In‐office bleaching with a commercial 40% hydrogen peroxide gel modified to have different pHs: Color change, surface morphology, and penetration of hydrogen peroxide into the pulp chamber

• Published in: Journal of esthetic and restorative dentistry Vol. 34; no. 2; pp. 322 - 327
• Main Authors: Acuña, Eric D., Parreiras, Sibelli O., Favoreto, Michael W., Cruz, Gustavo P., Gomes, Anderson, Borges, Christiane P. F., Loguercio, Alessandro D., Reis, Alessandra
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01-03-2022; Blackwell Publishing Ltd
• Subjects: Acetic acid; Bleaching; Color; color shade; Demineralization; Dental enamel; dental enamel permeability; Dental pulp; Dental Pulp Cavity; Enamel; Gels; Hydrogen Peroxide; Morphology; Permeability; pH effects; Premolars; Scanning electron microscopy; Teeth; Tooth Bleaching; Tooth Bleaching Agents - pharmacology; dental enamel permeability; scanning electron microscopy; color shade; tooth bleaching; hydrogen peroxide
• ISSN: 1496-4155; 1708-8240
• DOI: 10.1111/jerd.12453

Objective
In‐office bleaching gels are usually marketed in different pHs. This study is aimed at evaluating the efficacy, enamel surface morphology and concentration of hydrogen peroxide (HP) in the pulp chamber of teeth bleached with 40% HP with different pHs.
Materials and Methods
Forty premolars were randomly divided according to bleaching gel pH: 5.1, 6.3, 7.0, and control (no bleaching). Teeth were prepared, an acetate buffer was placed in the pulp chamber and teeth were bleached with two 20‐minutes applications. The amount of HP was determined on a UV‐VIS spectrophotometer. Color change was assessed by using a digital spectrophotometer before and 1 week after bleaching treatment. Five additional premolars were divided into four parts, assigned to the same groups above for analysis under scanning electron microscope. Data were subjected to anova and Tukey's tests (alpha = 0.05).
Results
The group pH 5.1 showed the highest HP diffusion in the pulp chamber (P < .001). No significant difference was detected in color change (P = .51). All groups presented the same pattern of enamel demineralization.
Conclusions
The bleaching agent with pH 5.1 presented the highest HP amounts in the pulp chamber, but color change and enamel morphology were similar among groups.
Clinical significance
Regardless of the pH, the bleaching effect can be observed in teeth submitted to high concentrations of HP, but a higher permeability of HP was found in the pulp chamber of teeth bleached with more acidic bleaching agents. Based on that, we suggest the use of alkaline gels for in‐office bleaching to minimize damage to the pulpal tissue.