Effects of Pre-operative Air-powder Polishing and Rubber-cup Prophylaxis on Tooth Bleaching Outcomes: Randomised Controlled Split-mouth Clinical Study

Tooth color was measured using spectrophotometer VITA Easyshade V (Vita Zahnfabrik, Germany). The spectrophotometer was calibrated before use in each participant and the device tip was placed on middle thirds of the labial surface of teeth as suggested by the manufacturer's manual.

The tooth color was measured before initial prophylaxis (baseline), immediately after bleaching and after one week. The digital spectrophotometer used in the current study measures the shade of teeth based on the CIE (Commission Internationale de l'éclairage) L*a*b* color space system. This system expresses color as three values: L* for the lightness from black (0) to white (100), a* from green (-) to red (+), and b* from blue (-) to yellow (+). The following values were recorded in the units of CIE L*a*b* color space.

-Data of lightness (L*) and a* and b*axis

-△e: a teeth color change (△e*) was derived as: △e = [(△L *)2+ (△a *)2 + (△b *)2]1/2 While making Shade guide units (SGU) measurements, the bleached index is set according to the VITA Bleached guide 3D-MASTER at spectrophotometer for the measured shade. The measured bleached index after treatment was subtracted from the baseline value. The difference corresponded to the change of the SGU (△ SGU) achieved immediately and 1 week after the bleaching treatment.

The patients had bleaching treatment on the maxillary anterior area including right and left canines. The right and left sides of the patients were randomized by toss of a coin to receive polishing with rubber cup prophylaxis or air powder polishing system before bleaching.