Abstract
Objective: To evaluate the surface roughness and microhardness of CAD/CAM lithium disilicate, feldspathic ceramic, polymer infiltrated ceramic and nanohybrid composite before and after the application of bleaching gel. Material and methods: Disc shaped specimens were polished and divided into quadrants for roughness (Ra) and microhardness (Vickers, 19.61 N, 20 s) measurements. The 35% hydrogen peroxide was applied simulating three in-office bleaching sessions. Results: Paired t-test (α=0.05) showed that bleaching gel application did not affect the surface roughness of the tested material. The microhardness of polymeric materials (polymer infiltrated ceramic and nanohybrid composite) presented statistical significant increase (2 % increase, which may be clinically insignificant). Conclusion: Microhardness of polymeric CAD/CAM materials may be affected by bleaching gel application.