Clinical trial evaluating the peroxide concentration response of whitening strips over 28 days.

PURPOSE The research evaluated the peroxide concentration whitening response following self-directed use of whitening strips over a 28-day period. METHODS A randomized, double-blind, parallel group clinical study was conducted. 37 healthy adult volunteers were randomly assigned to one of three groups based on tooth color at screening: 1.8% hydrogen peroxide strips (HPS), 3.3% HPS or 5.3% HPS. Subjects applied the assigned maxillary strips twice per day for 30 minutes over 28 days. Tooth color was evaluated at day 7, 14 and 28 from digital images of the maxillary six anterior teeth using a standard method. Treatments were compared using analysis of covariance (adjusting for baseline) at a 0.05 level of significance. RESULTS Hydrogen peroxide at concentrations ranging from 1.8-5.3% resulted in significant (P< 0.05) color improvement versus baseline as early as Day 7. There was a concentration-response for reduction in yellowness (deltab*) and lightness improvement (deltaL*) at all timepoints, favoring the higher concentrations. While the concentration-whitening relationship approached a linear response at Day 7, continued treatment resulted in incremental color improvement. All three peroxide concentrations were well tolerated, and no subjects discontinued early due to a treatment-related adverse event.