Only dental bleaching (BLE) group
In this group, the gingival tissue, lips and cheeks of the teeth to be bleached were isolated using a light-polymerized resin dam (Top Dam; FGM Prod. Odontol. Ltda., Joinville, SC, Brazil). Subsequently, 35% hydrogen peroxide was used for in-office dental procedures (Whiteness HP Maxx, FGM Prod. Odontol. Ltda., Joinville, SC, Brazil). The gel was applied for 15 min in triplicate. Two dental bleaching sessions were performed with a 1-week interval between sessions.