Bleaching procedure
Prophylaxis with pumice stone and water was performed. Alginate impressions (Jeltrate Plus, Dentsply, Petrópolis, RJ, Brazil) of each patient’s upper and lower arches were taken and stone models was fabricated. Ethylene vinyl acetate trays (Bio-Art Equip Odontológicos, Ltda, São Carlos, SP, Brazil) were fabricated using a vacuum-pressing machine (Equip Odontológicos Ltda, São Carlos, SP, Brazil). An electronic microsensor (TheraMon microelectronic system, Sales AgencyGschladt, Hargelsberg, Austria) was attached to the buccal surfaces of the acetate trays in order to monitor the daily usage time. The microsensor was included between the 2 acetate plates, each being 1 mm thick, during the preparation of the trays, in which borders were cut 2 mm beyond the gingival margin, following the gingival contour (scalloped tray), without the presence of reservoirs (
