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Preparation Design (preparation + design)
Selected AbstractsMarginal Adaptation of Cerec 3 CAD/CAM Composite Crowns Using Two Different Finish Line Preparation DesignsJOURNAL OF PROSTHODONTICS, Issue 3 2006Jaber Hussain Akbar DDS Purpose: The purpose of this study was to compare marginal discrepancies of Cerec 3 CAD/CAM composite crowns, fabricated on human prepared teeth with two different finish line designs, chamfer and shoulder. Materials and Methods: Sixteen human molar teeth were used to prepare full crowns. Eight teeth were prepared with a 1-mm-wide chamfer finish line and the other eight with a 1.2- to 1.5-mm circumferential shoulder. Cerec 3 crowns were fabricated from optical impressions using Paradigm MZ100 composite polymer. Marginal adaptation was evaluated in two ways: (1) using modified United States Public Health Service (USPHS) criteria to evaluate eight preselected sites on each crown margin, and (2) using scanning electron microscopy (SEM) to measure marginal gaps on all four axial walls with 15 measurements on each wall (60 measurements per crown). An evaluation of the number of acceptable crowns, determined by having all measured sites per tooth with margin gap size less than 100 ,m, as a function of finish line design was also conducted. Results: In both chamfer and shoulder groups, there were only two crowns (out of eight) with clinically acceptable ratings for all eight measurement sites according to USPHS criteria. Fisher's chi-square analysis showed that there was no statistically significant difference in marginal adaptability as a function of finish line design ( p > 0.05). With SEM imaging, overall mean marginal gaps for the chamfer group were 65.9 ± 38.7 ,m (range 35.0 to 130.0 ,m), and for the shoulder group were 46.0 ± 9.2 ,m (range 26.3 to 55.6 ,m); this difference was not found to be statistically significant ( p > 0.05). While crown assessment based on mean marginal discrepancy measurements indicated that both the chamfer and shoulder groups were considered clinically acceptable (<100 ,m); crown acceptability based on all measurement sites being less than 100 ,m indicated that in the chamfer and shoulder groups there were four and three acceptable crowns out of eight, respectively. The Fisher's chi-square test indicated no statistically significant difference between the groups ( p > 0.05). An agreement rate of 81.2% was calculated between the two evaluation methods, modified USPHS criteria and SEM measurements. Conclusions: Based on mean marginal discrepancy measurements, the typical marginal assessment technique, Cerec 3 Paradigm MZ100 crown restorations appear to have acceptable marginal adaptability (mean discrepancies <100 ,m). Thus, the evidence from this investigation would suggest that the finish line preparation design had no effect on marginal adaptation for Cerec 3 composite crowns. [source] A Prospective Ten-Year Clinical Trial of Porcelain VeneersJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 2 2006Article first published online: 25 APR 200 abstract Objective:, The purpose of this prospective clinical study was to evaluate the performance of porcelain veneers after 5 and 10 years of clinical service. Materials and Methods:, A single experienced clinician placed 87 porcelain veneers in 25 patients in 1990 and 1991. The teeth included maxillary central incisors to first premolars. As described in the 5-year report of this study, preparations included a chamfer margin, 0.3 to 0.7 mm labial enamel reduction, and incisal edge coverage. A single laboratory technician fabricated the veneers using feldspathic porcelain on refractory dies. Internal surfaces were etched with 5% hydrofluoric acid and silanated. Teeth were isolated with a rubber dam prior to veneer placement. All veneers were bonded with a light-activated resin cement. Patients were recalled at 5 to 6 years and at 10 years after initial veneer placement. Two evaluators examined each veneer for retention, fractures, color match, surface roughness, marginal adaptation, leakage, recurrent caries, pulp vitality, and patient satisfaction. Marginal adaptation was assessed further using scanning electron microscopy to examine epoxy replicas. Results:, Five years after placement, all 87 veneers remained in place and had "perfect" color match and surface smoothness. Four veneers had fractures, but only one of those required repair. Ninety-nine percent of the veneers had clinically acceptable marginal adaptation, although just 14% of the veneers had "perfect" marginal adaptation at all margins. One had clinically unacceptable staining from leakage. Recurrent caries was present at the proximal margin of two veneers. At the 10-year evaluation, which had a 93% recall rate, color match and surface roughness remained optimal. Thirteen of 22 patients were very satisfied with the esthetic result, whereas 7 complained of minor esthetic problems. The fracture rate increased substantially, to 34% at the 10-year recall. However, only 11% of the fractures were clinically unacceptable. None of the veneers had debonded, but the percentage of veneers with "perfect" marginal adaptation had declined to only 4%. Leakage was now evident around two-thirds of the veneers, and eight restorations had recurrent caries. Conclusion:, Porcelain veneers are a reliable and effective means for conservative esthetic treatment of anterior teeth in the long term. After 10 years of clinical service, esthetic results remained good, patient satisfaction was high, and the retention rate was excellent. The number of irreparable fractures was low. Appropriate preparation design, occlusion, and use of adhesive materials contribute to the ultimate outcome. [source] Marginal Adaptation of Cerec 3 CAD/CAM Composite Crowns Using Two Different Finish Line Preparation DesignsJOURNAL OF PROSTHODONTICS, Issue 3 2006Jaber Hussain Akbar DDS Purpose: The purpose of this study was to compare marginal discrepancies of Cerec 3 CAD/CAM composite crowns, fabricated on human prepared teeth with two different finish line designs, chamfer and shoulder. Materials and Methods: Sixteen human molar teeth were used to prepare full crowns. Eight teeth were prepared with a 1-mm-wide chamfer finish line and the other eight with a 1.2- to 1.5-mm circumferential shoulder. Cerec 3 crowns were fabricated from optical impressions using Paradigm MZ100 composite polymer. Marginal adaptation was evaluated in two ways: (1) using modified United States Public Health Service (USPHS) criteria to evaluate eight preselected sites on each crown margin, and (2) using scanning electron microscopy (SEM) to measure marginal gaps on all four axial walls with 15 measurements on each wall (60 measurements per crown). An evaluation of the number of acceptable crowns, determined by having all measured sites per tooth with margin gap size less than 100 ,m, as a function of finish line design was also conducted. Results: In both chamfer and shoulder groups, there were only two crowns (out of eight) with clinically acceptable ratings for all eight measurement sites according to USPHS criteria. Fisher's chi-square analysis showed that there was no statistically significant difference in marginal adaptability as a function of finish line design ( p > 0.05). With SEM imaging, overall mean marginal gaps for the chamfer group were 65.9 ± 38.7 ,m (range 35.0 to 130.0 ,m), and for the shoulder group were 46.0 ± 9.2 ,m (range 26.3 to 55.6 ,m); this difference was not found to be statistically significant ( p > 0.05). While crown assessment based on mean marginal discrepancy measurements indicated that both the chamfer and shoulder groups were considered clinically acceptable (<100 ,m); crown acceptability based on all measurement sites being less than 100 ,m indicated that in the chamfer and shoulder groups there were four and three acceptable crowns out of eight, respectively. The Fisher's chi-square test indicated no statistically significant difference between the groups ( p > 0.05). An agreement rate of 81.2% was calculated between the two evaluation methods, modified USPHS criteria and SEM measurements. Conclusions: Based on mean marginal discrepancy measurements, the typical marginal assessment technique, Cerec 3 Paradigm MZ100 crown restorations appear to have acceptable marginal adaptability (mean discrepancies <100 ,m). Thus, the evidence from this investigation would suggest that the finish line preparation design had no effect on marginal adaptation for Cerec 3 composite crowns. [source] The all-ceramic, inlay supported fixed partial denture.AUSTRALIAN DENTAL JOURNAL, Issue 2 2010Part 1. Abstract The effect of cavity design is a controversial and underrated factor in the clinical success of ceramic inlays and inlay supported prosthesis. Many articles and studies have been conducted into the advantages and disadvantages of isolated aspects of preparation design, but lacking is a review of the most relevant papers which bring together a consensus on all the critical features. Hence, a review and analysis of cavity depth, width, preparation taper and internal line angles is warranted in our attempts to formulate preparation guidelines that will lead to clinically successful, all-ceramic inlay restorations and ceramic inlay supported prosthesis. [source] An in vitro assessment of the strength of porcelain veneers dependent on tooth preparationJOURNAL OF ORAL REHABILITATION, Issue 12 2000P. Hahn The treatment of teeth using veneer restorations combines aesthetic and functional improvements with a low destructive technique. Different kinds of tooth preparation techniques are described in the literature for this kind of restoration. This in vitro study aimed to examine the influence of the incisal preparation on the loadability of teeth restored with porcelain laminate veneers. Thirty-six selected mandibular incisors were randomly assigned to three groups with 12 teeth per group. In the first group, only the facial surface was prepared. In the second group, the preparation included a rounded incisal edge and a distinct chamfer lingually. The third group served as an unprepared control. Empress® veneers were then fabricated and cemented with a low viscous luting composite material. After 120 days storage in Ringer's solution, the specimens were loaded incisally to the point of failure. Statistical analysis of the results showed significant differences between the series (P=0·0103). Group 2 (with preparation of the incisal edge) exhibited the lowest fracture resistance (466±99 N) (N, mean forces). When prepared only facially, the teeth restored with Empress® veneers reached the strength of unprepared teeth. Compared with the biting force described for incisors in the literature, the in vitro loadability reached in this investigation seems to jusitify the clinical use of both preparation designs tested. [source] | ||||||||||