Investigation of the effect of low torque and speed values on postoperative pain after root canal treatment: a randomised clinical trial

The aim of this study was to investigate the effect of using low torque and speed values in root canal shaping on post-operative pain in asymptomatic, nonvital, mandibular first molars. This randomised clinical trial included 80 patients. Patients were divided into four groups according to different torque and speed values of the Fanta V Taper Gold rotary file system used during root canal shaping: 1 N torque and 250 rpm speed, 1 N torque and 350 rpm speed, 2 N torque and 250 rpm speed, and 2 N torque and 350 rpm speed. Root canal preparation time (in seconds) was recorded during shaping. Patients recorded their post operative pain intensity on a 10 cm visual analogue scale at 6th, 24th, 48th, 72nd hours and 7th day. Chi-square test was used to compare gender, tooth localisation and presence/absence of periapical lesions, Kruskal-Wallis test was used for age comparison, Friedman and Wilcoxon tests were used for comparisons of groups over time, and Kruskal-Wallis test was used for comparisons between different torque and speed groups. (P < 0.05) According to the results of statistical analysis, low torque and speed values did not cause a significant difference in post operative pain level at different time intervals after the procedure. Root canal preparation time at the time of the procedure was significantly longer in the group shaped with 1 N, 250 RPM. There was no significant difference in post procedure analgesic drug intake according to different torque and speed values. Within the limitations of this study, it was determined that the application of torque and speed lower than the values specified by the manufacturer did not provide superiority in post operative pain after the procedure, and low torque and speed values prolonged the preparation time during the procedure. The study was approved by the Non-Interventional Clinical Research Ethics Committee of Afyonkarahisar Health Sciences University on 2023-02-03, with the decision number 2023/72. The trial was registered at ClinicalTrials.gov (NCT06309095) on 2024-02-21. All study protocols were predefined and strictly followed, with no deviations from the original methodology.