Morphology of mandibular and variationss

Mandibular molars

1. Mandibular MolarsMandibular Molars
The mandibular molars erupt 6 months to 1 year The mandibular molars erupt 6 months to 1 year
before the corresponding permanent maxillary before the corresponding permanent maxillary
molars.molars.
The crown of mandibular molars have four or The crown of mandibular molars have four or
five major cusps, of which there are always two five major cusps, of which there are always two
lingual cusps of about the same width. lingual cusps of about the same width.
All mandibular molars are wider mesiodistally All mandibular molars are wider mesiodistally
than buccolingually, unlike to anterior teeth.than buccolingually, unlike to anterior teeth.

2. Mandibular MolarsMandibular Molars
Each mandibular molar has two well-Each mandibular molar has two well-
developed roots: one mesial and one developed roots: one mesial and one
distal. distal.
A tooth with two roots is referred to as A tooth with two roots is referred to as
bifurcated, which means divided into two. bifurcated, which means divided into two.
A bifurcation is the area at which the two A bifurcation is the area at which the two
roots divide.roots divide.

3. Mandibular First MolarsMandibular First Molars
The permanent mandibular first molars The permanent mandibular first molars
erupt between 6 and 7 years of age. erupt between 6 and 7 years of age.
These teeth are usually the first These teeth are usually the first
permanent teeth to erupt in the oral cavity. permanent teeth to erupt in the oral cavity.

The two roots, mesial and distal, of a The two roots, mesial and distal, of a
mandibular first molar are larger and more mandibular first molar are larger and more
divergent than those of a second molar.divergent than those of a second molar.

4. Buccal aspectBuccal aspect
Crown-trapezoidal-cervical & occlusal Crown-trapezoidal-cervical & occlusal
outlines representing the uneven sidesoutlines representing the uneven sides
Occlusal--longerOcclusal--longer

5. GroovesGrooves
2 in crown portion-MBDG, DBDG2 in crown portion-MBDG, DBDG
MBDG- shorter-
terminates centrally
located CO
situated a little mesial
to the root bifurcation
buccally.
DBDG
Terminus near the
DB line angle at the
cervical third of the
crown

6. Cusps Cusps
MB,DB & D—relatively flatMB,DB & D—relatively flat
Distal cusp--smallDistal cusp--small

7. Cervical line—regular-dipping apically Cervical line—regular-dipping apically
toward the root bifurcation.toward the root bifurcation.
Mesial outline—concave at cervical third Mesial outline—concave at cervical third
up to its junction with the convex outline of up to its junction with the convex outline of
broad contact area.broad contact area.
Distal outline-straight above the cervical Distal outline-straight above the cervical
line to its junction with the convex outline line to its junction with the convex outline
of distal contact area-which is also the of distal contact area-which is also the
outline of the distal portion of distal cusp. outline of the distal portion of distal cusp.

9. Lingual aspect Lingual aspect
Cusps-3 two lingual and lingual portion of Cusps-3 two lingual and lingual portion of
distal cusp.distal cusp.

10. GroovesGrooves
LDG-extend short distance onlyLDG-extend short distance only

11. Mesial outline-convex from cervical line to Mesial outline-convex from cervical line to
MR.MR.
Distal outline-straight immediately above Distal outline-straight immediately above
the cervical line to a point immediately the cervical line to a point immediately
below the distal contact area.below the distal contact area.
Cervical line-irregular and tends to point Cervical line-irregular and tends to point
sharply toward the root bifurcation and sharply toward the root bifurcation and
immediately above it.immediately above it.

12. Lingual aspect Lingual aspect

13. Surface of crown lingually is smooth & Surface of crown lingually is smooth &
speroidal on each of the lingual lobes.speroidal on each of the lingual lobes.
Lingual aspect Lingual aspect

14. Mesial aspect Mesial aspect

15. BL measurement of crown is greater at BL measurement of crown is greater at
mesial aspect than distal.mesial aspect than distal.
BL measurement of root also greater at BL measurement of root also greater at
mesial aspect than distal.mesial aspect than distal.
Entire crown has lingual tilt. In relation to Entire crown has lingual tilt. In relation to
root axis. root axis.

16. Mesial aspectMesial aspect

17. Buccal outline-convex immediately above Buccal outline-convex immediately above
the cervical line.the cervical line.
Lingual outline-straight in lingual direction Lingual outline-straight in lingual direction
starting at the cervical line & joining the starting at the cervical line & joining the
lingual curvature at the middle thirdlingual curvature at the middle third
Cervical line- irregular & tends to curve Cervical line- irregular & tends to curve
occlusally about 1mm toward the center of occlusally about 1mm toward the center of
mesial surface of tooth.mesial surface of tooth.

18. Mesial aspectMesial aspect

19. Distal aspectDistal aspect

20. More tooth-seen from the distal aspect More tooth-seen from the distal aspect
because crown is shorter distally than because crown is shorter distally than
mesially and the buccal and lingual mesially and the buccal and lingual
surface of crown converge distally.surface of crown converge distally.
Buccal surface-shows more convergence Buccal surface-shows more convergence
than lingual surfacethan lingual surface

21. 0cclusal aspect0cclusal aspect

22. Occlusal aspect
Crown is pentagonal
(type trait)
B profile is longer than L
M profile is longer than D
B profile

3 regions

DB is the most prominent

Maximum BL diameter is
just D
to MB groove (type
trait)

23. Occlusal table
Fossae

Central fossa

2 M & D triangular fossae
Grooves

Central

MB & L terminate in the
Central Pit

DB (y-shape with MB & L
[type trait])
Pits

M, D & central

24. 0cclusal aspect0cclusal aspect

25. Pulp
MD section

2 horns

MB > DB

Narrow canals
BL section

2 horns

ML > MB

2 canals in M root
Transverse section

Rectangular

26. Differences between maxillary Differences between maxillary
molars and mandibular molarsmolars and mandibular molars
Maxillary molarsMaxillary molars
3-4 cusps; 3 roots3-4 cusps; 3 roots
Crown wider BL than MD.Crown wider BL than MD.
Large and small lingual Large and small lingual
cusps.cusps.
11
stst
molar wider on molar wider on
lingualthan buccallingualthan buccal
Carabelli cusp-presentCarabelli cusp-present
Oblique ridgeOblique ridge
Mandibular molarsMandibular molars
4-5 cusps;2 roots4-5 cusps;2 roots
Crown wider MD than BLCrown wider MD than BL
2 nearly equal sized 2 nearly equal sized
lingual cuspslingual cusps
11
stst
molars taper from molars taper from
buccal to lingual.buccal to lingual.
No cusp of CarabelliNo cusp of Carabelli
No oblique ridge.No oblique ridge.

27. Clinical Considerations with Clinical Considerations with
Mandibular MolarsMandibular Molars
The mandibular molars can present The mandibular molars can present
difficulty in positioning the oral evacuator difficulty in positioning the oral evacuator
because of the lingual inclination of the because of the lingual inclination of the
crowns.crowns.
Patients often have problems with their Patients often have problems with their
oral hygiene because of the lingual oral hygiene because of the lingual
inclination of the molar teeth, and they inclination of the molar teeth, and they
may miss cleaning the lingual gingiva with may miss cleaning the lingual gingiva with
the toothbrush.the toothbrush.