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1
1
Introduction to Dental Anatomy
Pretest Questions
1.
The dental formula for the permanent human dentition is
which of the following?
A.
I 2/2 C 1/1 M 2/2 = 10
B.
I 2/2 C 1/1 P 1/1 M 2/2 = 12
C.
I 2/2 C 1/1 P 2/2 M 2/2 = 14
D.
I 2/2 C 1/1 P 2/2 M 3/3 = 16
2.
The notation for the primary mandibular left canine is which
of the following according to the FDI system?
A. 53
B. 63
C. 73
D. 83
3.
The notation for the primary maxillary left lateral incisor is
which of the following according to the Universal system?
A. D
B. G
C. E
D. F
4.
Which of the following represents the name of the bone of the
tooth socket that firmly fixes each tooth root?
A. Alveolar process
B. Alveolus
C. Cementoenamel junction
D. Dentinoenamel junction
5.
Which of the following terms represents the surface of a tooth
that is facing toward an adjoining tooth in the same dental arch?
A. Occlusal
B. Incisal
C. Facial
D. Proximal
For additional study resources, please visit Expert Consult.
Dental anatomy is defined here as, but is not limited to, the study
of the development, morphology, function, and identity of each of
the teeth in the human dentitions, as well as the way in which the
teeth relate in shape, form, structure, color, and function to the
other teeth in the same dental arch and to the teeth in the oppos-
ing arch. Thus the study of dental anatomy, physiology, and occlu-
sion provides one of the basic components of the skills needed to
practice all phases of dentistry.
The application of dental anatomy to clinical practice can be
envisioned in Fig. 1.1A, where a faulty crown form has resulted
in esthetic and periodontal problems that may be corrected by an
appropriate restorative dental treatment, such as that illustrated in
Fig. 1.1B. The practitioner must have knowledge of the morphol-
ogy, occlusion, esthetics, phonetics, and functions of these teeth to
undertake such treatment.
LEARNING OBJECTIVES
1.
Correctly define and pronounce the nomenclature (terms)
as emphasized in the bold type in this and each following
chapter.
2.
Be able to identify each tooth of the primary and permanent
dentitions using the Universal, Palmer, and Fédération Den-
taire Internationale (FDI) systems.
3.
Correctly name and identify the surfaces, ridges, and ana-
tomic landmarks of each tooth.
4.
Understand and describe the methods used to measure ante-
rior and posterior teeth.
5.
Learn the tables of measurements and be able to discuss size
comparisons between the teeth from any viewing angle. A
useful skill at this point is to start illustrating the individual
teeth with line drawings.
B
A
• Fig. 1.1 Restoration of maxillary central incisors with porcelain veneers
taking into account esthetics, occlusion, and periodontal health. (Case
and photographs courtesy of Michael P. Webberson, DDS, Las Vegas,
NV.)

2 CHAPTER 1 Introduction to Dental Anatomy
Formation of the Dentitions (Overview)
Humans have two sets of teeth in their lifetime. The first set of
teeth to be seen in the mouth is the primary or deciduous denti-
tion, which begins to form prenatally at approximately 14 weeks in
utero and is completed postnatally at approximately 3 years of age.
In the absence of congenital disorders, dental disease, or trauma,
the first teeth in this dentition begin to appear in the oral cavity at
the mean age of 6 months, and the last emerge at a mean age of 28
± 4 months. The deciduous dentition remains intact (barring loss
from dental caries or trauma) until the child is approximately 6
years of age. At approximately that time, the first succedaneous or
permanent teeth begin to emerge into the mouth. The emergence
of these teeth begins the transition or mixed dentition period,
in which there is a mixture of deciduous and succedaneous teeth
present. The transition period lasts from approximately 6 to 12
years of age and ends when all the deciduous teeth have been shed.
At that time, the permanent dentition period begins. Thus the
transition from the primary dentition to the permanent dentition
begins with the emergence of the first permanent molars, shed-
ding of the deciduous incisors, and emergence of the permanent
incisors. The mixed dentition period is often a difficult time for
the young child because of habits, missing teeth, teeth of different
colors and hues, crowding of the teeth, and malposed teeth.
The permanent, or succedaneous, teeth replace the exfoliated
deciduous teeth in a sequence of eruption that exhibits some vari-
ance, an important topic considered in Chapter 16.
After the shedding of the deciduous canines and molars, emer-
gence of the permanent canines and premolars, and emergence of
the second permanent molars, the permanent dentition is com-
pleted (including the roots) at approximately 14 to 15 years of
age, except for the third molars, which are completed at 18 to 25
years of age. In effect, the duration of the permanent dentition
period is 12 or more years. The completed permanent dentition
consists of 32 teeth if none is congenitally missing, which may be
the case. The development of the teeth, dentitions, and the cra-
niofacial complex is considered in Chapter 2. The development of
occlusion for both dentitions is discussed in Chapter 16.
Nomenclature
The first step in understanding dental anatomy is to learn the
nomenclature, or the system of names, used to describe or classify
the material included in the subject. When a significant term is
used for the first time here, it is emphasized in bold. Additional
terms are discussed as needed in subsequent chapters.
The term mandibular refers to the lower jaw, or mandible. The
term maxillary refers to the upper jaw, or maxilla. When more
than one name is used in the literature to describe something,
the two most commonly used names will be used initially. After
that, they may be combined or used separately, as consistent with
the literature of a particular specialty of dentistry, for example,
primary or deciduous dentition, permanent or succedaneous
dentition. A good case may be made for the use of both terms. By
dictionary definition,1 the term primary can mean “constituting
or belonging to the first stage in any process.” The term decidu-
ous can mean “not permanent, transitory.” The same unabridged
dictionary refers the reader from the definition of deciduous tooth
to milk tooth, which is defined as “one of the temporary teeth of
a mammal that are replaced by permanent teeth; also called baby
tooth, deciduous tooth.” The term primary can indicate a first denti-
tion, and the term deciduous can indicate that the first dentition is
not permanent but not unimportant. The term succedaneous can
be used to describe a successor dentition and does not suggest
permanence, whereas the term permanent suggests a permanent
dentition, which may not be the case because of dental caries,
periodontal diseases, and trauma. All four of these descriptive
terms appear in the professional literature.
Formulae for Mammalian Teeth
The denomination and number of all mammalian teeth are
expressed by formulae that are used to differentiate the human den-
titions from those of other species. The denomination of each tooth
is often represented by the initial letter in its name (e.g., I for incisor,
C for canine, P for premolar, M for molar). Each letter is followed
by a horizontal line and the number of each type of tooth is placed
above the line for the maxilla (upper jaw) and below the line for the
mandible (lower jaw). The formulae include one side only, with the
number of teeth in each jaw being the same for humans.
The dental formula for the primary/deciduous teeth in humans
is as follows:
I
2
2
C
1
1
M
2
2
= 10
This formula should be read as: incisors, two maxillary and two
mandibular; canines, one maxillary and one mandibular; molars,
two maxillary and two mandibular—or 10 altogether on one side,
right or left (Fig. 1.2A).
A dental formula for the permanent human dentition is as follows:
I
2
2
C
1
1
P
2
2
M
3
3
= 16
Premolars have now been added to the formula, two maxillary
and two mandibular, and a third molar has been added, one max-
illary and one mandibular (see Fig. 1.2B).
Systems for scoring key morphologic traits of the permanent
dentition that are used for anthropologic studies are not described
here. However, a few of the morphologic traits that are used in
anthropologic studies2 are considered in later chapters (e.g., shov-
eling, Carabelli trait, enamel extensions, peg-shaped incisors).
Some anthropologists use di1, di2, dc, dm1, and dm2 notations
for the deciduous dentition and I1, I2, C, P1, P2, M1, M2, and M3
for the permanent teeth. These notations are generally limited to
anthropologic tables because of keyboard incompatibility.
Tooth Numbering Systems
In clinical practice, some “shorthand” system of tooth notation
is necessary for recording data. Several systems are in use around
the world, but only a few are considered here. In 1947 a commit-
tee of the American Dental Association (ADA) recommended the
symbolic system (Zsigmondy/Palmer) as the numbering method
of choice.3 However, because of difficulties with keyboard nota-
tion of the symbolic notation system, the ADA in 1968 officially
recommended the “universal” numbering system. Because of some
limitations and lack of widespread use internationally, recommen-
dations for a change sometimes are made.4
The Universal system of notation for the primary dentition uses
uppercase letters for each of the primary teeth: For the maxillary
teeth, beginning with the right second molar, letters A through J,
and for the mandibular teeth, letters K through T, beginning with

3
CHAPTER 1 Introduction to Dental Anatomy
Central incisor (first incisor)
Lateral incisor (second incisor)
Canine (cuspid)
First molar
Second molar
Second molar
First molar
A
Canine
RIGHT
LEFT
MANDIBULAR
MAXILLARY
Canine (cuspid)
First premolar (first bicuspid)
Second premolar (second bicuspid)
First premolar (bicuspid)
Canine (cuspid)
B
Second premolar (bicuspid)
First molar
First molar
Second molar
Second molar
Third molar
Third molar
RIGHT
LEFT
MANDIBULAR
MAXILLARY
• Fig. 1.2 (A) Casts of deciduous, or primary, dentition. (B) Casts of permanent dentition. (A, From Berkovitz
BK, Holland GR, Moxham BJ: Oral anatomy, histology and embryology, ed 3, St Louis, 2002, Mosby.)
(To view Animations 1 and 2, please go to Expert Consult.)

the left mandibular second molar. The Universal system notation
for the entire primary dentition is as follows:
t
f
e
L
t
h
g
i
R
T S R Q P O N M L K
A B C D E F G H I J
Midsagittal Plane
The symbolic system for the permanent dentition was intro-
duced by Adolph Zsigmondy of Vienna in 1861 and then modi-
fied for the primary dentition in 1874. Independently, Palmer
also published the symbolic system in 1870. The symbolic system
is most often referred to as the Palmer notation system in the
United States and less frequently as the Zsigmondy/Palmer nota-
tion system. In this system the arches are divided into quadrants,
with the entire dentition being notated as follows:
E D C B A A B C D E
E D C B A A B C D E
Thus, for a single tooth such as the maxillary right central inci-
sor, the designation is A. For the mandibular left central inci-
sor, the notation is given as A. This numbering system presents
difficulty when an appropriate font is not available for keyboard
recording of Zsigmondy/Palmer symbolic notations. For simplifi-
cation, this symbolic notation is often designated as Palmer dental
notation rather than Zsigmondy/Palmer notation.
In the Universal notation system for the permanent denti-
tion, the maxillary teeth are numbered from 1 through 16, begin-
ning with the right third molar. Beginning with the mandibular
left third molar, the teeth are numbered 17 through 32. Thus the
right maxillary first molar is designated as 3, the maxillary left
central incisor as 9, and the right mandibular first molar as 30.
The following universal notation designates the entire permanent
dentition:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17
The Zsigmondy/Palmer notation for the permanent denti-
tion is a four-quadrant symbolic system in which, beginning
with the central incisors, the teeth are numbered 1 through 8 (or
more) in each arch. For example, the right maxillary first molar
is designated as 6 , and the left mandibular central incisor as 1.
The Palmer notation for the entire permanent dentition is as
follows:
8 7 6 5 4 3 2 2 3 4 5 6 7 8
8 7 6 5 4 3 2
1 1
1 1 2 3 4 5 6 7 8
Viktor Haderup of Denmark in 1891 devised a variant of the
eight-tooth quadrant system in which plus (+) and minus (−)
were used to differentiate between upper and lower quadrants and
between right and left quadrants. In other words, +1 indicates the
upper left central incisor, and 1− indicates the lower right cen-
tral incisor. Primary teeth were numbered as follows: upper right,
05+ to 01+; lower left, −01 to −05. This system is still taught in
Denmark.5
The Universal system is acceptable to computer language,
whereas the Palmer notation is generally incompatible with com-
puters and word-processing systems. Each tooth in the universal
system is designated with a unique number, which leads to less
confusion than with the Palmer notation.
A two-digit system proposed by Fédération Dentaire Inter-
nationale (FDI) for both the primary and permanent denti-
tions has been adopted by the World Health Organization
and accepted by other organizations, such as the International
Association for Dental Research. The FDI system of tooth
notation is as follows.
For the primary teeth:
Upper Right
55 54 53 52 62 63 64 65
85 84 83 82
51 61
81 72 73 74 75
Lower Right
71
Upper Left
Lower Left
Numeral 5 indicates the maxillary right side, and 6 indicates
the maxillary left side. The second number of the two-digit num-
ber is the tooth number for each side. The number 8 indicates the
mandibular right side, and the number 7 indicates the mandibular
left side. The second number of the two-digit system is the tooth
number. Thus, for example, the number 51 refers to the maxillary
right central incisor.
For the permanent teeth:
Upper Right
18 17 16 15 14 13 12 22 23 24 25 26 27 28
48 47 46 45 44 43 42
11 21
41 31 32 33 34 35 36 37 38
Lower Right
Upper Left
Lower Left
Thus, as in the two-digit FDI system for the primary dentition,
the first digit indicates the quadrant: 1 to 4 for the permanent
dentition and 5 to 8 for the primary dentition. The second digit
indicates the tooth within a quadrant: 1 to 8 for the permanent
teeth and 1 to 5 for the primary teeth. For example, the perma-
nent upper right central incisor is 11 (pronounced “one one,” not
“eleven”).
Crown and Root
Each tooth has a crown and root portion. The crown is covered
with enamel, and the root portion is covered with cementum. The
crown and root join at the cementoenamel junction (CEJ). This
junction, also called the cervical line (Fig. 1.3), is plainly visible
on a specimen tooth. The main bulk of the tooth is composed of
dentin, which is clear in a cross section of the tooth. This cross
section displays a pulp chamber and a pulp canal, which normally
contain the pulp tissue. The pulp chamber is in the crown portion
mainly, and the pulp canal is in the root (Fig. 1.4). The spaces are
continuous with each other and are spoken of collectively as the
pulp cavity.
The four tooth tissues are enamel, cementum, dentin, and pulp. The
first three are known as hard tissues, the last as soft tissue. The pulp
tissue furnishes the blood and nerve supply to the tooth. The tissues
of the teeth must be considered in relation to the other tissues of the
orofacial structures (Figs. 1.5 and 1.6) if the physiology of the teeth
is to be understood.
The crown of an incisor tooth may have an incisal ridge or
edge, as in the central and lateral incisors; a single cusp, as in
the canines; or two or more cusps, as on premolars and molars.

5
Incisal ridges and cusps form the cutting surfaces on tooth
crowns.
The root portion of the tooth may be single, with one apex
or terminal end, as usually found in anterior teeth and some of
the premolars; or multiple, with a bifurcation or trifurcation
dividing the root portion into two or more extensions or roots
with their apices or terminal ends, as found on all molars and in
some premolars.
The root portion of the tooth is firmly fixed in the bony process
of the jaw, so that each tooth is held in its position relative to the
others in the dental arch. That portion of the jaw serving as sup-
port for the tooth is called the alveolar process. The bone of the
tooth socket is called the alveolus (plural alveoli) (Fig. 1.7).
The crown portion is never covered by bone tissue after it is
fully erupted, but it is partly covered at the cervical third in young
adults by soft tissue of the mouth known as the gingiva or gingival
tissue, or “gums.” In some persons, all the enamel and frequently
some cervical cementum may not be covered by the gingiva.
Surfaces and Ridges
The crowns of the incisors and canines have four surfaces and a
ridge, and the crowns of the premolars and molars have five sur-
faces. The surfaces are named according to their positions and uses
(Fig. 1.8). In the incisors and canines, the surfaces toward the lips
are called labial surfaces; in the premolars and molars, those fac-
ing the cheek are the buccal surfaces. When labial and buccal
surfaces are referred to collectively, they are called facial surfaces.
All surfaces facing toward the tongue are called lingual surfaces.
The surfaces of the premolars and molars that come in contact
(occlusion) with those in the opposite jaw during the act of closure
are called occlusal surfaces. These are called incisal surfaces with
respect to incisors and canines.
The surfaces of the teeth facing toward adjoining teeth in the
same dental arch are called proximal or proximate surfaces. The
proximal surfaces may be called either mesial or distal. These terms
have special reference to the position of the surface relative to the
median line of the face. This line is drawn vertically through the
A
R
CL
C
IE
• Fig. 1.3 Maxillary central incisor (facial aspect). A, Apex of root; C, Crown;
CL, Cervical line; IE, Incisal edge; R, Root. (To view Animations 3 and 4,
please go to Expert Consult.)
A
B
CR
A B
A
BI
CEJ
CU
F
PH
PCH
PC
A
AF
SC
B
C
PM
B
PC
G
GC
GM
PCH
D
E
A
• Fig. 1.4 Schematic drawings of longitudinal sections of an anterior and a posterior tooth. (A) Anterior
tooth. A, Apex; AF, apical foramen; B, bone; C, cementum; CR, crown; D, dentin; E, enamel; G, gingiva;
GC, gingival crevice; GM, gingival margin; PC, pulp canal; PCH, pulp chamber; PM, periodontal ligament;
SC, supplementary canal. (B) Posterior tooth. A, Apices; BI, bifurcation of roots; CEJ, cementoenamel
junction; CU, cusp; F, fissure; PC, pulp canal; PCH, pulp chamber; PH, pulp horn.

center of the face, passing between the central incisors at their point
of contact with each other in both the maxilla and the mandible.
Those proximal surfaces that, following the curve of the arch, are
faced toward the median line are called mesial surfaces, and those
most distant from the median line are called distal surfaces.
Four teeth have mesial surfaces that contact each other: the
maxillary and mandibular central incisors. In all other instances,
the mesial surface of one tooth contacts the distal surface of its
neighbor, except for the distal surfaces of third molars of perma-
nent teeth and distal surfaces of second molars in deciduous teeth,
which have no teeth distal to them. The area of the mesial or distal
surface of a tooth that touches its neighbor in the arch is called the
contact area.
Central and lateral incisors and canines as a group are called
anterior teeth; premolars and molars as a group, posterior teeth.
Other Landmarks
To study an individual tooth intelligently, one should recognize
all landmarks of importance by name. Therefore, at this point, it
is necessary to become familiar with additional terms, such as the
following:
cusp triangular ridge developmental groove
tubercle transverse ridge supplemental groove
cingulum oblique ridge pit
ridge fossa lobe
marginal ridge sulcus
Palatine vein
Palatine artery
Palatine glands
Palatine nerve
• Fig. 1.6 Section through the second maxillary molar and adjacent tissues.
• Fig. 1.7 Left maxillary bone showing the alveoli for the incisors, canines,
and premolar and molar teeth.
Vestibular
mucosa
Free gingival
margin
Attached
gingiva
Anterior oral
vestibule
Attached
gingiva
Labial
mucosa
• Fig. 1.5 Sagittal sections through the maxillary and mandibular central incisors.

7
A cusp is an elevation or mound on the crown portion of a tooth
making up a divisional part of the occlusal surface (Fig. 1.9; see
also Fig. 1.4).
A tubercle is a smaller elevation on some portion of the crown
produced by an extra formation of enamel (see Fig. 4.14A). These
are deviations from the typical form.
A cingulum (Latin word for “girdle”) is the lingual lobe of
an anterior tooth. It makes up the bulk of the cervical third of
the lingual surface. Its convexity mesiodistally resembles a girdle
encircling the lingual surface at the cervical third (Figs. 1.10; see
also Fig. 4.13A).
A ridge is any linear elevation on the surface of a tooth and is
named according to its location (e.g., buccal ridge, incisal ridge,
marginal ridge).
Marginal ridges are the rounded borders of the enamel that
form the mesial and distal margins of the occlusal surfaces of pre-
molars and molars, as well as the mesial and distal margins of the
lingual surfaces of the incisors and canines (Fig. 1.11A; see also
Figs 1.10A).
Triangular ridges descend from the tips of the cusps of molars
and premolars toward the central part of the occlusal surfaces.
They are so named because the slopes of each side of the ridge
are inclined to resemble two sides of a triangle (Fig. 1.12; see also
Figs. 1.11B and C). They are named after the cusps to which they
1. Central incisor (first incisor)
2. Lateral incisor (second incisor)
3. Canine (cuspid)
4. First premolar (first bicuspid)
5. Second premolar (second bicuspid)
6. First molar
7. Second molar
8. Third molar
There are eight tooth names
included in each quadrant of the
dental arches; they are repeated to
include right, left, maxillary and
mandibular, making a total of
thirty-two teeth in all.
Lingual
Labial
D
is
ta
l
F
a
c
i
a
l
B
u
c
c
a
l
Median
Line
1
2
3
4
5
6
7
8
Third Molar
A
w
a
y
f
r
o
m
m
e
d
i
a
n
l
i
n
e
T
o
w
a
r
d
m
e
d
i
a
n
l
i
n
e
M
e
s
i
a
l
• Fig. 1.8 Application of nomenclature. Tooth numbers 1 to 8 indicating left maxillary teeth. Tooth surfaces
related to the tongue (lingual), cheek (buccal), lips (labial), and face (facial), apply to four quadrants and the
upper left quadrant. The teeth or their parts or surfaces may be described as being away from the midline
(distal) or toward the midline (mesial).
CF
DBC
DMR
OR
DLC
DG
BCR
BG
MBC
SG
TF
MLC
• Fig. 1.9 Some landmarks on the maxillary first molar. BCR, Buccocervical
ridge; BG, buccal groove; CF, central fossa; DBC, distobuccal cusp; DG,
developmental groove; DLC, distolingual cusp; DMR, distal marginal ridge;
MBC, mesiobuccal cusp; MLC, mesiolingual cusp; OR, oblique ridge; SG,
supplemental groove; TF, triangular fossa. (To view Animations 3 and 4 for
tooth #3, please go to Expert Consult.)

B
A
MR
CL
CI
MR
IR
LF
C
• Fig. 1.10 (A) Maxillary right lateral incisor (lingual aspect). CI, Cingulum (also called the linguocervical
ridge); CL, cervical line; IR, incisal ridge; LF, lingual fossa; MR, marginal ridge. (B) Mamelons on erupting,
noncontacting central incisors. (C) Mamelon-like serrations on primary incisors. (B, From Bath-Balogh M,
Fehrenbach MJ: Illustrated dental embryology, histology, and anatomy, ed 2, St Louis, 2006, Saunders.)
Occlusal
TR
Trans R
CR
TR
BCR
CR
TR
DG
SG
P
TR
S
A B C
MR
• Fig. 1.11 (A) Mesial view of a maxillary right first premolar. BCR, Buccocervical ridge; CR, cusp ridge; MR,
marginal ridge; S, sulcus traversing occlusal surface. (B) Occlusal view of mandibular right first premolar.
CR, Cusp ridge; TR, triangular ridges; Trans R, transverse ridge, formed by two triangular ridges that cross
the tooth transversely. (C) Occlusal view of a maxillary right first molar. DG, Developmental groove; P, pit
formed by junction of developmental grooves; SG, supplemental groove; TR, triangular ridge.

9
belong, for example, the triangular ridge of the buccal cusp of the
maxillary first premolar.
When a buccal and a lingual triangular ridge join, they form a
transverse ridge. A transverse ridge is the union of two triangular
ridges crossing transversely the surface of a posterior tooth (see
Fig. 1.11B and C).
The oblique ridge is a ridge crossing obliquely the occlusal
surfaces of maxillary molars and formed by the union of the trian-
gular ridge of the distobuccal cusp and the distal cusp ridge of the
mesiolingual cusp (see Fig. 1.9).
A fossa is an irregular depression or concavity. Lingual fossae
are on the lingual surface of incisors (see Fig. 1.10). Central fos-
sae are on the occlusal surface of molars. They are formed by the
convergence of ridges terminating at a central point in the bottom
of the depression where there is a junction of grooves (see Fig.
1.12). Triangular fossae are found on molars and premolars on
the occlusal surfaces mesial or distal to marginal ridges (see Fig.
1.9). They are sometimes found on the lingual surfaces of maxil-
lary incisors at the edge of the lingual fossae where the marginal
ridges and the cingulum meet (see Fig. 4.14A).
A sulcus is a long depression or valley in the surface of a tooth
between ridges and cusps, the inclines of which meet at an angle.
A sulcus has a developmental groove at the junction of its inclines.
(The term sulcus should not be confused with the term groove.)
A developmental groove is a shallow groove or line between
the primary parts of the crown or root. A supplemental groove,
less distinct, is also a shallow linear depression on the surface of
a tooth, but it is supplemental to a developmental groove and
does not mark the junction of primary parts. Buccal and lingual
grooves are developmental grooves found on the buccal and lin-
gual surfaces of posterior teeth (see Figs. 1.9 and 1.12).
Pits are small pinpoint depressions located at the junction
of developmental grooves or at terminals of those grooves. For
example, central pit is a term used to describe a landmark in the
central fossa of molars where developmental grooves join (see Fig.
1.11C).
A lobe is one of the primary sections of formation in the devel-
opment of the crown. Cusps and mamelons are representative
of lobes. A mamelon is any one of the three rounded protuber-
ances found on the incisal ridges of newly erupted incisor teeth.
Although they are generally considered to be a feature of the per-
manent incisors, mamelon-like serrations may also be found on
newly erupted primary incisors (see Fig. 1.10B and C).6 (For fur-
ther description of lobes, see Figs. 4.11 to 4.14.)
The roots of the teeth may be single or multiple. Both max-
illary and mandibular anterior teeth have only one root each.
Mandibular first and second premolars and the maxillary second
premolar are single rooted, but the maxillary first premolar has
two roots in most cases, one buccal and one lingual. Maxillary
molars have three roots, one mesiobuccal, one distobuccal, and
one lingual. Mandibular molars have two roots, one mesial and
one distal. It must be understood that descriptions in anatomy
can never follow a hard-and-fast rule. Variations frequently occur.
This is especially true regarding tooth roots, such as the facial and
lingual roots of the mandibular canine.
Division Into Thirds, Line Angles, and Point
Angles
For purposes of description, the crowns and roots of teeth have
been divided into thirds, and junctions of the crown surfaces are
described as line angles and point angles. Actually, there are no
angles or points or plane surfaces on the teeth anywhere except
those that appear from wear (e.g., attrition, abrasion) or from
accidental fracture. Line angle and point angle are used only as
descriptive terms to indicate a location.
When the surfaces of the crown and root portions are divided
into thirds, these thirds are named according to their location.
Looking at the tooth from the labial or buccal aspect, we see that
the crown and root may be divided into thirds from the incisal or
occlusal surface of the crown to the apex of the root (Fig. 1.13).
The crown is divided into an incisal or occlusal third, a middle
TRR
DLC
TR
DC
DBC
DBG
CF
MLC
MMR
MBC
MBG
BCR
• Fig. 1.12 Mandibular right first molar. BCR, Buccocervical ridge; CF, cen-
tral fossa; DBC, distobuccal cusp; DBG, distobuccal groove; DC, distal
cusp; DLC, distolingual cusp; MBC, mesiobuccal cusp; MBG, mesiobuc-
cal groove; MLC, mesiolingual cusp; MMR, mesial marginal ridge; TR, tri-
angular ridge; TRR, transverse ridge.(To view Animations 3 and 4 for tooth
#30, please go to Expert Consult.)
Apical
Middle
Cervical
Cervical
Cervical
Middle
Occlusal
Middle
Incisal
Distal
Middle
Mesial
Mesial
Buccal
Middle
Lingual
Middle
Distal
Lingual
Middle
Labial
• Fig. 1.13 Division into thirds.

third, and a cervical third. The root is divided into a cervical third,
a middle third, and an apical third.
The crown may be divided into thirds in three directions: inci-
socervically or occlusocervically, mesiodistally, or labiolingually or
buccolingually. Mesiodistally, it is divided into the mesial, middle,
and distal thirds. Labiolingually or buccolingually, it is divided
into labial or buccal, middle, and lingual thirds. Each of the five
surfaces of a crown may be so divided. There will be one middle
third and two other thirds, which are named according to their
location (e.g., cervical, occlusal, mesial, lingual).
A line angle is formed by the junction of two surfaces and
derives its name from the combination of the two surfaces that
join. For example, on an anterior tooth, the junction of the mesial
and labial surfaces is called the mesiolabial line angle.
The line angles of the anterior teeth (Fig. 1.14A) are as follows:
mesiolabial distolingual
distolabial labioincisal
mesiolingual linguoincisal
Because the mesial and distal incisal angles of anterior teeth are
rounded, mesioincisal line angles and distoincisal line angles
are usually considered nonexistent. They are spoken of as mesial
and distal incisal angles only.
The line angles of the posterior teeth (see Fig. 1.14B) are as
follows:
mesiobuccal distolingual bucco-occlusal
distobuccal mesio-occlusal linguo-occlusal
mesiolingual disto-occlusal
A point angle is formed by the junction of three surfaces. The
point angle also derives its name from the combination of the
names of the surfaces forming it. For example, the junction of
the mesial, buccal, and occlusal surfaces of a molar is called the
mesiobucco-occlusal point angle.
The point angles of the anterior teeth are (Fig. 1.15A):
mesiolabioincisal mesiolinguoincisal
distolabioincisal distolinguoincisal
The point angles of the posterior teeth are (see Fig. 1.15B):
mesiobucco-occlusal mesiolinguo-occlusal
distobucco-occlusal distolinguo-occlusal
Tooth Drawing and Carving
The subject of drawing and carving of teeth is being introduced
at this point because it has been found through experience that a
laboratory course in tooth morphology (dissection, drawing, and
carving) should be carried on simultaneously with lectures and
reference work on the subject of dental anatomy. However, illus-
trations and instruction in tooth form drawing and carving are
not included here.
The basis for the specifications to be used for carving indi-
vidual teeth is a table of average measurements for permanent
teeth given by Dr. G. V. Black.7 However, teeth carved or drawn
to these average dimensions cannot be set into place for an ideal
occlusion. Therefore, for purposes of producing a complete set of
articulated teeth (Figs. 1.16 to 1.18) carved from Ivorine, minor
changes have been made in Dr. Black’s table. In addition, carving
Linguoincisal line angle
Distolabial line angle
Linguo-occlusal
line angle
Distolingual line angle
Distobuccal line angle
Mesio-occlusal line angle
Bucco-occlusal line angle
Mesiolingual line angle
Mesiobuccal line angle
Distolingual line angle
Labioincisal line angle
Mesiolabial line angle
Mesiolingual line angle
A
B
• Fig. 1.14 Line angles. (A) Anterior teeth. (B) Posterior teeth.
Distolabioincisal point
angle
Mesiolabioincisal point
angle
Mesiolinguoincisal point
angle
Distolinguo-occlusal point
angle
Distobucco-occlusal point
angle
Distolinguoincisal point
angle
A
B
Mesiolinguo-occlusal point
angle
Mesiobucco-occlusal point
angle
• Fig. 1.15 (A) Point angles on anterior teeth. (B) Point angles on posterior
teeth.

11
teeth to natural size, calibrated to tenths of a millimeter, is not
practical. The adjusted measurements are shown in Table 1.1. The
only fractions listed in the model table are 0.5 and 0.3 mm in a
few instances. Fractions are avoided whenever possible to facilitate
familiarity with the table and to avoid confusion.
A table of measurements must be arbitrarily agreed on so that a
reasonable comparison can be made when appraising the dimen-
sions of any one aspect of one tooth in the mouth with that of
another. It has been found that the projected table functions well
in that way. For example, if the mesiodistal measurement of the
maxillary central incisor is 8.5 mm, the canine will be approx-
imately 1 mm narrower in that measurement; if by chance the
central incisor is wider or narrower than 8.5 mm, the canine mea-
surement will correspond proportionately.
Photographs of the five aspects of each tooth—mesial, distal,
labial or buccal, lingual, and incisal or occlusal—superimposed on
squared-millimeter cross-section paper reduces the tooth outlines
of each aspect to an accurate graph, so that it is possible to com-
pare and record the contours (Figs. 1.19 and 1.20).
Close observation of the outlines of the squared backgrounds
shows the relationship of crown to root, extent of curvatures at
various points, inclination of roots, relative widths of occlusal sur-
faces, height of marginal ridges, contact areas, and so on.
It should be possible to draw reasonably well an outline of any
aspect of any tooth in the mouth. It should be in good propor-
tion without reference to another drawing or three-dimensional
model.
For the development of skills in observation and in the restora-
tion of lost tooth form, the following specific criteria are suggested:
1.
Become so familiar with the table of measurements that it is
possible to make instant comparisons mentally of the propor-
tion of one tooth with regard to another from any aspect.
2.
Learn to draw accurate outlines of any aspect of any tooth.
3.
Learn to carve with precision any design one can illustrate with
line drawings.
Measurement of Teeth
Readers who are not familiar with the Boley gauge should study
its use before reading the following instructions on the application
of the table of measurements.
To understand the table, let us demonstrate the calibrations as
recorded and the landmarks they encompass. There are eight cali-
brations of each tooth to be remembered. These measurements
are shown in the accompanying example for the maxillary central
incisor (see the example included in Table 1.1).
The method for measuring an anterior tooth is shown in Box
1.1 (Figs. 1.21 to 1.27), and the posterior method is shown in Box
1.2 (Figs. 1.28 to 1.34).
Summary
Terminology is an established basis for communication, and
therefore the importance of learning the nomenclature for dental
anatomy cannot be minimized. The terms used in describing the
morphology of teeth are used in every aspect of dental practice.
Although there is no such thing as an established invariable
norm in nature, in the study of anatomy it is necessary that there
be a starting point. Therefore we must begin with an arbitrary
criterion, accepted after experimentation and due consideration.
Because restorative dentistry must approach the scientific as
closely as manual dexterity will allow, models, plans, photographs,
and natural specimens should be given preference over the written
text on this subject.
Every curve and segment of a normal tooth has some func-
tional basis, and it is important to reproduce them accurately. The
successful clinician in dentistry or, for that matter, any designer
of dental restorations should be able to mentally create pictures
of the teeth from any aspect and relate those aspects of dental
anatomy to function. Complete pictures can be formed only when
one is familiar with the main details of tooth form.
• Fig. 1.16 Carvings in Ivorine of individual teeth made according to the
table of measurements (see Table 1.1). Because skulls and extracted teeth
show so many variations and anomalies, an arbitrary norm for individual
teeth had to be established for comparative study. Thus the 32 teeth were
carved at natural size and in normal alignment and occlusion, and from the
model a table of measurements was drafted.
• Fig. 1.17 Another view of the models shown in Fig. 1.16.

A
B
• Fig. 1.18 Occlusal view of the models shown in Figs. 1.16 and 1.17.

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