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南方医科大学学报 2011
changesinmechanicalpropertiesofsevenlight-curedcompositeresinsafterthermalcyclingKeywords: light-curedcompositeresins,thermalcycling,biaxialflexurestrength,knoophardness Abstract: abstract:objectivetoexaminethechangesofthemechanicalpropertiesof7differentlight-curedcompositeresinsafterthermalcyclingandthecorrelationsbetweentheseproperties.methodssevendifferentlight-curedcompositeresins,including2microfilledcomposites(a110:ahandesteliteσ:et),3microhybridcomposites(aelite:at,z250:zs,andcharmfilplus:cp),and2nanohybridcomposites(z350:zhandgrandio:gd),werepreparedintotestspecimenswithadiameterof12mmandathicknessof1.0mm.thespecimenswerestoredindistilledwaterat37℃for24hpriorto1000thermalcyclesof5℃for15sand55℃for15s.thebiaxialflexuralstrength(σf)wastestedusingtheball-on-three-ballmethodatacrossheadspeedof0.5mm/min(iso4049).thefracturesurfacewasobservedunderscanningelectronmicroscope(sem),andtheremainingspecimensunderwentknoophardnesstestwitha50-gloadingfor10s.resultsthehighestandlowestweibullmoduluswasobservedinah(18.752)andat(5.290)group,respectively.thehighestandlowestbiaxialflexuralstrengthwasobservedinzs(158.2mpa)andet(54.0mpa)groups,respectively.theσfofthetestedmaterialsdecreasedintheorderofmicrohybridcomposite,nanohybridcomposite,andmicrofillercomposite,andtheσfshowednosignificantdifferencebetweenthecompositeswithasimilarfiller(p>0.05).thefracturenumberwaspositivelycorrelatedtothestrengthofthematerial.theknoophardnessnumbers(h)wasthehighestingdgroup(110.81±14.77kg/mm2)andthelowestinahgroup(42.81±1.91kg/mm2).semshowedthattheinterfaceregionofthematrixandthefillerwasvulnerabletocrackformation.conclusionthenanohybridcompositeresinsbettersuitclinicalapplicationsthanmicrohybridcomposites.theapplicabilityofknoophardnesstestinhardnessmeasurementofthecompositeresinsneedstobefurtherdemonstrated.
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