PENETRAÇÃO E CITOTOXICIDADE DE UM GEL CLAREADOR ATIVADO COM LED/LASER EM DENTES RESTAURADOS

Abstract

This in vitro study aimed to evaluate the amount of hydrogen peroxide in the pulp chamber of teeth with composite resin and its cytotoxic effect on fibroblast cell line 3T3/NIH. Twelve hundred human premolars were randomized into seven groups according to the combination of factors: control (no treatment), restoration (no [C], shallow [S] and deep [D]) and activation by light (yes [A] or not [NA]). With exception of the groups (Control, CA and CNA), class V cavities were prepared and restored with composite resin according to the manufacturer’s instructions. To assess the amount of hydrogen peroxide in the pulp chamber, all teeth were sectioned 3 mm from the cement-enamel junction, the pulp tissue removed and acetate buffer was placed in the pulp chamber. The bleaching procedure was performed with hydrogen peroxide (35% Whiteness HP Maxx, FGM Dental Products) activated or not with a LED/Laser light. After treatment, the solution of acetate buffer in the pulp chamber of each tooth was removed and leucocristal violet and peroxide enzyme solutions were added. The optical density of the resulting blue solution was determined spectrophotometrically and converted into micrograms equivalent of hydrogen peroxide. For viability cell assays, different concentrations of hydrogen peroxide were applied to fibroblast cell line 3T3/NIH. After 24 h of exposure of hydrogen peroxide, the MTT and Neutral Red assays were evaluated. The letal concentration of 50% of cells (LC50) was determined. Data from each test were submitted to ANOVA and Tukey´s test (α = 0.05). All experimental groups showed the presence of hydrogen peroxide in the pulp chamber, but higher amount of hydrogen peroxide was found in the pulp chamber of teeth with deep restorations (p = 0.026), regardless of light activation. The concentrations of hydrogen peroxide that was found in the pulp chamber did not affect cell viability.