Premolars are transitional teeth that assist molars in grinding and canines in tearing food. There are typically two premolars in each quadrant of the mouth. The maxillary first premolar has two roots and two cusps. It is distinguished by having a mesial developmental depression and a longer mesial slope on the buccal cusp. The maxillary second premolar typically has a single root and rounded crown with cusps of similar length. The mandibular first premolar has a prominent buccal cusp and non-functional lingual cusp. It displays a mesiolingual developmental groove. The mandibular second premolar has two functional lingual c

1. Premolars

2. General Characteristics &
Functions:
• 2 premolars per quadrant
• At least 2 cusps, buccal cusp always larger
• Distal to the canines
• Succedaneous
• Shorter crown than anterior teeth

3. General Characteristics & Functions:
• ‘Transitional tooth’ during chewing, or
mastication
• It has properties of both the anterior canines
and posterior molars
• Assist molars in grinding, and canines in tearing
• Food can be transferred from the canines --
premolars -- molars for grinding
• Support facial muscles (aesthetics and speech)

4. Permanent Maxillary
First Premolars

5. General morphology
• From buccal aspect, crown resembles maxillary canine
• except that mesial slope is longer than distal slope
• Distinct depression on mesial surface, extending from cervical
half of crown to root bifurcation
• mesial developmental depression / fossa canina / canine
fossa
• *assumed to be caused by pressure from earlier completed
crown of maxillary first canine
• The only premolar with two roots
• *maxillary second premolars may also have double roots
• Buccal cusp larger than palatal cusp
• From occlusal aspect, buccal side wider than palatal side
• Two cusps separated by deep central groove

6. Principal identifying features
• Two roots, buccal and palatal (tend to curve distally)
• Two pulp horns and two pulp canals
• Two sharply defined cusps (buccal larger than palatal)
• Mesial developmental depression
• Mesial slope of buccal cusp longer than distal slope
• Palatal cusp tilts slightly mesially
• Occlusal outline more angular than maxillary second premolar

7. Buccal view features
• Widest mesiodistally (of all premolars)
• Mesial and distal contact – cervical to junction of
occlusal and middle third
• Mesial outline more rounded
• Imbrication lines and perikymata
• Mesial slope of buccal cusp is longer than distal
slope (helps to distinguish right from left)

8. Lingual view features
• Lingual surface is rounded in all
directions and smaller than buccal
surface
• Lingual cusp offset towards mesial
• Mesial cusp slope of lingual cusp is
shorter than distal cusp slope

9. Proximal view features
• Mesial developmental depression
extending to the root
• CEJ curvature deeper and more occlusal on
the mesial surface compared to distal
surface
• Distal surface is similar to mesial (except it
does not have a depression)
• More of occlusal surface shows because
distal marginal ridge is more cervical than
mesial marginal ridge

10. Occlusal view features
• Outline resembles a hexagon
• Wider buccolingually than mesiodistally
• Buccal ridge is prominent on buccal margin
• Lingual margin of occlusal outline is almost a
semicircle
• Lingual part narrower mesiodistally than
buccal part

11. Occlusal table components
• Four buccal cusp ridges descend from the
buccal cusp tip (buccal, lingual, mesial and
distal)
• Four buccal-inclined cuspal planes
(mesiobuccal, mesiolingual, distobuccal
and distolingual)
• Four lingual cusp ridges
• Four lingual-inclined cuspal planes

12. Occlusal table components
• Transverse ridge (buccal + lingual triangular ridge)
• Long central groove extending mesiodistally (dividing tooth
buccolingually)
• Marginal grooves (mesial and distal )
• Triangular grooves (mesiobuccal, distobuccal, mesiolingual and
distolingual)
• Two triangular fossa (mesial and distal)

13. Permanent Maxillary
Second Premolars

14. Chronology
Initial calcification : 2-2.5 years
Completion of crown : 6-7 years
Eruption : 10-12 years
Completion of root : 12-14 years

15. Maxillary 2nd Premolar (15 &
25)
• 5th Tooth from midline of maxilla.
• Maxillary 1st& 2nd premolar resemble
each other closely.
• Therefore comparisons are made in
relation to maxillary 1st Premolar to be
able to distinguish the features between
the two.

16. Description
• Less angular, more rounded crown
• Single root flattened mesiodistally
• Smaller crown cervico-oclusally and
mesiodistally, (it also may be larger in
those dimensions
• Root length slightly greater than maxillary
1st premolar
• No canine fossa

17. Buccal aspect

18. Buccal Aspect
• Shorter cusp, lest pointed
• Mesial slope of buccal cusp ridge is usually
shorter than the distal slope (opposite for 1st
premolar)
• Crown and root are thicker at the cervical
portion (not a rule)

19. Lingual aspect

20. Lingual Aspect
• Lingual cusp is longer
• Therefore crown is longer on lingual
side

21. Mesial aspect

22. Mesial Aspect
• Shorter Cusp , with the buccal and lingual cusp
more nearly the same length
• Greater distance between the cusp tips widens
the occlusal surface buccolingually
• Shallow developmental groove on the single
tapered root (not found on the Maxillary 1st
premolar)
• No developmental groove crossing the mesial
marginal ridge is evident.

23. Distal aspect

24. Distal Aspect
• Distal root depression is deeper than the mesial
depression ( opposite in maxillary 1st premolar;
depression on the mesial surface of the root)

25. Occlusal aspect

26. Occlusal Aspect
• Outline of crown is more rounded/oval rather than
angular
• Central developmental groove is shorter and more
irregular; tendency toward multiple supplementary
grooves radiating from the central groove
• Supplementary grooves terminate in shallow
depressions in the enamel that may extend to the
cusp ridges.
• Irregular and wrinkled occlusal surface

27. Permanent Mandibular
First Premolar

28. Chronology
• Initial calcification: 1 ¾ - 2 Years
• Crown completion: 5 – 6 Years
• Eruption: 10 – 12 Years
• Root completion: 12 – 13 Years

29. Tooth Identification
Universal Numbering System
Palmer Notation Method

30. Tooth Identification
International/FDI system

31. Buccal Aspect
• A large pointed buccal cusp is
seen
• Mesiobuccal cusp ridge is shorter
than the distobuccal cusp ridge
(similar to that of a canine)
• Concavity is seen occasionally at
the mesial and distal slope of the
buccal cusp

32. Lingual Aspect
• Crown tapers lingually
• Lingual cusp is non functional as
it is small and pointed
• Some lingual cusp is even shorter
than the cingulum of the maxillary
canine
• Mesiolingual developmental
groove is seen between the
mesiobuccal and lingual lobe

33. Mesial Aspect
• Lingual cusp is around two third
the size of the buccal cusp
• Extreme lingual slope is seen at
the mesial marginal ridge
• Between the mesial marginal ridge
and the mesiolingual cusp ridge is
the mesiolingual developmental
groove
• Mesial contact area is in the
middle third

34. Distal Aspect
• Distal marginal ridge is higher
compared to the mesial
marginal ridge and does not
have extreme lingual slope
• The cervical line curvature is
less curved

35. Occlusal Aspect
• Two depressions
(mesial and distal fossae)
seen on the occlusal surface
• Mesiolingual depression
and mesiolingual
developmental groove
commonly seen
• Lingual cusp tip is shifted
mesially

36. Root
• Single root
• On the mesial aspect of the root, a
deep developmental groove is seen
• On the distal aspect, a shallow
depression without any
developmental groove is present

37. Permanent Mandibular
Second Premolar

38. Chronology
• Initial calcification : 2 ¼ - 2 ½ years
• Completion of crown : 6-7 yrs
• Eruption : 11-12 years
• Completion of root: 13-14 yrs

40. Buccal side
R
-Resembles 1st
premolar
-Larger crown
-Shorter and less
pointed buccal cusps
-Broader

41. Lingual Side
R -Lingual cusp is smaller than
buccal cusp but it is larger than
mandibular first premolar
lingual cusp
-Occlusal surface of buccal
cusp can be seen

42. Mesial Side
• Dimension at cervical
3rd > occlusal 2rd
• Mesio-lingual cusp is
longer and sharper than
the mesiobuccal cusp
R

43. Distal Side
- Crown is narrower
distally than mesially
- Cervical line curves
occlusally
R

44. Variation
• May have 2 cusps
• Root may be partially bifurcated (Rare)

45. View Maxillary 1st Premolar Maxillary 2nd Premolar
Occlusal Larger Smaller
Edgy crown More rounded crown
Buccal cusp longer than lingual Two cusps same length
Long central groove Short central groove
More supplement grooves
Groove interrupts mesial marginal
ridge
Mesial marginal ridge not interrupted
Mesial/d
istal
Shorter root Longer root
Bifurcation with root trunk Single-rooted
Mesial developmental depression
(canine fossa)
Convex mesial surface
Buccal Mesial slope longer Distal slope longer

46. Mandibular 1st vs 2nd premolar
Traits Mandibular first premolar Mandibular second
premolar
Buccal cusp and buccal cusp
ridge
More prominent and longer Less prominent and shorter buccal
cusp
Lingual cusp One, nonfunctional
-very small
Usually 2 and functional
-longer
Lingual convergence Present, mesiolingual appears to be
pushed in
Little taper
Lingual groove Mesiolingual groove present Lingual groove between the 2
lingual cusps
Marginal ridge Mesial marginal ridge lower and
parallel to the buccal triangular
ridge
Distal marginal ridge lower and
mesial, and distal ridges are more
horizontal
Lingual crown tilt Severe lingual crown tilt less
Crown outline Diamond shaped Square / Round
Central groove and
Definite transverse ridge and central
transverse ridge
groove unlikely
3 cusp type has no transverse ridge
and ‘Y’ groove pattern

48. Maxillary vs Mandibular
Traits Maxillary Mandibular
Buccal ridge More prominent Less prominent
Buccal and lingual
cusp height
difference
Not very prominent More difference
Lingual tilt of crown Crown aligned over
the root
Crown tilts lingual
relative to the root
Crown width Wider bucco
lingually
Less oblong
buccolingually
Crown shape Oval or rectangular Square or round