Effects of tooth bleaching protocols with violet LED and hydrogen peroxide on enamel properties

• Published in: Photodiagnosis and photodynamic therapy 2022-06, Vol.38, p.102733, Article 102733
• Main Authors: Costa, Joatan Lucas de Sousa Gomes, Besegato, João Felipe, Zaniboni, Joissi Ferrari, Galvani, Lucas David, Kuga, Milton Carlos
• Format: Article
• Language: English
• Subjects: Animals; Cattle; Color change; Dental Enamel; Hydrogen peroxide; Hydrogen Peroxide - pharmacology; Hypochlorous Acid; LED; Microhardness; Photochemotherapy - methods; Roughness; Tooth Bleaching; Tooth Bleaching Agents - pharmacology; Tooth whitening; violet LED
• ISSN: 1572-1000; 1873-1597
• DOI: 10.1016/j.pdpdt.2022.102733

•35% HP and 6% HP + violet LED showed the best bleaching efficacy.•The use of violet LED alone promoted slight color change.•No enamel microhardness changes were observed.•35% HP and 6% HP + violet LED changed the enamel roughness. Background: This study evaluated the color change, enamel surface roughness and microhardness after different tooth bleaching protocols, using hydrogen peroxide (HP) and/or violet LED. Methods: Forty bovine specimens (7 × 7 × 2 mm) were randomly distributed into 4 groups: 35% HP, 6% HP, 6% HP + violet LED and violet LED alone. First, the specimens were stained with black tea and then submitted to two bleaching sessions of 30 min with an interval of 7 days. Color change (∆L*, ∆a*, ∆b* and ∆E00) after 24 h of each session and 1 week after the last session was evaluated. Enamel roughness and microhardness were evaluated immediately before the sessions, 24 h and 1 week after the last session. Data were evaluated by ANOVA for repeated measures and Bonferroni post-test or Kruskall-Wallis and Dunn tests (α = 0.05). Representative specimens from each group were analyzed by scanning electron microscopy. Results: 6% HP + violet LED and 35% HP showed the highest color change, while violet LED alone had the lowest results. Enamel roughness analyses showed that 6% HP + violet LED and 35% HP showed changes after two bleaching sessions. No differences were observed regarding enamel microhardness. Conclusions: The use of 6% HP + violet LED showed enhanced bleaching efficacy compared to 35% HP. However, violet LED used alone exhibited the lowest color change. 6% HP + violet LED and 35% HP promoted changes on enamel roughness, while no microhardness changes was observed for any group.