Impact of behavioral, clinical and demographic parameters on whitening response: Evidence from 18 clinical trials

Objective: This research investigates the impact of behavioral, clinical and demographic parameters on whitening response using an extensive clinical trials database collected as part of the development of a strip-based tooth whitening system. Methods: Data from 18 different clinical trials were included in the analysis. This inclusive assessment involved study subjects who used a flexible polyethylene, whitening strip coated with an adhesive hydrogen peroxide bleaching gel. All subjects used a common regimen, wherein whitening strips were worn twice daily over a 2-week period. Efficacy was measured in a common fashion using digital images of maxillary anterior teeth to objectively determine tooth color change in CIELAB units (b* yellowness, L* lightness, and a* redness). Results: The analysis included 300 subjects with complete demographic, behavioral and effectiveness data. Initial tooth color, age, tobacco use and race were significantly (p < 0.05) related to the primary clinical response (Db*). Subjects who regularly used tobacco experienced less whitening (0.33 Db*) on average compared to non-users. Coffee/tea/cola consumption was not significantly related to clinical response. Initial tooth color was the most significant (p < 0.0001) factor related to whitening. For subjects having the same age, racial background and smoking habits, each 1-unit increase in baseline yellow tooth color resulted in approximately 10% more color improvement after 14 days of treatment. Conclusion: This meta-analysis of whitening strip research demonstrates that baseline color and other factors are significant determinants of whitening effectiveness.