Kinetics of 10% Hydrogen Peroxide 2-hour Whitening Strips

Objectives: , It is well-established that peroxide concentration and contact time contribute to tooth whitening effectiveness and safety.  This research was conducted to establish the peroxide degradation profile of 10% hydrogen peroxide whitening gel delivered on a flexible polyethylene strip over a 2-hour wear time.  Methods: , 20 adult volunteers signed an informed consent and participated in this study. The average age was 46 and 80% of subjects were female.  At each study visit, the 10% hydrogen peroxide tooth whitening strip was applied to the maxillary anterior teeth under supervision. There were a total of 4 visits with one strip application per visit. Strips were removed after 10, 30, 60 and 120 min of wear time. Residual peroxide levels on the strip were measured by an indirect iodometric titration. Additionally, saliva samples were collected at baseline and at designated timepoints, and peroxide levels in saliva were measured by colorimetry.  Results: , Baseline median peroxide concentration on the strip was 9.75%, declining to 8.07%, 6.55%, 5.46% and 4.09% at 10, 30, 60 and 120 minutes, respectively. Salivary samples never exceeded a median concentration of 0.02% at any time point.  Median peroxide concentration on the strip remained above 4% after 120 minute wear time.  At all post-treatment time points, salivary peroxide concentration was at least 2 orders of magnitude lower than that on the strip.  Conclusions: , Use of 10% hydrogen peroxide whitening strip resulted in sustained directed peroxide release from the strip to the tooth over a 120 minute period, with very low accumulation of peroxide in saliva.