RESUMEN
BACKGROUND: This study aimed to evaluate the in vitro color of dental enamel bleached with the violet LED, associated with or without low-concentration of peroxide; analyzed in two time intervals: 24â¯h later and 6 months after the treatment. METHODS: Ninety fragments of bovine teeth (6â¯×â¯6â¯mm and 3â¯mm thick) were randomly divided into 6â¯groups according to bleaching treatment: NB - no bleaching, VL - Violet LED, HP- 7.5 % hydrogen peroxide, HPâ¯+â¯VL - 7.5 % hydrogen peroxideâ¯+â¯violet LED, CP - 22 % carbamide peroxide, CPâ¯+â¯VL - 22 % carbamide peroxideâ¯+â¯violet LED. The color change was analyzed by using a spectrophotometer, at time intervals of 24â¯h and 6 months after performing the bleaching techniques (nâ¯=â¯12). Scanning electron microscopy (SEM) was performed to verify the enamel surface morphology after treatment (nâ¯=â¯3). RESULTS: The color change data were analyzed using ANOVA and a post-hoc Tukey tests (αâ¯=â¯0.05). The VL group showed chromatic changes after 24â¯h of treatment, however the groups submitted to bleaching gel treatments associated with or without violet LED (CPâ¯+â¯VL, CP, HP, HPâ¯+â¯VL) showed the highest color change values at all time intervals analyzed, with color stability after 6 months of treatment for the CPâ¯+â¯VL group. Scanning electron microscopy analysis showed the greatest change in enamel surface for Groups CP and HP. CONCLUSIONS: It could be concluded that violet LED had immediate bleaching effect without promoting significant changes in enamel morphology, however the association with carbamide peroxide 22 % showed color stability and greater bleaching efficacy than the use of violet LED alone, after 6 months.