Effects of non-vital bleaching agents and resin composites on the color stability, translucency, and whiteness index of stained teeth at different time intervals: a laboratory investigation.

OBJECTIVES: The aim of this study was to investigate the effects of non-vital bleaching agents and resin composite types on the color stability, translucency parameter, and whiteness index of non-vital teeth at different time intervals. MATERIALS AND METHODS: 135 extracted single-rooted maxillary central incisors were used. The teeth were stained with coffee, baseline color values were measured, and root canal treatment was completed. The samples were randomly divided into three main groups: two bleaching agent groups (Opalescence and Whiteness-Super-Endo)and a control group. Each group was randomly divided into three subgroups (n = 15). The subgroups were restored with different resin composites (Filtek-Z250, FiltekBulk-Fill, Omnichroma) and subjected to thermocycling, and color measurements were repeated. The color differences (DeltaE(00)), relative translucency parameter (RTP(00)), and whiteness index (WI(D)) values of the samples were calculated. Data were analyzed using robust ANOVA (p < 0.05). RESULTS: Bleaching treatments caused color changes exceeding acceptable thresholds in all groups. Regarding color change and the translucency values, there was no significant difference between the two bleaching agents; however, both agents demonstrated significantly higher effectiveness compared with the control group (p < 0.001). In terms of WI(D), Opalescence group had higher values (p < 0.001). No significant variations in color change and WI(D) occurred across the groups after the application of various resin composites (p > 0.05). However, RTP(00) of Omnichroma group was significantly higher than that of the other materials (p < 0.001). CONCLUSION: Bleaching treatments caused color changes exceeding acceptable thresholds in all groups. An increase in RTP(00) values occurred after bleaching and thermal cycling. WI(D) values increased following bleaching and remained stable over time. CLINICAL RELEVANCE: This study enhances the understanding of how different non-vital bleaching agents and resin composites affect the long-term optical properties of endodontically treated teeth, providing valuable insights for optimal material selection in esthetic restorations.