Sonic Irrigation Activation for Postoperative Pain After Root Canal Treatment (VAS)

This is a prospective, two-arm, parallel-group randomized controlled clinical trial designed to compare the effect of sonic irrigation activation with conventional syringe irrigation on postoperative pain following root canal treatment in adults with pulp necrosis and asymptomatic apical periodontitis.

Eligible participants will be adults aged 18-60 years requiring primary root canal treatment of restorable permanent single-rooted premolars. Participants must have a clinical diagnosis of pulp necrosis and radiographic evidence of apical periodontitis/periapical radiolucency without spontaneous preoperative pain or clinically significant pain on percussion or palpation. Participants with symptomatic apical periodontitis, acute apical abscess, previous endodontic treatment, root fracture, severe root curvature, open apices, root resorption, severely calcified or obliterated canals, severe periodontal disease, or other specified exclusion criteria will not be enrolled.

A total of 176 participants will be recruited and allocated in a 1:1 ratio using a computer-generated randomization sequence with variable block randomization. Allocation will be concealed using sequentially numbered, opaque, sealed envelopes. The operator cannot be blinded because the irrigation activation method must be known during treatment. However, the postoperative outcome assessor will remain blinded to treatment allocation, and the statistician will analyze coded treatment groups.

In the conventional irrigation group, final irrigation will be performed using a sterile side-vented endodontic irrigation needle positioned approximately 1-2 mm short of the working length. In the sonic activation group, the same irrigants, concentrations, volumes, sequence, and exposure times will be used, followed by activation using the EndoActivator system. The EndoActivator tip will be positioned approximately 1-2 mm short of the established working length without binding. The activation protocol will be standardized before recruitment.

The primary outcome will be postoperative pain intensity measured on a 100-mm Visual Analog Scale, with 0 mm representing no pain and 100 mm representing the worst imaginable pain, assessed at 24 hours after treatment. Secondary outcomes will include pain intensity at 6, 48, and 72 hours and 7 and 14 days; the proportion of participants reporting postoperative pain; requirement for rescue analgesics; time to first analgesic use; total number of analgesic tablets consumed during the 14-day follow-up; and adverse events or procedural complications.

Postoperative pain will be assessed longitudinally over the 14-day follow-up period. A linear mixed-effects model will be used to analyze repeated pain measurements, with treatment group, time, and treatment-by-time interaction as fixed effects and participant as a random effect. The difference between groups at the primary 24-hour endpoint will be reported with a 95% confidence interval and p-value.

The study will be conducted at the Department of Operative Dentistry and Endodontics, Saidu College of Dentistry, Saidu Sharif, Swat, Khyber Pakhtunkhwa, Pakistan. Ethical approval and prospective trial registration will be obtained before recruitment.