INTRODUCTION
toxicity, postoperative pain, pain
SMEAR LAYER, SYMPTOMATIC APICAL PERIODONTITIS, CYTOTOXICITY
Sodium hypochlorite (NaOCl) is one of the most effective intracanal irrigants and has antibacterial properties; it dissolves vital and nonvital pulp tissues (Okino et al., The disadvantages of NaOCl include toxicity, unpleasant taste, and inability to remove the smear layer due to the lack of effect on minerals (McComb et al., Studies have shown that more cytotoxicity occurs with 5.25% NaOCl compared to 1.0% and 0.5% solutions (Chang et al., Heating low‐concentration solutions improve their tissue solubility without affecting their short‐term stability. Also, the systemic toxicity of solutions is lower compared to solutions with higher concentrations at lower temperatures with the same efficiency. NaOCl solution at 1%, 2.62%, and 5.25% concentrations showed an unusual decrease in chlorine for 1 h at 45°C and 60°C (Sirtes et al., In mandibular molars with symptomatic apical periodontitis, patients undergoing cryotherapy treatment exhibited a significant reduction in postoperative pain levels compared to the control group (Gundogdu & Arslan, Vera et al. (So far, the effect of different concentrations or temperatures of sodium hypochlorite on pain after endodontic treatment has been investigated (Bashetty & Hegde, 