Post on 07-May-2015
description
Prof. Rooban ThavarajahTooth Morphology
Lecture Series
Dr. Rooban Thavarajah
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.
Dr. Rooban Thavarajah
Dr. Rooban Thavarajah
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.
Dr. Rooban Thavarajah
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
Dr. Rooban Thavarajah
PALATAL ASPECT
Dr. Rooban Thavarajah
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
Dr. Rooban Thavarajah
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.
Dr. Rooban Thavarajah
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.
Dr. Rooban Thavarajah
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
Dr. Rooban Thavarajah
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
Dr. Rooban Thavarajah
DISTAL ASPECT
Distal marginal ridge is less pronounced
than is mesial.
Mesial cusps actually provide occlusal
outline from this aspect.
Dr. Rooban Thavarajah
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.
Dr. Rooban Thavarajah
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
Dr. Rooban Thavarajah
OCCLUSAL ASPECT
Dr. Rooban Thavarajah
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
Dr. Rooban Thavarajah
ROOTS
Roots Trifurcated
2 buccal & 1 lingual
Long, slender very flared
Lingual root is largest
Mesiobuccal next largest
Distobuccal is shortest & straightestDr. Rooban Thavarajah
Dr. Rooban Thavarajah
Dr. 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
Dr. Rooban Thavarajah
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
Dr. Rooban Thavarajah