Chapter 7
•
Head
934
and
cement
(L.
cementum
) over the root. The
pulp cavity
contains connective tissue, blood vessels, and nerves. The
root canal
(pulp canal) transmits the nerves and vessels to
and from the pulp cavity through the
apical foramen.
The
tooth sockets
are in the
alveolar processes
of the
maxillae and mandible (Fig. 7.80A); they are the skeletal
features that display the greatest change during a lifetime
(Fig. 7.81B). Adjacent sockets are separated by
interalveo-
lar septa;
within the socket, the roots of teeth with more
than one root are separated by
interradicular septa
(Figs.
7.81B and 7.82B). The bone of the socket has a thin cortex
separated from the adjacent labial and lingual cortices by a
variable amount of trabeculated bone. The labial wall of the
socket is particularly thin over the incisor teeth; the reverse
is true for the molars, where the lingual wall is thinner. Thus
the labial surface commonly is broken to extract incisors and
the lingual surface is broken to extract molars.
The roots of the teeth are connected to the bone of the alve-
olus by a springy suspension forming a special type of fibrous
joint called a
dento-alveolar syndesmosis
or
gomphosis.
The
periodontium
(periodontal membrane) is composed of
collagenous fibers that extend between the cement of the root
and the periosteum of the alveolus. It is abundantly supplied
with tactile, pressoreceptive nerve endings, lymph capillaries,
and glomerular blood vessels that act as hydraulic cushioning
to curb axial masticatory pressure.
Pressoreceptive nerve end-
ings
are capable of receiving changes in pressure as stimuli.
VASCULATURE OF TEETH
The
superior
and
inferior alveolar arteries,
branches of the
maxillary artery, supply the maxillary and mandibular teeth,
respectively (Figs. 7.73 and 7.74A; Table 7.12). The
alveolar
veins
have the same names and distribution accompany the
arteries.
Lymphatic vessels
from the teeth and gingivae pass
mainly to the
submandibular lymph nodes
(Fig. 7.77).
INNERVATION OF TEETH
The
nerves supplying the teeth
are illustrated in Figure
7.79A. The named branches of the
superior
(CN V
2
) and
inferior
(CN V
3
)
alveolar nerves
give rise to
dental plexuses
that supply the maxillary and mandibular teeth.
Palate
The
palate
forms the arched roof of the mouth and the floor
of the nasal cavities (Fig. 7.83). It separates the oral cavity
from the nasal cavities and the nasopharynx, the part of the
pharynx superior to the soft palate. The superior (nasal) sur-
face of the palate is covered with respiratory mucosa, and the
inferior (oral) surface is covered with oral mucosa, densely
packed with glands. The palate consists of two regions: the
hard palate anteriorly and the soft palate posteriorly.
HARD PALATE
The
hard palate
is vaulted (concave); this space is mostly filled
by the tongue when it is at rest. The anterior two thirds of the
palate has a bony skeleton formed by the palatine processes
of the maxillae and the horizontal plates of the palatine bones
(Fig. 7.84A). The
incisive fossa
is a depression in the midline
of the bony palate posterior to the central incisor teeth into
which the incisive canals open. The nasopalatine nerves pass
from the nose through a variable number of incisive canals and
foramina that open into the incisive fossa (Fig. 7.87B).
Medial to the 3rd molar tooth, the
greater palatine fora-
men
pierces the lateral border of the bony palate (Fig. 7.84A).
The
greater palatine vessels and nerve
emerge from this
Root
Neck
Crown
Enamel
Pulp cavity
(tooth cavity)
Root canal
Dentine
Cement
Apical foramen
(root foramen)
Root
Neck
Crown
Incisor tooth
Molar tooth
(A) Longitudinal section
(B) Lateral radiograph
5
1 1
2 2 3
4
7
6
8
7
1
Enamel
4
Root canal
7
Interalveolar septa (alveolar bone)
8
Interradicular septum (alveolar bone)
2
Dentine
5
Buccal cusp
3
Pulp cavity
6
Root apex
FIGURE 7.82.
Sections of teeth. A.
An incisor and a molar are shown.
In living people, the pulp cavity is a hollow space within the crown and neck
of the tooth containing connective tissue, blood vessels, and nerves. The
cavity narrows down to the root canal in a single-rooted tooth or to one
canal per root of a multirooted tooth. The vessels and nerves enter or leave
through the apical foramen.
B.
Bite-wing radiograph of maxillary premolar
and molar teeth demonstrating features shown and described in part
A.
Moore_Chap07.indd 934
11/15/2012 8:27:59 PM
