الفهرس | يوجد فقط 14 صفحة متاحة للعرض العام |
المستخلص Objectives: This study was designed to compare the cleaning efficiency and time needed of two rotary Ni-Ti systems dedicated for root filling removal, ProTaper Universal retreatment (PTUR) and Mtwo retreatment system (Mtwo R) versus conventional instruments (H-files combined with Gates-Glidden drills), in the removal of gutta-percha root filling material with or without the use of a solvent (chloroform). Methods: Sixty mandibular molar teeth were used in this study. All teeth had their crowns flattened, the distal roots were sacrificed. Only mesiobuccal canals which had angle of curvature 20°- 40° were prepared by modified-double flared technique using K-files and Gates-Glidden drills, and then obturated using the lateral condensaon technique. The samples were then divided into two main groups (n= 30) Group A: without solvent and Group B: with solvent (chloroform). Each group was further subdivided into three subgroups (n= 10) according to the method used in filling removal: Subgroup i: (PTUR), Subgroup ii: (Mtwo R), Subgroup iii: H-files and Gates-Glidden drills (HG). During filling removal, the time needed for the procedure was recorded using a stopwatch, then roots were split longitudinally. Samples were photographed under the stereomicroscope. The images were analyzed using image analysis software for quantitative evaluation of remaining filling debris at the three regions; coronal, middle and apical. Results: it was found that with solvent group left non-significantly less remaining filling material than without solvent group after retreatment. Regarding the method of root canal filling removal technique, H-files combined with Gates- Glidden drills showed significantly greater efficiency in root canal filling removal than both PTUR and Mtwo R files. There was no significant difference between both the two rotary systems. Regarding the root canal thirds, it was found that apical region recorded the highest statistically significant debris ratio followed by middle region group while coronal region group recorded the lowest statistically significant debris ratio. The time recorded for filling removal was significantly less using PTUR files while there was no significant difference between HG and Mtwo R. Conclusions: from the results of the present study, it could be concluded that: 1) None of the evaluated retreatment techniques was able to completely remove all the filling material. 2) H-files aided by Gates-Glidden drills were more efficient in filling removal than both PTUR and Mtwo retreatment files. 3) PTUR system was faster in filling removal than Mtwo R files and HG. 4) The use of solvent did not significantly improve the cleaning efficiency of the tested techniques. 5) The use of solvent shortened significantly the retreatment time. |