The influence of violet LED light on tooth bleaching protocols: In vitro study of bleaching effectiveness

•Visible light provides tooth whitening without bleaching gels containing peroxides.•The violet LED induces tooth whitening similar to that obtained with peroxides.•CP 16 % + violet LED obtained results similar to the association of two peroxides. Employing violet LED on tooth bleaching is a recent but promising technique. This study aimed to assess the bleaching effectiveness of violet light-emitting diodes (LEDs) associated or not with bleaching gels containing hydrogen peroxide (HP) or carbamide peroxide (CP). seventy bovine incisors were randomly assigned into 7 groups (n = 10) according to the technique and whitening product used. Group C: Artificial saliva (placebo); Group HP L-: three sessions of HP at 35 % without light activation; Group CP L-: three weeks of CP at 16 % for 4 h/day; Group HP CP L-: three sessions of HP at 35 % without light activation + 2 weeks of CP at 16 %, for 4 h/day; Group LED: four sessions with violet LED; Group HP L+: three sessions with HP at 35 % + violet LED; Group CP L+: three weeks with CP at 16 % for 4 h/day + violet LED. Color changes (ΔE and ΔL) were measured with a portable digital spectrophotometer. The results were similar between the groups of bleaching protocols, demonstrating that the use of the violet LED did not influence bleaching effectiveness when using HP 35 % or CP 16 % after 3 sessions. In addition, the use of the violet LED alone obtained ΔE values ​​similar to the protocols with the use of peroxides, however less variation of ΔL was observed for this group. The use of violet LEDs associated or not with bleaching gels was effective for tooth whitening. In addition, it was also concluded that the physical lightening technique with violet LED used alone produced less variation in dental brightness.