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

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.

Inclusion criteria

• Patients between 18- 65 years of ages
• Patients who agree to participate this study
• Patients had not used analgesic or antibiotics in last 7 days
• Mandibular molar teeth that have been endodontically treated only once
• Asymptomatic teeth with previous endodontic treatment but exhibiting inadequate root canal filling on radiographic examination.
• Teeth, although asymptomatic, but with newly developed periapical radiolucency within two years compared to the radiographic findings present 2 years ago at the time of root canal treatment was done.
• Teeth with periapical radiolucency, but with increased or unchanged according to pre-treatment radiography.
• Absence of a history of allergy to local anesthetics, medications, resin-based restorative materials or nickel.

Exclusion criteria

• Pregnant patients and patients in lactation period
• Having used corticosteroids in the last 6 months.
• Individuals with systemic diseases (endocarditis, immune system diseases, etc.) requiring antibiotic prophylaxis
• Having received immunosuppressive therapy within the last week
• Gingival recession exceeding 3 mm, deep periodontal pocketing, tooth mobility, or progressive periodontal disease
• The presence of a foreign body in the root canal that prevents entry (broken file, post, etc.)
• Fracture or crack in the root
• Teeth that cannot reach the working length due to calcification in the root canal and step formation
• Teeth that cannot be restored due to excessive loss of material in the coronal structure
• The presence of more than one adjacent tooth requiring endodontic treatment that may cause reflected pain in the same patient.
• Teeth that develop any complications (breakage of endodontic file, perforation, inability to determine the working length with the apex finder) during the removal of the canal filling material.