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Objective: To investigate the effect of the accelerated aging process on the color stability of feldspathic ceramic treated with dual ion exchange, overglaze, polishing, and autoglaze surface treatments., Method and Materials: A total of 40 disks (15 mm in diameter and 2 mm thick) of feldspathic ceramic were made in an A2 shade according to the manufacturer's recommendations. The samples were randomly divided into 4 groups: dual ion exchange, overglaze, polishing, and autoglaze. The samples were subjected to conditions in an accelerated aging machine for 150 and 300 hours. Differences in color before and after accelerated aging were calculated using spectrophotometric analyses. Overall color difference (DeltaE) was determined using the CIE L*a*b* system for measuring small color differences. Scanning electron microscopy was used to evaluate the surface texture of samples. Color difference data were evaluated statistically by Kruskal-Wallis and Mann-Whitney U tests, with a significance level of .05., Results: After 150 and 300 hours of accelerated aging, color changes of the 4 surface treatment groups ranged between 0.35 and 1.31 DeltaE units. All DeltaE values were below a quantitative level that would be considered clinically acceptable. Autoglazed samples were the most color stable, followed by ion exchanged, overglazed, and polished test samples., Conclusions: All groups demonstrated color stability below a quantitative level that would be considered clinically acceptable, but long-term clinical studies are necessary to verify these findings.

Objectives: The purpose of this study was to evaluate compressive and tensile stress values and patterns on implant-supported all-ceramic restorations applied in maxillary partially edentulous cases by utilizing the 3-dimensional (3-D) finite element stress analysis., Method and Materials: Two different 3-D finite element designs representing a maxillary implant-supported fixed partial denture (from maxillary canine to second premolar) were constructed with 3 different core materials (Inceram-Zirconia, IPS 2 disilicate glass-ceramic, cobalt-chromium). In the first design, the cross-sectional connector areas of the dentures were constructed to be 3.5 3 3.5 mm. In the second design, the cross-sectional areas were decreased to 2 3 2 mm. A load of 550 N was applied in oblique direction onto the pontic., Results: The compressive and tensile stress levels obtained in the second design were higher than the first one for all materials. The compressive and tensile stresses were higher when the loads were directly applied onto the cores and the framework than when they were applied onto the porcelain sets. The cross-sectional connector area between the abutment and the pontic component has a great effect on the success of all-ceramic implant-supported fixed partial dentures., Conclusions: All 3 materials seem to have sufficient characteristic strength for 3-unit posterior implant-supported fixed partial dentures. Only the tensile stress value obtained for IPS 2 disilicate glass core material in the second design was higher than the material's characteristic strength value when the load was applied directly onto the core.