Ersan CELIK, Sule Tugba DENIZ
Medical Records - 2026;8(1):1656367-1656367
Aim: The objective of this study is to assess the effect of different bleaching protocols and concentrations on the micro hardness of CAD/CAM materials in vitro. Material and Method: Five contemporary CAD/CAM blocks -resin nanoceramic, flexible nano-hybrid ceramic, hybrid ceramic, resin-infiltrated ceramic, and reinforced composite -were used. One hundred samples were prepared for each block and bleaching procedure (n = 10) with a thickness of 1.5 mm. Finishing and polishing were applied in accordance with the manufacturers' recommendations. Opalescence PF bleaching gel with a 16% carbamide peroxide content was applied to the at-home bleaching group for 14 days, 6 hours per day, whereas Opalescence Boost bleaching gel with a 40% hydrogen peroxide content was applied to the in-office bleaching group for 20 minutes, two times per session on days 1 and 7. The microhardness of the samples was measured with a Vickers hardness device before and after processing. The data were statistically evaluated using repeated-measures analysis of variance and the Bonferroni correction. Results: After bleaching, the highest microhardness values were observed in the resin-infiltrated ceramic group (p < 0.05). The microhardness values of the hybrid ceramic decreased significantly (p < 0.05). No significant difference was detected between in-office and at-home bleaching protocols in blocks other than the hybrid ceramic. Conclusion: Bleaching protocols, both in-office and at-home, do not decrease the microhardness of resin-infiltrated ceramic restorations, and they may better preserve esthetics during bleaching. Therefore, this type of CAD/CAM block may be preferred in cases involving bleaching treatments.
