Single site meta-analysis of 6% hydrogen peroxide whitening strip effectiveness and safety over 2 weeks

ObjectivesThis research evaluated efficacy and safety of 6% hydrogen peroxide whitening strips from a clinical trials database accumulated over a multi-year period at a single site.MethodsThe inclusive meta-analysis involved seven different randomized clinical trials at one dental school. Each study used 6% hydrogen peroxide whitening strips twice daily for 30 min over a 2-week period. Common efficacy (digital images) and safety (examination and interview) methods were used across studies. Pooled subject-level data were analyzed using a general linear mixed model to determine overall response and effects of treatment duration on whitening.ResultsThe 148 treated subjects were 18–71 years old, with b* (yellowness) ranging from 12 to 22, and L* (lightness) ranging from 69 to 80. After 1-week strip use, the adjusted mean (S.E.) for Δb* was −1.6 (0.08), differing significantly from baseline (p < 0.0001). After 2 weeks, the adjusted mean (S.E.) for Δb* was −2.3 (0.07), differing significantly from Week 1 (p < 0.0001). The estimated correlation between Weeks 1 and 2 for Δb* was 0.74. Study-to-study variation contributed less than 2% of Δb* variability. Results were similar for ΔL*, with Weeks 1 and 2 estimated means (S.E.) of 1.5 (0.13) and 2.0 (0.12). Occurrence of oral irritation (22%) and tooth sensitivity (20%) did not adversely affect whitening. Other side effects were unremarkable, and only 1 subject (0.7%) discontinued treatment early due to an adverse event.ConclusionsThe meta-analysis of multiple studies conducted at a single clinical site over several years establishes consistent, effective and safe vital bleaching with 6% hydrogen peroxide whitening strips.