Effectiveness and adverse effects of at-home dental bleaching with 37% versus 10% carbamide peroxide: A randomized, blind clinical trial.

PURPOSE: The aim of this trial was to evaluate bleaching effectiveness, tooth sensitivity and gingival irritation of whitening patients with 10% versus 37% carbamide peroxide (CP). METHODS: Eighty patients were selected by inclusion and exclusion criteria and randomly allocated into two groups (n = 40): 37% CP and 10% CP. In both groups, patients performed whitening for 3 weeks, 4 h/day for 10% group and 30 min/day for 37% group. Color was evaluated with Vita Classical, Vita Bleachedguide 3D Master and Spectrophotometer Easyshade, at baseline, weekly and 30 days after treatment. Absolute risk and intensity of tooth sensitivity (TS) and gingival irritation (GI) were assessed with numeric rating scale (NRS) and a visual analog scale (VAS). Color changes were compared with t-test for independent samples. TS and GI were evaluated with Fisher's exact tests. Mann-Whitney test was used for NRS, and t-tests for VAS (alpha = 0.05). RESULTS: The 37% CP group showed faster whitening than 10% group at 1-3 weeks. However, 1 month after conclusion, both groups showed equivalent bleaching (p = 0.06). Regarding sensitivity and gingival irritation, 10% and 37% groups met no significant differences (p > 0.05). CONCLUSION: The use of 37% CP 30 min/day showed equivalent results to 10% 4 h/day. CLINICAL SIGNIFICANCE: The use of 37% carbamide peroxide 30 min/day may decrease the time of tray use in at-home protocol for whitening because it presents equivalent results to 10% carbamide peroxide 4 h/day.