Cryotherapy and Intracanal Medicaments for Postoperative Pain in Apical Periodontitis

This randomized, participant- and outcome assessor-blinded, 2 × 2 factorial clinical trial evaluated the effects of intracanal cryotherapy and two intracanal medicaments-calcium hydroxide and metformin-on postoperative spontaneous and percussion pain in mandibular premolars with pulpal necrosis and symptomatic apical periodontitis. Eighty participants were randomly assigned to four groups: calcium hydroxide, metformin, cryotherapy plus calcium hydroxide, and cryotherapy plus metformin. All teeth underwent standardized two-visit root canal treatment. In the cryotherapy groups, final irrigation at the first treatment visit was performed using sterile saline at 4 °C. Spontaneous pain was assessed preoperatively and daily for 7 postoperative days using a 100-mm visual analog scale (VAS). Percussion pain was assessed preoperatively and on day 7 immediately before the second treatment visit. The effects of cryotherapy, intracanal medicament type, and their interaction were evaluated using mixed-effects modeling for spontaneous pain and analysis of covariance (ANCOVA) for day-7 percussion pain.

Inclusion Criteria: Systemically healthy participants. Mandibular premolar teeth diagnosed with pulpal necrosis and symptomatic apical periodontitis and indicated for root canal treatment. Periapical index (PAI) score of 1 or 2. Aged between 18 and 70 years. Able to understand and complete visual analog scale (VAS) assessments. Provided written informed consent. Exclusion Criteria: Any systemic disease or pregnancy. Use of analgesics within 24 hours prior to treatment. Severe bruxism. Presence of acute apical abscess or swelling. Periodontal pocket depth greater than 5 mm or tooth mobility exceeding grade 1. Teeth deemed unrestorable. Presence of vital pulpal tissue or immature apices. Radiographic evidence of root resorption, root fracture, perforation, or canal calcification.