Anatomical features of a permanent maxillary premolars.

1. Maxillary
Premolars
Dr. Ramil B. Simsuangco
Oral Anatomy Professor
College of Dentistry
Manila Central University

2. GENERAL DESCRIPTION
◦ There are eight(8)
premolars in the
human dentition; 2
upper, 2 lower
◦ For Maxillary:
Using 2-digit system
with notation tooth
numbers
14,15,24,25
14 24
15 25

3. Functions of Premolars
 1st premolars function with canine
1) In shearing or cutting food
2) Support the corners of the
mouth
 2nd premolars function with molars
1) To masticate
2) To maintain vertical dimension

4. DEVELOPMENTAL
LOBES
1) Developmental lobes
◦ Facial surface develops from
three lobes
◦ Buccal ridge more prominent in
maxillary arch
◦ One developmental lingual lobe
(cingulum or cusp)
◦ Exception:
Mandibular 2nd
premolar (can have 2 lingual
lobes)
123 1
exception
1 2

5. CURVATURE OF CEJ
◦ Proximal CEJ is
concave
Facial and lingual CEJ is
convex apically

6. CONVEXITY
Convex
4) Root shape
◦ Lingual and facial
surfaces are convex
◦ Lingual side of the root and crown are
narrower than the facial side

7. Differences To Anterior Teeth
Buccal
Labial
1) Terminology
Facial
◦ Facial surface now correctly called the
buccal
surface (not labial)
◦ Possess occlusal surfaces not incisal edges

8. Differences To Anterior Teeth
2) Occlusal surface versus incisal edges
◦ No incisal edge or cingulum
◦ Possess one facial cusp and one or two
lingual cusps
Incisal
Occlusal
Cingulum

9. CONTACT AREAS
Proximal contact areas are
more cervically located
than anterior teeth

10. BUCCAL ASPECT
Crown is broadest at level of
contact areas and
narrow at the cervix
 Has trapezoidal shape
 Mesial and distal sides straight from
contact to cervix

11. BUCCAL ASPECT
2) Cusp slope size
◦ Buccal cusp tip often slightly
mesial to long axis (like canine)
◦ Mesial cusp slope shorter than the distal
◦ Exception: Maxillary first premolar - cusp
tip
slightly to the distal

12. BUCCAL ASPECT
Buccal Ridge
4) Crown morphology
◦ Buccal surface is convex
◦ Buccal ridge runs occluso-cervically in the
middle of the crown

13. Buccal Aspect - Buccal Cusp
Tip Location
 Exception: Maxillary first
premolar has a cusp tip slightly
to the distal of the mid-tooth line
 This creates a mesial cusp ridge
longer than the distal cusp ridge
 The opposite is true for maxillary
second premolars

14. Buccal Class Traits Of
Premolars
Distal
Bend
5) Root
◦ Buccal surface is convex with an apical
taper
◦ The apical third may possess a distal bend

15. LINGUAL ASPECT
Exception 29
 Crown is narrower on the lingual
than the buccal
 Exception: Mandibular 2nd premolars
with three cusps
 Lingual surface is convex
 Mesial and Distal slope meets at 90 deg.
angle

16. Lingual Class Traits Of
Premolars
2) Root
◦ Lingual surface is convex and narrower
mesiodistally than the facial aspect

17. Lingual Aspect - Lingual Cusp
Position
 The cusp tip always bends
towards the mesial on
unworn
lingual cusps
 This makes it easy to tell
right from left
M

18. MESIAL ASPECT
1) Triangular ridges
◦ Buccal and lingual triangular ridges meet in
the central groove forming the transverse
ridge
◦ Exception: Mandibular 2nd premolar (three
cusp form)
Mesial
View

19. MESIAL ASPECT
Mesial
View
3) Marginal ridges
◦ Mesial marginal ridge more occlusal/higher
than the distal
◦ Exception: Mandibular first premolars

20. DISTAL ASPECT
 Crown outline is trapezoidal
 Crown is convex, with small flattened
area just cervical to the CA
 No evidence of deep developmental
groove and depression

21. Occlusal Class Traits Of
Premolars
4 5 28 29
1) Tooth proportions
◦ Considerably wider faciolingually than
mesiodistally

22. Occlusal Class Traits Of
Premolars
4 5 28 29
2) Occlusal table
◦ Both buccal and lingual cusps have mesial and
distal cusp ridges or slopes which travel
cervically to join the marginal ridges
◦ These structures form the occlusal table (or
outline)

23. Occlusal Class Traits Of
Premolars
4 5 28 29
4) Grooves and fossae
◦ Central developmental groove runs
mesiodistally
◦ Exceptions: Mandibluar 1st premolar and
three-cusped 2nd premolar
◦ Fossae possess supplemental grooves to the
buccal and lingual

24. Buccal Aspect - Contacts
 Mesial contact is in the middle third, near the
junction of the middle and occlusal thirds
 Distal contact is slightly more cervical (still in
middle third)
More
Cervical
As We
Go Distal

25. COMPARISON OF CUSP
HEIGHT
(Max. 1st PM and Max. 2nd PM)
Mesial Distal
B
5 4 4 5
 From this view buccal cusp tip is noticeably longer
than the lingual cusp tip on maxillary first premolars
 Nearly equal length on second premolars

26. Proximal Aspect - Marginal Ridge
Mesial Distal
 Distal marginal ridge is more cervical than
mesial marginal ridge
 Can see more of the occlusal surface from
the
distal
B
5 4 4 5

27. NUMBER OF ROOT
Mesial Distal
B B
5 4 4 5
 Frequently two(2) roots on Maxillary 1st
premolar
 The bifurcation is in the apical third to
half of the root

28. Proximal Aspect - Root
Depressions
Mesial Distal
B B
5 4 4 5
 Maxillary first premolar has prominent root
depressions
 On second premolars there is a mesial and distal root
depression, usually more prominent on the distal

29. Occlusal Comparison of
1st and 2nd premolar

30. MDD and MMDG
Mesial B Mesial Developmental
Depression(MDD)- mesial
concavity on the crown and
root
5 4 Mesial Marginal
Developmental
Groove(MMDG)-
developmental groove on the
mesial marginal ridge, in
alignment with mesial
developmental depression