Evaluating Postoperative Pain and Antibacterial Effect of Ultrasonic and 980 nm Diode Laser Combination

This study is a parallel randomized controlled clinical trial that was designed and interpreted according to Preferred Reporting Items for Randomized Trial in Endodontics (PRIRATE) 2020 guidelines. Patients of age range between 20 and 35 years old from the outpatient clinic of Endodontic Department, Faculty of Dental Medicine for Girls, Al-Azhar University will participate in this study. These patients have single rooted teeth with necrotic pulp and periapical radiolucency. Patients will be informed about all the study's procedures. They will be included in the study after fulfilling the inclusion criteria and sign an informed consent.Inclusion Criteria: * Patients have mature teeth with closed apex. * Single rooted teeth with root canal form type I. * Asymptomatic. * Have Periapical radiolucency with diameter up to 5 mm. * Restorable teeth. Exclusion Criteria: * Patients with symptomatic apical periodontitis. * Systemic disease. * Physical or mental disability. * Root fracture and tooth mobility.

Ethical approval for the human study was obtained by the Research Ethics Committee (REC) of the Faculty of Dental Medicine for Girls, Al-Azhar University, Egypt . All patients were provided with an informed consent form outlining the study's details including potential benefits and risks, which they read and signed prior to participation. Sample size calculation was performed using G\*Power version 3.1.9.7 based on the results of a previous study . A power analysis was designed to have adequate power to apply a two-sided statistical test to reject the null hypothesis that there is no difference between groups. By adopting an alpha level of (0.05) and a beta of (0.2), i.e. power = 80% and an effect size (d) of (0,332) calculated based on the primary outcome (Postoperative pain) and the results of a previous study. The predicted sample size (n) was (104), i.e., 26 subjects per group. This number is increased to 30 subjects per group to compensate for a drop-out rate of 15%.