الفهرس 
Introduction.Only 14 pages are availabe for public view
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Abstract
The aim of this study is to compare shaping ability and cutting efficiency of single file systems: Hyflex EDM files and Neoniti files versus multi-file system: Protaper NEXT files.
The shaping ability was evaluated via three parameters: change in angle of canal curvature, degree of canal transportation and centering ability of the three systems. This was done by analyzing and comparing CBCT scans taken before and after canal preparation and instrumentation at three different levels: at 3mm representing apical third, at 6mm representing middle third, and at 9mm representing coronal third.
A total of thirty human extracted permanent mandibular molars were selected for this study. The samples were de-coronated and canals were accessed. MesioBuccal canals were located, and their patency was confirmed. Distal roots were resected to improve CBCT images. The working length of the mesio-buccal canal were calculated, teeth were embedded in silicon impression material blocks prior to their scanning, to produce reproducible images.
The samples were equally and randomly allocated to three groups (n=10). Instrumentation of the canals were carried out using three different rotary systems according to the allocated group. Post instrumentation CBCT scans were taken and analyzed. The results were then statistically analyzed. Regarding the shaping ability, no statistical differences were found between the three tested systems in terms of change of canal curvature, degree of transportation and centering ability. As for the cutting efficiency measurement, a statistical difference was found between the three rotary systems, where Hyflex EDM showed superior cutting performance in comparison to Protaper Next and Neoniti which exhibited comparable results.
Within the limitations of the study, it was concluded that:
• The triangular cross-sectional design and EDM technology resulted in superior cutting efficiency of the file.