OR17 - Impact of Final Apical Size Preparation on Root Canal Treatment Success: A Randomized Clinical Trial with CBCT Volumetric Analysis

Abstract: Root canal treatment success following minimal versus conventional apical preparation is largely unknown. The aim of this randomized, double-blinded clinical trial is to investigate the effect of #25 versus #35 apical sizes on root canal treatment success using cone-beam computed tomography (CBCT) volumetric analysis. Methods: Mandibular molars diagnosed with pulp necrosis and periapical lesions with the mesial root were included. Patients were randomized into the small group (#25), or the large group (#35) and treated in two visits with inter-appointment calcium hydroxide(UltraCal). Pain levels were recorded at both visits and cases were followed for 1 and 2 years.Treatment outcome was classified as successful if the lesion was reduced or healed, and failed if the lesion remained same or increased, based on radiographic and clinical symptoms. Pre-operative and 2-year CBCTs were imported into the AMIRA software and lesion volumes were recorded. Data were analyzed using χ2-tests and mixed model analyses (α=0.05). Results: Interim results (n=35) showed 74% success in Group Small and 81% success in Group Large with no significant differences between the two apical size preparations (p >0.05). Pain levels were significantly reduced in both groups between the two visits (p< 0.05), with no differences between groups. Of the teeth assessed with complete healing based on periapical radiographs, 25% showed incomplete healing on volumetric analysis at 2 years post-treatment. Conclusions: There was no significant difference between a #25 and #35 apical size in root canal treatment success of mandibular molars diagnosed with pulp necrosis.