Lectures on Dental Anatomy

1. BASIM ZWAIN LECTURES
DENTAL ANATOMY
PERMANENT MAXILLARY MOLARS
Professor Dr. Basim Zwain
Faculty of Dentistry
University of Kufa
Basim.zwayen@uokufa.edu.iq

2. PERMANENT MAXILLARY MOLARS
The largest and strongest maxillary teeth.
Have 3 roots 2 buccal, and 1 lingual.
Unprecedented as they erupt behind deciduous molars.
The main functions of molars is grinding the food, and
supporting the muscles of mastication, and vertical
dimension.
They decrease in size as they go posteriorly therefore the
first molar is the largest, then the second molar and lastly
the third molar.

3. MAXILLARY FIRST MOLAR
It is the largest tooth in the maxillary arch.
Principal identifying features
1- Rhomboidal occlusal outline.
2- The cusp of carabelli (non functional cusp), on the lingual
surface of the mesiolingual cusp.
3- There is an oblique ridge between the mesiolingual and
distobuccal cusps.
4- Three well separated and well developed roots. The lingual
root is the longest.

4. MAXILLARY FIRST MOLAR
Buccal aspect
1- The crown is roughly
trapezoidal, and the cervical
line shows little convexity,
which is directed towards
the root.
2- The mesial outline of the
crown is straight curving
occlusally as it reaches the
contact area which is at the
junction of the occlusal and
middle thirds.
3- The distal outline of the
crown is convex, the crest
of curvature is at the centre
of the middle third.

5. MAXILLARY FIRST MOLAR
Buccal aspect
4- The mesiobuccal cusp is broader
than the distobuccal cusp, and its
mesial and distal slopes meet at an
obtuse angle, while the mesial and
distal slopes of the distobuccal
cusp meet at sharper right angle.
We may see the lingual cusps.
5- The buccal developmental groove
divides the 2 buccal cusps in equal
distance and it terminates apically.
6- The 3 roots are visible and inclined
distally. The lingual root is the
longest, and the mesiobuccal and
distobuccal roots are equal in
length.

6. MAXILLARY FIRST MOLAR
Lingual aspect
1- Only lingual cusps can be seen.
The mesiolingual cusp is the
largest cusp of in the tooth, and
accounts to 3/5 of the mesiodistal
width of the tooth, the distolingual
cusp accounts to 2/5.
2- The lingual developmental groove
starts approx. at the center
mesiodistally, and curves sharply
distally, then continues on the
occlusal surface.

7. MAXILLARY FIRST MOLAR
Lingual aspect
3- The fifth cusp (cusp of Carabelli) is
1.5 mm cervical to the mesioling.
cusp tip. An irregular dev. groove
separates the cusp from the
mesiolingual cusp.
4- There are 3 roots visible, the lingual
root makes most of the aspect.

8. MAXILLARY FIRST MOLAR
Mesial aspect
1- The buccal outline has a crest of
curvature within the cervical third,
then it continues with a convex
outline until the tip of the cusp.
2- The lingual outline has a crest of
curvature within the middle third,
and it shows a convex pattern
until it reaches cusp of Carabelli
which shows another convexity.
3- The mesial marginal ridge is
located at a level 1/5 of the height
of crown from the tip of the cusps.
4- The cervical line curves occlusally
about 1mm.

9. MAXILLARY FIRST MOLAR
Mesial aspect
5- The intercuspal distance of the 2
mesial cusps is a little more than
half the buccolingual dimension
of the crown.
6- The mesial contact area is buccal
to the buccolingual center of the
crown.
7- The lingual and the mesiobuccal
roots are seen, and the latter is
wider buccolingually.

10. MAXILLARY FIRST MOLAR
Distal aspect
1- The general outline is similar to that
of the mesial aspect, but the
buccolingual measurement is more
mesially than distally due to the tilt
of the buccal side of the crown.
2- The distal marginal ridge is located
more cervically so that we can see
part of the occlusal surface.
3- The cervical line’s curvature is zero.
4- All the 3 roots are visible. The
distobuccal root is the smallest
one.

11. MAXILLARY FIRST MOLAR
Occlusal aspect
1- The occlusal outline is
rhomboidal, with the mesial
and lingual measurements
being greater than distal and
buccal measurements
respectively.
2- Four well developed cusps,
mesiolingual (the largest),
then mesiobuccal, then
distolingual, then
distobuccal, then fifth
(Carabelli’s) cusp.

12. MAXILLARY FIRST MOLAR
Occlusal aspect
3- The mesiobuccal, and
distolingual line angles
are acute, and
mesiolingual, and
distobuccal line angles
are obtuse.
4- There is an oblique ridge
made from the union of
the ∆ ridge of the
distobuccal cusp and the
distal ridge of the
mesiolingual cusp. It
crosses the occlussal
surface obliquely.

13. MAXILLARY FIRST MOLAR
Occlusal aspect
5- There are 4 fossae
a) Major fossae
(i) Central fossa is roughly
triangular in shape, mesial
to oblique ridge.
(ii) Distal fossa is linear, distal
to oblique ridge.
b) Minor fossae
(i) Mesial ∆ fossa. It is distal
to mesial marginal ridge.
(ii) Distal ∆ fossa. It is mesial
to distal marginal ridge.

14. MAXILLARY FIRST MOLAR
Occlusal aspect
6- There are 6 developmental
grooves
a) Central developmental
groove. From central pit to
mesial ∆ fossa.
b) Buccal developmental
groove. From central pit
buccally between the
mesiobuccal and
distobuccal cusps.
c) Distal oblique groove. From
distal ∆ fossa going
obliquely.

15. MAXILLARY FIRST MOLAR
Occlusal aspect
6- There are 6 developmental
grooves
d) Lingual developmental
groove joins distal oblique
groove, goes between
mesiolingual and
distolingual cusps and
travels cervically.
e) Transverse groove of the
oblique ridge. It crosses the
oblique ridge.
f) Fifth cusp groove. Between
the fifth cusp and the
mesiolingual cusp.

16. MAXILLARY FIRST MOLAR
Occlusal aspect
7- There are 3 pits
a) Central pit is located in the
deepest part of the central
fossa. It is a result of the
junction of central and
buccal developmental
grooves.
b) Mesial pit is located in the
deepest part of the mesial
∆ fossa.
c) Distal pit is located in the
deepest part of the distal ∆
fossa.

17. MAXILLARY SECOND MOLAR
Principal identifying features
1- Fifth cusp is less evident.
2- Roots are less divergent, and may
be joined together.
3- Both distal cusps are less
developed.
4- The crown is smaller in overall
dimensions than the 6.

18. MAXILLARY SECOND MOLAR
Buccal aspect
1- The crown is shorter and
narrower mesiodistally.
2- The distobuccal cusp is smaller,
so some part of the distal
surface is seen.
3- The roots are closer together.

19. MAXILLARY SECOND MOLAR
Lingual aspect
1- The distolingual cusp is smaller.
2- Part of the distobuccal cusp is
seen distal to the distolingual
cusp.
3- No evidence of presence of the
fifth cusp.

20. MAXILLARY SECOND MOLAR
Mesial aspect
1- The divergence of the roots is less
than that of the max. first molar.

21. MAXILLARY SECOND MOLAR
Distal aspect
1- Because the distobuccal cusp
is smaller than the
mesiobuccal cusp more of the
mesiobuccal cusp is seen.

22. MAXILLARY SECOND MOLAR
Occlusal aspect
1- Rhomboidal shape of occlusal
aspect is more visible (acute angles
are less and obtuse angles are
more).
2- Buccolingual diameter is the same as
first molar, but mesiodistal diameter
is 1mm less.
3- The distal cusps are smaller and less
developed.
4- No fifth cusp.

23. MAXILLARY THIRD MOLAR
Principal identifying features
1- Triangular occlusal outline.
Distolingual cusp is often
absent.
2- Roots are shorter,
convergent, often fused, and
usually are 3 in numbers.
3- smallest maxillary molar.
4- The mesiolingual cusp is the
largest.

24. MAXILLARY THIRD MOLAR
5- It may have many variations
occlusally:
a)Heart shape type with three
cusps.
b) Rhomboidal shape type with
four cusps.
c) One cusp type (peg shaped).
d) Congenitally missing.

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