الفهرس يوجد فقط 14 صفحة متاحة للعرض العام
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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.