Efficacy of solvent-free retreatment files with different flute designs in removing aged bioceramic sealer: A...

Purpose: This study aimed to compare the efficacy of four contemporary retreatment file systems, i.e., R-Endo, XP-Endo Retreatment, HyFlex Remover, and MicroMega Remover, in the solvent-free removal of aged bioceramic sealers from root canals, and to elucidate the relationship between file design and retreatment performance using advanced micro-computed tomography (micro-CT). Methods: 40 extracted human mandibular premolars with single straight canals were prepared and obturated using either Total Fill BC or BioRoot RCS sealers, then aged for one year. Specimens were randomly assigned to four retreatment file systems (n = 5 per subgroup), and retreatment was performed without solvents according to manufacturers' protocols. Residual filling material was quantified pre- and post-retreatment using micro-CT. Data were analyzed with repeated-measures analysis of variance. Results: XP-Endo Retreatment and HyFlex Remover showed superior removal efficiency, particularly in middle and cervical thirds (>84%), whereas R-Endo consistently exhibited the lowest performance, especially apically. MicroMega Remover demonstrated intermediate efficacy, outperforming R-Endo but less effective than XP-Endo Retreatment and HyFlex. No significant differences were observed between Total Fill BC and BioRoot RCS sealers. Results indicated significant effects of canal third and file system ( p < 0.001) and a significant canal third × file system × sealer interaction ( p = 0.037). Conclusions: File design and metallurgical properties significantly influence the mechanical retrievability of aged calcium silicate-based sealers in solvent-free retreatment. XP-Endo Retreatment and HyFlex Remover provided superior cleaning under in vitro conditions. These findings inform clinicians on the selection of retreatment instruments for predictable removal of bioceramic sealers.