国外口腔解剖乳牙ppt课件

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

2、hisusuallyoccursbetweentheagesof6and13years.Thedeciduousincisorsandcanineshavepermanentsuccessorbutthefirstandseconddeciduousmolarsarereplacedbythefirstandsecondpremolarsrespectively.ThedeciduousdentitioncomprisesfewerteeththanthepermanentdentitionwithatotalofTENmaxillaryandTENmandibularteeth.GE

3、NERALCHARACTERISTICSThedeciduousteethgenerallyhaveseveralimportantdifferencesinmorphology,composition,sizecolouraslistedbelow:1-Thedeciduousteetharesmallerthanthepermanentteeth.PRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETHPRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETH2-Theenamelof

4、thedeciduousteethiswhiterandmoreopaque,whichgivesthecrownalightercolourthanthatofthepermanentteeth.3-Theenamelofthedeciduousteethismorepermeableandmoreeasilyworndown.Thedegreeofpermeabilityislessenedafterthestartofrootresorption.PRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETH4-TheDEPTHOFEN

5、AMELismoreconsistentandthinnerthaninthepermanentteeth,beingfrom0.5mmto1.00mmthick.PRINCIPALDIFFERENCESBETWEENDECIDUOUSTEETHANDPERMANENTTEETH5-Deciduousteethhaveapronouncedcervicalmargin.Theenamelbulges,insteadoftaperinggently,atthecemento-enamljunction,whichisstraighterthaninthepermanentteeth.Th

6、iscervicalbulgeisaccentuatedinthemesiobuccalareaofdeciduousmolars.PRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETH6-Innewlyerupteddeciduousteeth,thecuspstendtobemorepointed.PRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETH7-Therootsofthedeciduousteethareshorter,lessstrongandlighterincol

7、ourthanthoseofthepermanentteeth.PRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETH8-Therootsofanteriordeciduousteetharelongerinproportiontothecrown.Therootsofposteriorteetharemoredivergenttoallowforthedevelopingpermanents