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

Postoperative pain is a common complication following nonsurgical endodontic retreatmentand may be influenced by the instrumentation system used during root canal fillingremoval and final root canal shaping. This prospective, single‐center, single‐blind,randomized clinical trial was designed to compare the effects of differentnickel‐titanium instrumentation protocols on postoperative pain and operation time inmandibular first molar teeth requiring nonsurgical endodontic retreatment.Adult participants aged 18‐65 years with previously endodontically treated mandibularfirst molars meeting the eligibility criteria were included. All retreatment procedureswere performed in a single visit by one endodontist. Participants were randomly allocatedto one of four parallel treatment groups. Existing root canal filling materials wereremoved using either the ProTaper Universal Retreatment system or the MicroMega REMOVERsystem. Final root canal shaping was then performed using either the ProTaper Next rotarysystem or the MicroMega One RECI reciprocating system. Thus, the four intervention groupsconsisted of ProTaper Universal Retreatment plus ProTaper Next, ProTaper UniversalRetreatment plus MicroMega One RECI, MicroMega REMOVER plus ProTaper Next, and MicroMegaREMOVER plus MicroMega One RECI.Postoperative pain intensity was assessed using a 100‐mm visual analog scale, in which 0represented no pain and 100 represented unbearable pain. Participants recorded their painlevels at 6 and 12 hours and on postoperative days 1, 2, 3, 4, 5, 6, and 7. The use andfrequency of rescue analgesic medication were also recorded during the seven‐dayfollow‐up period. Clinical evaluations were performed at 48 hours and seven days toassess pain, tenderness to percussion, spontaneous pain, swelling, and the need forantibiotic treatment.Operation time was recorded using a digital stopwatch. The recorded period included thetime from the initial penetration into the existing root canal filling material untilworking length was reached and final root canal shaping was completed. Postoperative painscores, analgesic consumption, and operation time were compared among the fourinstrumentation groups.