mod morphology of deciduous dentition

MORPHOLOGY OF DECIDUOUS TEETHMORPHOLOGY OF DECIDUOUS TEETH

Deciduous dentition Set traits

Smaller in size Smaller crown height/tooth length ratio Greater crown width/height ratio

Set traits More bulging B & L cervical ridges

Constricted cervix Buccal cervical ridges on deciduous

molars Occlusal aspect: constricted occlusal table

Deciduous dentition

Set traits Molar roots

• More slender & relatively longer • More bowed & flared outward• Shorter root trunk

Milk-white in color Enamel is thinner & pulp chamber is large

Some class, arch & type traits in permanent dentition are applied to deciduous dentition

Only new traits will be discussed

Pulp chamber deciduous v/s permanent teeth

Dental formula

Deciduous teeth

Deciduous incisorsEruption

Mandibular before maxillary incisors Central before lateral incisors

No mamelons, labial grooves or lobes

Maxillary Central incisor

UNS--------------------E| |FFDI--------------------- 51, 61Eruption time------- 7.5months(FULLER)Order----------------- 1Shedding----------- 6-7 years

Maxillary Central incisor Increased mesiodistal width of

crown.Rounded mesioincisal and

distoincisal angle than permanent successor.

No mamelons on incisal surface+ flat incisal surface

No labial grooves, depressions or lobes

Pronounced bulge on labial surface.

Maxillary Central incisorProminent cingulum.Prominent marginal

ridgesDeeper lingual fossa.No lingual pit

Maxillary Central incisor MESIAL ASPECT: wider

labiolingually Cervical line exhibits less

curvature incisally. DISTAL ASPECT: Cervical line curvature

less on distal surface as compared to mesial surface.

Maxillary Central incisor

Incisal AspectStraight incisal edgeDivides the crown into

equal labial and lingual portions.

Greater mesiodistal width.

Maxillary Central incisorSingle rootTapers evenly to the

apexRoot longer reltive to

crown length.

Maxillary lateral incisor

UNS--------------------D| |GFDI--------------------- 52, 62Eruption time------- 9 months(FULLER)Order----------------- 2Shedding------------ 7 -8 yrs

Maxillary lateral incisorMuch smaller than central

(trapezoidal labially, triangular proximal aspect)

Crown is wider incisocervically than mesiodistally.

Distoincisal angle more rounded than mesioincisal angle

Marginal ridges on lingual surface more prominent

Deeper lingual fossa.Lingual fossa is deep

Maxillary lateral incisor

Incisal aspect Much narrowermesiodistal dimensionmore rhomboidal &

more convex.

Maxillary lateral incisor

ROOTLateral incisor root

relatively longerApex not so rounded.

Mandibular teeth

Mandibular central incisor

UNS-------------------- P, OFDI--------------------- 81, 71Eruption time------- 6 months(FULLER)Order----------------- 1Shedding------------ 6-7 yrs

Mandibular central incisor

Chisel shape incisor morphology Sharp mesioincisal and distoincisal

angles to the cervial line(90 DEGREES) Incisal margin straight,no mamelons. Smooth labial surface lacking

developmental depressions. Flatter than labial surface of permanent

incisors. Labially symmetrical crown Bulge on labial surface at CEJ.

Mandibular central incisorWell developed

lingual cingulumLess defined marginal

ridges than those of maxillary deciduous central incisor.

Shallow lingual fossa

Mandibular central incisor

Proximal aspect;Triangular in shape/ wedge shaped when seen from mesial or

distal aspect. Incisal edge located over root centre.Cervical line contour evenly curved towards incisal.Greater labiolingual width than that of permanent incisors.Distal aspect shows less depth of curvature towards incisal.

Mandibular central incisor Straight incisal edge Divides the labial and

lingual portions of the crown into nearly equal halves.

In deciduous maxillary central incisor the crown is wider MD.

M & D portions of crown symmetrical

Mandibular central incisorSingle ,long ,slender Convex labial and

lingual surfaces.Flattened mesial and

distal surfaces.

Mandibular lateral incisor

UNS--------------------Q , NFDI--------------------- 82, 72Eruption time------- 7 MONTHSOrder----------------- 2Shedding------------ 7-8 years

Mandibular lateral incisor Similar in form to

deciduous central incisor. Distoincisal angle is

rounded, mesioincisal angle is sharp.

Labial/lingual aspect: Incisal outline slopes slightly

towards the distal

Mandibular lateral incisorLingual AspectCingulum and

marginal ridges little larger.

Lingual fossa little deeper.

Mandibular lateral incisor Incisal aspect: crown

not symmetrical.Cingulum bulges

towards distal.

Mandibular lateral incisorSingle rootLonger root than

central incisorDistal curvature

apically.Distal longitudinal

groove.

Maxillary canine

UNS--------------------C (rt) , H(lt)FDI--------------------- 53, 63Eruption time------- 19 MONTHSOrder----------------- 4Shedding------------ 10-12 years

Maxillary canineMD width > crown

height(Incisocervical measurement)Labial or lingual views: diamond in

shapeRounder mesial and distal outlines.M & D outlines overhang the cervical

line.M& D contact areas located at the

same level incisocervically.Mesial cusp slope longer than distal

cusp slope.No labial ridge or depressionsNo imbrication lines.

Maxillary canine Well developed cingulum. Prominent marginal

ridges. ML and DL fossae are

present Tubercle often present on

the cingulum extending from the cusp tip to cingulum.

Maxillary canine Mesial aspect :Triangular

in shape Labial margin convex

incisocervically Lingual margin concave in

incisal half and convex in cervical half

Labiolingually tooth is thicker

Cervical line depth less

Maxillary canine Distal Aspect Similar to mesial except

that cervical line shows less curvature.

Incisal aspect Rhomboidal outline Exhibits more rounding

incisal than the permanent canine.

Cusp tip offset to distal. Mesial cusp ridge

therefore longer.

Maxillary canineROOTSingle root Root approx twice the

length of crownWider labiolingually

than mesiodistally.

Mandibular canine

UNS-------------------- R ,MFDI--------------------- 83, 73Eruption time------- 16 MONTHSOrder----------------- 4Shedding------------ 9-12 years

Mandibular canineSmaller and slimmer

overall than the maxillary deciduous canine.

MD width of mandibular primary canine< MD width of maxillary pri canine.

Incisocervical ht> MD Width.

Mandibular canineDistoincisal slope

longer than mesioincisal slope(reverse of max.dec canine)

Mandibular canineLL diameter < that of

deciduous max. canine( much narrower tooth labiolingually)

Less pronounced cingulum, MR & cervical ridges.

Shallower fossae than max canine.

Mandibular canine

Single but shorter root.

Maxillary deciduous molars

Maxillary 1st molar

UNS-------------------- B(rt) ,I(lt)FDI--------------------- 54, 64Eruption time------- 14 MONTHSOrder----------------- 3Shedding------------ 9-11 years

Maxillary 1st molar Most atypical of all primary or permanent molars Crown doesnot resemble any other primary or permanent

molar crown. Exhibit some similarities to the crowns of permanent

premolars

Maxillary 1st molar BUCCAL ASPECT MD diameter greater than

crown height Mesial and distal outlines

are convex ,constricted towards cervix.

Comparatively straight occlusal outlinetwo buccal cusps not sharp or prominent.

Maxillary 1st molar Essential difference from permanent

tooth Depth of curvature is much greater

towards the mesial than distal. Buccal surface smooth and lacks

grooves or depressions. MOLAR TUBERCLE OF

ZUCKERKANDL; pronounced bulge on mesial surface of buccal surface.

Flat surface occlusally

Maxillary 1st molar LINGUAL ASPECT Lingual surface shorter

mesiodistally than buccal surface.

ML cusp quite bulky and dominates the occlusal outline

DL cusp is so diminitive that DB CUSP is also partially visible from this aspect.

Maxillary 1st molar

LINGUAL ASPECT Cervical line is evenly

and slightly curved towards cervix.

Convex & smooth surface ,lacking grooves or depressions.

Maxillary 1st molar MESIAL ASPECT Disparity b/w the buccolingual

widths at its cervical and occlusal margins much more than in max.first permanent molars.

Wider dimension cervically due to prominent cervical ridge on buccal and greater taper of buccal and lingual outlines towards occlusal.

Maxillary 1st molar Mesial Aspect Buccal outline dominated by

cervical ridge and crest of curvature is in cervical third.Remainder of buccal outline straight.

Lingual outline convex.More cervically located crest of curvature than in permanent molars

Occlusal outline MB+ ML cusps and mesial marginal ridge make up the occlusal outline.

ML cusp more generous in height than MB cusp.

Maxillary 1st molar

MESIAL ASPECTCervical line slightly

curved towards occlusal.

Maxillary 1st molar Distal AspectConsiderably smaller than the mesial surface.Tapering of buccal surface towards the distal therefore much of the buccal surface visible from

distal aspect.DB cusp more prominent than minute DL cusp.Distal marginal ridge less pronounced than mesial

marginal ridge.Cervical line is straight to slightly curved

occlusally.

Maxillary 1st molar

OCCLUSAL ASPECT unusual five sided figure Cusps: 4 cusps 1) MB cusp 2) DB cusp 3) ML cusp 4) DL cusp

Maxillary 1st molarMesiolingual cuspLargest cusp and

longest.Mesiobuccal cuspMB cusp greater than

distobuccal.Distobuccal cuspDistolingual cuspSmallest cusp.

Maxillary 1st molar Transverse ridge:

prominent T-ridgeFormed by lingual

cusp ridge of MB cusp and buccal cusp ridge of ML cusp.

Oblique RidgeExtends from ML cusp

to DB cusp.

Maxillary 1st molar

Fossae: 3 fossae 1) central fossa 2) mesial triangular fossa 3) distal triangular fossa

Maxillary 1st molar ROOTS no root trunk. Root trunk: defined as that

portion of root situated b/w cervical line and the point of furcation.

Three roots: 1) MB root 2) DB ROOT 3) Palatal root Slender and flared roots Largest +longest palatal

root.

Maxillary 2nd molar

UNS-------------------- A,JFDI--------------------- 55, 65Eruption time------- 24 MONTHSOrder----------------- 5Shedding------------ 10-12 years

Maxillary 2nd molar Primary maxillary second

molar larger than primary maxillary first molar

Closely resembles the permanent maxillary first molar in form but is smaller in all dimensions.

Usually has a Cusp of Carabelli ,as its permanent counterpart.

Mandibular 1st molar

UNS-------------------- L &SFDI--------------------- 84, 74Eruption time------- 12 MONTHSOrder----------------- 3Shedding------------ 9-11 years

Mandibular 1st molar Primary mandibular first

molar has crown unlike any tooth of either dentition.

Prominent buccal cervical ridge on mesial half of buccal surface.

The HOC on the buccal is at cervical one third

The HOC on the lingual is in the middle one third.

Mandibular 1st molar CUSPS: 4 cusps:1)MB 2) ML 3) DB 4) DL

The two mesial cusps are considerably larger than distal cusps.

Mandibular 1st molarA transverse ridge

passes b/w the mesiobuccal and mesiolingual cusps.

Mandibular 1st molar

Roots2 roots i.e mesial and

distal .Mesial wider than

distal root.

Mandibular 2nd molar

UNS-------------------- K&TFDI--------------------- 85, 75Eruption time------- 20 MONTHSOrder----------------- 5Shedding------------ 10-12 years

Larger than the primary mandibular first molar.

This tooth closely resembles the permanent mandibular first molar, disregarding size and general differences.

5 cusps similar to permanent mand first molar.

Mandibular 2nd molar

Mandibular 2nd molar Major differences are: The 3

buccal cusps (MB,DB& distal) are nearly equal in size.

Occlusa table relatively longer buccolingually and less pentagonal than that of the first permanent molar.

The mesial root is longer and wider than the distal root whereas they are of equal length in permanent first molar.

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