Effect of Cryotherapy on Postoperative Pain Following Root Canal Treatment with Continuous Chelation: A Randomized Controlled Clinical Trial

Postoperative pain following root canal treatment is a common clinical problem. Continuous chelation using sodium hypochlorite in combination with etidronic acid (HEDP) provides effective canal disinfection while simultaneously managing the smear layer throughout instrumentation. Sodium hypochlorite (NaOCl) remains the primary endodontic irrigant because of its strong antibacterial, antibiofilm, and tissue-dissolving properties; however, its inability to remove the inorganic smear layer and the limitations of conventional chelators such as ethylenediaminetetraacetic acid.( EDTA) have led to the adoption of continuous chelation protocols. Etidronic acid (1-hydroxyethylidene-1,1-bisphosphonate; HEDP) is a mild, biocompatible chelating agent that can be safely combined with NaOCl without reducing its antimicrobial efficacy. In this study, continuous chelation will be performed using sodium hypochlorite 3% mixed with etidronic acid 9% (Twin Kleen®, Maarc Dental Innovations, Endo Division, India).

Intracanal cryotherapy using cold saline irrigation has been shown to reduce postoperative pain by decreasing periapical inflammation and nerve conduction. However, the combined effect of intracanal cryotherapy following continuous chelation has not been adequately evaluated.

This prospective, double-blind, randomized controlled trial will include 84 participants allocated into two groups (42 per group). All participants will undergo standardized root canal treatment. The control group will receive continuous chelation followed by final irrigation with room-temperature saline, while the intervention group will receive the same protocol followed by final irrigation with cold saline at 2.5 °C. Calcium hydroxide will be placed as an intracanal medicament, and obturation will be completed at a second visit after 7 days.

The primary outcome is postoperative pain intensity assessed using a Visual Analog Scale at 6, 12, 24, and 48 hours, and 7 days after the first treatment session. Secondary outcomes include postoperative analgesic consumption.