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Chapter

Dental Anatomy and Morphology

of Permanent Teeth
Emanuela Lidia Crăciunescu, Meda-Lavinia Negruţiu,
Mihai Romînu, Andreea Codruţa Novac, Cristina Modiga,
Borislav-Duşan Caplar, Cosmin Sinescu
and Daniela-Maria Pop

Abstract

The present chapter is proposing a detailed and illustrated description of dental

morphology of permanent dentition. The main topics are related to nomenclature, age
of emergence, a description of teeth’s tissues (pulp, dentin, enamel, and cement), and
morphology of all permanent teeth. The main focus of this chapter is the description
of individualized morphology and specific variations of each permanent tooth. The
goal of all treatment phases in dental medicine is to restore the function, integrity, and
morphology of the oral cavity, and all these achievements are reached through deep
knowledge of dental morphology. Cavities are restored with direct dental materials,
which need to be carved according to the natural shape, outlines, occlusal and proxi-
mal contacts of teeth’s morphology, reproducing also the shade and translucencies of
natural teeth. The same goal dominates the prosthodontic field. It is well known in
dental medicine that shape, size, and position assure the optimal function and pre-
serve the self-maintenance of dental arches and dento-maxillary system. For esthetic,
function, and self-preservation, all dental treatment fields have to first consider the
dental morphology.

Keywords: teeth, crown, root, morphology, contact areas, occlusion, esthetics, oral
cavity

1. Introduction

In the past decades, dental medicine has evolved according to the technological
progress, development of high quality and esthetic dental materials, and new and
conservative attitudes in clinical practice. Dental anatomy and morphology are the
basic components of the skills and knowledge needed in all dental treatment phases.
The knowledge related to function, shape, color, phonetics, position on the dental
arch, and the relations with the opposing arch is as important as dental anatomy and
morphology. The study of dental anatomy, morphology, physiology, and occlusion is
mandatory in all the curriculum of dental schools and provides the basic and the most
important component in developing a successful treatment plan for all phases of
1
Human Teeth – From Function to Esthetics

dental treatments, which include odontotherapy, endodontics, prosthodontics,

implantology, orthodontics, periodontology, and pediatric dentistry.
Dental practitioners, during the inspection of the oral cavity, will see the clinical
crowns, the attachment of gingival tissue, the shape, size, position and angulations of the
teeth, the relation of proximal contact areas, the occlusal contacts, and the evidence of
parafunctions and esthetics. Having this picture, the basic knowledge, and considering all
the factors and all related anatomical structures, a correct treatment plan will be made.

2. Introduction to dental anatomy and morphology

2.1 Nomenclature, numbering system, and dental tissues

For studying dental anatomy, a common language is required. Humans have two
dentitions in their lifetime that support the anatomical structures and orofacial func-
tions such as mastication, speech, and give shape and beauty to the face. Teeth are
highly calcified structures with individualized tissues, supported in the upper and
lower jaw by bony sockets also called alveolus. Teeth are comprised of four types:
incisors, canines (cuspids), premolars (bi-cuspids), and molars. The first set of teeth is
the primary or deciduous dentition, which begins to form prenatally at about 14 weeks
and is completed postnatal at about 3 years of age. In total, 20 teeth, 10 maxillary and
10 mandibular teeth, and 5 teeth on each side of the jaw are consisting the deciduous
dentition. The teeth in deciduous dentition are grouped on maxillary and mandibular
jaw as follows: four incisors, two canines, and four molars (Table 1). World Dental
Federation proposed a numbering system for deciduous and permanent dentitions,
and the system was adopted by the World Health Organization and accepted by other
organizations such as the International Association for Dental Research [1].
Morphological characteristics of deciduous teeth are different from permanent
ones. Deciduous teeth have smaller crowns and roots, more prominent cervical ridges,
and narrower “neck” or cervical diameter. The roots are narrower and flare, and the
buccolingual diameters are smaller than the permanent’s diameters. Crowns of decid-
uous anterior teeth have a mesiodistal diameter higher in comparison with the
cervical-incisal diameter. The roots of deciduous anterior are long and narrower, and
the roots of deciduous molars are longer, slender, and flare to allow more room for the
development of permanent crowns. The cervical ridges of the deciduous anterior teeth
are more prominent, the crowns and roots of deciduous molar are more slander
mesiodistally, the buccal and lingual surfaces of deciduous molars are flatter, and the
shade of deciduous is whiter [2].
The teeth supported by the upper jaw are called maxillary teeth and the ones
supported by the lower jaw are called mandibular teeth. The deciduous dentition lasts
until about 6 years of age when the first succedaneous or permanent teeth are emerg-
ing into the oral cavity. In this stage, the transitional dentition or mixed dentition is
formed, which is present in the oral cavity until 12 or 13 years of age and ends when all
the deciduous teeth are lost and all the permanent ones have emerged in the oral
cavity. Mixed dentition, present between 6 and 12 years of age, can be a difficult
period of time because of missing teeth, different shades and hues of the recently
emerged teeth, malposition, and crowning, which may need orthodontic treatment.
In total, 32 teeth, 16 maxillary and 16 mandibular teeth, and 8 teeth on each side of
the jaw are consisting the permanent dentition. Teeth in permanent dentition are
grouped on each jaw as follows: four incisors, two canines, four premolars, and six
2
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DOI: http://dx.doi.org/10.5772/intechopen.110223
Dental Anatomy and Morphology of Permanent Teeth
Upper right Upper left

Tooth Second First molar Canine Lateral Central Central Lateral Canine First molar Second
molar incisor incisor incisor incisor molar

Nomenclature 5.5 5.4 5.3 5.2 5.1 6.1 6.2 6.3 6.4 6.5

Age of emerge 25–33 months 13– 16– 9–13 months 8–12 months 8–12 months 9–13 months 16– 13– 25–33 months
19 months 22 months 22 months 19 months

Age of emerge 23–31 months 14– 17– 10–16 months 6–10 month 6–10 month 10–16 months 17– 14– 23–31 months
18 months 23 months 23 months 18 months

Nomenclature 8.5 8.4 8.3 8.2 8.1 7.1 7.2 7.3 7.4 7.5

Tooth Second molar First molar Canine Lateral incisor Central incisor Central incisor Lateral incisor Canine First molar Second molar

Lower right Lower left

Table 1.
Nomenclature and age of emergence of deciduous dentition.
Human Teeth – From Function to Esthetics

molars. The evolution of permanent dentition ends at about 14–15 years of age when
the roots have completed their development. The age of emergence of permanent
teeth is described in Table 2. The exception is related to third molars, which are
emerging at 18–25 years of age [1, 3].
Teeth have two primary components, one crown—exposed in the oral cavity—and
one or more roots supported by the alveolar socket. The tooth has four primary tissues
—enamel, dentine, cement, and pulp. The main component of a tooth is a bone-like
tissue called dentine.
Enamel covers the visible part of the crown in the oral cavity and is a highly
calcified tissue (95.5% inorganic, 0.5% organic, and 4% water). The upper incisors
reach the highest density of enamel, which is increasing progressively during devel-
opment. The thickness of the enamel layer varies from about 2.5 mm in the cusps area,
2.0 mm in the incisal edge, and 0.5 mm at the cervical enamel. The color is semitrans-
lucent and depends on the enamel thickness. In the thick opaque area, the color
appears bluish-white and yellow-white in the area where the enamel layer is thinner.
Enamel is the hardest structure of the body, having a value of 5–8 on the Moch scale
(diamond-10 Moch). The high hardness influences the tensile strength and compress-
ibility, which indicate that enamel is extremely brittle [4, 5].
The enamel is structured in enamel rods (prisms), rod sheaths, and cementing interred
substance. Generally, enamel rods are aligned perpendicular to dentine-enamel junc-
tion and usually in cervical area the rods become twisted. The rods are aligned in
planes best suited to withstand the occlusal forces as long as the forces are perpendic-
ular to the tooth surface. Rod sheath is an area identified in histologic sections of a
tooth, found where enamel rods, the functional unit of enamel, meet interrod enamel.
Both types of enamel meet at sharp angles and form the appearance of a space called
the rod sheath. The rod sheath consists of more protein and the rod sheath is charac-
terized as being hypomineralized in comparison to the rest of the highly mineralized
enamel. The rod sheath is Inorganic matrix tying the enamel rods together. The
interred substance cement the rods together. Enamel forms junctions with dentine
and cement. The dentine-enamel junction (DEJ) has a pitted aspect and in the rounded
pits fit the enamel rod, which generates a strong bond between the two tissues [3, 4].
Underlying the enamel tissue is the dentine root, a bone-like tissue that consists of a
spongy bone-like tissue, which consists of the root, and is covered by cementum which is
present only on the tooth surface. The crown delimited by the enamel and the root
delimited by the cement join in a junction called cementoenamel junction (CEJ), which
is also called the cervical line. The cementum is specially adapted to anchor and support
the tooth in the bony socket and covers the dentine root. Both enamel and cement are
covering the dentine, and three variations in their link may exist: the cervical enamel is
covered by cementum (65%), contact line between enamel and cementum (25%), or
enamel and cement do not touch, and in this situation, dentin is exposed (10%) [3, 6].
Dentin is the largest tissue of a tooth, gives the basic shape of the crown and root,
and forms the walls of the pulp cavity in the crown and root area. The color is light
yellow in deciduous teeth and yellow in permanent teeth, less hard than enamel, and
harder than the cementum. In contrast to the enamel, dentine is highly elastic, can
support the non-resilient enamel, and is highly permeable. In its chemical composi-
tion, dentine has 70% inorganic matter, 17% organic matter (collagen, proteins, and
citric acid), and 13% water. Dentine is structured into dentinal tubules that are ending
beneath the enamel and contain the Tome’s fibers also called processes of odontoblasts
cells present in the dental pulp. For this reason, dentine is a living and sensitive hard
tissue of the tooth. Dentine tubes have an “S” curved shape and start perpendicular to
4
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DOI: http://dx.doi.org/10.5772/intechopen.110223
Dental Anatomy and Morphology of Permanent Teeth
M3 M2 M1 P2 P1 C LI CI CI LI C P1 P2 M1 M2 M3

1.8 1.7 1.6 15 1.4 1.3 1.2 1.1 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8

17– 12– 6– 10– 10– 11– 8– 7– 7– 8– 11– 10– 10– 6– 12– 17–
21 years 13 years 7 years 12 years 11 years 12 years 9 years 8 years 8 years 9 years 12 years 11 years 12 years 7 years 13 years 21 years

17– 11– 6– 11– 10– 9– 7– 6– 6– 7– 9– 10– 11– 6– 11– 17–

21 Years 13 years 7 years 12 years 12 years 10 years 8 years 7 years 7 years 8 years 10 years 12 years 12 years 7 years 13 years 21 years

4.8 4.7 4.6 4.5 4.4 4.3 4.2 4.1 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8

M3 M2 M1 P2 P1 C LI CI CI LI C P1 P2 M1 M2 M3
CI—central incisor, LI—lateral incisor, C—canine, P1—first premolar, P2—second premolar, M1—first molar, M2—second molar, and M3—third molar.

Table 2.
Nomenclature and age of emerge for permanent dentition.
Human Teeth – From Function to Esthetics

the pulp chamber surface but are straight under the cusps and in the root area. The
dentine encloses the dental pulp, the soft tissue formed by blood vessels, nerves, and
specialized tissue, all responsible for the tooth’s vitality [3, 6].
Dental pulp is contained within the pulp chamber of the crown, close to the cervical
line and in the cervical third part of the crown, and is followed by the pulp canal along
the root. The pulp chamber and root canal form together the pulp cavity. Pulp has the
main role in forming the dentine, has a sensory function through which the tooth is
felt, and also has a nutrient function by supplying nutrition to the dentine through the
blood vessels and odontoblastic processes with an important role in maintaining the
tooth’s vitality. The last function is the defensive one, through which the pulp is
producing secondary dentine to maintain the vitality of the tooth in case of damaging
factors such as cavities, occlusal overloading, and aging. In young teeth, the pulp
chamber is bigger and follows the shape of the crown through the extension of pulp
chamber into the cusps. These extensions are called pulp horns. By aging, the pulp
chamber is reducing its size because of secondary dentine deposition. The root canal
and apical foramen are wide in case of young teeth and become narrow by aging. Root
canals can be straight or curved, single or not, with accessory lateral canals usually in
the apical foramen or at the floor of the pulp chamber. Apical foramen or root apex is a
small foramen through which the blood vessels and nerves enter the pulp chamber and
may be located on the lateral side of the apex. A tooth can have more than one
foramina. Through apical foramen, there is a communication with periodontal space.
Endodontic and periodontal pathology are interconnected and influenced one by
another through apical foramen or accessory foramens and root canals [7].
The three hard tissues of the tooth, enamel, dentine, and cementum, and the soft
tissue represented by dental pulp have to be considered in relation with the oral-facial
structures, oral cavity, and all surrounded soft tissues and anatomical structures.

2.2 Surfaces, ridges, and landmarks in dental morphology

The crowns of anterior teeth have four axial surfaces and one incisal ridge. The
premolars and molars have five surfaces, four axial, and one occlusal. The name of the
surface is given after the anatomical position and relation to the adjacent anatomical
structures. For upper and lower incisors and canines, the surfaces toward the lips are
called labial surface. The surfaces that face the median line of the face or toward
adjoining teeth are called mesial and opposite or the ones distant from the median
line are called distal surfaces. Mesial and distal surfaces are also called proximal
surfaces [1, 3].
The surfaces facing the tongue are called lingual. In case of premolars and molars,
the name of the surfaces is maintained with one exception, the surfaces facing the
cheeks are called buccal surfaces. Buccal and labial surfaces, when spoken collectively,
are called facial surfaces. The surfaces of premolars and molars, which establish
contact or occlusion with the ones positioned on the opposite jaw, are called occlusal
surfaces and incisal ridge with respect to incisors and canines (Figure 1) [1, 3].
Beyond surfaces, teeth have other landmarks divided into positive and negative
landmarks. The positive landmarks are cusps, tubercle, cingulum, marginal ridge,
triangular ridges, transversal ridges, oblique ridges, and lobes. The negative
landmarks are fossa, sulculus, pits, and developmental grooves [1, 3].
Cusps are elevations specific to premolar’s and molar’s crowns and divide the
occlusal surfaces. Every cusps has a pyramidal shape with a quadrangular base with
the exception of the mesial-lingual cusp of the upper first molar. Tubercles are small
6
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DOI: http://dx.doi.org/10.5772/intechopen.110223

Figure 1.
Upper central incisor. A—Buccal or facial surface, B—mesial surface-proximal view, C—lingual surface from
proximal view, D—facial surface from mesial view, E-cervical line—mesial view, and F—Incisal view—incisal
ridge.

elevations, similar in shape to the cusps but are actually an extra formation of enamel.
Cingulum is the lingual lobe of anterior teeth and gives a bulk aspect in the cervical
third of the lingual surface. Ridges are any linear elevation on the surface of the tooth
and receive the name after the position on the surface. Marginal ridges are the rounded
borders of the enamel that form and limit the margins of the occlusal surface. Each
premolar and molar has a mesial and distal ridge on the occlusal surface. The trans-
versal ridges start from the tips of the cusps of laterals toward the center of the occlusal
surfaces and are named after the cusps to which they belong, like triangular ridge of
the mesial-buccal cusp of the first mandibular molar. The union of two triangular
ridges crossing on transversal direction forms the transversal ridges. The oblique ridge is
specific to maxillary molars and is formed by the union of the triangular ridges of the
distal-buccal and mesial-buccal cusps. Lobes are the primary structures in the devel-
opment of the crown and cusps and mamelons are representations of lobes. Mamelons
are any rounded protuberances present on the incisal ridges of recently emerged
teeth, and by aging, their contour will become less evident [1, 3].
Fossae are irregular depressions or concavities present on the occlusal surfaces
of the premolars and molars and on the lingual surfaces of the incisors. The central
fossae, present on the occlusal surfaces, are formed by the convergences of ridges
with the grooves. The triangular fossae are present on the occlusal surface of
lateral teeth, mesial or distal to the marginal ridge, and also on the lingual surface
of the maxillary incisors where the lingual fossae and marginal ridge meet the
cingulum. Pits are point depressions found at the junction of developmental
grooves [1, 3].
For an accurate description and positioning of the landmarks, the crown and roots
are divided after the third rule, which means that each surface of the crown is divided
into three equal parts in mesiodistal direction and in the cervical-incisal/occlusal
direction. Following this rule, the buccal surface of the central upper incisor has three-
thirds on cervical-incisal distal direction, which are third incisal, third middle, and
third cervical. The buccal surface of the central upper incisor has three-thirds in
mesiodistal direction, which are third mesial, third middle, and third distal. By fol-
lowing this rule, a landmark can be placed more precisely, for example, the mesio-
incisal angle of the maxillary central incisor is placed in the third incisal (in cervical-
incisal direction) and in the third mesial part in mesiodistal direction. The same rule is
valid for the root [8].
7
Human Teeth – From Function to Esthetics

3. Dental anatomy of the anterior teeth

3.1 Common features of permanent incisors and canines teeth

The incisors are the cutting blades of human dentition and together with the canines
form the group of anterior teeth with great impact on esthetic, eating, speech and facial
expression, and harmony. Both deciduous and permanent dentitions have four incisors
on each jaw, two central incisors, and two lateral incisors, all single root teeth. The
central incisors are the closest to the midline, whereas the lateral is more distal to the
midline of the jaw. The mandibular central incisors emerge around 7 years of age,
followed by the maxillary central incisors, maxillary lateral and the last ones, mandibu-
lar lateral incisors around 8 years of age. Mandibular incisors have the smallest and
shortest root and the weakest resistance due to their reduced size. The relation between
upper and lower incisor is forming the overjet and overbite with great impact on
esthetic and normal relation between the upper and lower jaw. The evaluation of
overbite and overjet is done early and gives important information about the growth
pattern of the jaws, the length of the dental arches, and optimal space for permanent
teeth. The overbite is the overlap of the maxillary central incisors over the mandibular
central incisors measured relative to the incisal ridges. Normal overbite is approxi-
mately 1/3–1/2 (30 and 50%) of the height of the mandibular incisors. Overjet is defined
as the extent of horizontal overlap, anterior-posterior direction, of the maxillary central
incisors over the mandibular central incisors. The normal value of the overjet should be
maximum 2 mm. The relations between the upper and lower incisors indicated a
physiologic occlusion and development of the jaws or a malocclusion [9, 10].
Canines are the third teeth in line, from the median line of the dental arch and are
refer as cornerstones of the dental arch. Canine’s roots are the longest among all the
teeth and the crowns are usually as long as the crowns of central incisors. Canines are
single root teeth and their “V” crown shape and position are important for the guid-
ance of the lower jaw into the intercuspal position. These teeth have a great value for
an efficient function, stability, and natural facial expression. Lower permanent
canines emerge around 9–10 years of age and the upper permanent canines emerge at
11–12 years of age, being through the last permanent teeth that emerge between
incisors and premolars. Because of their timing emerge, placement between incisors
and premolars and molars, which already emerged, canine’s space can be restricted
and for this reason are predisposed for malposition, crowding and malocclusion. Being
located between incisors and premolars, canines support these teeth due to their
shape, size, and position on the dental arch. A quality that has to be overlooked
is the canine eminence that along with the bone ridge over the labial roots has an
esthetic value by contouring the normal facial expression at the corner of the lips.
Canines value is manifested through stability, efficiency, and natural facial
expression [4].

3.2 Maxillary and mandibular incisors

3.2.1 Maxillary incisors

Maxillary central incisors (1.1, 2.1) are single cone shape root teeth, next to the
median line. In smile and speech, the central incisors are the most exposed teeth with
a great impact on esthetics. Maxillary central incisors (1.1, 2.1) have four axial sur-
faces: labial, lingual, mesial and distal, and one incisal ridge.
8
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DOI: http://dx.doi.org/10.5772/intechopen.110223

The labial face is the widest, mesial-distally, and convex in the cervical incisal
direction. It is less convex than the lateral incisal and canine and has a rectangular
shape. The labial surface looks symmetrical and regularly formed for both centrals and
is having a straight incisal edge. The height of the crown is 10–11 mm and mesial-
distal measurement is 8–9 mm at the contact area. The mesial-distal diameter in the
cervical area is 6.5–8 mm. The maximum convexities from the mesial and distal
surfaces are consisting the contact area with its neighbors. The mesial outline is less
convex than the distal one, and these two surfaces by continuing with the incisal ridge
are forming two angles: mesial-incisal, more sharp than the distal-incisal. The incisal
outline is usually regular and straight in a mesial-distal direction, but after a long
function, it tends to become ascendant distally. The labial face has three lobes named
mamelons, divided by two cervical-incisal groves. Due to function, the mamelons
tend to become less evident. The cervical outline of the crown has a semicircular
direction and is concave toward the incisal ridge (Figure 2). From proximal view, the
facial surface is convex and the lingual surface is convex in the third cervical and
concave in the third incisal area [11].
The lingual outline of the cervical line is placed below a smooth convexity called
cingulum and has a similar shape with the labial cervical line. Cingulum is placed in
the third cervical part of the lingual surface. Mesial and distal from the cingulum are
the mesial and distal marginal ridges, which continue the incisal ridge. Below the
cingulum is present a shallow concavity called lingual fossa, which is bordered mesi-
ally by the mesial marginal ridge, incisally by the lingual area of the incisal ridge,
distally by the distal marginal ridge, and cervically by the cingulum. From the cingu-
lum starts developmental grooves into the lingual fossa.
The mesial and distal surfaces have a triangular shape with the base in the cervical
and the apex oriented toward the incisal ridge. The maximum convexities of both
mesial and distal surfaces are joining with neighbor teeth into the contact area that is
positioned into the third incisal and third labial of the proximal surface.
Viewed from incisal, the incisal ridge is positioned in the middle of the maximum
labial-lingual diameter of the central incisor and in the same time, centered over the
root (Figure 3).
The maxillary central incisor may show a wide range of particularities with regard
to labial outline, labial profile curvature, labial lobe grooves, mamelons, and cingulum
and are classified into three basic shapes: tapering when mesial and distal borders
converge toward cervical line, square when mesial and distal borders are almost

Figure 2.
A. Facial surface—the three mamelons divided by developmental grooves; B. Outline of distal ridge; C. Cervical
line on labial surface; D. Outline of mesial ridge; E. Mesial surface with the view of labial surface; F. Distal surface
—aspect of cervical line and outline of labial surface; G. Distal surface—aspect of cervical line and outline of
lingual surface; and H. Lingual surface—view of cingulum, marginal ridges, and developmental grooves.

9
Human Teeth – From Function to Esthetics

Figure 3.
A—Distal marginal ridge, B—Mesial marginal ridge, C—Cingulum, D—Incisal ridge from incisal view.

Figure 4.
Upper lateral incisor. A—Labial surface, B—lingual surface, C—mesial surface, and D—Lingual-distal surface.

parallel, and an ovoid shape when mesial and distal borders converge incisal and
cervical [1, 3, 11].
Maxillary lateral incisor (1.2, 2.2) varies more than any tooth and is smaller in all
dimensions except the root length that has a significant distal curvature of the apex
(Figure 4). The root has one root canal, with the pulp chamber centered within the
root. On cross-section, the root shows a large variation in shape and may be triangular,
oval, or round. The crown measures from 2 to 3 mm shorter than the central incisor.
The labial aspect is similar with the central incisor but has more accentuated curva-
ture, rounded incisal ridge, and rounded incisal angles. The mesial outline of the labial
face resembles with the central incisor but with a rounded mesial-incisal angle. The
distal outline is always more rounded and shorter than the mesial one. On labial
surface, the cingulum is prominent with deep developmental grooves within a more
concave lingual fossa. The mesial surface is similar with the central incisors one, the
distal surface appears thicker than the mesial one, and the cervical line is usually more
cervically than it is on the mesial surface. The incisal aspect can be similar with the
central incisor, but it also may resemble with a small canine [1].

3.2.2 Mandibular incisors

Mandibular central incisors (3.1, 4.1) are single-root anterior teeth, the smallest
ones with regular and symmetric surfaces and outlines. The crown is about half of the
mesial-distal diameter of the maxillary central incisor and the labial-lingual diameter
is only 1 mm less. Because of its size, the mandibular central incisor is the only tooth
that has occlusal contact with only one tooth, the upper central incisor. Except
10
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DOI: http://dx.doi.org/10.5772/intechopen.110223

mandibular central incisor, if present, the maxillary third molars have occlusal contact
only with the third mandibular molars. The permanent central incisors emerge at
6–7 years of age, after the permanent molars.
The labial surface is straight and its long axis is continued by the root, is wider in
mesial-distally then the lingual surface, and is wider in the cervical third because of
the presence of a smooth cingulum. From incisal view, more labial surface can be seen.
The mesial and distal outline are parallel and slightly tapered toward cervical line. The
labial surface is regular, convex, and flattened with a convexity in the middle third.
The mesial-incisal angle formed by the incisal margin and mesial outline is straight
with right angles and is characteristic of lateral lower incisor.
The lingual aspect is smooth with a concavity in the incisal third placed between
the marginal ridges. In some cases, the marginal ridges are more prominent near the
incisal edge and the concavity becomes more contoured. The lingual surface is flat in
the incisal third and convex in cervical third. The cingulum is not marked by any
developmental grooves.
The mesial surface is smooth in the incisal third, flatter in the middle third, and flat
in the cervical third receiving a slightly convex line. Immediately below the middle
third a concavity is present.
The distal surface is similar with the mesial one and has a developmental depres-
sion on the distal surface of the root with a deeper and defined groove. The cervical
line is placed incisal with about 1 mm on the mesial surface.
Usually, the lower lateral incisor does not exhibit too many variations, however,
labial surface may have a degree of labial inclination and over contoured mamelons
separated by well-defined grooves (Figure 5). The pulp cavity and root canal are
narrow but can also be very large in size. Usually, the tooth has one root canal narrow
in mesial-distal section but wider on labial-lingual cross-section. This tooth may have
the second root canal [1, 3, 11].

3.3 Maxillary and mandibular canines

The crown of upper canines is usually as long as the crowns of central incisors, but
the single strong developed root is the longest than those of any teeth. Canine crowns
have a single pointed cusp narrower more lingual than labial. The labial surface has a
smaller mesial-distal diameter in comparison with central incisors with about 1 mm.

Figure 5.
Labial view of upper and lower central incisors in mixed dentition—the mamelons and developmental grooves are
well defined.

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Human Teeth – From Function to Esthetics

The cervical line is concave toward incisal on facial and lingual surface and convex
toward incisal on mesial and distal surface as it is for any tooth. The mesial outline is
convex from the cervical line and forms the mesial contact area, which is approxi-
mately at the middle third to the incisal third junction. The distal outline is usually
concave between the cervical line and distal contact area that is found in the center of
the middle third of the distal surface.
The cusp tip is on the same line with the center of the root. The cusp has two
slopes, the mesial one being shorter than the distal one. The labial surface of the cusp
is smooth with ought any developmental lines, except the shallow depressions that
divide the three lobes. The middle labial lobe is the most developed one and forms a
ridge on the labial surface. The connection of the outline of the mesial slope of incisal
ridge with the outline of the mesial surface forms a rounded angle positioned more
incisal than the distal angle. The same link is present for the distal slope outline with
the outline of the distal surface but in this case, the angle is more rounded and placed
more cervically.
The lingual surface of the crown is narrower than the labial one and has a large
cingulum which can look like a small cusp. In this morphology type, the ridges and
developmental grooves of the lingual surface are well-defined. The marginal ridges are
converging, and link with the cingulum and occasionally a well-defined lingual ridge
is confluent with the cusp tip and extends near the cingulum. Between this lingual
ridge and the marginal ones are evident shallow concavities called mesial and distal
lingual fossae. In other cases, the lingual surface is smooth and the fossae and ridges
are difficult to distinguish (Figure 6).
The lingual surface of the root is narrower than the labial one and the mesial and
distal developmental depressions are evident on the root surface (Figure 6) [1, 3, 11].
The corwns of mandibular lower canines (3.3, 4.3) are narrower mesial-distal, less
than 1 mm when compared with the maxillary ones but are longer with about 0.5–
1 mm. The root is usually of same size or shorter and about 1 mm wider than lateral
lower incisors. The labial surface has a pentagon shape, and the lingual surface is
smoother with a less defined cingulum and marginal ridges being similar with the
lingual surface of the lower lateral incisor. The cusp is less structured, and the cusp
ridge is thinner labio-lingually in comparison with the upper canine. The cusp tip is
usually on a line with the center of the root from mesial to distal, but it can also lie
lingualy toward this line, same as mandibular incisors. Lower canines can have bifur-
cated roots, and this situation is not rare.

Figure 6.
A—“V” shape labial surface, labial ridge, mesio-incisal, and distal-incisal angles, B—incisal view of the cusp,
labial, and lingual surface, C—lingual surface, cingulum, marginal ridges, developmental grooves, and fossae,
and D—mesial surface with the high position of the cervical line.

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The differences between the labial surfaces of maxillary and mandibular canines
refer to a longer appearance of the lower one because of the narrower mesial-distal
diameter. The height of the contact areas is placed above the cervix. The mesial outline
is almost straight if the mandibular canine and contact area are positioned near the
mesio-incisal angle, and the distal contact area is also placed toward incisal. The distal
surface is very similar with the distal surface of the upper canine [1, 11].

4. Dental anatomy of lateral teeth

4.1 Common features of permanent premolars and molars

Premolars, referred as posterior or lateral teeth, are succedaneous teeth present only
in permanent dentition and replace the deciduous molars. There are four premolars on
each jaw and two on each quadrant. Premolars emerge between 10 and 12 years of age,
before the permanent canines and second molars. First maxillary and mandibular pre-
molars emerge earlier than second maxillary and mandibular premolars. These teeth are
referred as bicuspids and are taking their place on the dental arch between canines and
molars having a transitional morphology between the canines and molars.
Both maxillary premolars (1.4, 1.5, 2.4, 2.5) are developed from four lobes same as
anterior teeth, but, comparing with the anterior, the lingual cusp is well-defined. The
buccal cusps of first maxillary premolars are long and sharp similar with the canine’s
cusp. The second premolar has a shorter crown and root, the root being equal in height
with the molar’s roots though the crowns are slightly longer. Usually, the first maxil-
lary premolar has two roots—one buccal and one lingual, and the second maxillary
premolar has one root.
Permanent mandibular premolars (3.4, 3.5, 4.4., 4.5) have the same position on the
dental arch as the maxillary ones, replace the mandibular deciduous molars, and are
developed from four lobes, same as maxillary ones.
The first mandibular premolar has two cusps, the buccal one is larger and longer
and the lingual one is much smaller, similar with the cingulum, and is nonfunctional,
the morphology of this tooth being very similar with the mandibular canine’s. Second
premolars have three cusps, one buccal, and two small lingual cusps being more
similar with a molar. The first mandibular premolar is smaller than the second one,
but the first maxillary one is bigger than the second one.
Molar’s most important function is mastication, though the crowns and roots are
considerable in size, except the crown’s height which is shorter than premolars. The two
roots of mandibular molars and the three roots of maxillary molars are longer and curved.
Maxillary molars (1.6, 1.7, 1.8, 2.6, 2.7, 2.8) have three roots, two buccal and one
lingual, one massive crown with well-developed two buccal cusps, and two lingual
cusps. The first permanent maxillary molar emerges at 6 years old and soon after
emerges the mandibular first molars. Both emerge distally by the second deciduous
molars and do not replace any deciduous tooth. The first molar’s occlusal relation is
important for anticipating malocclusions.
Mandibular molars (3.6, 3.7, 3.8, 4.6, 4.7, 4.8) are the largest teeth, showing
variations related to cusps number, from 3 to 5, size, occlusal surface, length of the
crowns, and root. The outlines of the crowns are similar, quadrilateral, for all three
molars, and each has two roots, a mesial, and a distal one. Third molars show a fusion
of the two roots. The crowns are shorter cervical-occlusal, but the mesiodistal and
buccal-oral diameters are much larger than those of the mandibular anterior teeth.
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Human Teeth – From Function to Esthetics

The roots are bifurcated, not so long but more bulky and thick, and assure a great
anchorage and stability of the tooth in alveolar socket [1, 3, 11].

4.2 Maxillary and mandibular premolars

The first maxillary premolar (1.4, 2.4) emerges first after the canine at age of 10.
Premolar’s crowns have four axial surfaces (mesial, distal, buccal and lingual) and one
occlusal surface. The two cusps, buccal and lingual, form the occlusal surface. Both are
well shaped and defined. The buccal cusp is usually longer than the lingual one. The
long axis of the crown is continuing the long axis of the root.
The buccal and the mesial aspect of this tooth is trapezoidal, and the crown shows a
little curvature at the cervical line from a buccal point of view. Lingually, its gross
outline is the reverse of the buccal gross outline.
When it comes to the distal aspect, the crown of the first maxillary premolar
differs from the mesial aspect. The crown surface is convex at all points except for a
small flat area, the curvature of the cervical line which is less on the distal than on the
mesial surface, usually there is no groove crossing the distal marginal ridge of the
crown, and the root is flattened on the distal surface above the cervical line.
The occlusal aspect of this tooth resembles a six-sided or hexagonal figure, which
are called mesiobuccal, mesial, mesiolingual, distal, distolingual, and distobuccal. The
two buccal sides are approximately equal, but the mesial side is shorter and the
mesiolingual side is also shorter than the distolingual one. The occlusal surface is
limited by the cusp and marginal ridges, which are in the same line with each other.
The two ridges of the buccal cusp, the mesiobuccal, and distobuccal are in line, but
their alignment is on distobuccal direction and for this reason the distobuccal cusp
ridge is buccaly placed toward mesiobuccal cusp ridge. The two cusps are dived by the
central groove placed in the center of the occlusal surface (Figure 7). Usually, the
surface of the tooth has no supplemental grooves, which makes the surface relatively
smooth but has two pits, a mesial and a distal.
In most cases, it has two roots and two pulp canals or even two buccal roots, similar
with molars. In the less cases in which it only has one root, there are still two canals
found. However, the first maxillary premolar root(s) may be irregularly curved or
distally inclined in the apical third [1, 3, 11].
The maxillary second premolar (1.5, 2.5) is supplementing the first one in function.
It is less angular, which gives a more rounded effect to the crown. Just like the first

Figure 7.
Maxilary first premolar; A—Buccal surface—“V” shape buccal cusp, buccal ridge, and inclination toward the
root, B—Medial surface—buccal cusp is higher than the lingual one, C—Lingual surface—lingual cusp is smaller
than the buccal one, D—Occlusal surface—hexagonal shape, slopes of the cusps, marginal ridges, central groove,
and mesial and distal pits.

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one, it has two cusps, of the same height, but are less sharp. The buccal cusp is not as
long as one of the first maxillary premolars.
From a buccal point of view, in many cases, the crown and the root of this tooth
are thicker at their cervical area. Also, the buccal ridge of the crown may not be so
prominent in comparison with the first maxillary premolar.
Lingual, the crown of this tooth has a trapezoidal form, and because the buccal and
lingual cusps are almost the same length, the shape of it is generally symmetrical.
From mesial view, the buccal and lingual cusps are nearly equal as height, but the
buccal one is slightly more prominent than the lingual one. The mesial marginal ridge
is not crossed by a groove. Also, this surface of the crown is not marked by concavity,
but it is evenly convex from the cervical line to the marginal ridge. Distally, the aspect
of the second maxillary premolar is similar to the first one.
The occlusal aspect of this tooth is differentiated in many ways from the first
maxillary premolar. The shape is ovoid instead of hexagonal, and the mesial and distal
borders show little to any lingual convergence. This trait along with the equality of the
cusps determines a rectangular shape of the tooth. The central groove is placed more
lingual and as a result, the buccal cusp appears to be larger.
Most maxillary second premolars only have one canal and one root. In some excep-
tions, we can find two roots with two canals or one root with two canals [1, 3, 11].

4.2.1 The mandibular first premolar

The mandibular first premolar is the first tooth from the mandibular lateral group.
It is situated between the canine and the second mandibular premolar, and it has
characteristics from both.
The particularities that resemble those of the canine: the buccal cusp is long and
sharp, and it is the only occluding cusp; the buccolingual distance is approximately
equal with the canine one; the occlusal surface slopes sharply lingually, in cervical
direction; the mesiobuccal cusp ridge is shorter than the distobuccal one; and the
outline of the occlusal aspect resembles the outline of the incisal aspect of the canine.
The particularities that resemble those of the second mandibular premolar: except
for the longer cusp, the outline of the crown and root resembles the second premolar;
the contact areas, mesially and distally are similar; and the tooth has more than one
cusp.
Buccal, the crown, is roughly trapezoidal. The cervical margin is represented by
the shortest of the uneven sides. The middle buccal lobe is well-developed, creating a
large, pointed buccal cusp. The distal cusp ridge is longer than the mesial one.
From a lingual point of view, the crown tapers toward the lingual, since the lingual
measurement mesiodistally is less than that buccally. The lingual cusp is always small.
A major part of the crown is made up of the middle buccal lobe. This makes it
resemble the canine.
From the mesial aspect, the crown is roughly rhomboidal. This tooth shows an
outline that is fundamental and characteristic to all posterior teeth when viewed from
the mesial or distal aspect. The convexity of the outline of the lingual lobe is lingual to
the outline of the root.
The distal aspect of the mandibular first premolar is different from the
mesial one in some respects. The shape is spheroidal, and it has an unbroken curved
surface.
Occlusal, we can observe considerable variation in the gross outline of the tooth.
Both mandibular premolars exhibit more variations in form occlusally than the
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Human Teeth – From Function to Esthetics

maxillary premolars. The common characteristics of all mandibular first premolars,

regardless of type, from occlusal point of view are: the buccal lobe in the middle
makes up the major bulk of the tooth crown; the buccal ridge is prominent; and the
mesiobuccal and distobuccal line angles are prominent even though they are rounded.
In most cases, it has one root and one canal, and in very rare cases, two roots and
two canals. The mesial and distal surfaces of the roots are wider than the buccal an
lingual, so the root canal will follow the same pattern [1, 3, 11].

4.2.2 The mandibular second premolar

The mandibular second premolar is resembling the first premolar from the buccal
aspect only. Although the buccal cusp is not so pronounced, the mesiodistal propor-
tion of the crown and its general outline are similar. There are two common forms of
this tooth: the first form, which probably occurs more often, is the three-cusp type,
and the second is two-cusp type. The two types differ mainly from the occlusal point
of view.
From the buccal aspect, the mandibular second premolar (Figure 8) presents a
shorter buccal cusp than the first one, with mesiobuccal and distobuccal cusp ridges
describing angulation of less degree. The contact area seems higher because of the
short buccal cusp.
Lingual, this tooth’s crown shows considerable variations from the crown portion of
the first premolar: lingual lobes are developed to a greater degree; less of this occlusal
surface is visible. In the three-cusp type, the lingual development creates the greatest
variation between the two teeth. In the two-cusp type, the lingual cusp development
attains equal height as the three cusp. This surface of the crown is smooth and spheroi-
dal, showing a bulbous from above the constricted cervical portion.
Mesial, the second premolar differs from the first one as follows: the crown and
root are wider buccolingually; the buccal cusp is not centered over the root trunk; the
lingual lobe development is greater; the marginal ridge is at right angles at the long
axis of the tooth; less of the occlusal surface is visible; no mesiolingual developmental
groove on the crown; the root is longer and generally slightly convex on the mesial
surface; and the aspect of the root is usually blunter on the second premolar.
The distal aspect of this tooth is similar to the mesial aspect, except that more of
the occlusal surface may be visible. This is possible because the distal marginal ridge is
at a lower level than the mesial marginal ridge when we look at the tooth vertically.
From the occlusal point of view, the outline form of each type shows variations.
The square or three-cusp type is square lingual to the buccal cusp ridges when

Figure 8.
Mandibular second premolar; A buccal surface and root, B lingual surface, and C occlusal surface.

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developed. The three cusps are unequal: the buccal is the largest, the mesiolingual is
next, and the distolingual is the smallest. The round or two-cusp type viewed from
this point is much different than the three-cusp one: the outline of the crown is
rounded lingual to buccal cusp ridges; there is some lingual convergence of mesial and
distal sides, no more than in the square type; the mesiolingual and distolingual line
angles are rounded; and there is one well-developed lingual cusp directly opposite the
buccal one in a lingual direction.
For the majority of the population, the mandibular second premolar has a single
root and a single root canal, but rarely it can also have two roots and two root canals
[1, 3, 11].

4.3 Maxillary and mandibular molars

4.3.1 The maxillary first molar

The maxillary first molars (1.6, 2.6) are the largest and strongest teeth on the
maxillary arch (Figure 9). It has four well-formed large cusps, and a small low
functioning one called the Carabelli tubercle is placed on the mesio-lingual cusp. The
main cusps are the mesiobuccal, distobuccal, mesiolingual, and distolingual, while the
fifth, Carabelli tubercle, can take the form of a well-developed cusp, or it can down-
grade to a series of depressions, grooves, and pits on the mesial portion of the lingual
surface.
From a buccal aspect, the crown is roughly trapezoidal. It has cervical, and occlusal
outlines representing the uneven sides, the cervical one being the shorter one. The
buccal developmental groove dividing the buccal cusps is more or less equidistant
between the mesiobuccal and distolingual line angles.
Lingually, the gross outline of the maxillary first premolar is the reverse of the
buccal aspect. From this point, we can see the Carabelli tubercle situated on the
mesiolingual cusp.
From a mesial point of view, we can observe the increased buccolingual dimen-
sions and the cervical curvature of the crown outlines at the cervical third buccally
and lingually. The cervical line is irregular, and it curves occlusaly. Distally, the gross
outline of the first maxillary molar is the reverse of the mesial aspect.
The occlusal aspect of this tooth shows that its shape is roughly rhomboidal. An
outline following the four major cusp ridges and the marginal ridges is especially so.

Figure 9.
A Buccal surface and buccal roots, B distal surface, distal-buccal and lingual root, C lingual surface and root, and
D occlusal surface and oblique ridge.

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Human Teeth – From Function to Esthetics

Because of the mesiodistal and buccal-lingual diameter, the crown is wider mesially
than distally and wider lingually than buccally. The largest cusp is the mesiolingual,
followed by the mesiobuccal, distolingual, distobuccal, and Carabelli tubercle.
The occlusal surface has four fossae, two major fossae, the mesial one is triangular
and the distal one is linear and two minors ones, a mesial and a distal one, both
triangular in shape. The marginal ones are outlined by the marginal ridges, and the
central ones are divided by the oblique ridge.
The oblique ridge is crossing the occlusal surface and makes the union of the
triangular ridges of the distobuccal and mesiolingual cusps. The oblique ridge is
reduced in size in the center of the occlusal surface and in some morphological
variations is crossed by a developmental groove and the two major fossae are
connected. The mesial and distal marginal ridges are irregular and confluent with the
mesial and distal cusp ridges of the major cusps. The central fossa is concave and
connected with developmental grooves and also short grooves, and central
developmental pit.
There are three well-developed roots, two buccal and one lingual. They are well
separated, which gives maximum anchorage against the forces that tend to unseat
them. The lingual root is the largest, the mesiobuccal one is a little shorter but broader,
and the distobuccal is the smallest. The percentage in which the first maxillary molars
development deviates from the normal is small [1, 3, 11].

4.3.2 The maxillary second molar

The maxillary second molar supplements the first one in function. Its roots are as
long or even longer than the first molar’s. The distobuccal cusp is not as large and well-
developed, and the distolingual cusp is smaller. The crown of this tooth is approxi-
mately 0.5 mm shorter cervico-occlusally than the one of the first molar, but
buccolingually the dimensions are about the same.
Buccaly, the crown is slightly shorter cervico-occlusally and narrower
mesiodistally than the maxillary first molar. The apex of the mesiobuccal root is on the
same imaginary line as the buccal groove of the crown.
Lingual, there are a few important differences between the second and first
molars. The distolingual cusp of the crown is smaller and there is no fifth cusp evident.
Also, the distobuccal cusp may be seen through the sulcus between the mesiolingual
and distolingual cusp.
From a mesial aspect, the buccolingual dimension is about the same as the one of
the first molar, but the crown height is smaller. The roots do not spread as far
buccolingually, staying within the confines of the buccolingual crown outline.
From a distal aspect, because the distobuccal cusp is smaller than the one of the
first molar, more of the mesiobuccal cusp is visible from this angle. The mesiolingual
cusp cannot be seen.
The occlusal aspect shows a rhomboidal shape in most cases, although in compar-
ison with the first maxillary molar, the acute angles of the rhomboid are smaller, and
the obtuse angles are greater. It is common to find supplemental or accidental grooves
and pits on the occlusal surface of the second molar than are usually found on the first
one and.
Most maxillary second molars have three roots and three canals. Although the
presence of two canals in the mesiobuccal root of the maxillary second molar is not
common, it may occur [1, 3, 11].
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4.3.3 The maxillary third molar

All the third molars, mandibular and maxillary, show more development varia-
tions than any other teeth in the mouth. In describing the normal third maxillary
molar, direct comparisons will be made with the second one, which he supplements in
function. Their design is also similar. The maxillary third molar, known as “wisdom
tooth,” often appears as a developmental anomaly. It can vary considerably in size,
contour, and relative position to the other teeth.
From a buccal aspect, the crown is shorter cervico-occlusally and narrower
mesiodistally than the one of the second molar.
From the lingual point of view, there is only one large cusp and, therefore, no lingual
groove. However, in some cases, the third molar with the same essential particularities
has a poorly developed distolingual cusp with a developmental groove lingually.
Mesial, aside from the differences in size, the main features are the fused roots that
have a bifurcation in the apical third. The root is considerably short in relation to the
crown length. The crown and root portions are usually poorly developed, with
irregular outlines.
From the distal point of view, most of the buccal surface of the crown is at sight.
More of the occlusal surface may be seen than at the second molar, because of the
more acute angulation of the occlusal surface in relation to the long axis of the root.
The distance between the cervical line and the marginal ridge is short.
Occlusal, the third molar presents a heart-shaped outline. On this tooth, there are
three functional cusps: two buccal and one lingual. It presents many accidental
grooves unless the tooth is very much worn.
The number of roots can vary from one to five and the number of incased root
canals from one to even six. However, in most cases, one- to three-rooted third molars
are most frequent [1, 3, 11].

4.3.4 The mandibular first molar

The mandibular first molar (Figure 10) is the biggest tooth on the mandibular
arch. They have five well-developed cusps: mesiobuccal, distobuccal, mesiolingual,
distolingual, and distal. Although the crown is relatively short cervico-occlusally, the
mesiodistal and buccolingual measurements provide a broad occlusal form.

Figure 10.
Mandibular first molar; A—Occlusal surface with the three buccal cusps and two lingual, B—Buccal surface and
three buccal cusps and the mesial and distal roots, and C—Lingual surface with two lingual cuspa and mesial and
distal roots.

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Human Teeth – From Function to Esthetics

From a buccal point of view, the mandibular first molar’s shape is roughly trape-
zoidal, and the cervical and occlusal outlines represent the uneven side of the trape-
zoid. If posed vertically, all fives cusps are visible. This side also shows two groves: the
mesiobuccal developmental groove and the distobuccal developmental groove.
From the lingual aspect, there are three cusps visible: two lingual and the lingual
portion of the distal one. The lingual ones are pointed, so the cusp ridges are high
enough to hide the two buccal cusps’ view. The lingual developmental grove serves as
a line of demarcation between the lingual cusps. Some first molars show no groove on
this side but show a depression lingual to the cusp ridges.
From the mesial point of view, if held with its mesial surfaces at right angles to the
line of vision, two cusps and only one root are to be seen: the mesiobuccal and
mesiolingual cusps, and the mesial root. The buccolingual height of the crown is
greater at the mesial portion than it is at the distal portion. Also, the mesial root is
longer than the distal one.
Distal, the gross outline of the tooth is similar to the mesial view. From this point of
view, the distal cusp is in the foreground on the crown portion. The distal cusp is
placed a little buccal to center buccolingually, and the distal contact area appears on its
distal contour.
From the occlusal aspect, the mandibular first molar is somewhat hexagonal. The
crown measurement is 1 mm greater mesiodistally than buccolingually. The crown
converges lingually from the contact areas. The occlusal surface presents a major fossa
and two minor fossae. The development grooves on the occlusal surface are the
development groove, the mesiobuccal development groove, the distobuccal develop-
ment groove, and the lingual development groove.
This tooth usually has two roots: mesial and distal. The mesial root usually has a
more complicated root canal system because of the presence of two canals. The distal
root usually has one canal, but often there can be two also [1, 3, 11].

4.3.5 The mandibular second molar

The mandibular second molar has four well-developed cusps: two buccal and two
lingual, and it supplements the first molar in function. The anatomy differs in some
details. Normally, the second molar is smaller than the first molar by a fraction of a
millimeter, in all dimensions.
Buccal, comparing to the first molar, the crown is shorter cervico-occlusally and
narrower mesiodistally. The crown and root have a tendency toward greater overall
length, but they are not always longer. The only groove on this side is the buccal
developmental groove, which acts like a line of demarcation between the mesiobuccal
and distobuccal cusps.
From the lingual aspect, there are several differences between the second and first
mandibular molars. The crown and root of the second one converge lingually but to a
slight degree; the mesiodental calibration at the cervix lingually is always greater than
the one of the first molar; the mesial and distal curvatures that describe the contact
areas are more noticeable from the lingual aspect; they prove to be at a slightly lower
level than those of the first molar.
From the mesial aspect, except for the dimension differences between the second
and first mandibular molars, the differences are small: the cervical ridge buccally is
less pronounced; the cervical line shows less curvature; and the mesial root is some-
what pointed apically.
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From the distal aspect, the second molar is similar in shape to the first one, the only
difference being the absence of a distal cusp and a distobuccal groove.
Occlusal, the mandibular second molar differs considerably from the first one. The
small distal cusp of the first molar is not present at the second, and the distobuccal
lobe development is sometimes more pronounced than the messiobucal one. Many of
the second mandibular molars are rectangular from the occlusal point of view. Also,
many of them show considerable prominence cervically on the mesiobuccal lobe only.
Most of the second mandibular molars have two roots with three root canals, two
in the mesial root and one in the distal root. The proportions of the crown and roots
are very similar to the first molar. The roots of the second molar may be straighter
with less divergence from the furcation than in the first one and sometimes they are
shorter [1, 3, 11].

4.3.6 The mandibular third molar

The mandibular third molar varies considerably in different individuals and pre-
sents many form and position anomalies. It supplements the second molar in function,
but in general, it is showing irregular development of the crown portion, with under-
sized and malformed roots. However, its design conforms to the general plan of all
mandibular molars. In many cases, third molars have five or more cusps, with the
crown portions larger than the mandibular second molar. In these cases, the alignment
and occlusion may not be normal because there is insufficient room available.
From a buccal aspect, mandibular third molars vary considerably in shape and
outline. However, a well-developed third molar closely resembles the second molar.
The crown is wider at contact areas mesiodistally than at the cervix, the buccal cusps
are short and rounded, and the crest of contour, mesially and distally, is located a little
more than at half of the distance from the cervical line to the tip of the cusps.
Lingual, the observations of the third molars coincide with the buccal aspect.
When the tooth is well-developed, corresponds closely to the morphology of the
second molar, except for size and root development. Same as for the mesial and distal
points of view.
The occlusal aspect is in a big part similar to the second mandibular molar when
the development facilitates good alignment and occlusion. They tend toward a more
rounded outline and a smaller buccolingual measurement distally.
Most mandibular third molars have two roots and three canals. They are usually
shorter, with a poor development. The roots may be separated with a definite point of
bifurcation, or they may be fused in all parts of their way [1, 3, 11].

5. Conclusion

In conclusion, the present chapter summarizes the most essential terminology and
dental anatomy of permanent dentition, though the domain is much more extended.
Terminology is the basis for communication in the domain, and this aspect cannot be
minimized. Dental practitioners need an accurate communication about the dental
morphology with dental technicians and laboratories for performing highly esthetic
and functional prosthodontic restauration. The highest esthetic in prosthodontics and
odontotherapy is given by the finest details of dental morphology.
This chapter is presenting the nomenclature of permanent and deciduous teeth,
age of emerge, and replacement of the deciduous teeth which are essential for clinical
21
Human Teeth – From Function to Esthetics

evaluation and interception of any possible malposition or malocclusion. Each tooth

has individualized morphology given by curves, lines, ridges, and angles all having a
functional aim and basis. For this reason, it is important to be accurately reproduced
in all dental practical domains. Dental morphology can vary for each individual
because of the invariable norm in nature. The shape, size, and angles of the teeth are
related to the sex and constitutional type and therefore it is necessary to have a
starting point in the study of dental anatomy.
Dental anatomy is a teach in the first year of study of any dental school, being the
basic for the study of dental medicine. Having strong knowledge about dental anat-
omy, future subjects such as endodontics, restorative dentistry, prosthodontics even
extraction, surgery, implantology, and periodontics find their basics in dental mor-
phology. Composite resins, high quality, and highly esthetic dental materials used in
odontotherapy cannot reach highly esthetic fillings if are not modeled and laired
according to the morphology of the teeth and the optical parameters of dentin and
enamel. The biggest challenge is found for the restauration of the anterior teeth.
Restorative dentistry is approaching and considering all the dental concepts and
details of dental morphology in elaborating the treatment plan. A successful clinician
or a successful dental technician should be able to mentally create the picture of the
teeth from any aspect. This mental picture should be correlated with the patience’s
appearance, to esthetics, and with natural appearance but in the same time to support
the function of the dental-maxillary system.

Conflict of interest

The authors declare no conflict of interest.

Author details

Emanuela Lidia Crăciunescu, Meda-Lavinia Negruţiu*, Mihai Romînu,

Andreea Codruţa Novac, Cristina Modiga, Borislav-Duşan Caplar, Cosmin Sinescu
and Daniela-Maria Pop
Research Center in Dental Medicine Using Conventional and Alternative
Technologies, Department of Prostheses Technology and Dental Materials, Faculty of
Dental Medicine, Victor Babeș University of Medicine and Pharmacy, Timișoara,
Romania

*Address all correspondence to: meda_negrutiu@yahoo.com

© 2023 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of
the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0),
which permits unrestricted use, distribution, and reproduction in any medium, provided
the original work is properly cited.
22
Dental Anatomy and Morphology of Permanent Teeth
DOI: http://dx.doi.org/10.5772/intechopen.110223

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