The increasing demand for whitening teeth necessitates requirements and guidelines to ensure the efficacy of products and bleaching techniques. So far there is no comparative study to evaluate the effectiveness of pre-operative air-powder polishing device (APD) and rubber-cup prophylaxis on tooth bleaching in-office. Office-bleaching has some advantages such as avoiding soft tissue irritation, preventing the use of excess material and producing immediate esthetic results.

The aim this study is to compare the effects of pre-operative air-powder polishing and rubber-cup prophylaxis on tooth bleaching outcomes. The null hypothesis of this research was that there would be no difference in the change in according to the type of prophylaxis on tooth-bleaching outcomes.△L,△a,△b,△E and △SGU.

The results of the study show that both rubber cup prophylaxis and APD devices can be equally used before bleaching treatment as there were no statistical differences in color change.

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.

All prophylaxis procedures were performed by same clinician (M.O.). The rubber cup prophylaxis was applied with low-speed handpieces. A rubber cup was attached to the prophy-angle. The handpiece used at a steady slow pace of 2500-3000 rpm. The rubber cup contacted each tooth surface for an average of 5 seconds together with polishing paste consisting of flour of pumice, glycerin and fluoride.

The air polishing treatment was performed by AIRFLOW® Master device (EMS, Nyon, Switzerland) with a six LED (Light Emitting Diode) power setting (2.2 bars dynamic pressure inside powder chamber) and an 11 LED (35 mL/min) water setting for 30 seconds (powder consumption was 1.1 g). Sodium bicarbonate air-powder polishing powder (AIR-FLOW® Plus, EMS Electro Medical Systems, Nyon, Switzerland) was used. The nozzle was held 3-4 mm from the tooth surface and the tip was angulated diagonally. The spray was delivered for an average of 5 seconds using a constant circular motion for each tooth. The spray was directed towards the middle one-thirds of the exposed tooth.

All bleaching procedures were performed by same clinician (Z.G.B.K.). The bleaching agent (Opalescence Xtra Boost/ Ultradent, South Jordan, Utah, USA) was prepared and used following the manufacturer's instructions. Opal Dam (Ultradent, South Jordan, Utah, USA) was used for protection of the gingiva. The bleaching gel was then applied to form 1-2 mm thickness on the buccal surfaces of the teeth of both arches. The gel remained on teeth for 15 minutes and was then suctioned from teeth using a surgical suction tip. This application was repeated a second time in the same session.

Inclusion Criteria:

• - being at least 18 years of age
• having minimum of 20 natural teeth (including incisors, canines, and premolars in both arches)
• having good oral hygiene (Plaque index <1, Gingival index <1)

Exclusion Criteria:

• having restorations or active caries on the anterior teeth of either arch
• presence of tetracycline staining or fluorosis
• general hypersensitivity
• gingival recession or periodontal disease
• smokers
• pregnant or lactating women
• history of prior bleaching treatment

Single blind participant