Effects of Different NiTi Systems on Postoperative Pain and Operation Time in Nonsurgical Endodontic Retreatment

Overview

This prospective, randomized, single-center, single-blind clinical trial evaluated the effects of different nickel-titanium retreatment and final shaping systems on postoperative pain and operation time during single-visit nonsurgical endodontic retreatment of mandibular first molars. Participants were allocated to four groups according to the combination of the retreatment system used for root canal filling removal and the rotary or reciprocating system used for final root canal shaping. Postoperative pain, analgesic consumption, and operation time were assessed and compared among the groups.

Postoperative pain is a common complication following nonsurgical endodontic retreatment and may be influenced by the instrumentation system used during root canal filling removal and final root canal shaping. This prospective, single-center, single-blind, randomized clinical trial was designed to compare the effects of different nickel-titanium instrumentation protocols on postoperative pain and operation time in mandibular first molar teeth requiring nonsurgical endodontic retreatment. Adult participants aged 18-65 years with previously endodontically treated mandibular first molars meeting the eligibility criteria were included. All retreatment procedures were performed in a single visit by one endodontist. Participants were randomly allocated to one of four parallel treatment groups. Existing root canal filling materials were removed using either the ProTaper Universal Retreatment system or the MicroMega REMOVER system. Final root canal shaping was then performed using either the ProTaper Next rotary system or the MicroMega One RECI reciprocating system. Thus, the four intervention groups consisted of ProTaper Universal Retreatment plus ProTaper Next, ProTaper Universal Retreatment plus MicroMega One RECI, MicroMega REMOVER plus ProTaper Next, and MicroMega REMOVER plus MicroMega One RECI. Postoperative pain intensity was assessed using a 100-mm visual analog scale, in which 0 represented no pain and 100 represented unbearable pain. Participants recorded their pain levels at 6 and 12 hours and on postoperative days 1, 2, 3, 4, 5, 6, and 7. The use and frequency of rescue analgesic medication were also recorded during the seven-day follow-up period. Clinical evaluations were performed at 48 hours and seven days to assess pain, tenderness to percussion, spontaneous pain, swelling, and the need for antibiotic treatment. Operation time was recorded using a digital stopwatch. The recorded period included the time from the initial penetration into the existing root canal filling material until working length was reached and final root canal shaping was completed. Postoperative pain scores, analgesic consumption, and operation time were compared among the four instrumentation groups.