Aim: Heating sodium hypochlorite (NaOCl) to increase irrigation efficiency may cause postoperative pain. Intracanal cryotherapy, a protocol used in recent years, can be used to reduce postoperative pain. However, the tooth structure is affected by temperature changes. This study aimed to investigate the fracture resistance (FR) of teeth by applying cryotherapy after different irrigation protocols. Materials and Methods: Seventy extracted maxillary central incisor teeth were selected, decoronated, and divided into five groups according to the irrigation protocols (n=14). No preparation or irrigation was performed in Group 1 (control). Teeth were irrigated with room temperature NaOCl and saline in Group 2, with room temperature NaOCl and 2°C saline in Group 3, with 70°C NaOCl and room temperature saline in Group 4, and with 70°C NaOCl and 2°C saline in Group 5. FR was evaluated using a universal testing machine. For group comparisons, one-way ANOVA and Tamhane’s post hoc tests were used (p<0.05). Results: The highest FR was obtained in Group 1 (control) (660.36 ± 18.5 N). Except for the control group, the highest FR was observed in Group 2 (504.57 ± 10.76 N), and the lowest FR was obtained in Group 5 (352.71 ± 7.05 N). The differences between groups were statistically significant, except for Group 3 and Group 4 (p<0.05). Conclusion: Irrigation with NaOCl at different temperatures and subsequent cryotherapy affects the FR of endodontically treated teeth.
Küçükekenci et al. (2026) studied this question.