Comparative Evaluation of the Effectiveness of At-Home Dental Bleaching Using Different Concentrations of Carbamide Peroxide for Different Time Intervals: A Randomized Clinical Trial.

Background This randomized clinical trial evaluated the efficacy and safety of three concentrations of carbamide peroxide (CP) (10%, 22%, and 35%) for at-home tooth bleaching with reduced application times for the higher concentrations, comparing color change and tooth sensitivity to determine whether higher CP concentrations applied for shorter durations achieve equivalent or superior whitening outcomes without increasing patient discomfort. This study aimed to evaluate whether in adults aged 18-60 years with a baseline shade of A2 or darker (Population), does 22% or 35% CP for 30 minutes/day (Intervention), compared with 10% CP for four hours/day (Comparison), produce equivalent or superior tooth color change without increased sensitivity (Outcome) over three weeks with one-month follow-up. Methodology A total of 84 participants were randomly allocated 1:1:1 to Group I (10% CP, four hours/day), Group II (22% CP, 30 minutes/day), and Group III (35% CP, 30 minutes/day) for three weeks. Tooth color was assessed at baseline, weekly, and at one-month follow-up using VITA Classical and VITA Bleachedguide 3D-MASTER shade guides by a single blinded, calibrated evaluator. Tooth sensitivity was recorded daily using a Visual Analog Scale. Two-way repeated-measures analysis of variance with Tukey's HSD post-hoc test was used for color data; Kruskal-Wallis test was used for sensitivity data. Significance was set at a p-value of 0.05; pairwise mean differences with 95% confidence intervals (CIs) and Cohen's d were additionally computed. Results All 84 randomized participants (28 per group) completed the study with no losses to follow-up. All groups showed significant color improvement from baseline (p < 0.001). Groups II and III whitened faster than Group I during weeks one to two (mean difference = 1.7-2.2 SGU; Cohen's d > 0.7); Group II converged with Group I by week three, while Group III remained significantly higher through one month. Sensitivity was mild in all groups with no significant intergroup differences at any time point (p > 0.05). Sensitivity occurred in 9/28 (32%) of Group I, 13/28 (45%) of Group II, and 15/28 (53.5%) of Group III; relative risk versus Group I was 1.44 (95% CI = 0.74-2.82) for Group II and 1.67 (95% CI = 0.88-3.16) for Group III, neither of which was significant. Conclusions Higher CP concentrations (22% and 35%), applied for 30 minutes/day, produced faster initial whitening than conventional 10% CP for four hours/day and achieved comparable outcomes, without a statistically significant increase in tooth sensitivity, though wide CIs around the relative risk estimates mean a true dose-related difference cannot be excluded. These findings support 22% and 35% CP for 30 minutes/day as effective, time-efficient alternatives to the conventional protocol, pending confirmation with spectrophotometric measurement, patient-reported outcomes, and longer follow-up.