Different daily times for at-home bleaching with 10% carbamide peroxide: A randomized single-blind, noninferiority controlled trial.

Background: This single-blind, noninferiority trial evaluated whether 10% carbamide peroxide (CP) applied for 2 or 4 hours daily is noninferior to 8 hours.

Methods: A total of 120 healthy adults, with teeth shade A2 or darker, were randomly allocated to 3 groups (n = 40). All participants used 10% CP gel in a bleaching tray for 2, 4, and 8 hours daily for 14 days, with the option to extend treatment if they were dissatisfied. Color change was measured using a spectrophotometer and shade guides at baseline, every 5 days, and 1 month posttreatment. Risk and intensity of tooth sensitivity (TS) were assessed daily using a 0 through 10 visual analog scale. Satisfaction was recorded via a Likert scale wherein 1 corresponded to very dissatisfied and 7 corresponded to very satisfied and the Orofacial Esthetic Scale. Noninferiority was tested for color change using the 1976 formula (ΔEab) at 1 month postbleaching (primary outcome), color change using the 2000 formula (ΔE00), Whiteness Index, and shade guide units, whereas TS and satisfaction were analyzed with χ², analysis of variance, Kruskal-Wallis, and Friedman tests.

Results: Color change in ΔEab (2 vs 8 h: mean difference, -0.6; 90% CI, -2.1 to 1.0, 4 vs 8 h: mean difference, 0.0; 90% CI, -1.6 to 1.6) and ΔE00 values for shorter durations were noninferior to 8 hours at 1 month. Whiteness Index results were inconclusive. TS risk and intensity were similar (P > .05), and patient satisfaction improved across all groups similarly (P > .05).

Conclusions: Shorter 2- and 4-hour daily bleaching with 10% CP is noninferior to the 8-hour protocol.

Practical implications: Shorter periods of at-home bleaching (2 and 4 h) can be prescribed depending on the patient's availability or preferences without jeopardizing the bleaching efficacy. This clinical trial was registered at Registro Brasileiro de Ensaios Clínicos (RBR-10vvfpcm).