Avaliação da eficácia, microdureza e biocompatibilidade celular do clareamento dental com o LED violeta: um estudo in vitro

Abstract

Introduction: Recently, a new light-emitting diode (LED) tooth whitening technique in the violet spectrum has been suggested, which can be used with or without hydrogen peroxide. This light source has a wavelength of 405-410 nm, which is very close to that of ultraviolet (UV) radiation. This study aimed to evaluate the effectiveness of the violet LED tooth whitening technique analyzing changes in color and enamel surface. Cellular genotoxicity of violet LED irradiation was also analyzed. Methods: One hundred bovine dental blocks were divided into 5 groups according to the whitening technique (G1 - Hydrogen peroxide only; G2 - Hydrogen peroxide associated with blue LED; G3 - Blue LED only; G4 - Hydrogen peroxide associated with LED violet; and G5 – Violet LED only). After bleaching, the blocks were analyzed using Scanning Electron Microscopy (SEM), microhardness test, and spectrophotometry for color analysis. Cellular genotoxicity was assessed by counting micronuclei in human dental pulp stem cells (hDPSCs) and human gingival fibroblasts (FMM-1). For statistical analysis, the tests used were Kruskal-Wallis and Student's T. The level of significance adopted was 5%. Results: In groups G4 and G5 there was the formation of precipitate on top of the enamel surface. In microhardness, at the time of 14 days, it was observed that the G2 group had lower values than the G5 group. In the comparative analysis of ΔL between groups, it was observed that group G3 presented ΔL lower than groups G1, G2 and G4 immediately, and lower than G1 and G2 in 7 days. At times 14 and 30 days, groups G3, G4, and G5 presented ΔL lower than G1 and G2. Regarding ΔE, the comparative analysis between groups showed that G3 had lower ΔE than G1, G2, and G4 in the immediate period. At other times, it is highlighted that G1, G2, G4, and G5 had higher values than G3 in all experimental times. The mean percentages of micronuclei were similar in the control group and the violet LED group. Conclusion: Based on the results obtained from this in vitro study, it is possible to conclude that the use of violet LED alone can be favorable to the preservation of enamel structure in tooth whitening procedures. In addition, its isolated use promotes tooth whitening with significant color changes. In the genotoxicity analysis, the violet LED proved to be non-genotoxic. This result suggests that it is possibly safe for use in oral tissues, but further studies are needed to prove its safety.