Introduction: The traditional technique for in-office bleaching includes 3 applications of the whitening gel (15 min each) for a total of 45 min in 3 different sessions. The purpose of this study was to clinically evaluate the bleaching outcome and any relapse effect (darkening) when the gel was applied 3x for 15 min or once for 45 min.
Methods: This single-blinded, randomized clinical trial used a simultaneous split-mouth design. We selected 10 patients based on pre-defined inclusion and exclusion criteria. The patients' upper arches were split with a light-cured gingival barrier. The bleaching gel (hydrogen peroxide at 35%) was applied 3 times (15 min each) on the control side or for 45 min on the opposite side in each session. Three sessions were completed, separated by a week. The bleaching evaluation was completed by two blinded calibrated evaluators, who compared the baseline color of the 6 anterior teeth with a shade guide (VitaPan Classic) and color photographs 1 wk after the final session, and at 1 and 3 months. Patients were also surveyed about comfort, sensitivity (dental and gingival), and overall satisfaction with the treatment. Data were analyzed by one-way analysis of variance (ANOVA).
Results: A pronounced quantity of tooth whitening was noted. However, no statistically significant differences in efficacy and color stability (for both shade guide and photographs), comfort, sensitivity, or patient satisfaction were observed (P > 0.05). No differences could be observed between the right and left sides for any of the patients in all periods of evaluation.
Conclusions: Based on these clinical findings, the “in-office” bleaching technique might by modified by conducting a one-time, 45-minute gel application.