morphology of human deciduous maxillary molar tooth

Prof. Rooban ThavarajahTooth Morphology

Lecture Series

Dr. Rooban Thavarajah


Deciduous DentitionMaxillary Molars

BACK GROUND

Does not resemble any other CROWN -

nearest similarities to premolars

Root form is typical of maxillary molars.

Crown - greatest dimension BP

Two prominent cusps - MB & ML cusps.

two distal cusps esp. DL are diminished.



BUCCAL ASPECT

Does not resemble any other teeth Buccal

Greatest width MD @ contact areas Converges towards cervix Narrower look @ cervix Smaller than 2nd molar 3 roots- Palatal big, mesial, short distal Bifurcation of buccal roots @ CEJ

BUCCAL ASPECT

MD diameter is much greater than crown

height.

Proximal outlines are convex, and constrict

greatly toward cervix

Heights of contour – contact areas - near

junction of occlusal and middle thirds.


BUCCAL ASPECT Occlusal outline – straight - contour of cervical line -

depth of curvature - much greater toward mesial than

distal - crown - being offset toward mesial.

Occlusally, buccal surface is mostly flat, but in gingival

third cervical ridge is prominent, especially mesial

portion.

Surface has crest of curvature in cervical third.

Smooth surface


PALATAL ASPECT


PALATAL ASPECT ML cusp is short, bulky and prominent in

occlusal outline. DP cusp is small DB cusp is also visible Cervical line is evenly, slightly, curved toward

apex. Palatal surface is convex and smooth without

grooves or depressions. Height of contour - more cervically located, at

about middle & cervical third junction


MESIAL ASPECT Disparity between BP widths @ its cervical

and occlusal margins is much more

Cervically, dimension is considerably wider,

due to prominent cervical ridge on buccal, as

well as greater taper of buccal and lingual

outlines toward occlusal.


MESIAL ASPECT Buccal outline is dominated by cervical ridge

and crest of curvature in cervical third - remainder of outline is usually straight

Lingual outline is generally convex, but with a more cervically located crest of curvature than is present on permanent molars.


MESIAL ASPECT

2 mesial cusps and mesial marginal ridge make

up occlusal outline.

MP cusp is more generous in height and size

than is MB cusp – hence - at occlusal,

marginal ridge is relatively short.

Cervical line is slightly curved toward occlusal

surfaceDr. Rooban Thavarajah

MESIAL ASPECT


DISTAL ASPECT

Smaller than mesial surface.

As buccal surface tapers toward distal,

much of it is visible from this aspect.

DB cusp is more prominent than small DL

cusp


DISTAL ASPECT

Distal marginal ridge is less pronounced

than is mesial.

Mesial cusps actually provide occlusal

outline from this aspect.


DISTAL ASPECT

Cervical ridge is not so prominent in

buccal outline as it is from mesial aspect.

Cervical line is straight to slightly curved

occlusally.


OCCLUSAL ASPECT Crown outline converges Lingually, distally

Rectangular in shape- short side- marginal

ridges

Fossa: Central, mesial and distal triangular fossa

Ridges: Mesial, distal marginal ridge, Oblique

Pit: central, mesial, distal


OCCLUSAL ASPECT


OCCLUSAL ASPECT

Grooves: central, Buccal developmental, distal

developmental, disto-occlusal, supplemental

Major cusps : Mesiolingual & Mesiobuccal

Minor cusp: Distobuccal cusp

If 4 cusp 2 buccal & 2 lingual


ROOTS

Roots Trifurcated

2 buccal & 1 lingual

Long, slender very flared

Lingual root is largest

Mesiobuccal next largest

Distobuccal is shortest & straightestDr. Rooban Thavarajah


Maxillary Second Molar

Buccal aspect ~ to permanent 1st molar, but smaller 2 buccal cusp with well defined DG Larger than 1st molar

Palatal 3 cusps- MP – large, DP, Cusp of Carabelli Separated by 2 DG 3 roots seen


Proximal : ~ to first molar Occlusal

Resembles 1st permanent molar Rhomboidal in shape 4 or 5 cups Fossa: Central, MT, DT Pit: central, mesial, distal Ridge: MMR, DMR, Oblique ridge Groove: central, BDG< DDG, PDG

morphology of human deciduous maxillary molar tooth

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