262
UNIT 3
Organ Systems
Masticatory Mucosa
Alveolar bone
Alveolar bone
Alveolar bone
Mucogingival
Mucogingival
junction
junction
Mucogingival
junction
Enamel space
Enamel space
Enamel space
Junction epithelium
Junction epithelium
Junction epithelium
Junction epithelium
Junction epithelium
Junction epithelium
Sulcus epithelium
Sulcus epithelium
Sulcus epithelium
Sulcus epithelium
Sulcus epithelium
Sulcus epithelium
Free
gingiva
Attached
gingiva
Alveolar
mucosa
L
a
m
in
i
n
a
p
p
ro
r
o
p
ria
r
i
a
Lamina propria
Dentin
Dentin
Dentin
Dental
Dental
pulp
pulp
Dental
pulp
Cementum
Cementum
Cementum
A
Figure 14-4A.
Masticatory mucosa
,
gingiva
. H&E,
3
22
Masticatory mucosa
covers the gingiva and hard palate; it has a
keratinized stratif ed squamous
epithelium
, which is exposed to
more abrasion during chewing than the lining mucosa. Mastica-
tory mucosa lacks a submucosa layer. The lamina propria of the
masticatory mucosa consists of a dense network of collagen F bers
that are F rmly attached to the underlying bone. The
gingiva
(gum)
surrounds the cervix of the tooth and covers the upper part of the
alveolar bone at the tooth root. The gingiva can be divided into
±ree gingiva
and
attached gingiva
. The superior part of the gingiva
is
free gingiva
and surrounds, but does not attach to, the cervix of
the tooth. This nonattachment between the
sulcus epithelium
of the
free gingiva and enamel creates a space called the
gingival sulcus
, or
±ree gingival groove
, (normally 0.5–3
m
m
depth). The
attached gin-
giva
F rmly attaches to the underlying hard tissues (alveolar bone,
cementum, and edge of the enamel). The gingival-mucosal border
is called the
mucogingival junction
(see ±ig. 14-1), where the epi-
thelium changes from nonkeratinized to keratinized and the color
changes from bright pink (alveolar mucosa) to pale pink (gingiva).
Stratum
Stratum
basale
basale
Stratum
basale
Stratum
Stratum
granulosum
granulosum
Stratum
granulosum
Stratum corneum
Stratum
Stratum
spinosum
spinosum
Stratum
spinosum
Keratinized stratified
squamous epithelium
Lamina
Lamina
propria
propria
Lamina
propria
Collagen
Collagen
fibers
fibers
Collagen
fibers
B
Figure 14-4B.
Masticatory mucosa
,
hard palate
. H&E,
3
35
The
hard palate
forms the roof of the mouth and is covered
by masticatory mucosa with keratinized stratiF
ed squamous
epithelium and a dense lamina propria. It has one more layer
(stratum corneum)
than the lining mucosa. The collagen F
bers in
the lamina are thick and dense and F
rmly bind to the
periosteum
of the underlying bone. The periosteum consists of dense connec-
tive tissue, which covers the bone and contributes to bone forma-
tion (see Chapter 5, “Cartilage and Bone,” ±ig. 5-10B). Most of
the hard palate lacks a submucosal layer. However, the posterior
region near the alveolar process may present a submucosal layer
that contains minor mucous glands. The hard palate signiF
cantly
assists in mastication and speech.
Cle±t palate
is a birth defect in which there is a F
ssure in the hard
palate that is caused by the failure of two parts of the palate
to fuse during facial development. This condition impairs the
quality of speech (an individual is unable to pronounce certain
sounds) and also causes eating problems.
CLINICAL CORRELATION
Acanthosis
Orifice of the
gland ducts
Minor salivary
glands
Hyperkeratosis
Acanthosis
Acanthosis
Acanthosis
C
Figure 14-4C.
Nicotine Stomatitis
.
H&E,
3
25
Nicotine stomatitis
is a nonprecancerous condition characterized
by a
white lesion
in the oral mucosa of the
hard palate
of the
mouth. The causes of this condition are associated with long-
term tobacco smoking, especially pipe smoking, and hot beverage
consumption. The lesion has a white
cobblestone
or “
dried-
mud
” appearance because of excessive
keratin
production. The
hard palate may appear gray or white and contain many
papules
that are slightly elevated with red in their center. Histologically,
the squamous mucosa demonstrates
hyperkeratosis
(thickening
of the stratum corneum) and
acanthosis
(overgrowth of the
stratum spinosum). Complete smoking cessation usually helps
to diminish and resolve the condition within about two weeks. If
the lesion persists, close monitoring may be necessary.
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