This document provides information about the maxillary and mandibular first and second premolars. It describes the anatomical features of each tooth, including the number of cusps and roots, eruption timing, outline of facial and lingual surfaces, contact areas, and occlusal morphology. Key details provided include differences in cusp shape, prominence of ridges, position of developmental grooves and fossae, and root bifurcation location between the first and second premolars. Diagrams illustrate the characteristic features and anatomical terminology.

3. BY
Dr. Rehab Ali
Lecturer
Oral biology department

4. Maxillary first premolar
It has 5 aspects:
Buccal
Lingual
Mesial
occlusal
Distal

5. Maxillary second premolar
It has 5 aspects:
Buccal
Lingual
Mesial
occlusal
Distal

6. 1.5-2y
2-2.5y
4-5m
Eruption
Root
completed
10-11
10-12
10-12
11-12
11
9
years
3+
4
4
5
5
3
3
Crown
completed
years
5-
Beginning
of calc.
(month)

7. Geometric outline of the crown
• Facial and lingual aspects have
trapezoidal out line.
The smallest uneven side
cervically.

8. Facial Outlines and surface anatomy of the crown
4
D
M
B cusp is long and pointed
Longer M slope than D
Mesial contact area in the M1/3
while distally more occlusal.
Cervical line curved root wise.
5
D
M
B cusp is short and blunt
Shorter M slope than D
Mesial contact area at the jun. of
O and M1/3 while distally more
cervically.
Cervical line less curved.

9. 4
D
M
5
D
M
Prominent B ridge
Less prominent B ridge
Short root.
Longer root.

10. Lingual outline and surface anatomy of the crown
4
The L cusp is shorter
by 1 mm than the B
cusp.
80%, 2 roots
L root is shorter than
B root.
5
The L and B cusps
are nearly of same
height (0.5 mm shorter)
Rare to have 2 roots(20%)
In case of two roots the
L root is shorter.

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12. Geometric outline of the proximal aspect
Distal aspect
Trapezoidal in shape
Mesial aspect
Smallest uneven sides occlusaly

13. Mesial aspect
4
5
B cusp is longer than L
cusp by 1mm
The cusps are nearly at the
same level.
The occlusal table is
wide.
The occlusal table is
wide,but narrower than 4.
Mesial DG and canine
fossa.
Root trunk about half the
root length.
The crown surface is smooth
and convex while root has
shallow developmental
depression.

14. Mesial aspect
4
MMR at the M1/3
Contact area:
At the middle third (OC
dimension) and slightly
buccal to midline (BL
dimension)
5
MMR positioned more
occlusal.
At the jun. of O and M 1/3
(OC dimension) and
slightly buccal to midline
(BL dimension)

15. Distal aspect
4
5
DMR more occlusal than MMR
DMR more cervical than MMR
CA occlusally positioned and
more buccally than MCA.
CA cervically positioned and
more buccally than MCA.

16. Distal aspect
4
Root trunk is long as
the bifurcation is near
apical 1/3
Surface is smooth and
convex except shallower
DD on the root trunk than
mesially.
5
One root and if 2 the
bifurcation will be
more apically.
Surface is smooth and
convex except deeper
DD in the middle of the
root than mesially.

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18. Occlusal aspect
5
4
D
M
It’s hexagonal
D
M
It’s oval
B & L triangular ridges.
B & L triangular ridges.
M & D marginal ridges
Thicker M & D MRs

19. 4
5
Long Central DG
Shorter Central DG.
M developmental groove
Not found.
M and D
M and D
Not found.
fossae.
fossae.
Supplemental grooves
could be found (wrinkled)

20. Pulp cavity.
MD section
Root canals
BL section
2 root canals (B&L)
but rare 3 canals
L canal is larger
&more accessible
Narrow
Wide
Pulp chamber
In 5 one centralized large canal is present, but may two
canals could be exist.

22. Mandibular first premolar
It has 5 aspects:
Buccal
Lingual
Mesial
occlusal
Distal

23. Mandibular second premolar
:It has 5 aspects
Buccal
Lingual
Mesial
occlusal
Distal

24. Geometric outline of the crown
• Facial and lingual aspects have somewhat
wider trapezoidal shape due to wider cervical
third than 4.

25. Facial Outlines and surface anatomy
4
B cusp
pointed and long
Well prominent B ridge
5
B cusp
short and less pointed
Less prominent B ridge

26. Lingual outline and surface anatomy
4
5
Two cusp type
The L cusp is short and small reaching 2/3
. the crown length and has a pointed tip
L cusp is shorter and smaller
than B cusp but larger than of 4
The lingual surface is convex with
maximum convexity at M 1/3
The surface convex with
.maximum convexity at O1/3
ML developmental groove at the ML
.line angle
No MLDG

27. :Three
cusp type 5
ML cusp is longer and larger than M
DL cusp. They both shorter than B
. cusp and less pointed
The surface convex with maximum
.convixty at O1/3
The L developmental groove between
the 2 cusps
N.B. Very little or no lingual
.convergancy
D

28. Proximal outlines
4
5
.Rhomboidal
in shape with narrow occlusal table
Lingual inclination well
prominent
Lingual inclination less
prominent

29. 4
5
Maximum convexity at M1/3
Maximum convexity at O1/3
The L cusp is short and small reaching 2/3
the crown length
.The B cusp centered over the root
L cusp is shorter and smaller than
B cusp but larger than of 4
B cusp tip on line with junction
.of B & M 1/3 of the root
The mesial MR is oblique while
distally is straight
The mesial and distal marginal ridges
are straight

30. Proximal surface anatomy
Distal aspect
Mesial aspect
.
Contact area
nearly at same level
Contact area is broader,
MCA is directly
situated cervically and lingually
below the B
cusp
ML developmental groove
positioned.
present at the junction of L
. and M surfaces

31. Mesial aspect
Distal aspect
:Three cusp type
ML cusp is longer and larger than
. DL cusp
DL cusp is shorter and smaller
. than ML cusp
Both lingual cusps are shorter than the buccal cusp
and less pointed
Surface anatomy is simillar to that of 4

32. Geometric outline of the occlusal aspect
4
:Two cusp type
.It’s diamond-shaped
.Lingual convergence is sharp
:Three cusp type
The outline is square
5
The outline is oval
Slight lingual convergence

33. :Surface anatomy of occlusal aspect
4
:Elevations
5
.B triangular ridge
.L triangular ridge
Transverse ridge
M & D marginal ridges

34. 4
:Depressions 5
Central developmental groove Central developmental groove
M and D triangular fossae )M
fossa is oval while D fossa is
circular,larger & deeper(
snake eyes
Mesiolingual developmental
groove
.(H
or U shaped)
.M and D triangular fossae
both r circular,but D is)
(deeper

35. :Three cusp type
:Elevations
.B
triangular ridge
(. L triangular ridges )ML &DL
M & D marginal ridges
:Depressions
Developmental groove )Y shape formed of MB,DB & L
.(grooves
.M and D triangular fossae
Central fossa with central pit.
Remember the supplemental grooves!!!