Biomedical Engineering Reference
In-Depth Information
9.
Dental Applications of Bone Biology
Thomas W. Oates and David L. Cochran
9.1 Introduction
(resulting in gingivitis) or may spread to the
supporting periodontal tissues and bone,
causing their loss and periodontitis. Bone loss,
which compromises tooth support, is indica-
tive of periodontitis. In more severe cases, bone
loss causes the teeth to become mobile, to
become more susceptible to infection, and
ultimately to be lost. In the past, periodontal
therapy aimed at stopping the progression of
the disease and at reducing infection. This was
generally accomplished by mechanically clean-
ing the teeth and roots (by scaling and root
planing) to disrupt the microbial biofi lm. In
areas of greater tissue loss, surgery is needed to
access the root and bone loss areas. When bone
loss has been severe, bone grafting procedures
have been employed in an attempt to replace
the bony component of the periodontium. More
recent surgical efforts have focused on regen-
erating all the components of the periodontium
including the bone, periodontal ligament, and
cementum. When a tooth is lost, there gener-
ally remains a space where the tooth root was
located. New bone will therefore fi ll that space.
However, depending on how the tooth was lost,
the contour of the bony ridge can be compro-
mised, leading to a bone defect. This makes
restoration diffi cult, whatever the tooth replace-
ment. This problem is magnifi ed when two or
more contiguous teeth are lost. When all teeth
are lost in either the mandible or the maxilla,
other problems exist. One is that with time,
whether dentures are partial or complete, the
bone below the dentures is lost progressively
and little alveolar bone remains to support the
denture. A large nerve and blood vessel run
The teeth are implanted in depressions within
alveolar bone and are surrounded by the peri-
odontium which consists of bone, a suspensory
ligament (the periodontal ligament), cemen-
tum on the root surface, and gingiva. In health,
the bone tissue is located approximately
mm
below the cementoenamel junction which sepa-
rates the crown of the tooth and its root from
the bone (Fig.
2
). From a functional view-
point, the periodontium is a unique, very
dynamic and adaptable tissue. The periodontal
ligament has one of the fastest turnover rates of
connective tissue in the body and maintains its
dimensions even if the teeth are moved or the
ligament is regenerated. At the same time, the
periodontium provides support for the tooth,
resists biting forces, and, importantly, provides
a seal around the tooth. It is important to rec-
ognize that the tooth is a solid structure that
extends from inside the body to outside the
body. The biologic “seal” provided by the peri-
odontium is under constant microbial chal-
lenge from more than
9
.
1
microbial species.
Periodontal disease is a chronic infection of
the periodontium that results in the loss of the
periodontal ligament and surrounding alveolar
bone [
300
]. In a susceptible host, it is caused by
the bacterial biofi lm (plaque) that adheres to
the tooth surface. Susceptibility has been asso-
ciated with genetic polymorphisms and factors
such as smoking and diabetes. The plaque bac-
teria initiate an infl ammatory/immune reac-
tion that may be limited to the gingival tissues
45
129
