口腔解剖生理学之国外---the_deciduous_dentition乳牙ppt培训课件

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1、THEDECIDUOUSDENTITIONINTRODUCTIONTheworddeciduouscomesfromaLatinwordmeaningtofalloff.Deciduousteethfallofforareshedlikeleavesfromadeciduoustree.Thedeciduous,primary,or,astheyoftenreferredtocolloquially,(MILK)teeth,havearelativelyshortlife-spanbeforetheyexfoliatedtobere

2、placedbythepermanentteeth.Thisusuallyoccursbetweentheagesof6and13years.Thedeciduousincisorsandcanineshavepermanentsuccessorbutthefirstandseconddeciduousmolarsarereplacedbythefirstandsecondpremolarsrespectively.Thedeciduousdentitioncomprisesfewerteeththanthepermanentden

3、titionwithatotalofTENmaxillaryandTENmandibularteeth.Theyareasfollows,inorderofpositionfromthemidline:A-First(central)incisor.B-Second(lateral)incisor.C-Canine.D-Firstmolar.BCDEAE-Secondmolar.Theshorthandformulaforthedeciduousteethisasfollows:I2C1M2=10212GENERALCHARACTE

4、RISTICSThedeciduousteethgenerallyhaveseveralimportantdifferencesinmorphology,composition,sizecolouraslistedbelow:1-Thedeciduousteetharesmallerthanthepermanentteeth.PRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETHPRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEET

5、H2-Theenamelofthedeciduousteethiswhiterandmoreopaque,whichgivesthecrownalightercolourthanthatofthepermanentteeth.3-Theenamelofthedeciduousteethismorepermeableandmoreeasilyworndown.Thedegreeofpermeabilityislessenedafterthestartofrootresorption.PRINCIPALDIFFERENCESBETWEE

6、NDECIDUOUSANDPERMANENTTEETH4-TheDEPTHOFENAMELismoreconsistentandthinnerthaninthepermanentteeth,beingfrom0.5mmto1.00mmthick.PRINCIPALDIFFERENCESBETWEENDECIDUOUSTEETHANDPERMANENTTEETH5-Deciduousteethhaveapronouncedcervicalmargin.Theenamelbulges,insteadoftaperinggently,at

7、thecemento-enamljunction,whichisstraighterthaninthepermanentteeth.Thiscervicalbulgeisaccentuatedinthemesiobuccalareaofdeciduousmolars.PRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETH6-Innewlyerupteddeciduousteeth,thecuspstendtobemorepointed.PRINCIPALDIFFERENCESBET

8、WEENDECIDUOUSANDPERMANENTTEETH7-Therootsofthedeciduousteethareshorter,lessstrongandlighterincolourthanthoseoftheperma