Effects of a reduced in-office bleaching protocol with 37.5% hydrogen peroxide on effectiveness and tooth sensitivity: A double-blind randomized clinical trial

Objective This randomized clinical trial evaluated the effectiveness and tooth sensitivity (TS) of 37.5% hydrogen peroxide (37.5HP) in-office bleaching with reduced protocol. Materials and methods Forty participants with shade mean C2 or darker for the six maxillary anterior teeth were randomly allocated into two treatment groups (n = 20): two (37.5HP2) or three (37.5HP3) 8 min applications/clinical session. Three clinical sessions were performed with a 1 week interval. Color evaluations were done with a spectrophotometer at baseline and 1 week post-bleaching. TS was measured during and up to 48 h after bleaching using a five-point numeric rating scale. Color change was evaluated by Student's t-test for independent samples. The absolute risk and intensity of TS were analyzed by Fisher's and Mann-Whitney/Friedman tests (p < 0.05). Result Both treatment groups resulted in a significant tooth whitening 1 week post-bleaching (p < 0.001). There were no significant differences between 37.5HP2 and 37.5HP3 for Delta E*(ab), Delta E-00 and increment WID. Also, there were not differences between groups regarding high absolute risk (p = 1.0) and low intensity of TS at all time assessments (p > 0.7). Conclusions The in-office bleaching with two 37.5% HP applications produced the same whitening degree, risk and intensity of TS to that performed with three gel applications. Clinical significance Clinicians should opt to use a neutral 37.5% HP in-office bleaching gel for two 8 min applications/clinical session because produces the same whitening effectiveness, risk and low intensity of TS as the protocol proposed by manufacturer (three 8 min applications).