In-Office Bleaching Gel-Application Time Evaluation (3x15min X 1x45min) : Pilot studies

Objectives: The traditional technique for in-office bleaching includes 3 applications of the whitening gel (15 minutes each) for a total of 45 minutes. The purpose of these pilot studies was to evaluate the possibility for in-office bleaching by applying a single layer of whitening gel and leaving it in contact with teeth for 45 minutes straight. Methods: 1) Chemical Analysis: an in-vitro analysis was conducted to quantify the amount of hydrogen peroxide (HP) in function of the time elapsed. A 35% HP gel was assayed through a potassium permanganate titration method. The concentration of active HP was measured immediately after gel mixing and after 10, 20, 30, 40, 50 and 60 minutes. 2) In-Vitro Spectrophotometric Evaluation: 5 recently extracted teeth had their facial and lingual surfaces separated with a light-cured gingival barrier. One randomly assigned surface was bleached for 45 minutes straight and on the other one the gel was reapplied every 15 minutes (3X). Color coordinates (L*a*and b*) were measured with a spectrophotometer (CM2600-Minolta) and the bleaching outcome was evaluated by means of ΔL* calculation and one-way ANOVA analysis. Results: are described on the tables below. After 50 minutes only 6% of hydrogen peroxide was lost. No significant differences were observed for the spectrophotometric evaluation. Conclusions: Although further research is indicated to confirm these findings, IT SEEMS POSSIBLE TO MODIFY THE "IN-OFFICE" BLEACHING TECHNIQUE BY CONDUCTING A ONE-TIME, 45 MINUTES LONG, GEL APPLICATION.