1. IN THE NAME OF ALLAH THE MOST GRACIOUS THE MOST MERCIFUL
بسم الله الرحمن الرحيم
IN THE NAME OF ALLAH THE MOST GRACIOUS THE MOST MERCIFUL

2. PREMOLARS

3. Premolars Relations: 4 & 4 contact: 3 & 3 mesially and 5 & 5 distally
There are four maxillary and four mandibular premolars.
Relations:
4 & 4 contact:
3 & 3 mesially and
5 & 5 distally
5 & 5 contact:
4 & 4 mesially and
6 & 6 distally.

4. General Features of Premolars
They are transitional teeth located between the canine and molar teeth.
By definition: Premolars are permanent teeth distal to the canines, and successors to deciduous molars.
There are two premolars per quadrant and are identified as first and second premolars.

5. General Features of Premolars
They have usually two cusps(bicuspid) :
One large buccal cusp,
Smaller lingual cusp
The lower second premolar may- sometimes- have two lingual cusps.

6. MAXILLARY FIRST PREMOLAR
Chronology:
Enamel organ appearance: 7 mIU.
Beginning of calcification: 1½-1¾y
Crown completed: – 6y
Eruption: – 11y
Root completed: – 13y
Number of lobes: four lobes :
Three buccally
One lingually

7. Buccal Palatal Mesial Distal Occlusal
No. of roots
Two roots(60%).
One root(40%).
Occlusal

8. Geometric Outline of the Crown The smallest of the uneven sides
Facial and lingual aspects have trapezoid out line.
The smallest of the uneven sides 
cervically.

9. Buccal Aspect Outlines:
Mesial and distal outlines: are nearly concave and both become convex at cont. areas.
Buccal Aspect
Mesial and distal cusp slopes: are also slightly concave D M
Contact areas:
Mesially: at the middle third(broad) Distally: Little more cervically than the mesial one(broader)
M. slope > D. slope(sometimes convex)
Bucc. cusp pointed, long and the tip is slightly distal to the vertical axis
Cervical line:
convex rootwise.

10. Surface Anatomy of the Crown
Elevations:
Buccal Aspect
The surface is convex with maximum convexity at cerv. 1/3 representing cervical ridge
The middle lobe is prominent buccally forming bUCCAL ridge.
Depressions:
Shallow depressions are present mesial and distal to the buccal ridge.

11. Outline and Surface Anatomy of the Root
Buccal Aspect
The M and D outlines of the root taper to a pointed apex curved distally.
If two roots:
The buccal root hides the lingual root as it is shorter and narrower than the buccal root. D M .
The surface of the root is convex and smooth

12. Lingual Aspect Lingual convergence: Outlines:
Ling.s. is narrower than buccal s.
Outlines:
M and D outlines are convex M D
The L. cusp is shorter by 1 mm but sharper than the B cusp
The D slope of L cusp is longer than M slope
Cervical line: is convex rootwise.
Surface Anatomy :
The surface is convex with maximum convexity at the middle 1/3.
The root is convex.

13. Outline and Surface Anatomy of the Root
Lingual Aspect
The M and D outlines of the root taper to a pointed apex that curves distally. M D
If one root:
The ling. Surface is convex and narrower
MD than the buccal portion.
If two roots:
The lingual root appears shorter and narrower than the buccal root.

14. The smallest of the uneven sides
Proximal Aspects
Mesial aspect
Distal aspect
Proximal aspects have trapezoid out line.
The smallest of the uneven sides 
occlusally.

15. Outlines of Proximal Aspects
Mesial aspect
Distal aspect
Buccal outline :
Convex with maximum convexity at cervical 1/3
representing cervical ridge.
Lingual outline: convex with maximum convexity
at middle 1/3
Cervical line: curves occlusally and less curved distally

16. Mesial aspect Distal aspect Occlusal outline:
Bucc. cusp is longer than Ling. cusp by 1mm.
Bucc. cusp tip is below the center of Bucc root.
Ling. cusp tip is on line with Ling. border of the ling. root.
MMR concave, at the junction of occ. & middle thirds.
DMR more cervical.

17. Cervical line curvature:
Surface Anatomy of
Proximal
Aspects
Mesial Aspect
Distal Aspect
Contact areas:
At the middle 1/3,
bucc. to midline
More cervically positioned & more buccally.
Mesial marginal developmental groove crossing MMR and located lingual to the contact area.
Smooth and convex surface except for a small flat area cervical to contact area(no canine fossa or develop. groove crossing the DMR) .
Mesial Developmental depression in the crown & continues on the root  (canine fossa).
Cervical line curvature:
Curves occlusally
Less curved

18. Outline and Surface Anatomy of the Root
Mesial Aspect
Distal Aspect
In case of two roots (more common).
Root trunk about half the root length.
Root trunk is longer as bifurcation is near apical 1/3
Surface is smooth and convex except deep developmental depression below bifurcation that continue with the mesial dep. on the crown.
Surface is smooth and convex except shallow devlop. depr. on the root trunk

19. In case of one root (less common)
The B and L outlines tapere to a blunt apex in line with the center of the crown.
The surface is smooth and convex except for a shallow depression in the center that is deeper mesially than distally.

20. Occlusal Aspect Hexagonal Geometric outline
2 equal buccal sides (MB, DB)
M side shorter than D side.
ML side shorter than DL side.
Thickness(BL) is greater than width(MD).
The crown is wider buccally than lingually, due to lingual convergence of the crown D M

21. Occlusal Aspect Surface anatomy Elevations: Depressions:
Bucc. triangular ridge.
Ling. triangular ridge. D M
M & D marginal ridges
Depressions:
Central developmental groove
M and D triangular fossae.
M marginal developmental groove

22. The most charecteristic identifying feature of the max. first premolar
Mesial marginal
developmental groove

23. MAXILLARY
FIRST PREMOLAR

25. lingual canal is larger & more accessible
PULP CAVITY
MD section
BL section
Root canals:
2 root canals (B&L) but rarely 3 canals
lingual canal is larger & more accessible
Cervical cross sec.
oval or kidney shaped
Wide
Narrow
Pulp chamber:

26. MAXILLARY SECOND PREMOLAR

27. MAXILLARY SECOND PREMOLAR
Chronology:
Enamel organ appearance: 8 mIU.
Beginning of calcification: 2-2¾y
Crown completed: – 7y
Eruption: – 12y
Root completed: – 15y

28. Maxillary Second Premolar
Buccal
Lingual
Mesial
Distal
Occlusal

29. Comparison between Maxillary First and Second Premolars
Facial & Lingual Aspects
Geometric Shape of the Crown
Trapezoid shape.
The smallest of the uneven sides cervically.

30. Buccal Aspects D M D M Maxillary First Premolar
Maxillary Second Premolar D M D M
B cusp is long and pointed
B cusp is short and not pointed
Longer M slope than D
Shorter M slope than D
Mesial contact: in the middle1/3 while distally more cervical.
Mesial contact : in the occ.1/3 while distally more cervically.
Cervical line curved rootwise.
Cervical line less curved.

31. Buccal Aspects Less prominent B ridge Prominent B ridge Longer root.
Maxillary First Premolar
Maxillary Second Premolar
Less prominent B ridge
Prominent B ridge
Narrow cervical portion.
Wider cervical portion.
Short root.
Longer root.

32. Lingual Aspects The L cusp is shorter by 1 mm than the B cusp.
Maxillary First Premolar
Maxillary Second Premolar
The L cusp is shorter by 1 mm than the B cusp.
The L and B cusps are nearly of same height.
60% has 2 roots with
L root is shorter than B root and its apex is pointed.
Rarely has 2 roots
In case of two roots the L root is shorter & its apex more blunt.

33. Mesial and Distal Aspects
Geometric Shape of the Crown 4 5
Trapezoid in shape B L
Smallest of the
uneven sides:
 occlusaly

34. Mesial Aspects The cusps are shorter & nearly at the same level.
Maxillary First Premolar
Maxillary Second Premolar
B cusp is longer than L cusp by 1mm
The cusps are shorter & nearly at the same level.
The occlusal table is wide.
The occlusal table is narrow
Mesial marginal dev. groove in crown & deep canine fossa extending on root surface.
The crown surface is smooth & convex. The root has shallow dev. dep.

35. Mesial Aspects MMR at the junction of M1/3 &Occ1/3
Maxillary First Premolar
Maxillary Second Premolar
MMR at the junction of M1/3 &Occ1/3
MMR positioned more occlusal.
Contact area:
At the occlusal third (OC dimension) and slightly buccal to midline (BL dimension)
At the middle third (OC dimension) and slightly
buccal to midline (BL dimension)

36. Distal Aspects Maxillary First Premolar Maxillary Second Premolar
DMR more cervical than MMR
DMR more cervical than MMR
CA cervically positioned and more buccally than MCA.
CA cervically positioned and more buccally than MCA.
Smooth and convex surface except for a small flat area cervical to contact area.
Smooth and convex surface.

37. Distal Aspects
Maxillary First Premolar
Maxillary Second Premolar
One root and if 2 the bifurcation will be more apically.
Root trunk is long as the bifurcation is near apical 1/3
Surface is smooth and convex except deeper DD in the middle of the root than mesially.
Surface is smooth and convex except shallower DD on the root trunk than mesially.

38. Occlusal Aspect hexagonal oval(less angular) B & L triangular ridges.
Maxillary First Premolar
Maxillary Second Premolar
hexagonal
oval(less angular)
B & L triangular ridges.
B & L triangular ridges.
Thin M & D marginal ridges
Thicker M & D marginal ridges

39. Occlusal Aspect M and D fossae. M and D fossae.
Maxillary First Premolar
Maxillary Second Premolar
Shorter Central dev gr.
Long Central dev.gr.
M marginal dev. groove
Not present. Multiple supplemental grooves
M and D fossae.
M and D fossae.
Thin marginal ridges
Thick marginal ridges

40. MAXILLARY SECOND PREMOLAR

41. PULP CAVITY of maxillary second premolar
MD section
BL section
Root canals:
2 root canals one B & one L
Dentin island
Lingual
horn
Cervical cross sec.
Buccal horn
(longer)
Narrow(MD)
Wide(BL)
Oval or kidney

42. THANKS

43. IN THE NAME OF ALLAH THE MOST GRACIOUS THE MOST MERCIFUL
بسم الله الرحمن الرحيم
IN THE NAME OF ALLAH THE MOST GRACIOUS THE MOST MERCIFUL

44. MANDIBULAR FIRST PREMOLAR
Chronology:
Enamel organ appearance: 7 miu.
Beginning of calcification: 1 ¾ - 2y
Crown completed: – 6y
Eruption: – 12y
Root completed: – 13y

45. Mandibular First Premolar
Buccal
Lingual
Mesial
Distal
No. of roots
One root
Occlusal

46. Geometric Outline of the Crown The smallest of the uneven sides
Facial and lingual aspects have trapezoid out line.
The smallest of the uneven sides 
cervically.

47. Buccal Aspect Outlines: Mesial and distal outlines: are nearly concave
Bucc. cusp pointed and long
Mesial(shorter) and distal cusp slopes: are also slightly concave
Contact areas:
Mesially and Distally: are nearly at the same level, just occlusal to the middle of the crown. M D
Cervical line:
convex root wise.

48. Surface anatomy of the crown
Elevations:
Buccal Aspect
The surface is convex with maximum convexity at C 1/3 representing cervical ridge
The middle lobe is convex buccally forming prominent BUCCAL ridge.
Depressions:
Shallow depressions are present mesial and distal to the buccal ridge.

49. Buccal Aspect Outline and Surface Anatomy of the Root
The M and D outline of the root tapered to a pointed apex that curved distally(similar to canine but slightly shorter).
The surface of the root is convex and smooth.

50. Lingual Aspect Lingual convergence: Ling. s. is narrower than buc. s.
Outlines:
M and D outlines are convex D M
The L cusp is short and small reaching 2/3 of the length of the B. cusp(has a pointed tip).
Cervical line: is convex rootwise.
Surface Anatomy :
Elevations: The lingual surface is convex
with maximum convexity at middle 1/3
Depessions: ML developmental groove separating
the MM ridge from the M slope of the L cusp.

51. Lingual Aspect
Much of the occlusal and proximal surfaces can be seen from this aspect. D M
The root is much narrower than on the buccal surface. It tapers from the cervix to a pointed apex.

52. Prominent lingual inclination (much more than any other premolar)
Proximal Aspects
Proximal aspects have
rhomboid shape
Mesial
Distal
With narrow
occlusal table
Prominent lingual inclination
(much more than any other premolar)

53. Outlines of proximal aspects
Mesial Aspect
Distal Aspect
Buccal outline is convex with maximum convexity at
the junction of mid. and cerv. 1/3 (cervical ridge).
Lingual outline is less convex with maximum convexity at the center of the crown length.
Cervical line convex occl. and less curved distally

54. Mesial Aspect
Distal Aspect
Occlusal margin:
The two cusps are not on the same level
The lingual cusp is shorter by 1/3 length of crown
The B cusp tip centered over the root. This is due to the prominent lingual inclination.
The L cusp tip in line with lingual border of the root.

55. Mesial Aspect Distal Aspect
MMR inclined sharply from B to L surface // to ridge of B cusp
DMR is longer, straight and at right angle to the axis of the tooth.
MMR is cervical than DMR
DMR is occlusal than MMR
(The only post. tooth in which this is true).

56. M & D surfaces are smooth & convex except for the ML groove.
Proximal surface anatomy
Mesial Aspect
Distal Aspect
M & D surfaces are smooth & convex except for the ML groove.
Contact areas:
nearly at same level
Mesio-ling. dev.gr. Passes over the MM ridge(extension of M groove on the occl. surf.
Contact area is broader, more lingually situated than the mesial one.

57. Outline of the Root Mesial Aspect Distal Aspect
B & L outlines are nearly straight cervically then taper apically to a pointed apex.
The surface is smooth & flat with a deep dev. groove in the mid.& apical 1/3
The surface is more convex with a shallow dev. depres. centered on the root
Occasionally the apical 1/3
may be divided into a B. & L.
roots by a deep dev. groove

58. Occlusal Aspect It is diamond-shaped. M D
Lingual convergence is sharp.
Mesial outline is slightly curved.
Distal outline is more convex.
The B cusp is much larger than the L cusp.

59. Surface anatomy of occlusal aspect:
Elevations:
B triangular ridge(long).
L triangular ridge(short).
M & D marginal ridges(well marked).
Transverse ridge (formed by union of 2 triang. ridges).

60. . . Depressions: Central dev. groove crossing the transv. ridge.M
Central dev. groove crossing the transv. ridge. . .
M(oval) and D(circular) fossae.
Each fossa has a dev. pit (called snake eyes)
Mesio-lingual develop. groove – extension of M groove on the occ. surface.

61. Cross sec. at the cervix:
PULP CAVITY MD BL
Buccal p. horn: more
pronounced than the
lingual.
Resemble that of
The lower canine
Cross sec. at the cervix:
rounded or oval
Usually have a single RC

62. MANDIBULAR
FIRST PREMOLAR

63. Mandibular Second Premolar

64. MANDIBULAR SECOND PREMOLAR
Chronology:
Enamel organ appearance: 8 miu.
Beginning of calcification: 2 ¼ - 2 ½ y
Crown completed: – 7y
Eruption: – 12y
Root completed: – 15y

65. Mandibular Second Premolar:
Two Cusp Type
Lingual
Buccal
Mesial
Distal
No. of roots
One root
occlusal

66. Mandibular Second Premolar:
Three Cusp Type
Buccal
Lingual
Mesial
Distal
Occurs most often
occlusal

67. THE 2 TYPES DIFFER MAINLY FROM THE OCCLUSAL ASPECT
THE 2 TYPES DIFFER MAINLY FROM THE OCCLUSAL ASPECT. THE OUTLINES AND GENERAL APPEARANCE FROM ALL OTHER ASPECTS ARE SIMILAR.

68. Mandibular First and Second Premolars Geometric outline of the crown
Comparison Between
Mandibular First and Second Premolars
Geometric outline of the crown
Facial and lingual aspects have
trapezoid shape
But wider
cervically
than 4.

69. Crown is larger & B cusp is shorter and less pointed
Facial Outlines and surface anatomy
Mandibular First Premolar
Mandibular Second Premolar
Crown is larger & B cusp is shorter and less pointed
Crown is smaller & B cusp is longer & pointed
Less prominent B ridge
Prominent B ridge
Root: longer, broader, with blunt apex
Root: Shorter, narrower with pointed apex

70. Lingual outline and surface anatomy
Mandibular First Premolar
Mandibular Second Premolar
Two cusp type
Ling. s. not so
narrow as in 1st
premolar D M D M
L cusp is shorter and smaller than B cusp but larger than of 4
The L cusp is short and small reaching 2/3 the crown length and has a pointed tip.
The lingual surface is convex with maximum convexity in middle 1/3(center of crown)
The surface is convex with maximum convexity in Occ.1/3.
ML developmental groove at the ML line angle.
No MLDG

71. Three cusp type: No ling. convergency. M D
ML cusp is longer and larger than DL cusp. They both shorter than B cusp and less pointed.
The surface convex with maximum convexity at occ.1/3.
The L developmental groove between the 2 ling. cusps

72. Proximal outlines The crown is narrower BL The crown is wider BL
Mandibular First Premolar
Mandibular Second Premolar
The crown is narrower BL
The crown is wider BL
Rhomboid in shape with narrow occlusal table.
Prominent lingual inclination
Rhomboid in shape with narrow occlusal table.
Lingual inclination less prominent

73. Mandibular First Premolar Mandibular Second Premolar
The root is
wider BL
Maximum convexity at M1/3
Maximum convexity at O 1/3
The L cusp is short and small reaching 2/3 the crown length
L cusp is shorter and smaller than B cusp but larger than that of 4
The B cusp centered over the root.
B cusp tip on line buccal to the root axis.
The mesial MR is oblique while distally is straight
The mesial and distal marginal ridges are straight

74. Three Cusp Type of Mandibular Second Premolar
Mesial Aspect
Distal Aspect
Three Cusp Type of Mandibular Second Premolar
Develop.
depression
ML cusp is shorter than the B cusp & longer and larger than DL cusp.
DL cusp is shorter and smaller than ML cusp. Both are seen from this aspect.
Both lingual cusps are shorter than the buccal cusp
and less pointed
Cerv. line: slightly curved.
Cerv. line: nearly straight.

75. Lingual convergence is sharp.
Occlusal Aspect
Mandibular First Premolar
Mandibular Second Premolar
Two cusp type M D
The outline is round
Diamond-shaped.
U- shaped
H - shaped
Slight lingual convergence
Lingual convergence is sharp.
Three cusp type
The 3 cusps are
well developed
The outline is square M D

76. Surface Anatomy of Occlusal Aspect:
Lower 4
Lower 5
Two cusp type
Elevations:
B & L triang. ridges form a transv. ridge.
M & D marginal ridges

77. . . Depressions: Lower 5 Two cusp type Lower 4 M D M D
Shallow central devel. groove
Central devel. groove extending MD across the occ. surface, over the transv. ridge.
M(oval) and D(round) fossae.
M and D fossae: Circular.
The D fossa is larger than
the M one
Mesiolingual devel. gr.

78. Lower 5 Three cusp type Elevations & DepressionsM D
Each cusp has triang. ridge that converge toward a central fossa, which has cent. pit.
M & D marginal ridges are well marked.
The D triang. fossa is smaller than the M one.
No central devel. gr. or transv. ridge
Three devel. gr.(M,D, & L) radiate
from the cent. Pit : Y-shaped.

79. MANDIBULAR SECOND PREMOLAR
3 cusp type
2 cusp type

80. Cross sec. at the cerv. line
PULP CAVITY MD BL
Cross sec. at the cerv. line
round or oval

81. Thank you