Comparative Evaluation of Rotary and Reciprocating Systems in Root Canal Retreatment with Subsequent Apical Enlargement

Abstract This study evaluated the efficacy of different endodontic file systems in removing obturation material from root canal walls after apical enlargement. Sixty extracted human mandibular premolars with single canals (Vertucci type I) were instrumented with the T-Endo Must system and obturated using warm vertical compaction with AH Plus sealer. Following storage for 1 month, specimens were randomly assigned to four retreatment groups with subsequent apical enlargement with apical size 40# (n = 15): (1) ProTaper Universal Retreatment (PTUR) + ProTaper Next, (2) MicroMega Remover (MMR) + 2Shape, (3) Reciproc Blue (RB) system, and (4) T-Endo Must system. Retreatment was performed without solvents, followed by passive ultrasonic irrigation activation. Teeth were sectioned longitudinally and examined under stereomicroscope. Scanning electron microscope images at 100× magnification at coronal, middle, and apical thirds from one sample from each group was also obtained. Residual filling materials and debris were evaluated using ImageJ program. Statistical analysis was conducted using two-way analysis of variance and Tukey honestly significant difference tests (α = 0.05). None of the tested file systems achieved complete removal of filling materials. While MMR and PTUR systems removed more remnants than RB and T-Must in the apical and coronal thirds, no significant differences were observed among groups in the middle third. Across all systems, the least amount of residual gutta-percha and sealer was consistently detected in the middle third. Although all file systems left residual filling material, the rotary file systems demonstrated superior performance in the apical and coronal thirds than the reciprocating file systems. Nevertheless, the coronal third of root canals remained the most challenging region for complete filling removal, regardless of the system used.