Efficacy of XP-endo instruments in removing 54 month-aged root canal filling material from mandibular molars

To investigate the effectiveness of XP-endo Shaper (XPS) and XP-endo Finisher R (XPFR) instruments in removing aged root filling material from root-treated mandibular molars.Thirty mandibular molars were instrumented and divided into three groups: single-cone obturation using AH Plus sealer (AHS) or EndoSequence BC sealer (BCS), and warm vertical compaction using AH Plus sealer (AHW). The specimens were stored at 100% humidity and 37 °C for 54 months. Retreatment was performed using XPS and XPFR. Micro-computed tomography was used to scan the specimens after 54 months, after XPS retreatment and after the supplementary approach using XPFR.The XPS removed more filling material in the BCS and AHS groups, compared with the AHW group (P 0.05). After supplementary instrumentation XPFR, the proportion of the remaining filling material decreased significantly in all groups (P 0.05). The XPFR instruments were more efficient in removing filling material in the BCS group than in the AHS or AHW group (P 0.05). The combined use of XPS and XPFR instruments efficiently removed filling material in the BCS group, followed by the AHS and AHW groups (P 0.05).Although the combined use of XPS and XPFR instruments helped remove the bulk of aged root filling material from mandibular molars, material removal from canals filled using warm vertical condensation in the critical apical area remains a concern.Removal of the aged filling materials using XP-endo instruments from the apical area is challenging when instrumented root canals are filled using warm vertical condensation.