Efficacy of various heat-treated rotary file systems on the removal of obturated material in single-rooted teeth using nanocomputed tomography

Aim: This study aimed to assess and compare the effectiveness and residual obturation material following retreatment using three distinct heat-treated rotary file systems. Methods: Forty-five extracted human single-rooted teeth were sectioned to a standardized 18 mm length. Following access preparation, canals were shaped with ProFit S3 rotary instruments up to PF2 (size 25, 6% taper) and obturated with matched-taper gutta-percha cones. The specimens were randomly assigned to three groups ( n = 15) based on the retreatment file system used: Group 1 – Solite RS3, Group 2 – Solite RS3 Black, and Group 3 – Solite RE Black. All procedures were completed by a single operator. The time taken to remove gutta-percha was measured using a stopwatch. Nanocomputed tomography was employed to obtain pre- and postretreatment scans, and volumetric analysis was carried out by superimposing the images. Statistical analysis was conducted using one-way analysis of variance and independent t -tests. Results: The Solite RE Black group exhibited the least volume of residual filling material and required significantly less retreatment time compared to the other groups ( P < 0.05). No notable difference was observed between Solite RS3 and RS3 Black. Conclusion: Solite RE Black outperformed the other file systems in both retreatment efficiency and gutta-percha removal, likely due to its variable taper and enhanced metallurgical design. Solite RS3 and RS3 Black produced comparable results.