Evaluation of Tooth Color Change and Sensitivity Following Laser-assisted In-office Tooth Bleaching Using Er,Cr:YSGG Laser: a Split-mouth Clinical Study

The study description adheres to the guidelines of the Consolidated Standards of Reporting Trials (CONSORT) statement. A factorial, single-blind, split-mouth design was employed in this study, with the following factors being examined:

1. Bleaching treatment: two treatment protocols were used, Group 1 (control) - 40% H2O2 bleaching agent and Group 2 - 40% H2O2 bleaching agent + Er,Cr:YSGG laser.
2. Evaluation time: three time points were used for the analysis of bleaching efficacy (T1 at immediately after the treatment, T2 at 7 days after the treatment and T3 at 30 days after the treatment). All color measurements were compared with the baseline values recorded prior to the start of the bleaching treatments. Additionally, tooth sensitivity was assessed at two time points: T1, just before the treatments began, and T2, immediately after the treatments were completed. Patients and the researchers administering the bleaching treatment were not blinded, as it was not possible to conceal whether the bleaching gel was exposed to laser irradiation. However, the evaluator responsible for recording color and sensitivity remained blinded to the treatment conditions.

Bleaching procedure

The study took place at the Postgraduate Dental Clinic of the Department of Operative Dentistry of Aristotle University of Thessaloniki. Initially, twenty volunteers (11 women and 9 men) between the ages of 22 and 48 (mean age 31.1±7.0 years) were enrolled. Patient selection was based on clinical and radiographic examinations, along with a detailed medical history, all conducted prior to the bleaching treatments. Participants were informed about the study's purpose, as well as the potential risks and benefits of the experimental treatment. Those who agreed to participate signed an informed consent form and were provided with both written and verbal instructions regarding hygiene, bleaching gel application, and diet. One week before the tooth bleaching treatment a periodontal treatment using an ultrasonic scaler type Cavitron (KaVo Dental GmbH, Biberach/Riss, Germany) was carried out to remove any external stains or calculus deposits.

All patients received a conventional in-office bleaching treatment using a red-colored bleaching agent with a neutral pH, consisting of 40% H2O2 (Opalescence Boost™ PF 40%, Ultradent Products, Inc., South Jordan, UT, USA). According to the manufacturer's instructions, the contents of the two syringes were blended 25 times and applied in a layer approximately 1 mm thick on the labial surface of the anterior teeth and buccal surface of premolars. After application of a light-cured liquid dam on the gingiva, the bleaching gel was applied on the surface for 20 min, with agitation every 5 min, and subsequently removed using a surgical suction tip. This procedure was repeated for another 20 min (40 min in total) and finally a thorough rinsing with water was followed.