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Purpos: The aim of this study was to quantify and compare the clinical performance of cast conical double crown-retained removable partial dentures (C-RPDs) and electroplated double crown-retained removable partial dentures (EP-RPDs). Materials and Methods: A total of 60 RPDs were placed in 54 patients. Participants were randomly assigned to two study groups (C-RPD and EP-RPD). Altogether, 217 abutment teeth were provided with double crowns. Patients were reexamined after 6, 12, 24, and 36 months. The main endpoints were the survival times of RPDs and abutment teeth; secondary endpoints included failure of the facing, loss of cementation of primary crowns, and postprosthetic endodontic treatment. Chi-square tests were used to evaluate group differences regarding characteristics of patients and RPDs. Survival differences were investigated using the log-rank test and Cox regression; secondary endpoints were assessed using logistic regression. Results: After 36 months, survival was 100% for C-RPDs and 93.3% for EP-RPDs. Cumulative survival for abutment teeth was 97.3% (C-RPDs) and 96.2% (EP-RPDs). Survival differences between the two study groups did not reach statistical significance. The survival of abutments depended on tooth vitality and position; for example, the hazard of tooth loss was 676% higher for nonvital teeth. No differences were found between study groups regarding facing failure, decementation of primary crowns, or postprosthetic endodontic treatment. Conclusions: Vitality and position are important to the survival of teeth supporting partial dentures. Longer follow-up and larger patient collectives are needed to evaluate possible differences between cast conical and electroplated telescopic double crown-retained partial dentures. [ABSTRACT FROM AUTHOR]

PURPOSE: Improvements in the physical properties of modern composites have led to continuous expansion of their field of application to include extensive, occlusion-bearing posterior restorations and even metal-free polymer crowns. The objective of this clinical study was to investigate the influence of gender, arch, and crown location on the occlusal wear of metal-free ceramic-filled polymer crowns and to compare their wear with the mean annual occlusal wear of enamel (15 to 38 microm). MATERIALS AND METHODS: One hundred fourteen ceramic-filled polymer crowns made of Artglass (Heraeus Kulzer) were placed in 74 patients. After 1 year, 93 crowns were available for wear measurement. After 2 years, 76 crowns were available. Wear was determined by use of replicas. A 3-dimensional optical profilometer (Laserscan 3D, Willytec) was used to digitize and superimpose the occlusal surfaces of the baseline and recall replicas (occlusal matching). RESULTS: After 1 year, median wear of the entire occlusal surface was 19 microm for anterior and canine teeth, 19 microm for premolars, and 21 microm for molars. After 2 years, median wear was 36 pm for anterior and canine teeth, 44 microm for premolars, and 84 microm for molars. The wear of the occlusal contact areas was significantly higher. Significant effects of crown location (premolar or molar) on the extent of wear of the occlusal contact areas were found. CONCLUSIONS: Ceramic-filled polymer crowns are subject to measurable occlusal wear that exceeds that of natural enamel. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effect of gender, antagonistic teeth, and type of denture on clinical wear of denture teeth. Wear measurements were made on gypsum replicas of 204 posterior denture teeth after 6 months using an optical 3-dimensional profilometer. Data were analyzed using univariate and mixed regression procedures. The mean wear of all denture teeth was -20.5 microm (+/- 14.6). Males demonstrated significantly higher wear than females. Interactions of the variables 'gender' and 'type of denture' and 'antagonist material' and 'type of denture' also showed significant influences on wear. The results indicate that some clinical parameters may affect wear of denture teeth. [ABSTRACT FROM AUTHOR]