Obama and his family moved to Washington D.C. after he was elected President in 2008. The document then provides detailed anatomical descriptions of the premolars, including their number, shape, features, eruption timeline, and relations to other teeth. It describes the maxillary and mandibular first and second premolars, discussing differences between them. Diagrams illustrate aspects of the premolars like occlusal outlines, root structures, and pulp cavities.

1. ‫الرحمن‬ ‫ا‬ ‫بسم‬
‫الرحيم‬

8. THETHE
PREMOLARSPREMOLARS
Dr: 3mmar

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

10. General Features of PremolarsGeneral Features of Premolars
They areThey are transitionaltransitional teethteeth
located between the caninelocated between the canine
and molar teeth.and molar teeth.
By definition:By definition: PremolarsPremolars
are permanent teeth distalare permanent teeth distal
to the canines, andto the canines, and
successors to deciduoussuccessors to deciduous
molars.molars.
There are two premolarsThere are two premolars
per quadrant and areper quadrant and are
identified as first andidentified as first and
second premolars.second premolars.

11. They have usually twoThey have usually two
cusps(bicuspid) :cusps(bicuspid) :
 One large buccal cusp,One large buccal cusp,
 Smaller lingual cuspSmaller lingual cusp
The lower secondThe lower second
premolar may-premolar may-
sometimes- have twosometimes- have two
lingual cusps.lingual cusps.
General Features of PremolarsGeneral Features of Premolars

12. MAXILLARY FIRST PREMOLARMAXILLARY FIRST PREMOLAR
ChronologyChronology::
•Enamel organ appearance: 7 mIU.
•Beginning of calcification: 1½-1¾y
•Crown completed: 5 – 6y
•Eruption: 10 – 11y
•Root completed: 12 – 13y
Number of lobes: four lobesNumber of lobes: four lobes::
• Three buccallyThree buccally
• One linguallyOne lingually

13. DistalDistalMesialMesialPalatalPalatal
OcclusalOcclusal
BuccalBuccal
No. of rootsNo. of roots
Two roots(60%Two roots(60%(.(.
One root(40%One root(40%(.(.

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

15. Buccal AspectBuccal Aspect Outlines:
•Mesial and distal outlines: are
nearly concave and both
become convex at cont. areas.
•Mesial and distal cusp slopes:
are also slightly concave
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.
MD

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

17. .
 Outline and Surface AnatomyOutline and Surface Anatomy
of the Rootof the Root
The surface of the root is
convex and smooth
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.
Buccal AspectBuccal Aspect
MD

18. • The surface is convex with maximum
convexity at the middle 1/3.
• The root is convex.
 Outlines:
• M and D outlines are convex
• 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
M D
Cervical line: is convex rootwise.
 Surface Anatomy :Surface Anatomy :
Lingual AspectLingual Aspect•Lingual convergence:
Ling.s. is narrower than buccal s.

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

20. Proximal AspectsProximal Aspects
Mesial aspect Distal aspectProximalProximal
aspects haveaspects have
trapezoid outtrapezoid out
line.line.
The smallest of
the uneven
sides

occlusally.

21. Lingual outline: convex with maximum convexity
at middle 1/3
Cervical line: curves occlusally and less curved distally
Outlines of Proximal AspectsOutlines of Proximal Aspects
Buccal outline :
Convex with maximum convexity at cervical 1/3
representing cervical ridge.
MesialMesial
aspectaspect
DistalDistal
aspectaspect

22. 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.
MesialMesial
aspectaspect
DistalDistal
aspectaspect

23. Surface AnatomySurface Anatomy
ofof
ProximalProximal
AspectsAspects
Contact areas:
MesialMesial
AspectAspect
DistalDistal
AspectAspect
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

24. In case of two roots (more common).
MesialMesial
AspectAspect
DistalDistal
AspectAspect
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
 Outline and Surface AnatomyOutline and Surface Anatomy
of the Rootof the Root

25. 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.

26. OcclusalOcclusal
AspectAspect
Hexagonal
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
MD
Geometric outlineGeometric outline

27. Surface anatomySurface anatomy
Elevations:
Bucc. triangular ridge.
Ling. triangular ridge.
M & D marginal ridges
Depressions:
Central developmental groove
M and D triangular fossae.
M marginal developmental groove
OcclusalOcclusal
AspectAspect
MD

28. Mesial marginalMesial marginal
developmental groovedevelopmental groove
The most charecteristic identifying
feature of the max. first premolar

29. MAXILLARY
FIRST PREMOLAR

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

33. MAXILLARY SECOND PREMOLARMAXILLARY SECOND PREMOLAR

34. MAXILLARY SECOND PREMOLARMAXILLARY SECOND PREMOLAR
ChronologyChronology::
•Enamel organ appearance: 8 mIU.
•Beginning of calcification: 2-2¾y
•Crown completed: 6 – 7y
•Eruption: 10 – 12y
•Root completed: 13 – 15y

35. Maxillary Second PremolarMaxillary Second Premolar
BuccalBuccal LingualLingual MesialMesial DistalDistal
OcclusalOcclusal

36.  Geometric Shape ofGeometric Shape of
the Crownthe Crown
Facial & LingualFacial & Lingual
AspectsAspects
The smallest of
the uneven sides
cervically.
Trapezoid shapeTrapezoid shape..
Comparison betweenComparison between
Maxillary First and Second PremolarsMaxillary First and Second Premolars

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

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

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

40. Mesial and DistalMesial and Distal
AspectsAspects
Trapezoid in shape
Smallest of the
uneven sides:
 occlusaly
4 5 Geometric Shape ofGeometric Shape of
the Crownthe Crown
BL

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

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

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

44. Distal AspectsDistal Aspects
Maxillary First Premolar Maxillary Second Premolar
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.
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.

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

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

47. MAXILLARY
SECOND PREMOLAR

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

49. Obama and family move to Washington

50. Obama and family move to Washington

53. MANDIBULAR FIRST PREMOLARMANDIBULAR FIRST PREMOLAR
ChronologyChronology::
•Enamel organ appearance: 7 miu.
•Beginning of calcification: 1 ¾ - 2y
•Crown completed: 5 – 6y
•Eruption: 10 – 12y
•Root completed: 12 – 13y

54. Mandibular First PremolarMandibular First Premolar
BuccalBuccal LingualLingual MesialMesial
OcclusalOcclusal
DistalDistal
No. of rootsNo. of roots
One rootOne root

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

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

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

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

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

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

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

62. Lingual outline is less convex with maximum
convexity at the center of the crown length.
Cervical line convex occl. and less curved distally
 Outlines of proximal aspectsOutlines of proximal aspects
Buccal outline is convex with maximum convexity at
the junction of mid. and cerv. 1/3 )cervical ridge(.
MesialMesial
AspectAspect
DistalDistal
AspectAspect

63. 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.
MesialMesial
AspectAspect
DistalDistal
AspectAspect

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

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

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

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

68.  Surface anatomy of occlusal aspect: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).

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

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

71. MANDIBULARMANDIBULAR
FIRST PREMOLARFIRST PREMOLAR

72. Mandibular Second PremolarMandibular Second Premolar

73. MANDIBULAR SECOND PREMOLARMANDIBULAR SECOND PREMOLAR
ChronologyChronology::
•Enamel organ appearance: 8 miu.
•Beginning of calcification: 2 ¼ - 2 ½ y
•Crown completed: 6 – 7y
•Eruption: 11 – 12y
•Root completed: 13 – 15y

74. Mandibular Second PremolarMandibular Second Premolar::
Two Cusp TypeTwo Cusp Type
BuccalBuccal LingualLingual MesialMesial
occlusalocclusal
DistalDistal
No. of rootsNo. of roots
One rootOne root

75. BuccalBuccal LingualLingual MesialMesial
occlusalocclusal
DistalDistal
Mandibular Second PremolarMandibular Second Premolar::
Three Cusp TypeThree Cusp Type
Occurs most oftenOccurs most often

76. the 2 types (2&3) differ mainlythe 2 types (2&3) differ mainly
from the OCCLUSAL ASPECT.from the OCCLUSAL ASPECT.
The outlines & generalThe outlines & general
appearance from all othe aspectsappearance from all othe aspects
are SIMILAR.are SIMILAR.

77. Geometric outline of the crownGeometric outline of the crown
Facial and lingual aspects haveFacial and lingual aspects have
trapezoid shapetrapezoid shape
But widerBut wider
cervicallycervically
than 4.than 4.
Comparison BetweenComparison Between
Mandibular First and Second PremolarsMandibular First and Second Premolars

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

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

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

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

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

83. Three CuspThree Cusp
Type ofType of
MandibularMandibular
SecondSecond
PremolarPremolar
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
MesialMesial
AspectAspect
DistalDistal
AspectAspect
Develop.
depression
Cerv. line: slightly curved. Cerv. line: nearly straight.

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

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

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

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

88. MANDIBULARMANDIBULAR
SECOND PREMOLARSECOND PREMOLAR
3cusp type
2cusp type

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

90. ANY QUESTION?