Effect of Low-Temperature Intracanal Sodium Hypochlorite on Root Surface Temperature Reduction and Organic Matter Dissolution: An In Vitro Study

Introduction: This study aimed to evaluate the effect of low-temperature intracanal sodium hypochlorite (NaOCl) irrigation on root surface temperature reduction and its ability to dissolve organic matter. Methods Twenty-five mandibular premolars were accessed and instrumented to size 40.05. Final irrigation protocols with 20 mL of 2.5% NaOCl, at two different temperatures: room temperature (control) and 2.5°C (experimental), were applied. Initial and minimum root surface temperatures (last 4 mm of the root) were recorded using a digital thermometer. For tissue dissolution analysis, glass capillaries filled with catgut were attached to the cervical and apical thirds of twenty 3D-printed maxillary incisors and weighed before and after the same irrigation protocols. Data was statistically analyzed. Results Low-temperature NaOCl irrigation led to a significantly greater reduction in root surface temperature (p < 0.05). Both room-temperature and low-temperature NaOCl showed similar organic matter dissolution capabilities, with no significant difference between them (p > 0.05). Conclusion Low-temperature NaOCl effectively reduced root surface temperature while maintaining its tissue-dissolving capacity compared to the control group. Clinical relevance: Cold sodium hypochlorite effectively reduces external root surface temperature while maintaining its ability to dissolve organic tissue, providing clinicians with a practical and efficient intracanal cryotherapy strategy for minimizing postoperative inflammation without compromising chemo-mechanical preparation.