Assessment of Antagonist Enamel Wear and Clinical Performance of Full-Contour Monolithic Zirconia Crowns: One-Year Results of a Prospective Study.

PURPOSE: To assess the clinical performance and survival of full-contour monolithic zirconia (MZ) crowns and enamel wear produced over a 1-year period. MATERIALS AND METHODS: 60 patients requiring full-coverage restorations for endodontically treated posterior teeth opposed by healthy unrestored antagonistic teeth were selected. MZ crowns were fabricated. Vinyl polysiloxane impressions of the antagonist teeth were made, and the stone casts were digitized using a 3D laser scanner. Wear of the opposing natural teeth was evaluated at baseline (1 week), 6 months, and 1 year after crown cementation. Superimposition of the follow-up scans on the baseline scans were performed to evaluate wear. Survival and function of the restorations were evaluated by the modified USPHS rating criteria at the same timeframes. RESULTS: Comparison of the baseline and the follow-up wear values was statistically tested using the paired t-test. Statistical significance was noted between the wear values at 6 months (15.5 µm) and at 12 months (16.3 µm) (p < 0.05). The Wilcoxon signed rank sum test was performed to evaluate each parameter of the modified USPHS criteria and to analyze the change in the follow-up scores of the restorations. The survival rate for the crowns was 100%. Results were classified as "excellent" over a 1-year follow up. CONCLUSIONS: MZ crowns showed promising results related to antagonist enamel wear and survival/clinical performance.

Comparison of photographic and conventional methods for tooth shade selection: A clinical evaluation.

AIM: This study aimed to compare three different methods used for shade selection, i.e., visual method, spectrophotometer, and digital photography method. MATERIALS AND METHODS: Fifty participants were selected from the Out Patient Department of Prosthodontics. Presence of the maxillary right central incisor with no history of any restorative or endodontic procedures was the primary inclusion criterion. The shade of the right maxillary central incisor was determined using all the three shade selection procedures, namely, visual, spectrophotometric, and digital photography method for all the selected participants. The shades obtained in the visual method using a shade guide were noted down for further comparisons. The spectrophotometer reported the L*, a*, and b* values along with the actual shade whereas the digital photography method reported only the L*, a*, and b* values. The agreement between the readings obtained by the three different methods was compared and subjected to appropriate statistical analysis. RESULTS: The results showed that when the three methods studied were compared, there was a statistically significant proportion of agreement between spectrophotometric and visual method (P < 0.01) with higher proportion of "yes" (agreement) and between the spectrophotometric and digital photography method (P < 0.01) with higher proportion of "yes" (agreement). Coefficient of agreement (using Kappa coefficient) between spectrophotometric and visual shades revealed a fair agreement. The mean ΔE was 1.69. There was a statistically significant difference between the proportion of ΔE more than and <2, between spectrophotometric and digital photography methods (P < 0.01) with higher proportion of <2 ΔE. Furthermore, percentage of agreement between shades obtained by the visual and spectrophotometric method showed maximum agreement with A1 shade. CONCLUSION: It was concluded that the digital photography method emerged as a reliable method for shade selection in a clinical setup.