Manual dynamic irrigation was performed using a well-fitting gutta-percha cone inserted to WL with in-and-out vertical strokes of 5 mm at a rate of approximately 100 strokes per minute in order to hydrodynamically displace the irrigant.

Passive ultrasonic irrigation was performed using a non-cutting size 25 file attached to a piezoelectric ultrasonic unit.

Sonic irrigation was performed using an EndoActivator sonic handpiece (Dentsply Tulsa Dental Specialties, Tulsa, OK, USA). A suitable-size activator tip was selected and loosely placed at 2 mm from working length, and the device was operated at 10,000 cycles/min using a pumping action to move the tip to produce vertical strokes of 2-3 mm.

Conventional needle irrigation was performed with short, in-and-out vertical strokes of 2-3 mm at a rate of approximately 100 strokes per minute.

passive ultrasonic irrigation, sonic irrigation, manual dynamic irrigation

Pain was measured using a modified visual analogue scale (VAS) with 4 levels, as follows: 1, no pain; 2, slight pain (mild discomfort, no treatment needed); 3, moderate pain (pain required analgesics for relief); 4, severe pain (pain and/or swelling not relieved by simple analgesics and required unscheduled visit). Patients were provided forms and asked to record preoperative pain as well as pain at 24 hours, 48 hours and 1 week postoperatively, and to note down the number of analgesics taken. Patients returned their completed forms at their 1-week follow-up visits.

Periapical tissue was evaluated using a 5-point periapical index (PAI) (Ørstavik et al. 1986) and scored as follows: 1: Normal periapical structures; 2: Small changes in bone structures; 3: Changes in bone structure with some mineral loss; 4: Periodontitis with well-defined radiolucent area; 5: Severe periodontitis with exacerbating features. If scores varied among roots in the same tooth, the highest score was recorded for that tooth. Similarly, if scores varied between observers for the same tooth, the higher score was recorded.

Treatment was considered successful if the patient had no discomfort, no percussion/palpation pain, no sinus tract, no mobility or associated soft-tissue swelling, and a PAI score of ≤ 2. Treatment was considered a failure if the patient could not perform normal masticatory functions, experienced discomfort and percussive pain upon examination, and/or had a PAI score of ≥ 3 .