Fixed orthodontic appliance + dental bleaching (FOA + BLE) group
tooth
The same procedure was performed in this group as in the FOA and BLE groups. However, the bleaching procedure, as described in BLE group, was performed with the brackets in position. For this purpose, the orthodontic wire and aesthetic ligatures were removed before dental bleaching and reinstalled after the procedure. In this group, the FOA was removed 7 days after the second bleaching session, corresponding to 42 days of treatment.As in the BLE group, 35% hydrogen peroxide gel was used (Whiteness HP Maxx, FGM Prod. Odontol. Ltda., Joinville, SC, Brazil) for 15 min in triplicate, and two dental bleaching sessions were performed with a 1-week interval. In the FOA + BLE group, gel was applied around the orthodontic bracket until it completely covered the tooth to be bleached, as previous described by Gomes et al. [For all groups, participants were instructed to brush their teeth regularly using toothpaste without desensitizing or bleaching agents during the entire investigation period. The participants were also instructed to use dental floss on interproximal surfaces. To ensure ethical considerations, individuals assigned to the FOA group who desired teeth bleaching underwent the bleaching procedure after the final data collection. Similarly, individuals assigned to the BLE group who desired fixed orthodontic appliances underwent the procedure after the final data collection. Following the conclusion of the research study, all individuals in the FOA groups (FOA and BLE + FOA) received treatment with the fixed orthodontic appliance according to the predefined treatment plan for each clinical case.