Clinical Evaluation of the Effect of pH Values of Hydrogen Peroxide (35%) on the Ability of Whitening Teeth in Office Bleaching Technique

Office bleaching is one of the conservative and common treatments for teeth discoloration. Because of increasing shelf life, most of the whitening gels contain a pH near 2 and that is below the critical level, which caused the enamel demineralization. The aim of this research was investigating the clinical study of changing the bleaching agent's pH for improving the color of discolored teeth.
This clinical study was performed on 36 volunteer patients for bleaching. Patients were divided randomly into three groups. Patients received an office bleaching treatment sessions with 35% hydrogen peroxide at pH 8 and 10 and in the control group pH was 6.4. For changing the pH of bleaching agent, it was used 2.5 molar NaOH solutions. Color evaluation was performed in 2 maxillary central of patients with Easy Shade device (vita, Germany) before, immediately and one week after bleaching. Then, ΔE for each tooth according to the criteria a, b and l was calculated. Data were studied by Bundle SPSS20 and ANOVA Two-way statistical tests and multiple comparison of Tukey. Meanwhile, the 0.05 was considered statistically significant.
Changing of color before and after bleaching in each group was significantly different (p-value Due to the limitations of this study, it seems that there is a similar effect in improving the color of teeth in three groups, soit is better to prevent the destruction of tooth enamel it is used the pH above the critical level of demineralization.