cancellous bone. When viewed by a radiograph,
trabecular bone has a web-like appearance.
Alveolar Bone Proper
The alveolar bone proper is a thin layer of compact
bone, that is a specialized continuation of the cortical
plate and forms the tooth socket. The lamina dura
(fig. 4-10) is a horseshoe shape white line on a dental
radiograph that roughly corresponds to the alveolar
The periodontal ligament (fig. 4-8) is a thin,
fibrous ligament that connects the tooth to the bony
socket. Normally, teeth do not contact the bone
directly; a tooth is suspended in its socket by the fibers
of the ligament. This arrangement allows each tooth
limited individual movement. The fibers act as shock
absorbers to cushion the force of the chewing impact
TISSUES OF THE ORAL
The oral cavity is made up of specialized epithelial
tissues that surround the teeth and serve as a lining.
These tissues are called the oral mucosa and consist of
three types: masticatory mucosa, lining mucosa, and
Masticatory mucosa is comprised of the tissue that
covers the hard palate and the gingiva.
Masticatory mucosa is usually light pink in color
(can vary with skin color) and is keratinized.
Keratinized tissue has a horny, tough, protective outer
layer of tissue. Characteristics of masticatory mucosa
no submucosa lies under the masticatory
held in place firmly to bone and does not move,
has a dense, hard covering, and
functions to withstand the active process of
chewing and swallowing food.
HARD PALATE.The hard palate or roof of the
mouth (fig. 4-9) is covered with masticatory mucosa
and is firmly adhered to the palatine process (bone). Its
Figure 4-9.Masticatory mucosa of the hard palate.
color is usually pale pink. Important structures of the
hard palate are:
Incisive papillaLocated at the midline,
directly posterior of the maxillary central incisors
(pear-shaped in appearance).
Palatine rapheExtends from the incisive
papilla posteriorly at the midline (may be ridge shaped
in appearance with a whitish streak at the midline).
Palatine rugaeExtends laterally (along side)
from the incisive papilla and from the palatine raphe
(wrinkled, irregular ridges in appearance).
GINGIVA.The gingiva, shown in figure 4-10,
is specialized masticatory mucosa covering the
alveolar process. In a healthy mouth, gingiva is firmly
in place encircling the necks of the teeth. It aids in the
support of the teeth, and protects the alveolar process
and periodontal ligament from bacterial invasion.
Healthy gingiva is firm and resilient. Healthy gingiva
under normal flossing and brushing activities does not
bleed. The color of healthy gingiva can range from pale
pink to darker shades (purple to black) depending on
each individuals pigmentation. The surface of the
attached gingiva and interdental papillae may be
stippled (resembling the texture of the skin of an
Like the tongue, the gingiva is highly vascular and
receives its blood supply from the lingual, mental,
buccal, and palatine arteries. Other important aspects
of the gingiva are discussed in the following
Unattached Gingiva.The portion of gingiva
that extends from the gingival crest to the crest of the
bone is called unattached gingiva. It can also be called
the free gingiva. It can be displaced and is not bound
directly to the tooth or bone. In a healthy mouth, this