口腔解剖生理学之国外THEDECIDUOUSDENITION乳牙课件

THEDECIDUOUSDENTITIONTHEDECIDUOUSDENTITION1INTRODUCTIONINTRODUCTION2TheworddeciduouscomesfromaLatinwordmeaningtofalloff.Deciduousteethfallofforareshedlikeleavesfromadeciduoustree.

Theworddeciduouscomesfrom3Thedeciduous,primary,or,astheyoftenreferredtocolloquially,(MILK)teeth,havearelativelyshortlife-spanbeforetheyexfoliatedtobereplacedbythepermanentteeth.Thisusuallyoccursbetweentheagesof6and13years.口腔解剖生理学之国外THEDECIDUOUSDENITION乳牙课件4Thedeciduousincisorsandcanineshavepermanentsuccessorbutthefirstandseconddeciduousmolarsarereplacedbythefirstandsecond

premolars

respectively.Thedeciduousincisorsandcan5ThedeciduousdentitioncomprisesfewerteeththanthepermanentdentitionwithatotalofTENmaxillaryandTENmandibularteeth.Thedeciduousdentitioncompri6Theyareasfollows,inorderofpositionfromthemidline:A-First(central)incisor.B-Second(lateral)incisor.C-Canine.

D-First

molar.

BCDEAE-Second

molar.Theyareasfollows,inorder7Theshorthandformulaforthedeciduousteethisasfollows:

I

2

C

1

M2=10212Theshorthandformulaforthe8GENERALCHARACTERISTICSGENERALCHARACTERISTICS9Thedeciduous

teethgenerallyhaveseveralimportantdifferencesinmorphology,composition,sizecolouraslistedbelow:

1-Thedeciduousteetharesmallerthanthepermanentteeth.PRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETHPRINCIPALDIFFERENCESBETWEENDECIDUOUS

ANDPERMANENT

TEETHThedeciduousteethgenerally102-Theenamelofthedeciduousteethiswhiterandmoreopaque,whichgivesthecrownalightercolourthanthatofthepermanentteeth.3-Theenamelofthedeciduousteethismorepermeableandmore

easilyworndown.Thedegreeofpermeabilityislessenedafterthestartofrootresorption.PRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETH2-Theenamelofthedeciduous114-TheDEPTHOF

ENAMEL

ismoreconsistentandthinnerthaninthepermanentteeth,beingfrom0.5mmto1.00mmthick.

PRINCIPALDIFFERENCESBETWEENDECIDUOUSTEETHANDPERMANENTTEETH4-TheDEPTHOFENAMELismore125-Deciduousteethhaveapronounced

cervicalmargin.Theenamelbulges,insteadoftaperinggently,atthecemento-enamljunction,whichisstraighterthaninthepermanentteeth.Thiscervicalbulgeisaccentuatedinthemesiobuccalareaof

deciduousmolars.PRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETH5-Deciduousteethhaveapron136-Innewlyerupted

deciduousteeth,

thecuspstendtobemorepointed.

PRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETH6-Innewlyerupteddeciduoust147-Therootsofthedeciduousteethareshorter,lessstrongandlighterincolourthanthoseofthepermanentteeth.PRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETH7-Therootsofthedeciduoust158-Therootsof

anteriordeciduousteetharelongerinproportiontothecrown.Therootsofposteriorteetharemoredivergenttoallowforthedevelopingpermanentsuccessor.Theyflareoutfromeachotherwiderthanthecrownmeasurement,andformaminimalcommonroottrunk.PRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETH8-Therootsofanteriordecidu169-Thepulpchambersarelargerthaninthepermanentteethandfollowtheexteriormorphologyofthetoothmore

closely,theretends,thereforetobeless

depthofdentine.PRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETH9-Thepulpchambersarelarger1710-The

rootcanal

ofdeciduousteethareveryfine.

PRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETH10-Therootcanalofdeciduou1811-Usuallytherearenodepressionsorperikymataonthelabialsurfaceofthecrownoftheincisors.Thesesurfacesaresmooth.ONTHEANTERIORTEETH11-Usuallytherearenodepres19ONTHEANTERIORTEETH12-Therearenomamelonesontheincisaledges.ONTHEANTERIORTEETH2013-Thecervicalridgeonthefacialsurfacesisprominent.ONTHEANTERIORTEETH13-Thecervicalridgeonthef21

15-Therootisnarrowmesiodistally. ONTHEANTERIORTEETH14-Thecingulaeareprominentorseemtobulgeandoccupyaboutonethirdofthecervicoincisallengthlingually

15-Therootisna22ONTHEPOSTERIORTEETH16-Themolarcrownhaveanarrowchewing(occlusaltable)buccolingually.17-Themolarsoccluosal surfacesareshallow.Inotherwords,thecuspsareshort,

theridgesarenotpronounced,andthegroovesarecorrespondinglynotasdeep.ONTHEPOSTERIORTEETH16-The23ONTHEPOSTERIORTEETH18-Themolarcrownsarewidemesiodistally,yetveryshort

cervico-occlusally.19-Thebuccalcuspsofmolarsarenotpointedorsharp,withcuspslopesmeetingataverywideobtuseangle.

ONTHEPOSTERIORTEETH18-Them2420-Therearefew

groovesordepressionsinallsurfacesofthecrowns.ONTHEPOSTERIORTEETH20-Therearefewgroovesord2521-Thecervicalridgeisprominentmesially(itiseasytodistinguish

rightsfromleft).ONTHEPOSTERIORTEETH21-Thecervicalridgeispromi2622-The

secondmolarsarelargerthanthefirst

molars.23-Therootfurcationisnearthecrown,andthereislittleifanyroottrunk.ONTHEPOSTERIORTEETHONTHEPOSTERIORTEETH22-Thesecondmolarsarelarg2724-Therootsarewidelyspreadbeyondtheconfinesofthecrowntoallowforthedevelopingpermanentsuccessors.ONTHEPOSTERIORTEETHONTHEPOSTERIORTEETH24-Therootsarewidelyspread28ONTHEPOSTERIORTEETH25-Rootsarethinorslender.ONTHEPOSTERIORTEETHONTHEPOSTERIORTEETH25-Roots29ONTHEPOSTERIORTEETH26-Thesecond

molarrootsare

spreadmorewidelythanthefirstdeciduous

molar(oppositeofthepermanent

molars).ED67ONTHEPOSTERIORTEETH26-Thes30IMPORTANTFUNCTIONSOFSOUND

DECIDUOUSTEETHMaintenanceofanormalappearance.FormulationEfficientmasticationoffood.ofclearspeech.Maintenanceofaproperdiet.Missingorbadlydecayedteethmaybeonereasonthatyoungchildrenrejectfoodsthataredifficulttochew.

IMPORTANTFUNCTIONSOFSOUNDD31IMPORTANTFUNCTIONSOFSOUND

DECIDUOUSTEETH5-Avoidanceofinfectionandconcomitantpain.Anabscessfromadeciduoustoothcancausedarkspots(Turner’sspots)onthepermanenttoothdevelopingbeneathit.6-Maintenanceofspaceandarchcontinuityfortheemergenceofpermanentteeth.IMPORTANTFUNCTIONSOFSOUNDD32Chronology:Initial

calcification3-4monthsinuteroCompletionofcrown4months

Eruption7½monthsCompletionofroot1½yearsMAXILLARYFIRST(CENTRAL)DECIDUOUSINCISORMAXILLARYFIRST(CENTRAL)DECIDUOUSINCISORChronology:MAXILLARYFIRST(CEN33PRINCIPALIDENTIFYINGFEATURES:1-

Roundeddisto-incisalangle:sharp

mesio-incisalangle.2-Similartomaxillaryfirstpermanentincisorbutsmallerand

chubbieroverall.3-Largelingualcingulumandpronounced

bulgeonlabialsurface.MAXILLARYFIRST(CENTRAL)DECIDUOUSINCISORMDMDPRINCIPALIDENTIFYINGFEATURES34PRINCIPALIDENTIFYINGFEATURES:4-Roottiltsdistallyandlabiallyfrom

longaxisofcrown.

5-Onerootcanal;twopulphorns,onemesial,onedistal.

Mesialhornslightlylarger.VARIATIONSNonoticeablevariations.

MAXILLARYFIRST(CENTRAL)DECIDUOUSINCISORPRINCIPALIDENTIFYINGFEATURES35MAXILLARYSECOND(LATERAL)DECIDUOUSINCISORChronology:Initial

calcification4½

monthsinuteroCompletionofcrown5months

Eruption8-9monthsCompletionofroot1½-2yearsMAXILLARYSECOND(LATERAL)DECIDUOUSINCISORMAXILLARYSECOND(LATERAL)DECIDUOUSINCISORChronology:Initial

calcification4½

monthsinuteroCompletionofcrown5months

Eruption8-9monthsCompletionofroot1½-2yearsChronology:Initial

calcification4½

monthsinuteroCompletionofcrown5months

Eruption8-9monthsCompletionofroot1½-2yearsMAXILLARYSECOND(LATERAL)DEC36MAXILLARYSECOND(LATERAL)DECIDUOUSINCISORPRINCIPALIDENTIFYINGFEATURES:1-Similarshape

tomaxillarydeciduouscentralincisorbutcrownissmallerandnarrower

inproportion.2-Lingualcingulumlesspronounced.

MAXILLARYSECOND(LATERAL)DEC37MAXILLARYSECOND(LATERAL)DECIDUOUSINCISOR3-Roundeddisto-incisalangle;sharpmesio-incisalangle.4-Onerootcanal;twopulphorns,onemesial,onedistal.Mesialhornslightlylarger.VARIATIONSRare,incontrasttothehighlyvariablemaxillarypermanentPRINCIPALIDENTIFYINGFEATURES:MAXILLARYSECOND(LATERAL)DEC38MANDIBULARFIRST(CENTRAL)DECIDUOUSINCISORChronology:Initialcalcification4½monthsinuteroCompletionofcrown4

months

Eruption61/2

monthsCompletionofroot1½-2yearsMANDIBULARFIRST(CENTRAL)DEC39PRINCIPALIDENTIFYINGFEATURES:1-Singletaperedrootmoreroundedthanthatoflowermandibularpermanentincisor,tendstoinclinedistally.2-Smallestoothinthedeciduousdentition.3-Sometimesalogitudinalgrooveonthedistalsurfaceofroot.4-cervicalmarginmostsinuousonmesialside.MANDIBULARFIRST(CENTRAL)DECIDUOUSINCISORPRINCIPALIDENTIFYINGFEATURES40MANDIBULARFIRST(CENTRAL)DECIDUOUSINCISORPRINCIPALIDENTIFYINGFEATURES:5-Large,convexcingulumandpronouncedbulgeonlabialsurface.6-Onerootcanal;twopulphorns,onemesial,onedistal.VARIATIONS:Thepronouncedcervicalbulgeonthelabialsurfacemaybereducedorcompletelyabsent.MANDIBULARFIRST(CENTRAL)DEC41MANDIBULARSECOND(LATERAL)DECIDUOUSINCISORMANDIBULARSECOND(LATERAL)DECIDUOUSINCISORChronology:Initialcalcification4½monthsinuteroCompletionofcrown41/2months

Eruption 7

monthsCompletionofroot1½-2yearsChronology:Initialcalcification4½monthsinuteroCompletionofcrownEruptionMANDIBULARSECOND(LATERAL)DE42PRINCIPALIDENTIFYINGFEATURES:1-Singletaperedrootwithroundcross-section,tendtoinclinedistally.2-Roundeddisto-incisalangle;sharpmesio-incisalangle.

MANDIBULARSECOND(LATERAL)DECIDUOUSINCISORPRINCIPALIDENTIFYINGFEATURES43MANDIBULARSECOND(LATERAL)DECIDUOUSINCISOR3-Incisiveedgeslopesdownwardsfrommesialtoslightlylowerdistalsurface.4-Crownmay,insomecases,showtwistingonrootforincisiveedgetofollowmandibulararch.

PRINCIPALIDENTIFYINGFEATURES:MANDIBULARSECOND(LATERAL)DE44MANDIBULARSECOND(LATERAL)DECIDUOUSINCISORPRINCIPALIDENTIFYINGFEATURES:5-Largerthanlowerfirst(central)deciduousincisor.6-Lingualsurfacemaybemoreconcavethanthatofthemadibularcentraldeciduousincisor.7-Singleroot;twopulphorns,onemesial,onedistal.

VARIATIONSNonoticeablevariations.Afeatureofthedeciduousdentitionisitsconsistencyinitsmorphology..MANDIBULARSECOND(LATERAL)DE45MAXILLARYDECIDUOUSCANINEChronology:Initialcalcification 5

monthsinuteroCompletionofcrown9monthsEruption 16-20

monthsCompletionofroot3years

MAXILLARYDECIDUOUSCANINEMAXILLARYDECIDUOUSCANINEChro46PRINCIPALIDENTIFYING1-Mesialslopeofcusplongerthandistalslope.2-Conicalcrownwithpronouncedcervicalbulgeandpointedcusp.

MAXILLARYDECIDUOUSCANINEMAXILLARYDECIDUOUSCANINEMAXILLARYDECIDUOUSCANINEMAXILLARYDECIDUOUSCANINEMAXILLARYDECIDUOUSCANINEMAXILLARYDECIDUOUSCANINEMAXILLARYDECIDUOUSCANINEMAXILLARYDECIDUOUSCANINEMDFEATURES:DMPRINCIPALIDENTIFYINGMAXILLARY47MAXILLARYDECIDUOUSCANINEPRINCIPALIDENTIFYINGFEATURES

3-Labialandlinguallogitudinalridgesextendingfromcusptips:

4-Crownmorebulbousthanthatofmaxillarypermanentcanine.

MAXILLARYDECIDUOUSCANINEPRIN48MAXILLARYDECIDUOUSCANINEPRINCIPALIDENTIFYINGFEATURES:5-Diamond-shapeoutlineroundedcornersfromincisalaspect.6-Cervicalmarginrisesfurtherincisallyonthemesialthanonthedistalsurface.DMMAXILLARYDECIDUOUSCANINEPRIN49PRINCIPALIDENTIFYIN7-Singlerootoftenmorethantwicethelengthofthecrown.Slendertaperwithsimilarcross-sectiontothatofthemaxillarypermanentcanine;distallyinclined.8-Singlerootcanal;pulpchamberelongatedanddirectedtowardscusp.VARIATIONSAsymmetricalandsymmetricalcrownformsareequallycommon.Otherwisenonoticeablevariations.

MAXILLARYDECIDUOUSCANINEFEATURES:

PRINCIPALIDENTIFYINMAXILLARY50MANDIBULARDECIDUOUSCANINEMANDIBULARDECIDUOUSCANINEChronology:Initialcalcification5monthsinuteroCompletionofcrown9

months

Eruption16-20

monthsCompletionofroot2½-3yearsMANDIBULARDECIDUOUSCANINEMA51PRINCIPALIDENTIFYINGFEATURS:1-SmallerandslimmeroverallthanthemaxillarydeciduousCanine.2-Lesswell-definedlabialandlinguallongitudenallyridges;lingualridgeoftencompletelyabsent.3-Concavelingualsurface.4-Distalslopelongerthanmesial.5-Cervicalmarginmoresinuousonmesialside.6-Singletaperingrootinclinesdistallyandslightlylabially.7-Singlerootcanal;pulpchamberelongatedanddirectedtowardscusp.VARIATIONS:Nonoticeablevariations.Linguallogitudenalridgeoccasionallypresentonlingualsurface.MANDIBULARDECIDUOUSCANINEPRINCIPALIDENTIFYINGFEATURS:1-SmallerandslimmeroverallthanthemaxillarydeciduousCanine.2-Lesswell-definedlabialandlinguallongitudenallyridges;lingualridgeoftencompletelyabsent.3-Concavelingualsurface.4-Distalslopelongerthanmesial.5-Cervicalmarginmoresinuousonmesialside.6-Singletaperingrootinclinesdistallyandslightlylabially.7-Singlerootcanal;pulpchamberelongatedanddirectedtowardscusp.VARIATIONS:Nonoticeablevariations.Linguallogitudenalridgeoccasionallypresentonlingualsurface.PRINCIPALIDENTIFYINGFEATURS:52MAXILLARYFIRSTDECIDUOUSMOLARChronology:Initialcalcification5monthsinuteroCompletionofcrown 6months

Eruption12-16monthsCompletionofroot2-2½yearsMAXILLARYFIRSTDECIDUOUSMOLA53

PRINCIPALIDENTIFYINGFEATURES:1-Pronouncedbulgeonmesialsideofbuccalsurface:molartubercleofZuckerkandl.2-Trapezoidcoronaloutlinewithnarrowocclusalsurfacerunningmesiodistally.MAXILLARYFIRSTDECIDUOUSMOLARMAXILLARYFIRSTDECIDUOUSMOLARPRINCIPALIDENTIFYINGFEATURE54MAXILLARYFIRSTDECIDUOUSMOLAR

PRINCIPALIDENTIFYINGFEATURES:3-Lingualsurfaceshorter,mesiodistally,thanthebuccal.4-Mesiolingualcusplargestandpointed.5-Widestlabiolingualcrownmeasurementatmesialend.

MAXILLARYFIRSTDECIDUOUSMOLARMAXILLARYFIRSTDECIDUOUSMOLA55

PRINCIPALIDENTIFYINGFEATURES:6-Threerootcanals;fourpulphorns:mesiobuccal,distolingual,distobuccalandmesiolingual.VARIATIONS:Palatalanddistobucclrootssometimesfuse.Mesiobuccalcuspsometimeshasanaccessorycuspmesialtoit.Distolingualcuspsometimesabsent.Zuckerkandl,tubercleisoccasionallyscarcelydiscernible.MAXILLARYFIRSTDECIDUOUSMOLARMAXILLARYFIRSTDECIDUOUSMOL56MAXILLARYSECONDDECIDUOUSMOLARChronology:Initialcalcification6

monthsinuteroCompletionofcrown10-12

months

Eruption1¾-2½yearsCompletionofroot3years

MAXILLARYSECONDDECIDUOUSMOL57PRINCIPALIDENTIFYINGFEATURES:

1-Morphologyofmaxillaryfirstpermanentmolarduplicatedonasmallerscale.

2-Moreprominentbulgeoncervicalpartof buccalsurface.

MAXILLARYSECONDDECIDUOUSMOLARDDLLMMBBPRINCIPALIDENTIFYINGFEATURES58PRINCIPALIDENTIFYINGFEATURES:3-Rootshavewiderdivergencethanthoseofmaxillaryfirstpermanentmolar.4-CuspofCarabellipresentinmostcases.MAXILLARYSECONDDECIDUOUSMOLARPRINCIPALIDENTIFYINGFEATURES59MAXILLARYSECONDDECIDUOUSMOLARPRINCIPALIDENTIFYINGFEATURES:5-Threerootcanals;threepulphorns:mesiolingual,distobuccalanddistolingual.VARIATIONS:CuspofCarabellimaybeabsent.Veryrarelythedistolingualcuspmaybesoreducedastobescarcelydiscernible.Thepalatalanddistobuccalrootsmaysometimesbefused.MAXILLARYSECONDDECIDUOUSMOL60MANDIBULARFIRSTDECIDUOUSMOLARMANDIBULARFIRSTDECIDUOUSMOLARMANDIBULARFIRSTDECIDUOUSMOLARChronology:Initialcalcification5monthsinuteroCompletionofcrown6months

Eruption12-16monthsCompletionofroot2-2½yearsMANDIBULARFIRSTDECIDUOUSMOL61PRINCIPALIDENTIFYINGFEATURES:1-MolartubercleofZuckerkandl:anexaggeratedcervicalbulgeonthebuccalsurfaceofthecrownoverthemesialroot,withaconsiderablecervicalconstriction.

2-Fourcusps:buccalcuspscompressedlabiolinguallywithno

clearseparationbetweenthemincontrasttothetwolingualcuspswhichareclearlydefinedandroughlyconicalinshape.3-Mesiolingualcusplargest.

MANDIBULARFIRSTDECIDUOUSMOLARMANDIBULARFIRSTDECIDUOUSMOLARMANDIBULARFIRSTDECIDUOUSMOLARMANDIBULARFIRSTDECIDUOUSMOLARMANDIBULARFIRSTDECIDUOUSMOLARLBDMPRINCIPALIDENTIFYINGFEATURES62PRINCIPALIDENTIFYINGFEATURES:4-Toothlongermesiodistallythanlabiolingually.5-Mesialmarginalridgemorepronouncedthandistal.6-Tworootsflattenedmesiodistally.Mesialisthelongerandfromthemesialaspectappearsrectangular.7-Tworootcanals;threepulphorns;mesiobuccal,lingual,distobuccal.VARIATIONS:Mesiolingualcuspsometimesveryinsignificant.Buccolingualcrestoccasionallyabsent.

MANDIBULARFIRSTDECIDUOUSMOLARMANDIBULARFIRSTDECIDUOUSMOLARMANDIBULARFIRSTDECIDUOUSMOLARMANDIBULARFIRSTDECIDUOUSMOLARMANDIBULARFIRSTDECIDUOUSMOLARPRINCIPALIDENTIFYINGFEATURES63MANDIBULARSECONDDECIDUOUSMOLARChronology:Initialcalcification6monthsinuteroCompletionofcrown10-12months

Eruption1¾-2½

years

Completionofroot3yearsMANDIBULARSECONDDECIDUOUSMO64PRINCPALIDENTIFYINGFEATURES:1-Samenumberofcuspsandroots;similararrangementtothemandibularfirstpermanentmolar.2-Smallerthanmadibularfirstpermanentmolarbutlargerthanthemandibularfirstdeciduousmolar.3-Prominentcervicalbulgeonbuccalsurfaceofcrown.Buccalsurfaceinclinedlingually.MANDIBULARSECONDDECIDUOUSMOLARMMPRINCPALIDENTIFYINGFEATURES:65MANDIBULARSECONDDECIDUOUSMOLARPRINCPALIDENTIFYINGFEATURES:4-Occlusaloutlinerectangular.5-Buccalcuspsapproximatelyequalinsize..MANDIBULARSECONDDECIDUOUSMO66MANDIBULARSECONDDECIDUOUSMOLARPRINCPALIDENTIFYINGFEATURES:6-Twowidelydivergentroots;mesialrootlongerandflattenedmesiodistally7-Twooroccasionallythreerootcanals;fourorfivepulphorns,onetoeachcusp.VARIATIONS:Nonoticeablevariations.Mesialrootsometimesshowatendencytodividepartiallyorcompletelyintotworoot

canals,onebuccalandonelingual.MANDIBULARSECONDDECIDUOUSMO67THEDECIDUOUSDENTITIONTHEDECIDUOUSDENTITION68INTRODUCTIONINTRODUCTION69TheworddeciduouscomesfromaLatinwordmeaningtofalloff.Deciduousteethfallofforareshedlikeleavesfromadeciduoustree.

Theworddeciduouscomesfrom70Thedeciduous,primary,or,astheyoftenreferredtocolloquially,(MILK)teeth,havearelativelyshortlife-spanbeforetheyexfoliatedtobereplacedbythepermanentteeth.Thisusuallyoccursbetweentheagesof6and13years.口腔解剖生理学之国外THEDECIDUOUSDENITION乳牙课件71Thedeciduousincisorsandcanineshavepermanentsuccessorbutthefirstandseconddeciduousmolarsarereplacedbythefirstandsecond

premolars

respectively.Thedeciduousincisorsandcan72ThedeciduousdentitioncomprisesfewerteeththanthepermanentdentitionwithatotalofTENmaxillaryandTENmandibularteeth.Thedeciduousdentitioncompri73Theyareasfollows,inorderofpositionfromthemidline:A-First(central)incisor.B-Second(lateral)incisor.C-Canine.

D-First

molar.

BCDEAE-Second

molar.Theyareasfollows,inorder74Theshorthandformulaforthedeciduousteethisasfollows:

I

2

C

1

M2=10212Theshorthandformulaforthe75GENERALCHARACTERISTICSGENERALCHARACTERISTICS76Thedeciduous

teethgenerallyhaveseveralimportantdifferencesinmorphology,composition,sizecolouraslistedbelow:

1-Thedeciduousteetharesmallerthanthepermanentteeth.PRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETHPRINCIPALDIFFERENCESBETWEENDECIDUOUS

ANDPERMANENT

TEETHThedeciduousteethgenerally772-Theenamelofthedeciduousteethiswhiterandmoreopaque,whichgivesthecrownalightercolourthanthatofthepermanentteeth.3-Theenamelofthedeciduousteethismorepermeableandmore

easilyworndown.Thedegreeofpermeabilityislessenedafterthestartofrootresorption.PRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETH2-Theenamelofthedeciduous784-TheDEPTHOF

ENAMEL

ismoreconsistentandthinnerthaninthepermanentteeth,beingfrom0.5mmto1.00mmthick.

PRINCIPALDIFFERENCESBETWEENDECIDUOUSTEETHANDPERMANENTTEETH4-TheDEPTHOFENAMELismore795-Deciduousteethhaveapronounced

cervicalmargin.Theenamelbulges,insteadoftaperinggently,atthecemento-enamljunction,whichisstraighterthaninthepermanentteeth.Thiscervicalbulgeisaccentuatedinthemesiobuccalareaof

deciduousmolars.PRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETH5-Deciduousteethhaveapron806-Innewlyerupted

deciduousteeth,

thecuspstendtobemorepointed.

PRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETH6-Innewlyerupteddeciduoust817-Therootsofthedeciduousteethareshorter,lessstrongandlighterincolourthanthoseofthepermanentteeth.PRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETH7-Therootsofthedeciduoust828-Therootsof

anteriordeciduousteetharelongerinproportiontothecrown.Therootsofposteriorteetharemoredivergenttoallowforthedevelopingpermanentsuccessor.Theyflareoutfromeachotherwiderthanthecrownmeasurement,andformaminimalcommonroottrunk.PRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETH8-Therootsofanteriordecidu839-Thepulpchambersarelargerthaninthepermanentteethandfollowtheexteriormorphologyofthetoothmore

closely,theretends,thereforetobeless

depthofdentine.PRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETH9-Thepulpchambersarelarger8410-The

rootcanal

ofdeciduousteethareveryfine.

PRINCIPALDIFFERENCESBETWEENDECIDUOUSANDPERMANENTTEETH10-Therootcanalofdeciduou8511-Usuallytherearenodepressionsorperikymataonthelabialsurfaceofthecrownoftheincisors.Thesesurfacesaresmooth.ONTHEANTERIORTEETH11-Usuallytherearenodepres86ONTHEANTERIORTEETH12-Therearenomamelonesontheincisaledges.ONTHEANTERIORTEETH8713-Thecervicalridgeonthefacialsurfacesisprominent.ONTHEANTERIORTEETH13-Thecervicalridgeonthef88

15-Therootisnarrowmesiodistally. ONTHEANTERIORTEETH14-Thecingulaeareprominentorseemtobulgeandoccupyaboutonethirdofthecervicoincisallengthlingually

15-Therootisna89ONTHEPOSTERIORTEETH16-Themolarcrownhaveanarrowchewing(occlusaltable)buccolingually.17-Themolarsoccluosal surfacesareshallow.Inotherwords,thecuspsareshort,

theridgesarenotpronounced,andthegroovesarecorrespondinglynotasdeep.ONTHEPOSTERIORTEETH16-The90ONTHEPOSTERIORTEETH18-Themolarcrownsarewidemesiodistally,yetveryshort

cervico-occlusally.19-Thebuccalcuspsofmolarsarenotpointedorsharp,withcuspslopesmeetingataverywideobtuseangle.

ONTHEPOSTERIORTEETH18-Them9120-Therearefew

groovesordepressionsinallsurfacesofthecrowns.ONTHEPOSTERIORTEETH20-Therearefewgroovesord9221-Thecervicalridgeisprominentmesially(itiseasytodistinguish

rightsfromleft).ONTHEPOSTERIORTEETH21-Thecervicalridgeispromi9322-The

secondmolarsarelargerthanthefirst

molars.23-Therootfurcationisnearthecrown,andthereislittleifanyroottrunk.ONTHEPOSTERIORTEETHONTHEPOSTERIORTEETH22-Thesecondmolarsarelarg9424-Therootsarewidelyspreadbeyondtheconfinesofthecrowntoallowforthedevelopingpermanentsuccessors.ONTHEPOSTERIORTEETHONTHEPOSTERIORTEETH24-Therootsarewidelyspread95ONTHEPOSTERIORTEETH25-Rootsarethinorslender.ONTHEPOSTERIORTEETHONTHEPOSTERIORTEETH25-Roots96ONTHEPOSTERIORTEETH26-Thesecond

molarrootsare

spreadmorewidelythanthefirstdeciduous

molar(oppositeofthepermanent

molars).ED67ONTHEPOSTERIORTEETH26-Thes97IMPORTANTFUNCTIONSOFSOUND

DECIDUOUSTEETHMaintenanceofanormalappearance.FormulationEfficientmasticationoffood.ofclearspeech.Maintenanceofaproperdiet.Missingorbadlydecayedteethmaybeonereasonthatyoungchildrenrejectfoodsthataredifficulttochew.

IMPORTANTFUNCTIONSOFSOUNDD98IMPORTANTFUNCTIONSOFSOUND

DECIDUOUSTEETH5-Avoidanceofinfectionandconcomitantpain.Anabscessfromadeciduoustoothcancausedarkspots(Turner’sspots)onthepermanenttoothdevelopingbeneathit.6-Maintenanceofspaceandarchcontinuityfortheemergenceofpermanentteeth.IMPORTANTFU