Biomedical Engineering Reference
In-Depth Information
dental pulp. The dental pulp is considered a low-compliance system that does not suffer disease or
injury in a manner to retain those cells, connective tissue, nerve fibers, and blood vessels as they
were originally formed embryonically and postbirth
[73]
.
The dental pulp is a difficult tissue to access in humans without causing an inflammatory
response. It is a result of its environment and the hard tissues (enamel, dentin) that surround it.
From the standpoint of the possibility of repair and/or regeneration when the dental pulp is injured,
infected, or necrosed, its nature must be understood before any treatment modalities are attempted.
Another unusual aspect of the dental pulp is that it is a completely sensory tissue. That sensory
design implies that the adult pulp is protective of that tissue throughout the life of the tooth.
However, that same protective nature can be disturbed due to its location and its functions.
The following is a brief review of the nature of the dental pulp's location that mitigates against
its ability to survive, repair itself, and regenerate a pulp-like tissue. First, the pulp has a terminal
microvascular supply with few, if any, anastomoses (with the exception of multirooted teeth).
Second, the dental pulp has a relatively large volume of tissue with a relatively small vascular sup-
ply. The largest vessels to enter and exit the tissue are arterioles and venules. Last, and probably
the major deterrent to repair and regeneration in response to injury or infection occurs due to it
being surrounded by a hard, unyielding tissue (dentin) and itself surrounded on the crown of the
tooth by enamel and the root by cementum
[74]
. However, in spite of its environment, the pulp has
in infinite capacity to repair itself.
21.4
Repair and regeneration
The main culprit in relation to untoward events occurring in the dental pulp is due to the onset of
dental caries. The hard tissue surrounding the pulp is susceptible to the microorganisms that cause
enamel and dentin to become infected, with extension into the pulp tissue. When caries begins on
the outer surface of enamel, the effect pulpally is an inflammatory response. As caries develops
deeper into the enamel and dentin, microorganisms and their toxins travel directly into the pulp tis-
sue. If caries is removed early in the pulpal inflammation process, any damage occurring within the
pulp will be repaired by specialized cells (odontoblasts). Another form of dentin matrix will be
formed and mineralized. This repair process narrows the pulp space but is still considered protec-
tive. The tooth is eventually restored and, if there are no further insults, will remain in the mouth
over the lifetime of the patient. However, if caries is not removed early enough, the pulp continues
to create dentin matrix. Sensory nerves, connective tissue, and blood vessels are compromised and
narrowing becomes profound. Reduction of the space occurs and function is lost. The repair process
occurs due to materials placed near to or into the pulp which cause the replacement of the original
cells with cells that function in a manner not unlike the original cells. Today, ongoing research
indicates that repair and regeneration can occur in a low-compliance environment. By necessity,
the greater numbers of studies utilize animals whose teeth function in a manner similar to human
teeth. Furthermore, bench-top research also is used to test theories before turning to animals
[75]
.
The ultimate aim of these studies is to generate a natural tooth, including its hard and soft tissues
to replace a missing tooth. Unfortunately, there is still very much to learn about these tissues and
the therapy needed to return them to normal form and function.
