Ph Stability of Whitening Hydrogen Peroxide Gels with Different Application Times

Introduction: Tooth whitening is an aesthetic and conservative technique, with hydrogen peroxide in high concentrations being one of the most commonly used agents. Objective: This study evaluated the pH stability of whitening gels with a high hydrogen peroxide concentration during the application with and without bovine tooth enamel contact. Material and methods: The pH of three hydrogen peroxide bleaching gels was measured with the help of a calibrated pH meter. These were OpalescenceTM BoostTM 40% (OpB), Whiteness HP Blue 35% (WHPB), and Whiteness HP 35% (WHP). The gels were used following the manufacturer’s recommendations, and the pH was measured every 5 minutes until reaching the application time of each product, respectively, 20 minutes for OpB, 40 minutes for WHPB and 15 minutes for WHP. The measurement was also made with the gels in contact with bovine tooth enamel. Results: OpB and WHPB presented an alkaline and stable pH, while WHP started with a neutral pH at the time of application but became acidic over time. There were no significant differences between the pH of the gels alone or on enamel. Conclusion: The pH of OpB and WHPB remained stable during use, both alone and in interaction with dental tissue, while WHP decreased its pH after 15 min.