الفهرس 
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Abstract
Summary
In thisstudy wecomparedcenteringability,canal transportation, ability to maintain canal curvature and change in canal volume while usingManiSilkfile, Revo-S and One shape incontinues rotation.
Atotalofforty fivehumanmandibularfirstmolarwithmature apexandnormalrootmorphology withmoderatecanalcurvatureof the mesialroot25-40 accordingtoSchneiderwere used in these study.
Sampleswere dividedintothree groups (fifteeneach),according tothe systemthatusedforinstrumentation.
Teeth wereaccessed using an Endo-Access bur. distalrootswith therespective partof thecrown ofall sampleswere sectionedatthe furcation level using stainless steel disc under coolant and discarded. Determinationof theworking lengthwasperformedat magnification4X usingdentalloupes by inserting#10K-filetothe mesio-buccalrootcanal terminusandsubtracting1mm fromthe toothlength.
Specimensweremountedincoldcure acrylicmaterialinsix plasticholderfor preoperativeconebeam computerized tomography scanning(CBCT),eachholder containing7-8 specimens.
Theforty fivesampleweredividedinto3groupsaccordingto canalpreparationtechnique:GroupI:15samplewereprepared withMani silkfile,GroupII:15samples werepreparedwithRevo- S,GroupIII:15sample were preparedwithOne shape,specimens instrumented according to manufactures instructions using Endomate DTendo motor.
Post-operative (CBCT) scanforall specimens, Imagesobtained comparedwith pre-operative imagesfor each specimento evaluate centeringability,canal transportation,ability tomaintaincanal curvature andchangeincanalvolume.
Resultwere tabulatedandstatisticallyanalyzed.
Theresultshowedthattherewasnostatistically significant difference betweenthree differentrotarysystemsincanalcentering abilityoverallandateachlevel(3,5,7mm).
Concerningtransportationtherewerestatistically significant differencesbetweenthreedifferentrotarysystems overallandat
3mmlevel. There were no statisticallysignificant differences at
5mmand7 mmlevels.
Byanalyzingtheabilityofdifferentfiles inpreservingcanal curvature,there were statisticallysignificantdifferencesbetweenthe threedifferentrotarysystems.Theoneshapefilesystemwasthe leastin preservingcanalcurvature.
By measuringchangeincanal volume, therewere statistically significantdifferences between three differentrotary systems. The one shape file system wastheleastinchange incanalvolume.