Influence of 35% hydrogen peroxide gel renewal on color change during in-office dental photobleaching with violet LED: A split-mouth randomized controlled clinical trial

Background: To clinically evaluate the effect of 35% hydrogen peroxide gel renewal in association with violet LED (405-410nm) through a split-mouth randomized controlled clinical trial. Methods: The treatment consisted in 3 bleaching sessions of 15 min each, with an interval of 7 days between them, using 35% hydrogen peroxide combined to violet LED irradiation. Selected patients had two experimental segments for the split-mouth design: No change of the bleaching gel during each session (NBGR) and 3 changes of the bleaching gel every 5 min for each session (BGR). During the 3 bleaching sessions, the selected quadrant received the same treatment. Patients had their upper canines and central incisors teeth color measured with a subjective (color scale - VITA Classical) and an objective (spectrophotometer - VITA Easyshade) method and their teeth sensitivity measured using a Visual Analog Scale (VAS) before, immediately after each bleaching session, and 14 days and 2 months (60 days) after the end of the treatment. Results: The protocol adopted in the present study reached satisfactory results regarding color change. No statistical difference between groups was observed immediately after the end of the treatment and in the follow-up analysis for both subjective and objective color evaluation. No difference in tooth sensitivity between segments was observed. Conclusion: There is no need for bleaching gel renewal when following the clinical protocol of 3 sessions of 15 min in a bleaching protocol of 35% hydrogen peroxide combined with violet LED.