Home Dentistry Articles Periodontal ligament
The periodontal ligaments are considered part
of the periodontium, as they are supporting tissue of a tooth.
These ligaments are a specialized connective tissue that attach
teeth from the cementum to the surrounding alveolar bone. They
are about .2 millimeters in width, which decreases with age.
Since teeth are not embedded in bone directly,
large compressive forces can occur on teeth without destruction
of the bone. Instead, the tooth, pulling downward on the periodontal
ligaments, create tension which is actually the stimulus for
Another function of the periodontal ligaments
is to serve as a method for sensation. There are recepetors
within the periodontal ligaments which sense differing amounts
of tension. This helps the body discern the amount of force
being placed on a tooth, during chewing for example, because
enamel has no sensory receptors itself.
The periodontal ligament has fibers composed
of Type I and Type II collagen. Compared to most other ligaments
of the body, these are highly vascularized.
Types of Fibers
Individually having a diameter of 55 nanometers,
fibers of the periodontal ligament are catagorized by their
orientation to the teeth. They are organized together along
the tooth and serve different fuctions.
Transeptal fibers run between two adjacent
teeth in the same arch. They attach from the cementum just apical
to where the gums attach to one tooth and insert at the cementum
of an adjacent tooth. Transeptal fibers are believed responsible
for returning teeth to their original state after orthodontic
therapy. Although techinically part of the gingival ligament,
it is frequently included in studies involving the periodontal
Alveolar Crest Fibers
Alveolar crest fibers attach to the cementum
just apical to the cementoenamel junction, run downward, and
insert into the alveolar bone.
Horizonal fibers attach to the cementum apical
to the alveolar crest fibers and run perpendicularly from the
root of the tooth to the alveolar bone.
Oblique fibers are the most numerous fibers
in the periodontal ligament. They attach apical to the horizontal
fibers and run diagonally toward the crown of the tooth inserting
to the alveolar bone there. Because they are the most numerous,
these fibers are believed to be the most responsible in compensating
for the chewing forces directed on the teeth.
Apical fibers are at the apex of a root. The
attach from the cementum and insert to the surrounding bone
at the base of the socket.
Interradicular fibers are only found between
the roots of a multi-rooted tooth, such as a molar. They also
attach from the cementum and insert to the nearby alveolar bone.