الفهرس 
ENGLISH ABSTRACTOnly 14 pages are availabe for public view
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Abstract
This study aimed to evaluate the influence of a solvent (chloroform) in enhancing endodontic material removal from single, straight canals of lower premolar teeth during endodontic retreatment and the supplementary cleaning effect of passive ultrasonic irrigation (PUI) with or without chloroform for three successive cycles of irrigation while replenishing the irrigant between each cycle. Evaluation of the residual filling materials was done using CBCT volumetric analysis. Teeth were decoronated, shaped with ProTaper Next files till file X3, and obturated using lateral compaction technique. All roots were sealed with Cavit temporary restoration and stored in saline solution at 37°C for 48 hours to allow the sealer completely set based on manufacturer instructions. The roots were embedded in blocks of wax, and CBCT images were taken for all the samples before retreatment. The volume of endodontic filling material was measured using OnDemand3D software. Samples were distributed into two groups of 20 each according to using chloroform or not during retreatment procedures as follows; group A (with chloroform) and group B (without chloroform). Retreatment was done with PTU-retreatment files in all teeth. Irrigation was performed with 1 mL 2.5% NaOCl at each instrument change using a 31 gauge luer lock syringe. After retreatment was completed, the specimens were irrigated with 5 mL 17% EDTA for three minutes and subsequently with a flush of 5mL 2.5% NaOCl for three minutes. After finishing retreatment procedures, samples were further subdivided into four subgroups of 10 based on the use of PUI with or without chloroform as supplementary cleaning step as follows; Subgroup A1 (chloroform/PUI), Subgroup A2 (chloroform /without PUI), Subgroup B1 (without chloroform/PUI), Subgroup B2 (negative control) (without chloroform / without PUI ). After the additional cleaning step was completed, the samples
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were once again scanned with CBCT to measure the residual volume of endodontic filling material, repeating the same pre-retreatment scanning protocol. The difference between the pre and post-retreatment volumes was calculated, as well as the residual volume in each third of the canal along the root length.
Results revealed that complete removal of endodontic material was not achieved by any tested technique. However, the negative control group (B2) showed the least mean percentage of the residual volume (5.95%), while chloroform with the PUI group (A1) showed the highest mean percentage of the residual volume (17.98%), with no significant difference between the four study groups. The coronal third demonstrated the greatest mean residual volume in all study groups.