fracture resistance of coronal restoration in …：在冠修复断裂阻力…

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1、a)BRIEFRESUMEOFTHEINTENDEDWORKNEEDFORTHESTUDYThestructuralrehabilitationofendodonticallytreatedteethisanimportantsteptoensuresuccessfulfunctionofteethintheoralcavity.Lossofanatomicstructuressuchascuspsandarchedroofofthepulpchambermayresultintoothfractureafterthefinalrestoration.1Th

2、erefore,intracoronalreinforcementofteeth,especiallyposteriors,isimportantinordertoprotectthemagainstfracture.2Maxillarypremolars,whichareestheticallyimportant,arealsoexposedtoshearandcompressiveforces,hence,requireestheticrestorationwithhighstrength.Studieshaveshownthatpremolarsres

3、toredwithfibrepostsandcompositerestorationhavesimilarfractureresistancetothoserestoredwithfibrepostsandfullcoveragecrownssuggestingtheuseofcompositerestorationinsteadoffullcoveragecrowns.3Differentreinforcementmethodshavebeensuggestedsuchasusinghorizontalpins,fibrepostsandcuspcappi

4、ngwithcomposites.Studieshaveshownthathorizontalpinscannotreinforcetoothstructureinendodonticallytreatedteeth.4Similarly,afewstudiesindicatethattheuseoffibrepostsmayreducethefractureresistanceandcreatehigherstressconcentrationintooth-restorationcomplex.5Recentdevelopmentsinadhesivet

5、echnologyhaveledtotheuseoffibrereinforcedcompositeswhichhavehighflexuralmodulusandprovidegoodesthetics.1Thoughithasbeenestablishedthatthefibrepostsystempreservesmoretoothstructurethanotherpostsystems,useoffibreinsertsonlyinthecoronalrestorationcanbeamoreconservativeprocedureprovide

6、dtheybothhaveacomparableflexuralstrength.Thepurposeofthisstudyistocomparethefractureresistanceofendodonticallytreatedteethwithfibrepostandthosewithfibreinsertsincoronalrestorationwithcompositeresin.REVIEWOFTHELITERATUREInastudy,therestoredpremolarswithoutpostsshowedasimilarorevenhi

7、gherfractureresistancethanthosewiththreepostsystemshencesuggestingtheneedforre-evaluationofpostuseespeciallywhereadhesivetechniquesareusedtoconstructthecore.6Inanex-vivostudyitwasprovedthatseverelydamagedandroot-filledmaxillarypremolar,restoredwithdirectresincompositecompletecrowns

8、withoutpostshavesimilarfra