tester. Survival statistics were calculated and Weibull modulus was measured from fitted load-cycle-failure diagrams. Scanning electron microscopy was performed to fractographically analyze fractured surfaces. Data were analyzed using two way analysis of variance and Bonferroni post hoc tests (α=0.05). Dynamic fatigue resulted in significant reduction (F=7.54, Pceramics and (IPS)Empress demonstrated the highest percent of fracture incidences under the influence of fatigue (35-45% splitting). None of the tested veneered zirconia restorations were fractured during testing, however, chipping of the veneer ceramics was observed in 6 crowns. The lowest percent of failure was observed for (IPS)e.max crowns manifested as 3 cases of minor chipping in addition to two complete fracture incidences. SEM images demonstrated the internal structure of the tested materials and detected location and size of the critical crack. The internal structure of the tested materials significantly influenced their fatigue behavior. Resin infiltrated ceramics were least influenced by fatigue while

  15. Engineering ceramics

    CERN Document Server

    Bengisu, Murat

    2001-01-01

    This is a comprehensive book applying especially to junior and senior engineering students pursuing Materials Science/ Engineering, Ceramic Engineering and Mechanical Engineering degrees. It is also a reference book for other disciplines such as Chemical Engineering, Biomedical Engineering, Nuclear Engineering and Environmental Engineering. Important properties of most engineering ceramics are given in detailed tables. Many current and possible applications of engineering ceramics are described, which can be used as a guide for materials selection and for potential future research. While covering all relevant information regarding raw materials, processing properties, characterization and applications of engineering ceramics, the book also summarizes most recent innovations and developments in this field as a result of extensive literature search.

  16. Evaluation of the occlusal contact of crowns fabricated with the bite impression method.

    Science.gov (United States)

    Makino, Sachi; Okada, Daizo; Shin, Chiharu; Ogura, Reiko; Ikeda, Masaomi; Miura, Hiroyuki

    2013-09-30

    In prosthodontic treatment, reconstruction of a proper occlusal contact relationship is very important as well as reconstruction of a proper interproximal relationship and marginal fitness. Unfortunately, occlusal relationships are sometimes lost in the process of occlusal adjustment of crowns. The purpose of this study was to compare the occlusal contacts of single crown fabricated by two different types of impression techniques. Nine subjects, whose molars required treatment with crown restoration, were enrolled in this study. Full cast crowns were fabricated using two types of impression techniques: the conventional impression method (CIM) and the bite impression method (BIM). The occlusal contacts of crowns were precisely evaluated at the following stages: after occlusal adjustment on the articulator (Step 0), before occlusal adjustment in the mouth (Step 1), after occlusal adjustment at the intercuspal position (Step 2), and after occlusal adjustment during lateral and protrusive excursions (Step 3). The number of occlusal contacts of the crowns on the functional cusps fabricated with BIM was significantly greater than that with CIM after occlusal adjustment. For this reason, the crowns fabricated with BIM might have a more functionally desirable occlusal surface compared to the crowns fabricated with CIM.

  17. Effect of water temperature on the fit of provisional crown margins during polymerization: An in vitro study

    Directory of Open Access Journals (Sweden)

    Vivekanandan Ramkumar

    2012-01-01

    Full Text Available Aim: To evaluate the effect of water temperature on the marginal fit of bis-acrylic composite provisional crown during resin polymerization. Materials and Methods: Precisely machined 10 brass master dies were designed to simulate molar teeth. Five brass dies were selected and precisely machined to simulate all ceramic crown preparation. An acrylic jaw replica was made in which brass dies were arranged equidistant from each other. A custom-made metallic tray was fabricated on the acrylic jaw replica to make polyvinyl siloxane impression matrix. Bis-acrylic composite resin provisional crowns were made using polyvinyl siloxane impression matrix. Provisional crowns were polymerized at room temperature (Group I direct technique, on dental stone cast; Group I indirect technique crowns and at different water temperatures (Group II direct technique crowns. The vertical marginal gap between all the provisional crown margins and the finish line of brass dies was measured using a Research Stereomicroscope System. Results: The results were statistically analyzed using one-way analysis of variance (ANOVA test and Newman-Keul′s test. The results showed that crowns polymerized in 20°C and 30°C water had marginal gap approximately three times smaller than those polymerized in 30°C air, due to the reduced polymerization shrinkage. Conclusion: This study shows that crowns polymerized in 20°C and 30°C water had mean vertical marginal gap approximately three times smaller than those polymerized in 30°C air. It was approximately closer to that of crowns fabricated by indirect technique. Warmer water also supposedly hastens polymerization.

  18. Structural Ceramics Database

    Science.gov (United States)

    SRD 30 NIST Structural Ceramics Database (Web, free access)   The NIST Structural Ceramics Database (WebSCD) provides evaluated materials property data for a wide range of advanced ceramics known variously as structural ceramics, engineering ceramics, and fine ceramics.

  19. Effect of the crown design and interface lute parameters on the stress-state of a machined crown-tooth system: a finite element analysis.

    Science.gov (United States)

    Shahrbaf, Shirin; vanNoort, Richard; Mirzakouchaki, Behnam; Ghassemieh, Elaheh; Martin, Nicolas

    2013-08-01

    The effect of preparation design and the physical properties of the interface lute on the restored machined ceramic crown-tooth complex are poorly understood. The aim of this work was to determine, by means of three-dimensional finite element analysis (3D FEA) the effect of the tooth preparation design and the elastic modulus of the cement on the stress state of the cemented machined ceramic crown-tooth complex. The three-dimensional structure of human premolar teeth, restored with adhesively cemented machined ceramic crowns, was digitized with a micro-CT scanner. An accurate, high resolution, digital replica model of a restored tooth was created. Two preparation designs, with different occlusal morphologies, were modeled with cements of 3 different elastic moduli. Interactive medical image processing software (mimics and professional CAD modeling software) was used to create sophisticated digital models that included the supporting structures; periodontal ligament and alveolar bone. The generated models were imported into an FEA software program (hypermesh version 10.0, Altair Engineering Inc.) with all degrees of freedom constrained at the outer surface of the supporting cortical bone of the crown-tooth complex. Five different elastic moduli values were given to the adhesive cement interface 1.8GPa, 4GPa, 8GPa, 18.3GPa and 40GPa; the four lower values are representative of currently used cementing lutes and 40GPa is set as an extreme high value. The stress distribution under simulated applied loads was determined. The preparation design demonstrated an effect on the stress state of the restored tooth system. The cement elastic modulus affected the stress state in the cement and dentin structures but not in the crown, the pulp, the periodontal ligament or the cancellous and cortical bone. The results of this study suggest that both the choice of the preparation design and the cement elastic modulus can affect the stress state within the restored crown

  20. Effect of Metal Collar on Marginal Distortion of Base Metal Crowns

    Directory of Open Access Journals (Sweden)

    Grami Panah F

    2000-06-01

    Full Text Available It has been shown that noble alloys require metal collar to resist distortion when subjected to"nrepeat firing cycle of porcelain. Metal collar is undesirable due to esthetic concerns. Since base metal"nalloys have superior physical properties, it seems that metal collar would not be necessary for obtaining"nbetter marginal adaptation of base metal crowns. The Purpose of this study was to evaluate the effect of"nmetal collar on marginal distortion of base metal- ceramic crowns, Twenty base metal copings were"nconstructed and divided into two groups with and without collars. After surface preparation, porcelain"nwas applied onto the surface of specimens. Marginal gap was measured by scanning electron microscope"nduring three stages of crown fabrication: before degassing, after degassing and after glazing. The mean"nmeasurements in collarless group were; 21.4±13.4, 2I.4±14.9 and 21.9±11.9 u_m, respectively, and in-"ngroup with collar; 24.7±11.4, 24.0±! 1.5 and 26.6±11.7 urn, respectively. Two- way ANOVA revealed"nno significant difference in the mean values between two groups and among different stages of crown"nfabrication. The results of this study showed that base metal alloys did not distort during crown"nfabrication and metal collar had no effect on the amount of marginal opening (gap.

  1. Analysis of regenerated single-shaft ceramic gas-turbine engines and resulting fuel economy in a compact car

    Science.gov (United States)

    Klann, J. L.; Tew, R. C., Jr.

    1977-01-01

    Ranges in design and off-design operating conditions of an advanced gas turbine and their effects on fuel economy were analyzed. The assumed engine incorporated a single stage radial flow turbine and compressor with fixed geometry. Fuel economies were calculated over the composite driving cycle with gasoline as the fuel. At a constant turbine-inlet temperature, with a regenerator sized for a full power effectiveness the best fuel economies ranged from 11.1 to 10.2 km/liter (26.2 to 22.5 mpg) for full power turbine tip speeds of 770 to 488m/sec (2530 to 1600ft/sec), respectively.

  2. Evaluation of tensile retention of Y-TZP crowns after long-term aging: effect of the core substrate and crown surface conditioning.

    Science.gov (United States)

    Amaral, R; Rippe, M; Oliveira, B G; Cesar, P F; Bottino, M A; Valandro, L F

    2014-01-01

    This study evaluated the effect of the core substrate type (dentin and composite resin) on the retention of crowns made of yttrium oxide stabilized tetragonal zirconia polycrystal (Y-TZP), submitted to three inner surface conditionings. For this purpose, 72 freshly extracted molars were embedded in acrylic resin, perpendicular to the long axis, and prepared for full crowns: 36 specimens had crown preparations in dentin; the remaining 36 teeth had the crowns removed, and crown preparations were reconstructed with composite resin plus fiber posts with dimensions identical to the prepared dentin. The preparations were impressed using addition silicone, and 72 Y-TZP copings for the tensile test were produced. Cementation was performed with a dual-cured cement containing phosphate monomers. For cementation, the crown preparation (dentin or resin) was conditioned with the adhesive system, and the ceramic was subjected to one of three surface treatments: isopropyl alcohol, tribochemical silica coating, or thin low-fusing glassy porcelain layer application plus silanization. After 24 hours, all specimens were submitted to thermocycling (6000 cycles) and placed in a special tensile testing device in a universal testing machine to determine failure loads. The failure modes of all samples were analyzed under a stereomicroscope. Two-way analysis of variance showed that the surface treatment and substrate type (α=0.05) affected the tensile retention results. The dentin substrate presented the highest tensile retention values, regardless of the surface treatment. When the substrate was resin, the tribochemical silica coating and low-fusing glaze application plus silanization groups showed the higher retention values.

  3. Dental students' preferences and performance in crown design: conventional wax-added versus CAD.

    Science.gov (United States)

    Douglas, R Duane; Hopp, Christa D; Augustin, Marcus A

    2014-12-01

    The purpose of this study was to evaluate dental students' perceptions of traditional waxing vs. computer-aided crown design and to determine the effectiveness of either technique through comparative grading of the final products. On one of twoidentical tooth preparations, second-year students at one dental school fabricated a wax pattern for a full contour crown; on the second tooth preparation, the same students designed and fabricated an all-ceramic crown using computer-aided design (CAD) and computer-aided manufacturing (CAM) technology. Projects were graded for occlusion and anatomic form by three faculty members. On completion of the projects, 100 percent of the students (n=50) completed an eight-question, five-point Likert scalesurvey, designed to assess their perceptions of and learning associated with the two design techniques. The average grades for the crown design projects were 78.3 (CAD) and 79.1 (wax design). The mean numbers of occlusal contacts were 3.8 (CAD) and 2.9(wax design), which was significantly higher for CAD (p=0.02). The survey results indicated that students enjoyed designing afull contour crown using CAD as compared to using conventional wax techniques and spent less time designing the crown using CAD. From a learning perspective, students felt that they learned more about position and the size/strength of occlusal contacts using CAD. However, students recognized that CAD technology has limits in terms of representing anatomic contours and excursive occlusion compared to conventional wax techniques. The results suggest that crown design using CAD could be considered as an adjunct to conventional wax-added techniques in preclinical fixed prosthodontic curricula.

  4. Effect of Cervical Collar Removal on the Fracture Load of Anterior Zirconia Crowns.

    Science.gov (United States)

    Campos, Fernanda; Cardoso, Mayra; de Melo, Renata Marques; Bottino, Marco Antonio; Souza, Rodrigo Oa

    The objective of this study was to assess the influence of the extension of collar and fatigue cycling on the fracture load of anterior zirconia crowns. A total of 60 anterior full-crown preparations (central incisor) were machined in glass fiber-filled epoxy resin. Zirconia copings were designed and milled using computer-aided design/computer-assisted manufacture (thickness: buccal = 0.62 mm, lingual = 0.65 mm, incisal = 0.72 mm). The cervical collars (occlusogingival height = 0.8 mm, buccolingual width = 1.0 mm) were totally or partially (buccal face) removed for modified copings. They were randomly allocated to six groups according to the type of cervical collar design and the presence (or not) of fatigue cycling (n = 10). The veneering ceramic layer was pressed, and the crowns were cemented with resin cement. The samples were tested until fracture in a universal testing machine and analyzed by stereomicroscopy. Data were statistically analyzed by two-way analysis of variance and Tukey test (5%). Removal of the cervical collar significantly affected the fracture strength of zirconia crowns (P = .000), whereas fatigue cycling did not (P = .428). The mean failure load was lower in the groups with no collar. The most frequent failure modes were cracking of the veneer porcelain in collarless crowns and catastrophic failure in the others. The authors concluded that removal of the vestibular collar of zirconia copings in anterior crowns does not reduce the fracture load of the crowns. However, removal of the entire collar reduces the fracture load and cannot be recommended.

  5. Ceramic Laser Materials

    Energy Technology Data Exchange (ETDEWEB)

    Soules, T F; Clapsaddle, B J; Landingham, R L; Schaffers, K I

    2005-02-15

    Transparent ceramic materials have several major advantages over single crystals in laser applications, not the least of which is the ability to make large aperture parts in a robust manufacturing process. After more than a decade of working on making transparent YAG:Nd, Japanese workers have recently succeeded in demonstrating samples that performed as laser gain media as well as their single crystal counterparts. Since then several laser materials have been made and evaluated. For these reasons, developing ceramic laser materials is the most exciting and futuristic materials topic in today's major solid-state laser conferences. We have established a good working relationship with Konoshima Ltd., the Japanese producer of the best ceramic laser materials, and have procured and evaluated slabs designed by us for use in our high-powered SSHCL. Our measurements indicate that these materials will work in the SSHCL, and we have nearly completed retrofitting the SSHCL with four of the largest transparent ceramic YAG:Nd slabs in existence. We have also begun our own effort to make this material and have produced samples with various degrees of transparency/translucency. We are in the process of carrying out an extensive design-of-experiments to establish the significant process variables for making transparent YAG. Finally because transparent ceramics afford much greater flexibility in the design of lasers, we have been exploring the potential for much larger apertures, new materials, for example for the Mercury laser, other designs for SSHL, such as, edge pumping designs, slabs with built in ASE suppression, etc. This work has just beginning.

  6. Ex vivo fracture resistance of direct resin composite complete crowns with and without posts on maxillary premolars.

    NARCIS (Netherlands)

    Fokkinga, W.A.; Bell, A.M. Le; Kreulen, C.M.; Lassila, L.V.; Vallittu, P.K.; Creugers, N.H.J.

    2005-01-01

    AIM: To investigate ex vivo the fracture resistance and failure mode of direct resin composite complete crowns with and without various root canal posts made on maxillary premolars. METHODOLOGY: The clinical crowns of 40 human extracted single-rooted maxillary premolars were sectioned at the cemento

  7. Fracture behavior of structurally compromised non-vital maxillary premolars restored using experimental fiber reinforced composite crowns.

    NARCIS (Netherlands)

    Fokkinga, W.A.; Kreulen, C.M.; Bell-Ronnlof, A.M. Le; Lassila, L.V.; Vallittu, P.K.; Creugers, N.H.J.

    2006-01-01

    PURPOSE: To study the fracture behavior of direct resin composite crowns with or without experimental fiber reinforcement. METHODS: Clinical crowns of single-rooted maxillary premolars were cut off at the cemento-enamel junction. Canals were prepared with Gates Glidden drills up to size 4. No additi

  8. SiHf(B)CN-based ultra-high temperature ceramic nanocomposites: Single-source precursor synthesis and behavior in hostile environments

    OpenAIRE

    Yuan, Jia

    2015-01-01

    Hf-containing ultra-high-temperature ceramics (UHTCs) are being pursued for Thermal Protection Systems (TPSs) for high-temperature applications (i.e., future hypersonic vehicles) in harsh environments. Most of these ceramic composites have been prepared using traditional powder techniques; however, the grain sizes of the resulting composites are limited to the micrometer range. Furthermore, nano-sized Hf-containing materials have proven to exhibit tremendously improved structural/functional p...

  9. [Artificial crowns influence upon edge parodontium status].

    Science.gov (United States)

    Zhulev, E N; Serov, A B

    2010-01-01

    With the aim of prosthetic treatment efficacy increase study of edge parodontium tissue reaction upon different types of artificial crowns was done and methods of chronic localized parodontitis prevention were developed. Changes of the main gingival fluid characteristics (amount, acidity, interleukine-1beta concentration) and indicators of microcirculation in edge parodontium of the teeth under the artificial crowns influence were disclosed. There were developed methods of chronic localized parodontitis prevention produced by artificial crowns edge.

  10. Pericoronal radiolucency associated with incomplete crown

    Energy Technology Data Exchange (ETDEWEB)

    Nah, Kyung Soo [Dept. of Oral and Maxillofacial Radiology, School of Dentistry, Pusan National University, Yangsan (Korea, Republic of)

    2013-12-15

    The author experienced 8 cases of pericoronal radiolucency involving an incomplete tooth crown that had not developed to form the cemento-enamel junction, and the underdeveloped crown sometimes appeared to be floating within the radiolucency radiographically. The first impression was that these cystic lesions had odontogenic keratocysts, but half of them turned out to be dentigerous cysts histopathologically. There has been no report concerning odontogenic cysts involving an incompletely developed crown. The purpose of this paper is to report that dentigerous cysts may develop before the completion of the cemento-enamel junction of a developing crown.

  11. Factors to achieve aesthetics in all-ceramic restorations.

    Science.gov (United States)

    Barão, Valentim Adelino Ricardo; Gennari-Filho, Humberto; Goiato, Marcelo Coelho; dos Santos, Daniela Micheline; Pesqueira, Aldiéris Alves

    2010-11-01

    The demand for aesthetic restorations has increased during the last years. Dental ceramics are a successful alternative for some cases because of aesthetics and biocompatibility. Therefore, the aim of this literature review was to present the factors necessary to fabricate all-ceramic restorations with aesthetics similar to natural dentition. A search of English-language peer-review literature was completed using MEDLINE database from 1975 to 2009 including the keywords "aesthetic," "metal-free crown," "all-ceramic," and "color." It was observed that several factors influence aesthetics of all-ceramic restorations. Color scale, light source during color evaluation, characteristic of core material, color of supporting tooth, presence of root post, and type of cement are clinical factors that may influence color of the restorations. Laboratorial factors as technique for ceramic condensation, thickness, temperature, and number of firing cycles also influence the result of these crowns. Although several clinical and laboratorial factors influence aesthetics of all-ceramic restorations, the aesthetic success and longevity of these restorations depend on the integration with surrounding periodontal tissue.

  12. Spectroscopic properties of long-lifetime Tm3+ optical centers in Ca-Sr-Ba fluorides in the form of single crystals and ceramics at the 1G4-3H5 magnetic dipole allowed transition

    Science.gov (United States)

    Doroshenko, M. E.; Papashvili, A. G.; Martynova, K. A.; Konyushkin, V. A.; Nakladov, A. N.; Osiko, V. V.

    2017-02-01

    The spectroscopic properties of new long-lifetime Tm3+ tetragonal optical centers at low (77 K) temperature were investigated using a site-selective time-resolved technique. The absorption and excitation spectra at the 3H6-1G4 transition and the fluorescence spectra at the 1G4-3H5 transition were measured in CaF2, SrF2, and BaF2 single crystals. The appearance of additional weak lines in the excitation and fluorescence spectra in hot-formed ceramics produced from the same crystals was observed. These lines were attributed to the recently observed long-lifetime tetragonal optical centers with a modified local environment formed in fluoride ceramics.

  13. Evaluation of fracture toughness in dental ceramics using indentation and SEVNB (Single Edge V-Notched Beam)-method; Avaliacao da tenacidade a fratura de ceramicas dentarias atraves do metodo de entalhe - SEVNB (Single Edge V-Notched Beam)

    Energy Technology Data Exchange (ETDEWEB)

    Santos, L.A.; Santos, C.; Souza, R.C.; Ribeiro, S. [Universidade de Sao Paulo (DEMAR/EEL/USP), Lorena, SP (Brazil). Escola de Engenharia de Lorena. Dept. de Engenharia de Materiais. Polo Urbo-Industrial; Strecker, K. [Universidade Federal de Sao Joao del-Rei (DME/UFSJ), MG (Brazil). Dept. de Materiais Eletricos; Oberacker, R. [Karlsruhe Univ. (Germany)

    2009-07-01

    In this work, the fracture toughness of different ceramics based on Al{sub 2}O{sub 3} and ZrO{sub 2} were evaluated using, comparatively two methods, Vickers indentation and SEVNB (Single Edge V-Notched Beam) method. Al{sub 2}O{sub 3}, ZrO{sub 2}(3%Y{sub 2}O{sub 3}) micro-particled and ZrO{sub 2}(3%Y{sub 2}O{sub 3}) nanometric, ZrO{sub 2}-Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}-ZrO{sub 2} composites were sintered at different temperatures. Samples were characterized by relative density, X-ray diffraction, SEM, and mechanical evaluation by hardness, bending strength and fracture toughness obtained by ickers indentation and SEVNB-method. The results were presented comparing the densification and microstructural results. Furthermore, the advantages and limitations of each method were discussed. (author)

  14. Ceramic Seal.

    Energy Technology Data Exchange (ETDEWEB)

    Smartt, Heidi A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Romero, Juan A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Custer, Joyce Olsen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hymel, Ross W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Krementz, Dan [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Gobin, Derek [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Harpring, Larry [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Martinez-Rodriguez, Michael [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Varble, Don [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); DiMaio, Jeff [Tetramer Technologies, Pendleton, SC (United States); Hudson, Stephen [Tetramer Technologies, Pendleton, SC (United States)

    2016-11-01

    Containment/Surveillance (C/S) measures are critical to any verification regime in order to maintain Continuity of Knowledge (CoK). The Ceramic Seal project is research into the next generation technologies to advance C/S, in particular improving security and efficiency. The Ceramic Seal is a small form factor loop seal with improved tamper-indication including a frangible seal body, tamper planes, external coatings, and electronic monitoring of the seal body integrity. It improves efficiency through a self-securing wire and in-situ verification with a handheld reader. Sandia National Laboratories (SNL) and Savannah River National Laboratory (SRNL), under sponsorship from the U.S. National Nuclear Security Administration (NNSA) Office of Defense Nuclear Nonproliferation Research and Development (DNN R&D), have previously designed and have now fabricated and tested Ceramic Seals. Tests have occurred at both SNL and SRNL, with different types of tests occurring at each facility. This interim report will describe the Ceramic Seal prototype, the design and development of a handheld standalone reader and an interface to a data acquisition system, fabrication of the seals, and results of initial testing.

  15. Clinical crown lengthening to improve implant results.

    Science.gov (United States)

    Kohner, J

    1992-01-01

    Clinical crown lengthening is used as an adjunct to implant procedures, and can help provide a better long-term prognosis by establishing proper occlusal planes and aiding in preparation of the abutment teeth. Crown lengthening procedures may be especially useful when caries or a fracture extends below the gingival margin, compromising impression taking and marginal fit.

  16. Crown lengthening: a surgical flap approach.

    Science.gov (United States)

    Lundergan, W; Hughes, W R

    1996-09-01

    In many instances it is not possible to place a restoration margin without encroaching on the periodontal attachment apparatus. A surgical crown-lengthening procedure can provide a good solution to this common clinical problem. This article discusses indication and contraindication for surgical crown-lengthening procedures and presents an appropriate surgical technique.

  17. Fracture resistance of zirconia-composite veneered crowns in comparison with zirconia-porcelain crowns.

    Science.gov (United States)

    Alsadon, Omar; Patrick, David; Johnson, Anthony; Pollington, Sarah; Wood, Duncan

    2017-02-11

    The objectives were to evaluate the fracture resistance and stress concentration in zirconia/composite veneered crowns in comparison to zirconia/porcelain crowns using occlusal fracture resistance and by stress analysis using finite element analysis method. Zirconia substructures were divided into two groups based on the veneering material. A static load was applied occlusally using a ball indenter and the load to fracture was recorded in Newtons (N). The same crown design was used to create 3D crown models and evaluated using FEA. The zirconia/composite crowns subjected to static occlusal load showed comparable results to the zirconia/porcelain crowns. Zirconia/composite crowns showed higher stress on the zirconia substructure at 63.6 and 50.9 MPa on the zirconia substructure veneered with porcelain. In conclusion, zirconia/composite crowns withstood high occlusal loads similar to zirconia/porcelain crowns with no significant difference. However, the zirconia/composite crowns showed higher stress values than the zirconia/porcelain crowns at the zirconia substructure.

  18. Esthetic crown lengthening for maxillary anterior teeth.

    Science.gov (United States)

    Sonick, M

    1997-08-01

    In the maxillary anterior region, the gingival labial margin position is an important parameter in the achievement of an ideal smile. The relationship between the periodontium and the restoration is critical if gingival health and esthetics are to be achieved. Periodontal therapy is a necessary and useful adjunct when any anterior restoration is undertaken. Anterior surgical crown lengthening may be undertaken to avoid restorative margin impingement on the biologic width. Crown lengthening is also used to alter the gingival labial profiles. This article discusses the esthetic parameters of ideal gingival labial positions and presents a classification of crown-lengthening procedures and the procedure for a two-stage crown-lengthening technique. The two-stage crown-lengthening technique is surgically precise because healing is predictable.

  19. Dimethylammonium perchlorate 18-crown-6 monohydrate clathrate

    Directory of Open Access Journals (Sweden)

    Jia-Zhen Ge

    2010-07-01

    Full Text Available The reaction of dimethylamine, 18-crown-6, and perchloric acid in methanol yields the title compound, C2H8N+·ClO4−·C12H24O6·H2O. The dimethylammonium cation and the water molecule interact with the 18-crown-6 unit: N—H...O hydrogen bonds are formed between the ammonium NH2+ group and four O atoms of the crown ether, while the water molecule on the other side of 18-crown-6 ring forms O—H...O hydrogen bonds with two other O atoms of the crown ether. All conventional donors and acceptors in the cations are thus engaged in hydrogen bonding. The ClO4− anion is disordered over two sites, and occupancies for the disordered O atoms were fixed at 0.5. In the crystal, the cations and anions are arranged in alternating layers.

  20. Esthetic rehabilitation of anterior discolored teeth with lithium disilicate all-ceramic restorations.

    Science.gov (United States)

    Prevedello, Gustavo Costa; Vieira, Marcelo; Furuse, Adilson Yoshio; Correr, Gisele Maria; Gonzaga, Carla Castiglia

    2012-01-01

    The esthetic treatment of darkened anterior teeth represents a great challenge to dentists, because dental materials ideally should match the natural teeth. The optical behavior of the final restoration is determined by the color of the underlying tooth structure, the color of the luting agent, and the thickness and opacity of the ceramic material used. This article reports a case in which veneers and full crowns made of heat-pressed, lithium disilicate glass-ceramic were used for the esthetic rehabilitation of anterior discolored teeth. The patient was referred for treatment with defective anterior composite resin restorations, provisional acrylic resin crowns, darkening of the gingival margins, and uneven gingival contours. The multidisciplinary treatment plan included dental bleaching, periodontal plastic surgery to create gingival symmetry, and indirect all-ceramic restorations using high-opacity lithium disilicate glass-ceramic ingots. The treatment was successful and an excellent esthetic result was achieved.

  1. Fracture strength of all-ceramic restorations after fatigue loading

    Science.gov (United States)

    Baladhandayutham, Balasudha

    Fracture strength of monolithic and bilayered LAVA and e. max lower molar crowns after load cycling was measured and compared. The study included three groups (n = 8) from LAVA zirconia and three groups from e. max lithium disilicate to compare influences of different layers, thicknesses and manufacturing techniques. Prefabricated anatomically designed crowns were cemented to dies made from Z 100 composite resin using Rely X Luting Plus resin modified glass ionomer cement. Cemented crowns were stored at 37° C for 24 hours then cyclic loaded to test fatigue properties. The crowns were loaded to 200,000 cycles at 25N at a rate of 40 cycles / minute to simulate oral function. Subsequently, fracture properties for each group were measured using an Instron Universal Testing machine. Microscopic evaluation of the surface of fatigued samples did not reveal micro-cracks at the end of 50,000 cycles but minor wear facets were observed at the site of contact from the steatite ball antagonist. Crowns from LAVA bilayered groups showed step by step fractures while crowns from all other groups fractured as a single event as observed by the high speed camera. Zirconia bilayered crowns showed the highest loads to fracture while lithium disilicate monolithic crowns showed the lowest, within the limitations of the study. The study also showed that monolithic zirconia crowns of 0.6mm thickness resulted in relatively high magnitude for forces at fracture.

  2. Single-phase ceramics with La{sub 1-x}Sr{sub x}Ga{sub 1-y}Mg{sub y}O{sub 3-{delta}} composition from precursors obtained by mechanosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Moure, A.; Tartaj, J.; Moure, C. [Instituto de Ceramica y Vidrio, CSIC, C/Kelsen 5, 28049 Madrid (Spain); Castro, A. [Instituto de Ciencia de Materiales de Madrid, CSIC, c/Sor Juana Ines de la Cruz, 3 Cantoblanco, 28049 Madrid (Spain)

    2009-03-15

    Dense ceramics with La{sub 0.80}Sr{sub 0.20}Ga{sub 0.85}Mg{sub 0.15}O{sub 2.825} and La{sub 0.80}Sr{sub 0.15}Ga{sub 0.85}Mg{sub 0.20}O{sub 2.825} compositions have been prepared by sintering of mechanosynthesized precursors. The perovskite is synthesized after 85 h of milling in a planetary mill. Single phases have been obtained at conditions that are not possible if traditional solid-state reaction (SSR) method is used. The influence of milling time and composition in the reactivity of the precursors is studied. Highest purity is obtained in Sr = 0.15 and Mg = 0.20 composition, with relative density higher than 97%. The total elimination of typical secondary phases for these compositions, as SrLaGaO{sub 4} and SrLaGa{sub 3}O{sub 7}, allows the total conductivity of the ceramics to be improved. The influence of the grain size and the nature of the grain boundaries on the electrical characteristic of the ceramics are also discussed. (author)

  3. Lifetime Prediction of All-ceramic Crowns of the Mandibular First Molar: A three-dimensional Finite Element Analysis%下颌第一磨牙全瓷冠疲劳寿命预测的三维有限元分析

    Institute of Scientific and Technical Information of China (English)

    贾骏; 段嫄嫄; 周建学; 王忠义; 吴舜; 张少锋

    2006-01-01

    目的:对EmpressⅠ、EmpressⅡ、In-Ceram Alumina以及In-Ceram Zirconia 4种不同材料的下颌第一磨牙全瓷冠进行疲劳寿命预测.方法:模拟1、5、10年间,相当于最大咬合力的循环疲劳载荷,加载于全瓷冠模型.通过有限元疲劳分析软件MSC.Fatigue预测各种材料全瓷冠的失效概率.结果:基于本有限元疲劳分析,EmpressⅠ、EmpressⅡ、In-Ceram Alumina以及In-Ceram Zirconia这4种均可应用于后牙全瓷冠.其中采用EmpressⅠ制作的全瓷冠较其他3种材料具有较高的失效概率(3.15%~7.486%).结论:有限元疲劳分析有助于全瓷修复材料临床应用前的耐疲劳强度的判断.

  4. Composite ceramic/metal piston assembly and method of making

    Energy Technology Data Exchange (ETDEWEB)

    Hartsock, D.L.

    1987-03-17

    This patent describes an integrally cast composite assembly of a cylindrical cap attached to a piston having a higher thermal expansion characteristic than the cylindrical cap, the cap being adapted to receive a ceramic insert, comprising: (a) a piston body comprised substantially as a body of revolution about an axis and comprised of a material having a higher thermal expansion characteristic than the cylindrical cap. The piston body has a crown top and an annular crown side wall with an upper edge, and an annular undercut surface terminating the crown side wall. The undercut surface makes an angle with a plane extending perpendicular to the axis and passing through the upper edge of the crown side wall. The angle is substantially equal to the arc tangent of H/R where H is the median distance of the undercut surface from the plane and R is the median radius fo the undercut surface from the axis of the piston; and (b) a cylindrical cap disposed on the piston crown top and having a cap side wall depending about the crown side wall, the cap side wall having an annular lip extending radially inwardly from the cap side wall. The lip has surface mateable with the undercut surface of the piston body so that there exists a tightly stressed camming relationship between the mateable surfaces as a result of the shrinkage of the piston body upon solidification.

  5. All-ceramic prosthetic rehabilitation of a worn dentition: Use of a distal cantilever. Two-year follow-up

    Directory of Open Access Journals (Sweden)

    Usama N Chekhani

    2013-01-01

    Full Text Available The rehabilitation of heavily abraded occlusion in patients with parafunctional habits is a restorative challenge to the dentist. Use of all-ceramic systems in such cases is widely considered, but uncertainty over their resistance hinders their broad use. The authors would like to illustrate a possible approach by mixing two all-ceramic systems based on zirconium dioxide and lithium disilicate. A 48-year-old female patient attended with reduced vertical dimension in a full dentition. She suffered from craniomandibular (CMD pain and desired an esthetic rehabilitation. Prosthodontic treatment was started in a pain-free condition, after correction of the vertical dimension with an occlusal splint, over four months. Determination of the treatment was based on the clinical findings: IPS e.max® ZirCAD frameworks veneered with IPS e.max® Ceram were used for discolored retainers or subgingival finishing lines. All the rest received IPS e.max® Press crowns. A zirconia-based, single-tooth-retained distal cantilever reconstruction was used to replace a missing second molar. No technical or biological complication was observed 24 months after treatment. The patient was highly satisfied and pain-free.

  6. Reliability of reduced-thickness and thinly veneered lithium disilicate crowns.

    Science.gov (United States)

    Silva, N R F A; Bonfante, E A; Martins, L M; Valverde, G B; Thompson, V P; Ferencz, J L; Coelho, P G

    2012-03-01

    The present investigation hypothesized that the reliability of reduced-thickness monolithic lithium disilicate crowns is high relative to that of veneered zirconia (Y-TZP) and comparable with that of metal ceramic (MCR) systems. CAD/CAM first mandibular molar full-crown preparations were produced with uniform thicknesses of either 1.0-mm or 2.0-mm occlusal and axial reduction, then replicated in composite for standard crown dies. Monolithic 1.0-mm (MON) and 2.0-mm CAD/CAM lithium disilicate crowns, the latter with a buccal thin veneer (BTV) of 0.5 mm, were fabricated and then sliding-contact-fatigued (step-stress method) until failure or suspension (n = 18/group). Crack evolution was followed, and fractography of post mortem specimens was performed and compared with that of clinical specimens. Use level probability Weibull calculation (use load = 1,200 N) showed interval overlaps between MON and BTV. There was no significant difference between the Weibull characteristic failure loads of MON and BTV (1,535 N [90% CI 1,354-1,740] and 1,609 N [90% CI 1,512-1,712], respectively), which were significantly higher than that of Y-TZP (370 N [90% CI 322-427]) and comparable with that of MCR (1,304 N [90% CI 1,203-1,414]), validating the study hypothesis.

  7. [Prosthetic rehabilitation of partially edentulous patients: fixed - removable - combined? Metal - ceramics - all - ceramics? Implants? Anything goes! Part 1: two example cases of a combined fixed-removable restoration].

    Science.gov (United States)

    Schnabl, Dagmar

    2015-01-01

    After a careful diagnosis, treatment planning and pretreatment, two partially edentulous patients were restored partly by onlays, crowns and bridges, partly by removable prostheses. According to esthetic and functional demands all- and/or metal-ceramic restorations were used as well as cast frame prostheses with clasps or extracoronal attachments.

  8. Sensitivity analysis of bi-layered ceramic dental restorations.

    Science.gov (United States)

    Zhang, Zhongpu; Zhou, Shiwei; Li, Qing; Li, Wei; Swain, Michael V

    2012-02-01

    The reliability and longevity of ceramic prostheses have become a major concern. The existing studies have focused on some critical issues from clinical perspectives, but more researches are needed to address fundamental sciences and fabrication issues to ensure the longevity and durability of ceramic prostheses. The aim of this paper was to explore how "sensitive" the thermal and mechanical responses, in terms of changes in temperature and thermal residual stress of the bi-layered ceramic systems and crown models will be with respect to the perturbation of the design variables chosen (e.g. layer thickness and heat transfer coefficient) in a quantitative way. In this study, three bi-layered ceramic models with different geometries are considered: (i) a simple bi-layered plate, (ii) a simple bi-layer triangle, and (iii) an axisymmetric bi-layered crown. The layer thickness and convective heat transfer coefficient (or cooling rate) seem to be more sensitive for the porcelain fused on zirconia substrate models. The resultant sensitivities indicate a critical importance of the heat transfer coefficient and thickness ratio of core to veneer on the temperature distributions and residual stresses in each model. The findings provide a quantitative basis for assessing the effects of fabrication uncertainties and optimizing the design of ceramic prostheses. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  9. A simple procedure for retrieval of a cement-retained implant-supported crown: a case report.

    Science.gov (United States)

    Buzayan, Muaiyed Mahmoud; Mahmood, Wan Adida; Yunus, Norsiah Binti

    2014-02-01

    Retrieval of cement-retained implant prostheses can be more demanding than retrieval of screw-retained prostheses. This case report describes a simple and predictable procedure to locate the abutment screw access openings of cementretained implant-supported crowns in cases of fractured ceramic veneer. A conventional periapical radiography image was captured using a digital camera, transferred to a computer, and manipulated using Microsoft Word document software to estimate the location of the abutment screw access.

  10. Ingot selection for aesthetic restorations using contemporary pressed ceramics.

    Science.gov (United States)

    Ritter, Robert G; Culp, Lee

    2002-08-01

    Accurate communication among the patient, clinician, and laboratory technician is critical to the development of a functional, aesthetic restoration. The use of pressed ceramic restorations has provided a durable, consistent alternative for full-coverage crowns, veneers, onlays, and short-span fixed partial dentures. This article discusses the importance of proper ingot selection in the fabrication of aesthetic restorations and in the realization of patients' expectations for smile design. Ceramic ingots are available in a variety of colors and opacities that provide the clinician and laboratory technician with the latitude to select an ingot that will ultimately ensure patient satisfaction.

  11. Which mechanical and physical testing methods are relevant for predicting the clinical performance of ceramic-based dental prostheses?

    Science.gov (United States)

    Anusavice, K J; Kakar, Kunjan; Ferree, N

    2007-06-01

    , implant-supported prostheses, crowns, inlay- or onlay-supported prostheses, a total of 37 articles remained for detailed review. After excluding review articles and articles involving resin-bonded bridges, single-author clinical research articles, cantilever designs and implant-supported FDPs, 11 clinical research articles remained. For these articles, it was not possible to determine conclusively the probability of failure for three-unit FDPs compared with four-unit and larger prostheses or the location of the crowns and pontics. This systematic review of studies on ceramic-based FDPs confirms the results of previous studies that, in most cases, less than 15% of these prostheses were removed or were in need of replacement at 10 years. However, there was considerable variability in the number of parameters that were reported as well as the range of details on failures that occurred. In some studies, a standardized evaluation system was used in which USPHS or Ryge criteria were applied. However, there was also great uncertainty in the definition of failure with respect to repairable fractures and whether the identified causative factors were directly or indirectly associated with the replacement of the prostheses. This review indicates that there is no single in vitro test variable that can predict clinical performance in these prostheses. Based on these reviews, there is an urgent need to develop a comprehensive classification system for identifying clinical prosthesis failures, technical complications and biologic complications. Guidelines on the retrieval of fractured prostheses and/or impressions that capture the fracture surface details should also be developed. The predictive power of in vitro data can be increased by finite element stress analysis and computer programs such as the CARES/Life software (NASA Lewis Research Center, Cleveland, OH) that estimates the time-dependent nature of ceramic structure survival.

  12. Numerical Simulation of Single Pulse Discharge Machining Insulating Ceramics with High Instantaneous Energy Density%绝缘陶瓷高瞬时能量密度单脉冲放电的数值模拟

    Institute of Scientific and Technical Information of China (English)

    纪仁杰; 刘永红; 房磊; 张彦振; 王飞; 申泱

    2011-01-01

    The temperature field of the single pulse discharge with the high instantaneous energy density for insulating ceramics is modeled based on the heat conduction theory. Three-dimensional numerical simulation for the temperature fields of insulating ceramics, tool electrode, and assisting electrode has been carried out. The effects of various dielectrics and peak voltages on the temperature fields of insulating ceramics, tool electrode, and assisting electrode have been investigated. The comparison between the results of numerical simulation and experiment shows that the single discharging model is able to forecast the change of the crater depth and crater volume effectively.%基于热传导理论建立了绝缘陶瓷高瞬时能量密度单脉冲放电的温度场模型,并对陶瓷工件、工具电极和辅助电极的温度场进行了三维数值模拟,得到了不同介质和峰值电压对陶瓷工件、工具电极和辅助电极上温度场影响规律的关系.将数值模拟与试验结果进行了对比,结果表明,所建立的绝缘陶瓷高瞬时能量密度单脉冲放电模型能较好地预测放电坑深度和体积的变化,仿真结果与试验结果相吻合.

  13. Effect of Loading Rate Upon Conventional Ceramic Microindentation Hardness

    Science.gov (United States)

    2002-01-01

    silicate crown glass. In this modification of the tradi- tional Vickers hardness test, both load and displacement were monitored during the indentation...loads up to 30 N. Alumina, two aluminum nitrides, and two zirconias had a dynamic hardness from 9 % to 19 % greater than the static hardness at loads up...M. Hooper, Indentation Creep in Zirconia Ceramics Between 290 K and 1073 K, in Mechanics of Creep, Brittle Materials, A. Cooks and A. Ponter, eds

  14. Success of Hall technique crowns questioned.

    Science.gov (United States)

    Nainar, S M Hashim

    2012-01-01

    Hall technique is a method of providing stainless steel crowns for primary molars without tooth preparation and requires no local anesthesia. Literature review showed inconclusive evidence and therefore this technique should not be used in clinical practice.

  15. Activity relationships for aromatic crown ethers

    CERN Document Server

    Wilson, M J

    1998-01-01

    This thesis involves an investigation of aromatic crown ethers and a study of their binding constants for alkali metals. The study was motivated by the current needs of the semiconductor industry to improve the scavenging of mobile ions from fabricated circuits. A number of aromatic crown ethers have been sulphonated in an attempt to improve their water solubility and cation binding activity. These materials have been extensively studied and their binding activity determined. In collaboration with a molecular modelling study, the effect of ionisable sulphonate groups on the macrocycles' behaviour has been investigated. The broader issue of the effect of substituents in aromatic crown ethers has also been studied with the preparation of a wide range of substituted crown ethers. The cation binding activity of these materials has been found to bear a simple relationship to the electron withdrawing nature of the aromatic substituents. This relationship can be accurately monitored using electronic charge densities...

  16. A novel transferable individual tree crown delineation model based on Fishing Net Dragging and boundary classification

    Science.gov (United States)

    Liu, Tao; Im, Jungho; Quackenbush, Lindi J.

    2015-12-01

    This study provides a novel approach to individual tree crown delineation (ITCD) using airborne Light Detection and Ranging (LiDAR) data in dense natural forests using two main steps: crown boundary refinement based on a proposed Fishing Net Dragging (FiND) method, and segment merging based on boundary classification. FiND starts with approximate tree crown boundaries derived using a traditional watershed method with Gaussian filtering and refines these boundaries using an algorithm that mimics how a fisherman drags a fishing net. Random forest machine learning is then used to classify boundary segments into two classes: boundaries between trees and boundaries between branches that belong to a single tree. Three groups of LiDAR-derived features-two from the pseudo waveform generated along with crown boundaries and one from a canopy height model (CHM)-were used in the classification. The proposed ITCD approach was tested using LiDAR data collected over a mountainous region in the Adirondack Park, NY, USA. Overall accuracy of boundary classification was 82.4%. Features derived from the CHM were generally more important in the classification than the features extracted from the pseudo waveform. A comprehensive accuracy assessment scheme for ITCD was also introduced by considering both area of crown overlap and crown centroids. Accuracy assessment using this new scheme shows the proposed ITCD achieved 74% and 78% as overall accuracy, respectively, for deciduous and mixed forest.

  17. The Crown Bite Jumping Herbst.

    Science.gov (United States)

    Owen, Reuel

    2003-01-01

    The Crown Bite Jumping Herbst Appliance is evaluated and combined with Straight Wire Arch Fixed Orthodontics in treatment of Class II, Division I malocclusions. This article will evaluate a combined orthodontic approach of "straightening teeth" and an orthognathic approach of "moving jaws or making skeletal changes." Orthodontic treatment cannot be accomplished well without establishing a healthy temporomandibular joint. This is defined by Keller as a joint that is "noiseless, painless and has a normal range of motion without deviation and deflection." It is not prudent to separate orthodontic treatment as its own entity without being aware of the changes in the temporomandibular joint before, during and after treatment. In other words, "If you're doing orthodontics you're doing TMJ treatment." One should treat toward a healthy, beautiful face asking, "Will proposed treatment achieve this goal?" Treatment should be able to be carried out in an efficient manner, minimizing treatment time, be comfortable and affordable for the patient, and profitable for the dentist. The finished treatment should meet Andrews' Six Keys of Occlusion, or Loudon's Twelve Commandments. Above all, do no harm to the patient. We think that a specific treatment plan can embrace these tenets. The focus will be to show Class II treatment using a modified Herbst Appliance and fixed straight wire orthodontics.

  18. Clinical crown lengthening in the esthetic zone.

    Science.gov (United States)

    Camargo, Paulo M; Melnick, Philip R; Camargo, Luciano M

    2007-07-01

    Periodontal surgical procedures consisting of gingival flaps and osseous recontouring are indicated for crown lengthening of several contiguous teeth in the esthetic zone; both in cases where restorations are required and in cases where no restorations are planned, such as in patients with excessive gingival display due to altered passive eruption. Forced tooth eruption via orthodontic extrusion is the technique of choice when clinical crown lengthening is necessary on isolated teeth in the esthetic zone.

  19. Treatment of crown dilaceration: an interdisciplinary approach.

    Science.gov (United States)

    Subramaniam, P; Naidu, P

    2010-01-01

    Trauma to primary teeth can result in a wide range of disturbances to the underlying permanent teeth, such as dilaceration. Root dilacerations occur more commonly than crown dilacerations. This paper is a report of an 11-year-old girl with a missing maxillary left anterior tooth. Past history revealed premature loss of primary maxillary anterior teeth due to trauma. Radiographic examination revealed crown dilaceration of permanent maxillary left central incisor. An interdisciplinary approach in the management of this child is presented herewith.

  20. A new system for posterior restorations: a combination of ceramic optimized polymer and fiber-reinforced composite.

    Science.gov (United States)

    Rosenthal, L; Trinkner, T; Pescatore, C

    1997-01-01

    Due to the need for increased strength characteristics and enhanced aesthetic expectations of the patients, metal-free, aesthetic restorative systems for the anterior and posterior dentition are currently available. A new "space-age" restorative material has been developed that is a combination of a ceramic optimized polymer (Ceromer) (Targis/Vectris, Ivoclar Williams, Amherst, NY) and a fiber-reinforced composite framework material. The purpose of this article is to discuss the qualities that render this material particularly suitable for a variety of indications, including laboratory-fabricated restorations for the stress-bearing posterior regions. The material lends itself to diversification. Its indication for inlays, onlays, full-coverage crown restorations, and conservative single pontic inlay bridges is presented.

  1. The clinical and radiographic success of bonded resin composite strip crowns for primary incisors.

    Science.gov (United States)

    Kupietzky, Ari; Waggoner, William F; Galea, Jon

    2003-01-01

    The aim of this study was to examine the clinical and radiographic success of the treatment of maxillary anterior primary incisors with composite resin strip crowns placed in a private practice setting. This was a retrospective, clinical study of patients who had strip crowns (SC) placed on maxillary primary incisors, returned for at least 1, 6-month recall examination, and whose parents consented to participate in the study. Radiographic and photographic examinations were used for evaluation. Two evaluators rated the images independently. When ratings were not in agreement, the 2 examiners reviewed the photograph or radiograph together and reached a consensus rating. One hundred twelve restorations placed in 40 children were evaluated. The evaluations were performed after the crowns had been in place for an average of 18 months. None of the restorations were totally lost, and only 12% were rated as having lost some resin material, resulting in an 88% overall retention rate. There was no difference in restoration success if the crowns were placed 4 at a time, or if fewer crowns were placed in a single sitting; the failure rates were comparable. Teeth that had pulpal treatment were judged to have far more significant color match discrepancies than those teeth without pulpal treatment. Ninety-one percent of the teeth demonstrated healthy pulps. Eight percent had some pulpal changes but did not require immediate attention. Only 1 tooth showed radiographic evidence of pulpal necrosis. Only 11 teeth had pulpal treatment, but of these, 10 demonstrated clinical success. Composite resin strip crowns for restoring primary incisors with large or multisurface caries performed well. Color match of these crowns with adjacent teeth may be significantly reduced when placed upon teeth that have undergone pulpectomy treatment and have been obturated with an iodoform paste. However, based upon the results of this study, the strip crown may provide an esthetic and durable restoration

  2. Biomechanical influence of crown-to-implant ratio on stress distribution over internal hexagon short implant: 3-D finite element analysis with statistical test.

    Science.gov (United States)

    Ramos Verri, Fellippo; Santiago Junior, Joel Ferreira; de Faria Almeida, Daniel Augusto; de Oliveira, Guilherme Bérgamo Brandão; de Souza Batista, Victor Eduardo; Marques Honório, Heitor; Noritomi, Pedro Yoshito; Pellizzer, Eduardo Piza

    2015-01-02

    The study of short implants is relevant to the biomechanics of dental implants, and research on crown increase has implications for the daily clinic. The aim of this study was to analyze the biomechanical interactions of a singular implant-supported prosthesis of different crown heights under vertical and oblique force, using the 3-D finite element method. Six 3-D models were designed with Invesalius 3.0, Rhinoceros 3D 4.0, and Solidworks 2010 software. Each model was constructed with a mandibular segment of bone block, including an implant supporting a screwed metal-ceramic crown. The crown height was set at 10, 12.5, and 15 mm. The applied force was 200 N (axial) and 100 N (oblique). We performed an ANOVA statistical test and Tukey tests; p0.05) under axial load. However, crown heights of 12.5 and 15 mm caused statistically significant damage to the stress distribution of screws and to the cortical bone (p<0.001) under oblique load. High crown to implant (C/I) ratio harmed microstrain distribution on bone tissue under axial and oblique loads (p<0.001). Crown increase was a possible deleterious factor to the screws and to the different regions of bone tissue.

  3. An investigation of crown fuel bulk density effects on the dynamics of crown fire initiation in shrublands

    Science.gov (United States)

    Watcharapong Tachajapong; Jesse Lozano; Shankar Mahalingam; Xiangyang Zhou; David R. Weise

    2008-01-01

    Crown fire initiation is studied by using a simple experimental and detailed physical modeling based on Large Eddy Simulation (LES). Experiments conducted thus far reveal that crown fuel ignition via surface fire occurs when the crown base is within the continuous flame region and does not occur when the crown base is located in the hot plume gas region of the surface...

  4. 前牙残根冠延长术后纤维桩核冠修复的临床研究%Clinical research of fiber post-core crown restoration after crown lengthening for upper anterior teeth residual root

    Institute of Scientific and Technical Information of China (English)

    罗永宏; 尹丽媚; 李慧; 刘青; 冯建国

    2016-01-01

    Objective To investigate curative effect by fiber post-core crown restoration after crown lengthening for upper anterior teeth residual root. Methods A total of 20 upper anterior fractured, or decayed to subgingival 2~4 mm teeth were repaired by fiber post-core and all-ceramic crown restoration on subgingival fracture surface after crown lengthening. Results There were 12 patients (19 teeth) received successful operation, along with good postoperative condition and successful crown restoration. Shallow defect group (10 teeth) had higher instant satisfaction degree as (9.5±0.3) points than (9.3±0.3) points of deep defect group (9 teeth) (P>0.05). The difference of mean plaque index and periodontal pocket depth had no statistical significance between shallow defect group and deep defect group (P>0.05), while the difference of their mean bleeding index and gingival index had statistical significance (P0.05)。浅缺损组和深缺损组残根修复后的平均菌斑指数、牙周袋深度比较(P>0.05);平均出血指数、牙龈