Dental anatomy

1. Dental Anatomy and
Chronology
Dr. Razan Ahmad Al Majali

2. Tooth Morphology

3. General informations
 Humans have two generations of teeth :
deciduous and permanent
 By the age of 3 years all deciduous teeth
have erupted .
 By 6 years, the first permanent teeth appear
and hence the deciduous teeth are exfoliated
one by one replaced by their permanent
successors.
 A complete permanent dentition is present at
around 18 years .
 20 teeth – 10 in each jaw. (primary dentition )
 32 teeth – 16 in each jaw.

4.  Three basic tooth form : incsiform ,
caniniform , molariform .
 Incisors : cutting teeth , thin , blade- like
crowns.
 Canines : piercing or tearing teeth ,
single pointed cone-shaped crown .
 Molars : grinding teeth possessing a
number of cusps on an otherwise
flattened biting surface .
 Premolars: bicuspid teeth ,replace the
deciduous molars.

5. Some terms for the description of tooth form :
 Crown : clinical crown : that portion of a tooth visible
in the oral cavity
 Anatomical crown :that portion of a tooth covered with
enamel .
 Root : clinical root : portion of tooth which lies within
the alveolus .
 Anatomical root : that portion covered by cementum .
 Cervical margin : the junction of the anatomical crown
and anatomical root .
 Occlusal surface : biting surface .
 Cusps : pronounced elevation of occlusal surface .
 Incisal margin :cutting edge
 Tubercle : small elevation on the crown .
 Cingulum : bulbous convexity near cervical region of
the tooth .

6.  Ridge : linear elevation on the surface of a
tooth.
 Marginal ridge : ridge at the mesial or distal
edge .
 Fissure : long cleft between cusps or ridges .
 Fossa : rounded depression in a surface of a
tooth .
 Buccal : toward cheeks.
 Labial : toward lips .
 Palatal : toward palate .
 Lingual : toward the tongue .
 Mesial : toward the median .
 Distal : away from the median .

8. Dental notation:
 For deciduous teeth DI 2/2 DC 1/1 DM 2/2 = 10
 For permanent teeth I 2/2 C 1/1 PM 2/2 M 3/3 =16
 Zsigmondy system : 8 7 6 5 4 3 2 1 1 2 3 4 5 6
7 8
8 7 6 5 4 3 2 1 1 2 3 4 5 6 7
8
E D C B A A B C D E
E D C B A A B C D E

9. • Federation Dentaire Internationale (FDI) :
1= max. rt. Quadrant
2= max. left quadrant for
PERMANENT
3 = mand. Lft quadrant
4 = mand . rt quadrant
5= max. rt. Quadrant
6= max. left quadrant
7 = mand. Lft quadrant for
DECIDUOUS
8 = mand . rt quadrant

11. Differences between deciduous teeth
and permanent :
1 . The deciduous teeth are smaller, although
the mesiodistal dimension of the permanent
premolars are generally less than those for
deciduous molar .
2. Deciduous teeth have a greater constancy of
shape .
3. The crown of deciduous teeth appear
bulbous , often having pronounced labial or
buccal cingula .
4. the cervical margins of deciduous teeth are
more sharply demarcated and pronounced ,
enamel bulging rather than gently tapering .
5. the cusps of newly erupted deciduous teeth
are more pointed .

12. 6. the crowns of deciduous teeth have
thinner enamel ( 0.5-1.0 mm ) than the
crowns of permanent teeth (2.5 mm )
7. the enamel of deciduous teeth are more
opaque , gives the crown a whiter
appearance
8. the enamel is softer and more easily
worn in deciduous teeth .
9. enamel is more permeable in dec. teeth
.
10. the aprismatic layer of surface enamel
is wider in dec. teeth .

13. 11. the enamel and dentine of ALL dec . teeth exhibit
neonatal lines .
12. the roots of dec. teeth are shorter and less robust
than those of permanent teeth .
13. the roots of dec. incisors and canines are longer
in proportion to the crown than those of permanent
ones.
14. the roots of the dec. molars are widely divergent
extending beyond the dimensions of the crown.
15. the pulp chambers of dec. are proportionally
larger in relation to the crown than those of
permanent teeth. the pulp horns in dec. are more
prominent.
16. the root canals of dec. are extremely fine .
17 . the dental arch for dec. dentition are smaller .

14. A, The enamel cap of primary molars is thinner and has a more consistent depth. B, A
comparatively greater thickness of dentin is over the pulpal wall at the occlusal fossa of primary
molars. C, The pulpal horns are higher in primary molars, especially the mesial horns, and pulp
chambers are proportionately larger. D, The cervical ridges are more pronounced, especially on the
buccal aspect of the first primary molars. E, The enamel rods at the cervix slope occlusally instead
of gingivally as in the permanent teeth. F, The primary molars have a markedly constricted neck
compared with the permanent molars. G, The roots of the primary teeth are longer and more slender
in comparison with crown size than those of the permanent teeth. H, The roots of the primary molars
flare out nearer the cervix than do those of the permanent teeth.

15. THE INCISORS :
THE MAXILLARY FIRST CENTRAL PERMANENT
INCISOR :
 Incisal view :
- The crown and incisal margin
are centrally positioned over
the root of the tooth.
- The incisal margin presents as
narrow flattened ridge rather
than as a fine sharp edge.
- The crown outline is bilaterally
symmetrical, being triangular.
Mesial appears slightly larger.
- may have two grooves, the
labial lobe grooves; correspond
to three developmental lobes
(mammelones) which are lost
by attrition.

16.  Labial view :
 Smooth , convex .
 Convexity marked cervically . flat
at the middle and incisal regions.
 Crown length almost as great a
root length .
 Two faint grooves which are
extensions of the labial lobe
grooves.
 Mesial surface is straight and at
right angle to incisal margin .
 Distal outline is convex and the
distoincisal angle is more
rounded.

17.  Palatal view :
 More irregular ,shovel –
shaped
 Bordered by mesial and distal
marginal ridges .
 Middle and incisal third being
concave.
 Prominent cingulum lies near
the cervical margin… maybe
single ,divided

18.  Mesial and distal :
 Wedge shaped or
triangular .
 The root :
 Single root tapers
toward the apex .
 The root is conical in
cross section ,
narrower palataly .

19. THE MAXILLARY PERMANENT
LATERAL INCISOR :
The smallest mesiodistal dimensions
of any teeth in permanent dentition.
One of the most variable teeth in
dentition .
It is morphologically a diminutive form
of maxillary incisor with slight
modifications .
The crown is much narrower and
shorter , the crown:root ratio is
decreased .

20.  Incisal aspect :
 More rounded than
central.
 Labial view :
 The mesioincisal
and distoincisal
angles and mesial
and distal crown
margins are more
rounded .

22.  Palatal view :
 Similar to central . marginal ridges
and cingulum are more pronounced
, and palatal concavity appears
deeper.
 In front of the cingulum is a pit (
foramen caecum)that may extend
into the root.
 The root :
 Slightly compressed and grooved on
the mesial and distal surfaces .
 CAN BE DISTINGUISHED : by their
size , the marked lingual inclination
of the crowns over the roots ,
mesiodistal compression of their
roots , poor development of the
marginal ridges and cingula .

23. THE MANDIBULAR
PERMANENT CENTRAL
INCISOR :
 Incisal view :
 Bilaterally symmetrical triangular
shape .
 Labial view :
 The crown is almost twice as long
as it is wide .
 Straight incisal angle .
 Mesio and distoincisal angles are
sharp and approximately at right
angle .
 Mesial and distal surfaces are
similar , being flattened in the
middle and cervical thirds and
convex in the incisal third .

25.  Lingual view :
 Smooth and slightly concave
 Lingual cingulum and mesial
and distal marginal ridges are
less distinct .
 Mesial and distal view :
 Wedge shape .
 The cervical margin on the
distal side is less curved than
that of the mesial .
 The root :
 Narrow , conical .
 Frequently grooved on the
mesial and distal surfaces ,
distal groove more marked
and deeper .

26. THE MANDIBULAR LATERAL
PERMANENT INCISOR :
 Closely resembles the mand. Central incisor .
 Slightly wider mesiodistally and asymmetric
in shape.
 Distal surface diverges , giving it a fan-
shaped apperance .
 Distoincisal angle more acute and rounded .
DISTINGUISHING characteristic : the
angulation of the incisal margin relative to the
labiolingual axis of the root is twisted distally in
a lingual direction , where as in the central it
forms a right angle .

28. THE CANINES:
 The only teeth in the dentition with a
single cusp .
 Triangle.. mesially and distally
 Trapezoidal .. buccally and palataly ..

29. THE MAXILLARY PERMANENT
CANINE :
 Well developed cingulum and
the longest root of any tooth.
 Incisal view :
 The distal portion is much
wider than the mesial portion.
 The pointed shape of the
canine is thought to be related
to an increase in the size of a
central mammelon
 Prominent longitudinal ridges
pass from the cusp tip down
both the labial and palatal
surfaces.
 Variations : like an accessory

30.  Labial view :
 Marked by longitudinal ridge
extends from the cusp to the
cervical margin .
 The incisal part occupies at
least 1/3 of the crown height
.
 The mesial arm is shorter
than the distal arm.
 The distoincisal angle is
more rounded.
 The mesial profile is slightly
convex with a straight line
with the root . the distal is
markdly convex an obtuse
angle with the root .

32.  Palatal view :
 Well defined cingulum and
distinct marginal ridges .
 Longitudinal ridge meets the
cingulum and is separated
from the marginal ridges by a
distinct groove or fossa
 Mesially and distally :
 Great width of the cervical
third of both the crown and
the root .
 The curvature of cervical
margin distally is less
marked than mesially.

33.  The root :
The largest and stoutest in the
dentition.
Triangular in cross section .
Mesial and distal surfaces of the root
are often grooved longitudinally.

34. THE MANDIBULAR CANINE :
 Similar to the maxillary ,
but smaller , more
slender , more
symmetrical .
 The cusp is less
developed . with attrition
it may resemble max.
lateral incisor.
 Incisal view :
 No distinct longitudinal
ridges from the tip of the
cusp onto the labial and
lingual surfaces .

36.  Labial view :
 The cusp is less pointed , the
incisal margin occupies only
1/5 of the crown height .
 Crown is narrower
mesiodistally , it appears
longer , narrower and more
slender .
 Mesial and distal profiles are
parallel.
 Lingual view :
 Surface of cingulum ,marginal
ridges and fossa are indistinct
.
 Lingual surface is flatter than

37.  Mesially and distally :
 Wedge-shaped
appearance .
 Cervical margin follows a
course similar to the
incisors , more marked
distally .
 The root :
 Normally single
.occasionally it may
bifurcate .
 Oval cross section .
 The root is grooved

38. THE PREMOLARS :
 Bicuspids ( two cusps buccal and
lingual separated by mesiodistal
occlusal fissure).
 To distinguish upper and lower
premolar … when viewed mesially or
distally upper premolars are
trapezoidal in shape while the lowers
are rhomboidal in shape and inclined
lingually .

39. THE MAXILLARY FIRST PREMOLAR :
 Occlusal view :
 Ovoid . border buccaly
than palatally
 Mesio and distobuccal
corners are less rounded
than mesio and
distopalatal .
 Distinct mesial and distal
marginal ridges.
 Central occlusal fissure
that crosses mesial
marginal ridge onto mesial

40. Maxillary first premolar, occlusal aspect. TBC, Tip of buccal cusp; MBCR, mesiobuccal
cusp ridge; MBDG, mesiobuccal developmental groove; MTF, mesial triangular fossa;
MMDG, mesial marginal developmental groove; MMR, mesial marginal ridge; MLCR,
mesiolingual cusp ridge; LTR, lingual triangular ridge; TLC, tip of lingual cusp; CG,
central groove; DLCR, distolingual cusp ridge; DMR, distal marginal ridge; DTF, distal
triangular fossa; DBDG, distobuccal developmental groove; BTR, buccal triangular
ridge; DBCR, distobuccal cusp ridge.

41.  Buccal view :
 Resemble the canine .
 Longitudinal ridge .
 Prominent mesio and disto-
occlusal angles .
 Mesial slope is longer than
distal slope .
 Palatal view :
 Palatal cusp is smaller and
lower than buccal .
 The tip lies more mesially .

43.  Mesial view :
 Canine groove across
the mesial marginal ridge
.
 Cervical third marked by
a distinct concavity “ the
canine fossa “
 Distal veiw :
 Lacks the canine groove
and fossa .
 The roots :
 Usually two roots ,
sometimes single root
which is deeply grooved
.

44. THE MAXILLARY SECOND
PREMOLAR :
Similar to first premolar
except :
 Occlusally :
 More rounded mesio
distobuccal corners.
 Mesial and distal profiles
parallel to each other .
 Smaller mesiodistally.
 Central fissure doesn’t
cross the marginal ridge.

45.  Buccally :
 Less prominent disto and
mesio-occlusal angles.
”narrow shouldered
appearance “
 Smaller cusps , equal in
size cusps.
 Mesially :
 No canine fossa and
groove .
 The root :
 Single root .

47. THE MANDIBULAR FIRST PREMOLAR
:
 Smallest premolar .
 Dominant buccal cusp and very
small lingual cusp.
 Occlusal view :
 More than 2/3 of buccal aspect is
visible.
 Diamond shaped.
 Broad buccal cusp , its apex at
midpoint of the crown.
 Buccal and lingual cusps are
connected by a transverse ridge that
divides the occlusal fissure to mesial
and distal fossa ( mesial fossa is
smaller).
 Canine groove crosses the mesial
marginal ridge .

48.  Buccally :
 nearly Symmetrical .
 lingual view :
 the entire buccal profile and
occlusal surface are visible .
 2nd premolar differs from other
premolars that the occlusal plane
doesn’t lie perpendicular to the
long axis of the tooth .
 The root :
 Single , conical ,and oval cross
section .
 Root is grooved longitudinally
mesial and distal .

50. THE MANDIBULAR 2nd PREMOLAR :
 The crown is generally larger.
 Lingual cusp is better developed.
 Occlusal aspect :
Round or square .
 Well defined mesiodistal occlusal
fissure .
 Distal fossa is larger then mesial
fossa.
 Accessory cusplets are common
on both buccal and lingual .
 Lingual cusp is usually
subdivided to mesio and
distolingual cusps.
 Mesiolingual is wider and higher
.

51.  Buccal aspect :
 Symmetrical .
 Appears shorter and more rounded
than 1st mand premolar .
 Lingually :
 Little if any of the occlusal surface
and buccal profile is visible .
 Mesial and distal :
 Mesial marginal ridge is higher
than the distal .
 Occlusal surface appears
horizantal to the long axis .
 The root :
 Single , conical , nearly round in
cross section.

52. THE MOLARS :
 largest occlusal surfaces of all teeth .
 have 3-5 MAJOR cusps.
 Have more than one buccal cusp .
 In general .. 3 roots upper , 2 roots lower
.
 Buccally and lingually are trapezoidal.
 Mesially and distally .. upper trapezoidal
, lower rhomboidal.

53. MAXILLARY 1st PERMANENT MOLAR :
 Occlusally :
 Rhombic in outline.
 Four major cusps separated by an irregular H-
shaped occlusal fissure.
 Occlusal table is divided to two components
(trigon and talon )by the oblique ridge.
 Oblique ridge passes from the mesiopalatal cusp
to the distobuccal cusp.
 Mesiopalatal .. the largest cusp
 Trigon ; triangular in shape ,apex directed
palataly . bears the mesiobuccal ,mesiopalatal,
and distobuccal cusps .
 Apex: mesiopalatal base : buccal
cusps
 Mesial marginal ridge and the oblique ridge form
its sides.
 Central fossa , central fissure terminate in mesial
pit , buccal fissure,

54.  Talon : bears distopalatal
cusp .”the smallest cusp”
 Distopalatal fissure
separates the palatal cusps
,ends in a distal pit.
 Accessory cusplet “ the
tubercle of Carabelli “ : seen
on mesiopalatal cusp
,variable sizes,found on
60% of max 1st molars.
 CHARACTERISTIC of max.
molar : the tips of palatal
cusps are nearer the mid-
mesiodistal diameter of the
crown than buccal cusps.

55. Maxillary right first molar, occlusal aspect. MBCR, Mesiobuccal cusp ridge;
CF, central fossa (shaded area); MTF, mesial triangular fossa (shaded area);
MMR, mesial marginal ridge; MLCR, mesiolingual cusp ridge; OR, oblique
ridge; DLCR, distolingual cusp ridge; DF, distal fossa; DTF, distal triangular
fossa (shaded area); DMR, distal marginal ridge; DBCR, distobuccal cusp
ridge.

56.  Buccal view :
 Mesiobuccal cusp is wider
than distobuccal . but equal
in heights .
 Buccal groove extends to
end about half way .
 Distal profile.. convex all
regions . mesial profile
concave in cervical 1/3 and
convex n the middle and
occlusal thirds .
 Palatal view :
 Mesiopalatal is larger , blunt
.
 Palatal groove extends
approximately halfway up
the palatel surface.

57.  Mesial and distal :
 Maximum bucco-palatal
dimension is at the cervical
margin.
 Mesial marginal ridge is more
prominent and have a no. of
destinct tubercles which are
rare distally.
• The roots:
 3 roots : 2 buccaly , 1 palataly
.from a common root stalk .
 At the root stalk palatal root is
more related to distobuccal root
.
 Palatal is the longest and
strongest.
 Buccal roots are more slender
and mesiodistally flattened .

58. THE 2nd MAXLLARY MOLAR :
 Resembles 1st molar but
shows some reduction in
size and cusps
relationship.
 Common variations in
morphology .
 Occlusal view :
 More pronounced
rhomboid form.
 Smaller oblique ridge ,
the talon is reduced.
 More variable occlusal
fissure pattern.

60.  Buccal view :
 Two features that
differentiate the 2nd
molar : smaller size
and distobuccal cusp .
 Palatal view :
 Reduction in size of
the distopalatal cusp is
more visible.
 Tubercle of Caraballi is
not always found.

61.  Mesial and distal :
 The tubercles on marginal
ridges are less pronounced.
 The roots :
 3 roots , shorter and less
divergent, maybe partly
fused.
 Apex of mesiobuccal root is
in line with the center of the
crown . while in 1st molar is in
line with the tip of
mesiobuccal cusp.

62. THE MAXILLARY 3rd MOLAR :
 Most variable in dentition .
 Most often absent congenitally.
 Most commonly , the crown is
triangular in shape having cusps of
trigon but no talon.
 Roots are often fused and irregular in
form .

64. MANDIBULAR MOLARS :
 Differences with the upper :
1. Mand. Molar have two roots ,mesial
and distal .
2. Derived from a five cusped form.
3. Are oblong , broader mesiodistally than
buccolingually .
4. The fissure pattern is cross-shaped.
5. Lingual cusps are more equal size.
6. The tips of buccal cusps are shifted
lingually ,the whole buccal surface is
visible occlusally.

65. THE MANDIBULAR 1st MOLAR :
 Pentagonal in outline.
 Occlusal view :
 Occlusal surface is divided
into buccal and lingual by a
mesiodistal occlusal fissure.
 Buccal side three distinct
cusps : mesiobuccal
,distobuccal , and distal .
rounded cusp tips displaced
lingually rounded and lower
than lingual cusps .
 Lingual side two cusps
:mesiolingual , distolingual .
large and pointed .
 Smallest cusp is the distal

66.  90% of cases
mesiolingual and
distobuccal are joined
across the floor of the
central fossa . this
feature and the five
cusped pattern is termd
dryopithecus pattern.
 dryopithecus pattern
sometimes referred to Y5
due to Y-shaped tissue
pattern with 5 cusps.

67. Mandibular right first molar, occlusal aspect. DBCR, Distobuccal cusp ridge; DBDG,
distobuccal developmental groove; DCR, distal cusp ridge; DTF, distal triangular fossa
(shaded area); DLCR, distolingual cusp ridge; LDG, lingual developmental groove;
MLCR, mesiolingual cusp ridge; MTF, mesial triangular fossa (shaded area); SG, a
supplemental groove; MBCR, mesiobuccal cusp ridge; MBDG, mesiobuccal
developmental groove.

68.  Buccal view :
 Three cusps , distal cusp is the smallest .
 buccal surface is markedly convex especially at
cervical third.
 Lingual view :
 Mesiolingual cusp appears slightly larger.
 Fissure separating the two cusps doesn’t extend
significantly to lingual surface.
 Surface convex then flat or concave cervically.

69.  Mesially and distally :
 Mesial and distal
marginal ridges appear
V-shaped .
 Distal surface is more
convex .
 The roots :
 Two roots ,mesial and
distal . arise from
common root stalk.
 Mesial root is usually
deeply grooved.
 Both roots curve
distally.

70. THE MANDIBULAR 2nd MOLAR :
 Occlusal view :
 Rectangular . buccal
equal to lingual .
 Four cusps , mesial
cusps are slightly larger
than distal cusps .
 Cusps separated by a
cross shaped groove ,
complicated by
supplementary grooves .
 Buccal ;
 Smaller than 1st molar.
 Buccal surface is highly
convex .

71.  Mesial and distal :
 The proximal surfaces
have more equal
convexity.
 The roots :
 Smaller , less divergent ,
partly fused .
 Distal inclination is more
marked.

72. THE MANDIBULAR 3rd MOLAR :
 Variable morphology . not as variable
as the max. 3rd molar .
 Usually 4-5 cusps . rounded rectangle
.
 Very irregular occlusal pattern.
 Roots greatly reduced in size , more
fused , marked distal inclination .

73. PULP MORPHOLOGY

74. MAX. PERM. CENTRAL INCISOR :
 Labial aspect :
 Pulp chamber follows the outline of the crown .
 In young tooth , pulp chamber has three pulp horns
correspond to the mammelones.
 Distally :
 Pulp tapers towards the incisal edge and widen
cervically.
 Cross section :
 Ovoid ,becomes round as it nears the apex.
 With age :
 Reduced dimensions of the pulp chamber and root
canal .
 Pulp chamber recedes and may disappear completely .

76. MAX. LATERAL PERM. INCISOR :
Similar to central but smaller.
Root canal is single , slightly ovoid ,
commonly curves both distally and palataly.

77. MAND. PERM. CENTRAL INCISOR :
 Pulp chamber is similar to max. central , but
much smaller .
 Pulp chamber is oval in cross section.
 Root canal is ovoid in cross section.
 30% have two canals , most of them fuse
near the apex and exit by single foramen.

79. MAND. LATERAL INCISOR :
 Tooth and root canal are larger than central.
 43% two root canals “more common than cental “ .
 Exit by separate foramina.

80. CANINES :
MAX. CANINE :
 Narrow pulp chamber with a single
pulp horn points cuspally .
 Pulp chamber and single canal are
wider labiopalataly than mesiopalatly.
 Root canal doesn’t constrict markedly
until apical third .
 Root canal are ALWAYS single .

82. MAND. CANINE :
 Pulp cavity resembles max. canine but smaller in
all dimensions .
 6% have two root canals usually with separate
foramina.

83. PREMOLARS :
MAX 1ST PREMOLAR :
 85% has two roots , sometimes fused. The
two canals exit by separate foramina .
 Less than 10% ,single root with single root
canal .
 5% have three canals (sometimes in three
roots ).
 Two distinct pulp horns pointing towards the
cusps.
 Pulp chamber is closest to the surface
mesially .
 In cross section root canals are generally
round.

85. MAX. 2ND PREMOLAR :
 75% single root with single root canal .
 If two canals are present , mostly they have
separate apical foramina.
 In cross section the root canal is oval .

86. MAND. 1ST PREMOLAR :
 Pulp chamber is wider buccolingually .
“ like max. premolar”
 Usually only one pulp horn extends
into buccal cusp. “unlike max.
premolar “.
 75% single root canal .
 Most teeth that have two canals have
two apical foramina .

88. MAND. 2ND PREMOLAR :
85% have single canals .
and usually two well developed pulp horns pointing
towards the cusps.

89. MOLARS:
MAX. 1ST PERM. MOLAR :
 pulp chamber is rhomboidal in shape , wider
buccopalatally.
 Four pulp horns , one to each major cusp.
 The pulp horn to mesiobuccal cusp is the longest
.
 The floor lies below cervical margin .
 Three root canals . or four canals on 60% ( 4th
canal in the mesiobuccal root ).
 2/3 of the 4th canals rejoin the main canal of the
mesiobuccal root near apex.
 Palatal root canal is the widest and longest .
 Floor of the chamber is marked by series of
developmental grooves that join the orifice of the
root canals.

91. MAX. 2ND MOLAR :
 Similar to 1st molar pulp cavity but
smaller with the rhomboidal shape
more compressed.
 Roots are more convergent. Orifices
are closer together.
 Roots are commonly fused.
 2nd mesiobuccal canal is less common
( 40% of cases ).

93. MAND. 1ST MOLAR :
 Pulp chamber is wider mesiodistally
than buccolingually . wider mesially than
distally.
 Five pulp horns pointing to the cusps.
 Lingual pulp horns are longer and more
pointed.
 Floor of chamber lies at or below the
level of cervical margin .
 The mesial root has two root canals
(mesiobuccal and mesiolingual). Both
are circular in cross section.
 30% of teeth the distal root has two
canals

95. MAND. 2ND MOLAR :
 Pulp chamber closely resembles 1st molar.
 But it has only four pulp horns.
 Only rarely (8% of cases)two canals in distal root.

96. PULP CHAMBERS IN
DECIDUOUS TEETH :

97.  The chamber is relatively larger and the pulp
horns longer and closer to the surface of the
tooth.
 All incisors and canines have single canals .
 10% on mand. Incisor there are two canals .
 Pulp chamber of deciduous mand molar are
proportionally larger than those of max.
molars.
 The mesiobuccal pulp horn is near the
occlusal surface and highly vulnerable to
exposure .
 Small canals from the floor to the furcation
region are common.
 Severe curvature of deciduous teeth.

98.  Features to bear in mind :
- Maxillary D has 2-4 roots canals (75% 2
canals in the mesiobuccal root and palatal
and distobuccal roots .
- Maxillary E has 2-5 root canals (90% of cases
mesiobuccal root contains two canals) ,
(palatal and distobuccal roots sometimes
fuse and contain a single common canal .
- Mandibular D may have 2-4 canals ( 75% of
mesial roots have two canals , and 25% of
distal).
- Mandibular E usually has 3 canals (but vary
2-5) (85% of mesial roots , 25% of distal roots
have two canals ).

99. DECIDUOUS TEETH :

100. Upper A :
 No mammelons are seen on the
incisal margin .
 Cingulum is very prominent .
 Marginal ridges are poorly defined .
 Cervical margins are pronounced but
less sinuous than permanent teeth.
 Compared with permanent incisor ,
the root is longer in proportion to the
crown.

102. Upper B :
 Similar to A , one obvious difference is
the more acute mesioincisal angle and
more rounded distoincisal angle.
 Palatal surface is more concave ,
marginal ridge more pronounced .

103. Lower A :
 Similar to permanent . however ,its
much shorter .
 No mammelon grooves .
 Lingual cingulum and marginal ridges
are poorly defined.
 More rounded root , tends to incline
distally .

105. Lower B :
 The mesioinciasal angle is more
obtuse and rounded than lower A
 Distoincisal angle is markedly rounded
, it distinguishes it from upper B .
 Unlike the permanent , the root is
rounded .and its longer than lower A .

106. Upper C :
 Similar to permanent ,but more bulbous .
 Generally symmetrical , but if there is
asymmetry the mesial slope tends to be
longer than distal slope.
 The width of the crown is greater than the
length.
 Longitudinal ridges on the labial and palatal
surfaces .it divides the palatal surface into
two shallow pits.
 Marginal ridges are indistinct .
 The root is long compared with the crown
height. triangular in cross section .

107. Lower C :
 More slender than upper C .
 The crown is asymmetrical , the cusp
tip displaced mesially.
 Poorly developed longitudinal ridges
on labial and lingual surfaces .
 The width of the crown is less than the
length .
 Root is triangular in cross section .

109. Upper D :
 Most atypical of all molars , primary and
permanent .
 Its the smallest molar .
 Occlusally :
- Irregular quadrilateral .buccal and palatal parallel.
- Mesiobuccal angle is extended to produce a
prominent bulge , the molar tubercle.
- Mesiopalatal angle is obtuse.
- Generally it’s a bicuspid tooth . buccal and palatal
.
- Buccal cusp is divided by shallow buccal fissure
into two , mesial part is larger.
- Palatal cusp may also be subdivided into two .
- Tips of the cusps converge towards the midline .

111.  Buccal aspect :
- Height less than width .
- On mesial side lies the buccal cingulum.
 Mesial and distal :
- Cervical bulbosity of the buccal and palatal
surfaces .
- Prominent molar tubercle mesially .
- No fissure crosses the marginal ridges .
 The roots :
- Three roots ( two buccal and one palatal ) arise
from a common root stalk .
- The palatal root is the largest.
- The distobuccal and palatal roots maybe partly
fused .

112. Upper E :
 Resembles the max. permanent first
molar .
 Size , whiteness , widely diverging
roots and low buccal cingulum
distinguish it .
 A tubercle of Carabelli is often well
developed.

113. Lower D :
 Occlusally :
- Irregular quadrilateral with parallel buccal and
lingual surfaces . Elongated mesiodistally.
- Mesiobuccal corner is extended forming a
molar tubercle . mesiolingual is obtuse .
- Buccal and lingual part . mesiodistal fissure .
- Buccal part has two cusps , mesiobuccal is
larger .
- Lingual part narrower , two cusps separated
by lingual fissure . mesiolingual is larger.
- Transverse ridge connect the mesial cusps ,
form a distal fissure and a mesial pit.
- Supplemental groove extends over mesial
marginal ridge .

114.  Buccal aspect :
- The mesiobuccal cusp occupies 2/3 of the
crown.
- The profile of mesial is flat and distal is
convex .
 Mesially and distally :
- Buccal and lingual aspects converge toward
the midline .
 The roots :
- Two divergent roots . mesial and distal .
- Mesial root is often grooved .

116. Lower E :
 A small version of lower first
permanent molar .
 Narrower , whiter , widely diverging
roots.
 The mesiobuccal corner of the crown
,the greater convexity of the mesial
and distal surfaces .
 The mesiolingual and distobuccal
cusps are not usually joined to give
the Dryopithecus pattern .

118. ETHIC AND RACIAL
DIFFERENCES IN TOOTH
MORPHOLOGY