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Abstract Summary and Conclusion The aim of this study was to evaluate cutting efficiency and the dentin walls preparation in root canals produced by different rotary systems XP-endo Shaper, IRace rotary system and HYFLEX CM. In the present study 60 unidentified single rooted human mandibular premolars extracted for orthodontic and periodontal reasons were collected and divided into three groups: group A (n= 20) XP-endo Shaper ,group B (n= 20) IRace rotary system and group C (n= 20) HYFLEX CM files Following conventional access preparations, patency of the root canal was established with a #15 K-file.Teeth were embedded up to the cervical line in an epoxy resin blocks and the roots of were sectioned from the apex at 3, 6 and 9 using isomete and reassembled using silicon mold. All root canals were flushed with warmed 2 mL of a 2.5% NaOCl solution and additional rinse with 3 mL 17% EDTA was performed, followed by a 2 mL rinse with saline to flush out the EDTA instrumentation procedures occurred in a warm water bath at 36.7°C. Warm water bath was used to keep the irrigant solution and the files at 36.7°C throughout the experiment. Pre and postinstrumentation cross-sectional images were superimposed and evaluated through measuring changes in root canal parameters including percentage of touched root canal surface and cross section area and using Autocad software and stereomicroscope. Regarding the results of this study, Non of three instrumentation technique completely prepared the dentin walls entirely in oval-shaped root canal.with the highest mean percentage of touched canal surface was XPendo Shaper and HYFLEX CM respectively and lowest mean percentage was IRace system. The highest change in cross sectional area was IRace Summary and Conclusion 57 system compared to HYFLEX CM and XP-endo Shaper respectively. For all groups, there was a significant difference between coronal, middle and apical thirds in touched canal walls and change in cross sectional area of root canals. The conclusions of the present study were: x Non of three instrumentation technique completely prepared the dentin walls entirely in oval-shaped root canal x XP-endo Shaper group and HYFLEX CM group respectively have more cutting efficiency and maintain root stability through preservation dentin of root canal compared to IRace group . This was observed at all canal levels (coronal, middle and apical ) x For all groups, there was a significant difference between coronal and middle third, between middle and apical third, and between coronal and apical third in touched canal walls and change in cross sectional area of root canals Recommendations: x Further studies are necessary for easy detect of buccal and lingual extensions of oval shaped canals as they difficult to be prepared. which could harbor remnants of necrotic pulp tissue, bacterial biofilms and dentin debris . x Further studies with larger sample size to detect the efficacy of single file comparables to multi file systems in compelet preparation and preservation anatomy of long oval root canals. x Further in vitro and in vivo studies comparable different rotary alloys systemes to detect their cutting effeciecy and preservation anatomy of long oval root canals. . |