The Effect of Different Sodium Hypochlorite Concentrations and Activation Techniques on Postoperative Pain

The Effect of Different Sodium Hypochlorite Concentrations and Activation Techniques on Postoperative Pain in Permanent Molars With Chronic Apical Periodontitis: A Randomized Controlled Trial

The goal of this clinical trial was to evaluate the effect of different sodium hypochlorite (NaOCl) concentrations and irrigation activation techniques on the intensity of postoperative pain following single-visit root canal treatment in molar teeth with asymptomatic chronic apical periodontitis.

The primary research questions of this study were as follows:

Does using 2.5% or 5.25% sodium hypochlorite solution during root canal irrigation influence the severity of postoperative pain? Do activation techniques such as sonic activation using EDDY (a flexible polyamide tip-driven sonic irrigation device operating at 6,000 Hz; VDW GmbH, Munich, Germany) or passive ultrasonic irrigation (PUI) significantly reduce postoperative pain compared to conventional needle irrigation? In the non-activation groups, root canals were irrigated with 2.5% or 5.25% NaOCl using a 30-gauge side-vented needle without any further activation.

In the EDDY groups, root canals were irrigated using 2.5% or 5.25% NaOCl, followed by activation with a flexible polyamide EDDY tip (25/04) at 6,000 Hz, three times for 20 seconds.

In the PUI groups, root canals were irrigated using 2.5% or 5.25% NaOCl, and then subjected to passive ultrasonic activation with a suitable ultrasonic tip three times for 20 seconds, without contacting dentinal walls.

Inclusion Criteria:

• Patients aged between 16 and 60 years
• Systemically healthy individuals
• Presence of mandibular or maxillary first or second molar diagnosed with asymptomatic chronic apical periodontitis
• Negative response to electric pulp test, cold test, percussion and palpation tests
• Teeth eligible for single-visit root canal treatment
• Patients who provided written informed consent

Exclusion Criteria:

• Pregnant or breastfeeding individuals
• Patients with uncontrolled systemic diseases (e.g., uncontrolled hypertension, uncontrolled diabetes mellitus, chronic renal failure, hematologic disorders)
• Patients undergoing chemotherapy or radiotherapy
• Individuals with infective endocarditis or immunosuppressive conditions
• Patients requiring antibiotic prophylaxis prior to dental treatment
• Use of anti-inflammatory or analgesic medications within 24 hours before treatment
• Teeth with calcified canals, internal/external resorption, or root fractures
• Patients unable to attend follow-up appointments or complete pain assessment forms