The document provides information about the permanent posterior teeth, specifically the maxillary and mandibular premolars. It defines key anatomical terms and describes the identifying features, eruption timing, root morphology, occlusion relationships, and clinical considerations of each individual premolar tooth. The maxillary and mandibular first premolars generally have two cusps and one or two roots, while the mandibular second premolar uniquely has three cusps. The document emphasizes how the premolar teeth assist in grinding food through their interdigitation with antagonists in the opposing jaw.

1. Permanent Posterior
Teeth
MAXILLARY AND MANDIBULAR PREMOLARS

2. General Information
Key Terms
 Fossa: shallow depression named by its shape
 Circular fossa: rounded depression
 Triangular fossa: a “V” shaped depression
 Irregular fossa: A depression without definite shape
 Ridge: A linear elevation, named by its location or direction
 Marginal ridge: a ridge around the perimeter of the occlusal surface
 Oblique ridge: a ridge that diagonally crosses the occlusal surface– for example, from Mesiobuccal to
distolingal
 Transverse Ridge: A ridge that crosses the occlusal surface from buccal to lingual
 Triangular ridge: A ridge that slants from the cusp tip toward a groove and forms a triangular slope
 Cusp Ridge: a ridge that slopes from the tip of the cusp toward the mesial or distal surface

3. General Information
Key Terms
 Communution: chewing
 Intercuspation or Interdigitation: interlocking; a cusp-to-fossa
relationship of the maxillary teeth to the mandibular teeth
 How they come together
 Groove: a linear depression
 Each posterior tooth has a primary groove pattern unique to that tooth.
 Pit: a pinpoint depression where two or more grooves meet

4. General Information
Key Terms
 Root Trunk: portion of the root that extends from the cemento-enamel junction to the furcation
 Furcation: the area on the root trunk where it separates, AKA forking
 Bifurcation: divides into two trunks
 Trifurcated: divides into three trunks
 Pulp Horn: portion in the pulp chamber, or coronal pulp, that is elevated toward a cusp
 Pulp Canals: located in the root of the tooth
 Lobes: Centers of calcification. All teeth develop from AT LEAST 4 lobes. Anterior teeth=4
 Maxillary first and second and mandibular first premolar=4 lobes
 Mandibular second premolar=5 lobes
 For molars, the number of cusps = the number of lobes

5. General Information
 Because the mouth has less space toward the posterior region, distal
surfaces of the teeth are generally smaller than the mesial structures.
 Crowns tip distally so that more of the occlusal surface can be seen
when the distal side of the tooth is viewed.
 The cusps and gooves of maxillary teeth are arranged to contact the
occlusal surfaces of the mandibular cusp and grooves, so that they
fit together (interdigitate)
 Food can be easily chewed (comminution) because of this

6. Maxillary Premolars
4, 5, 12, 13

7. General Information
Maxillary Premolars
 There are four maxillary premolars; two in each quadrant
 They are named by their position in the arch from anterior to
posterior
 First and second premolars
 Maxillary premolars have one buccal and one lingual cusp
 Both premolars have prominent middle buccal lobe extending
from the cervix to the tip of the buccal cusp
 Similar to the canine, with shallow depressions on each side

8. General Information
Maxillary Premolars
 The root trunk of the maxillary first premolar is bifurcated, dividing
into two roots (buccal and lingual) that are only seen from the
proximal view.
 The maxillary second molar only has one root
 Viewed from the buccal, all premolars resemble one another, with
their pointed buccal cusp and tapered root
 Difficult to differentiate them
 Each has unique structure on another surface that will assist in its
identification.

9. General Information
Maxillary Premolars
 Premolars replace deciduous molars
 There are NO DECIDUOUS PREMOLARS
 The first premolar succeeds the deciduous first molar
 The second premolar succeeds the deciduous second molar
 With their triangular-shaped cusps and fossae, the
premolars are structured to assist with grinding of food.

10. Maxillary right second premolar (#4)Maxillary right first premolar (#5)

11. Maxillary First Premolar
5, 12

12. Maxillary First Premolar
#5 and #12
Eruption Date: 10-11 years old
First Evidence of Calcification: 1.5 years old
Crown Completion: 5-6 years old
Root Completion: 12-13 years old

13. Maxillary First Premolar
Function: grinding
Length of Crown: 8.5mm
Length of Root: 14mm
Antagonists: mandibular first and second
premolar

14. Maxillary First Premolar
Identifying Features
 Two cusps: one buccal, one lingual
 Two roots: one buccal, one lingual
 Two pulp canals: one in each root
 Resemble canine, but it shorter
 Mesial marginal groove
 Mesial root depression (mesial inter radicular groove) from CEJ to
furcation

15. Maxillary First Premolar
Buccal Surface
 Prominent buccal ridge
 Pointed buccal cusp
 Mesial side that is concave from cervix to the contact area; a
contact area that is in the middle of the surface; a cusp slope that is
straighter and longer than distal
 A distal side that is straight from the cervix to the contact area; a
contact area that is more occlusal than on the mesial; a cusp slope
that is shorter than the mesial
 Only buccal root is visible

16. Maxillary First Premolar
Lingual Surface
Both cusps are visible
A smooth lingual cusp that is shorter and
narrower than the buccal cusp
Visible mesial and distal surfaces

17. Maxillary First Premolar
Proximal Surface
 Two visible cusps; a lingual cusp that is 1mm shorter than the buccal
cusp
 Two visible roots (two pulp canals)
 Cusps that are within the confines of the root trunk, to absorb some
pressure from mastication.
 A mesial crown surface with the mesial marginal groove and a mesial
concavity that extends from the crown to the root bifurcation
 A distal crown surface with no grooves and no depressions
 Both roots straight until the apical third, the incline toward each other
 Root that bifurcates for one-half its length with a deep mesial
Interradicular groove

18. Maxillary First Premolar
Occlusal Surface
 Crown shape forms a hexagon
 Visible buccal and lingual surfaces, because cusps tip inward
 A buccal cusp centered between the mesial and distal side
 Fossa: mesial and distal triangular
 The slope from the tip of the buccal cusp to the central goove, and from the tip of the lingual
cusp to the central groove forms a triangular ridge.
 Major Grooves: central, Mesiobuccal, mesiomarginal, distobuccal, and distolingual
 Located at the base of the cusp
 There are also several supplementary grooves
 Common to find a pit where two or move grooves converge
 Mesial and distal pit likely

19. Maxillary First Premolar
Clinical Considerations
 Root length: 14mm
 Root depressions/furrows: deep depression on mesial surface extending from
crown to root furcation, where there is a deeper groove into the bifurcation.
Length of root trunk is approximately 7mm from cervix to bifurcation. Distal
root trunk has a depression extending from cervix to bifurcation.
 CEJ: very slight curvature (0-1mm toward occlusal) on both mesial and distal
 Cervical Area: concave on both mesial and distal surfaces, with deeper concavity
on the mesial surface
 Furcation: approximately 7mm from cervix

20. Maxillary Second Premolar
4, 13

21. Maxillary Second Premolar
#4 and #13
Eruption Date: 10-12 years old
First Evidence of Calcification: 2 years old
Crown Completion: 6-7 years old
Root Completion: 12-14 years old

22. Maxillary Second Premolar
 Function: grinding
 Length of Crown: 8.5mm
 Length of Root: 14mm
 Antagonists: mandibular second premolar and first molar

23. Maxillary Second Premolar
Identifying Features
 Two cusps: one buccal, one lingual
 One root, one pulp canal
 Resembles first premolar with slight variations
 Only one root
 Mesial buccal cusp slope is shorter than distal buccal cusp slope
 Both cusps are about the same length (lingual is slightly shorter)
 Mesial surface of the crown has no groove and no concavity
 From occlusal, there may be a mesial marginal groove, but it seldom extends onto mesial surface
 A shallow depression is evident on the mesial surface of the root

24. Maxillary Second Premolar
Clinical Considerations
 Root length: 14mm
 Root depressions/furrows: a shallow depression on both mesial
and distal surfaces extending the length of the root
 CEJ: very slight curvature (0-1mm toward occlusal) on both mesial
and distal surfaces
 Cervical Area: concave on both mesial and distal surfaces, with
deeper concavity on mesial surface
 Furcation: none

25. Mandibular Premolars
 Four mandibular premolars, two in each quadrant
 Mandibular first premolar has one buccal and one lingual
cusp.
 Differing from others, the mandibular second premolar
often has one buccal and two lingual cusps; it is the only
premolar with three cusps
 Both mandibular premolars usually have one root
 Mandibular premolars assist the maxillary premolars with
grinding and chewing food

26. Mandibular First Premolar
21, 28

27. Mandibular First Premolar
#21 and #28
Eruption Date: 10-12 years old
First Evidence of Calcification: 1 ¼ -2 years old
Crown Completion: 5-6 years old
Root Completion: 12-13 years old

28. Mandibular First Premolar
Function: grinding
Length of Crown: 8.5mm
Length of Root: 14mm
Antagonists: maxillary cuspid and first
premolar

29. Mandibular First Premolar
Identifying Features
Two cusps: one buccal, one lingual
Lingual cusp is small and non-functioning
One root, which sometimes tends to bifurcate
at the apex
Mesiolingual groove

30. Mandibular First Premolar
Buccal Surface
 Prominent buccal ridge
 Pointed cusp
 Narrow cervix
 A mesial side that is concave from the cervix to the contact area; a
contact area at the middle of the tooth; a mesial cusp slope
shorter than the distal
 A distal that is concave from the cervix to the contact area; a
contact area that is in the middle of the tooth; a cusp slope tha tis
longer than the mesial

31. Mandibular First Premolar
Lingual Surface
Visible mesial and distal surfaces
A short lingual cusp that is two-thirds the
height of the crown
A lingual cusp that is non functional
A mesiolingual groove the delineates the
lingual cusp

32. Mandibular First Premolar
Proximal Surface
Both cusps visible
The tip of the buccal cups centered over
the root
A visible occlusal surface

33. Mandibular First Premolar
Mesial Surface
 A mesial surface with a mesiomarginal ridge that is parallel
to the buccal triangular ridge
 a mesiolingual groove that interrupts the mesiomarginal
ridge
 a slight curve in the cervical line
 a broad root with deep developmental groove at the apical
third

34. Mandibular First Premolar
Distal Surface
 A distal surface with a distal marginal ridge that is
perpendicular to the buccal cusp ridge
 a marginal ridge that is uninterrupted
 a root that has a shallow depression but seldom has a
groove
 a cervical ling that is straight
 a concavity on the surface near the cervical line

35. Mandibular First Premolar
Occlusal Surface
A visible buccal surface
Two irregular fossae; mesial and distal
Grooves: mesiobuccal, distobuccal, and
mesiolingual
A prominent transverse ridge

36. Mandibular First Premolar
Clinical Considerations
 Root length: 14mm
 Root depressions/furrows: the mesial depression becomes a deep groove near
the apical third. This groove often bifurcates the root tip. The distal surface has a
shallow depression but no groove at the apical third.
 CEJ: very slight curvature (0-1mm toward occlusal) on both mesial and distal
surfaces
 Cervical Area: concave on both mesial and distal surfaces, with deeper concavity
on mesial surface
 Furcation: none

37. Mandibular Second Premolar
20, 29

38. Mandibular Second Premolar
#20 and #29
Eruption Date: 11-12 years old
First Evidence of Calcification: 2.5 years old
Crown Completion: 6-7 years old
Root Completion: 13-14 years old

39. Mandibular Second Premolar
Function: grinding
Length of Crown: 8mm
Length of Root: 14.5mm
Antagonists: maxillary first and second
premolar

40. Mandibular Second Premolar
Identifying Features
Three cusps: buccal, mesiolingual, distolingual
One root, one pulp canal

41. Mandibular Second Premolar
Buccal Surface
 A resemblance to the mandibular first
premolar, but slightly shorter and broader
 Contact areas in the middle of the tooth, but
slightly more occlusal than the first premolar

42. Mandibular Second Premolar
Lingual Surface
Three visible cusps: buccal, mesiolingual,
distolingual
Cusps are all functioning
Lingual cusps are shorter than buccal
cusp
A lingual groove that divides the two
lingual cusps

43. Mandibular Second Premolar
Proximal Surface
Cusps, which are in order of size are
buccal, mesiolingual, and distolingual
A broad root tapering at the apical
third

44. Mandibular Second Premolar
Mesial Surface
Visible buccal and mesiolingual cusps
Mesial marginal ridge that forms a right angle
with the buccal cusp slope
A cervical line that has a slight curvature

45. Mandibular Second Premolar
Distal Surface
Has more occlusal surface visible
All three cusps visible

46. Mandibular Second Premolar
Occlusal Surface
Two triangular fossae: mesial
and distal
Mesiobuccal, distobuccal, and
lingual grooves
Grooves that form a Y shape
on a three-cusp tooth

47. Mandibular Second Premolar
Clinical Considerations
 Root length: 14.5mm
 Root depressions/furrows: Generally smooth, but mesial may have a
shallow depression
 CEJ: Very slight curvature (0-1mm toward occlusal) on both mesial
and distal surfaces
 Cervical Area: slightly concave on both sides
 Furcation: none

48. Premolars cannot always be called
bicuspids because which of the
following may have more than two
cusps?
 Maxillary first premolar
 Maxillary second premolar
 Mandibular first premolar
 Mandibular second premolar

49. Which of the premolars has a cuspid
for an antagonist?
 Maxillary first premolar
 Maxillary second premolar
 Mandibular first premolar
 Mandibular second premolar

50. Most of the occlusal surface is visible
from the lingual view on which of the
following premolars?
 Maxillary first premolar
 Maxillary second premolar
 Mandibular first premolar
 Mandibular second premolar

51. Which of the premolars has a
nonfunctioning cusp?
 Maxillary first premolar
 Maxillary second premolar
 Mandibular first premolar
 Mandibular second premolar

52. The mandibular first premolar replaces
which of the following deciduous
teeth?
 Deciduous first premolar
 Deciduous second premolar
 Deciduous first molar
 Deciduous second molar