الفهرس 
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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.
.