Can all highly concentrated in-office bleaching gels be used as a single-application?

• Published in: Clinical oral investigations 2023-07, Vol.27 (7), p.3663-3671
• Main Authors: da Silva, Karine Letícia, Favoreto, Michael Willian, Centenaro, Gabrielle Gomes, Bernardi, Laís Giacomini, Borges, Christiane Philippini Ferreira, Reis, Alessandra, Loguercio, Alessandro D.
• Format: Article
• Language: English
• Subjects: Bleaching; Cosmetic dentistry; Dental Enamel; Dental pulp; Dentin; Dentistry; Diffusion; Gels; Hydrogen Peroxide; Hypochlorous Acid; Medicine; pH effects; Premolars; Spectrophotometry; Statistical analysis; Tooth Bleaching - methods; Tooth Bleaching Agents
• ISSN: 1436-3771; 1432-6981; 1436-3771
• DOI: 10.1007/s00784-023-04980-w

Objective This in vitro study aims to evaluate of hydrogen peroxide (HP) diffusion into the pulp chamber, bleaching efficacy (BE), and pH stability (pH) of single-application high concentrated in-office bleaching gels. Materials and methods Eighty-eight healthy premolars were randomly into eleven groups ( n = 8) according to the in-office dental bleaching: DSP White Clinic 35% calcium (DW), Nano White 35% (NW), Opalescence XTra Boost 40% (OB), Pola Office + 37.5% (PO), Potenza Bianco Pro SS 38% (PB), Total Blanc 35% (TB), Total Blanc One-Step 35% (TO), Whiteness Automixx 35% (WA), Whiteness Automixx Plus 35% (WP), and Whiteness HP Blue 35% (WB). A group not exposed to bleaching agents was the control group (CG). All bleaching agents were applied in one session with a single application. After the bleaching procedure, the concentration of HP diffusion (μg/mL) into the pulp chamber was assessed using UV-Vis spectrophotometry. The BE (Δ E ab and Δ E 00 ) was evaluated before and 1 week after the bleaching procedure using a digital spectrophotometer. The pH of each bleaching gel was evaluated by digital pHmeter. The one-way ANOVA and Tukey’s was used for a statistical analysis ( α = 0.05). Results The concentration of HP diffusion into the pulp chamber was higher in all in-office bleaching gels when compared to CG ( p < 0.0000001). However, there are a significant difference between them ( p = 0.0001). A significant BE was observed in all in-office bleaching gels ( p < 0.0001 for Δ E ab and Δ E 00 ), with a significant difference between them ( p < 0.0001). PO, OB, TB, WP, and WB showed a higher BE when compared to DW, PB, and WA ( p < 0.0001). Most bleaching gels were slightly acidic or alkaline during the total application time, while DW, PB, TB, and WA showed a high acidic behavior after 30 min of application. Conclusions A single application was able to produce a bleaching efficacy. However, usually, gels with slightly acidic or alkaline pH during the application time reduces the HP diffusion into the pulp chamber. Clinical relevance The single-application of bleaching gels with slightly acidic or alkaline and stable pH decreased the penetration of hydrogen peroxide into the pulp chamber in in-office bleaching and maintained the bleaching efficacy.