Dental bleaching gels do not alter the surface roughness and microhardness of feldspathic porcelain

ABSTRACT Objective: To evaluate whether two different bleaching gels affect the microhardness and surface roughness of feldspathic ceramic specimens, in vitro. Methods: A total of 48 feldspathic porcelain IPS In Line (Ivoclar-Vivadent) discs (16/treatment group) were immersed in distilled water (Group I, Untreated control, UN), or treated with the bleaching gels: Opalescence (15% carbamide peroxide; OPA) and Opalescence Xtra Boost (38%hydrogen peroxide; OPAXB), for 1h or 6h daily for 14 days. Surface roughness (Ra) and microhardness (Knoop, or KNP) measurements were made before and after treatment, and data were subjected to statistical analysis by paired Student’s t-test (p