Effects of violet radiation and nonthermal atmospheric plasma on the mineral contents of enamel during in-office dental bleaching

Author(s)

Kury, Matheus ; Antonialli, Fernanda Moura ; Soares, Luis Eduardo S. ; Tabchoury, Cinthia Pereira Machado ; Giannini, Marcelo ; Florez, Fernando Luis Esteban ; Cavalli, Vanessa

• Document type: Journal article
• Source: Photodiagnosis and Photodynamic Therapy; v. 31, p. 7-pg., 2020-09-01.

Abstract

Aim: This in vitro study assessed the effects of in-office bleaching with gels (35% hydrogen peroxide [HP] or 37% cabamide peroxide [CP]) and two activation sources (violet radiation [LED] or nonthermal atmospheric plasma [NTAP]) on the mineral content of bovine enamel. Material and methods: Dental blocks (n = 90) were assessed for initial microhardness before random distribution into nine groups: LED, LED + HP, LED + CP, NTAP, NTAP + HP, NTAP + CP, HP, CP and control (without treatment). Specimens were subjected to bleaching (2 clinical sessions, 7 days apart) using LED [20x/session, 1-min/each, 30s apart] or NTAP [1x/session, 10 min]. mu Raman determined contents of phosphate (PO43) and carbonate (CO32). Micro-energy dispersive X-ray fluorescence (mu EDXRF) and spectrophotometry of enamel microbiopsy evaluated the calcium to phosphorous ratios (Ca/P). Two-way ANOVA and Tukey tests analyzed mu RAMAN and mu EDXRF results. Spectrophotometry results were analyzed using Kruskal-Wallis and Dunn tests. Pearson correlation tested mu EDXRF and spectrophotometry results (alpha = 5%). Results: NTAP and NTAP + HP exhibited greater PO43- content than LED, LED + HP and control (p < 0.05). No statistical differences were detected between CO32- among groups. While mu EDXRF evaluation demonstrated that NTAP and LED did not alter Ca/P ratio of enamel (p > 0.05), spectrophotometry showed that Ca/P reduced for LED + HP (p < 0.05). No correlation was found between mu EDXRF and enamel microbiopsy spectrophotometry (p > 0.05). Conclusions: Activation sources did not adversely impact enamel's phosphate and carbonate concentrations after specimens' exposure to bleaching gels (either HP or CP). Visible light radiation emitted by a LED source was shown to adversely impact specimens' Ca/P ratios when treated with HP-containing bleaching gels. (AU)

• FAPESP's process: 17/08625-0 - In vitro purple led and argon plasma analysis on the color alteration, mineral content, morphology and safety of dental bleaching
• Grantee: Matheus Kury Rodrigues
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 17/23841-1 - In vitro/in vivo led Violeta and in vitro argon plasma analysis on color alteration, mineral content, morphology and safety of teeth bleaching
• Grantee: Vanessa Cavalli Gobbo
• Support Opportunities: Regular Research Grants