Background: Removal of initial endodontic filling material during retreatment is mandatory for favorable outcomes.
Objectives: This study aimed to assess the influence of chloroform and passive ultrasonic irrigation (PUI) on the retrieval of endodontic filling material during retreatment using CBCT for evaluation.
Methods: Forty extracted single canaled lower premolars were decoronated, instrumented with ProTaper Next files (X3), and filled with lateral condensation technique. Samples were randomly distributed into two groups with further subdivision into four subgroups according to the use of chloroform and PUI as follows: Group A1 (chloroform/PUI), Group A2 (chloroform /without PUI), Group B1 (without chloroform/PUI), Group B2 (negative control) (without chloroform / without PUI). Retreatment was done with ProTaper Universal retreatment (PTU) files in all teeth. Before and after-retreatment CBCT-scans were done for all samples, and the residual volumes were measured. Statistical analysis was performed with a level of significance set at a P-value of 0.05.
Results: Complete removal of endodontic filling material was not achieved by any tested techniques. However, the negative control group (B2) showed the least mean percentage of residual volume (5.95%), while chloroform with the PUI group (A1) showed the greatest mean percentage of the residual volume (17.98%), with no significant difference between the four study groups. The greatest mean residual volume was revealed at the coronal third in all study groups.
Conclusion: PTU-file without chloroform and PUI was the most effective in removing endodontic filling material.
Keywords: CBCT, Chloroform, Endodontic retreatment, Passive ultrasonic irrigation.
Running title: Endodontic retreatment using chloroform and PUI.