Today's Veterinary Practice provides comprehensive information to keep every small animal practitioner up to date on companion animal medicine and surgery as well as practice building and management.
PRACTICAL DENTISTRY |
UÊReversible pulpitis indicates that the tooth will respond favorably to therapy and remain vital.
UÊIrreversible pulpitis eventually results in pulp death and necrosis.
Direct pulp exposure will invariably result
in pulp death, necrosis, and subsequent infec- tion, unless treated immediately with vital pulp therapy. This therapy protects the pulp with a medi- cant; then 2 layers of restorative material. The goal is to maintain long-term tooth vitality and in order to have a chance at success, this therapy must be per-
HYDRODYNAMIC THEORY OF DENTIN SENSITIVITY
Figure 2. Diagram showing the relationship of the pulp, odontoblastic process, and dentinal tubules
UÊDentin: The middle layer, between the pulp cham- ber and enamel, is called dentin. Dentin makes up the majority of the tooth structure in mature
animals and has a similar mineral density to bone. » Dentin contains millions of dentinal tubules that radiate from the root canal to the periph- ery of the dentin, which is covered with enamel (Figure 2).
The intimate association of nerve fibers with odontoblasts (cells that produce tooth dentin) is an area of active speculation. It is still unclear how odontoblasts and nerve endings interact. One theory regarding this interaction is the Hydrodynamic Theory of Dentin Sensitivity. It states that the movement of fluid in dentinal
» Each one of these dentinal tubules contains an odontoblastic process with nervous inner- vations, resulting in a dynamic living struc- ture with sensory ability and the capability to respond to stresses.3
» Canine dentin has 50,000 to 100,000 tubules/ mm2, which is twice the number of tubules in human teeth.4
twice as sensitive as ours.
RESPONSE TO INFLAMMATION Teeth are subject to many sources of inflammation; in veterinary medicine, the result is generally traumatic.5 Once the tooth undergoes trauma, it reacts with inflammation. This reaction is termed pulpitis, which can be reversible or irreversible:
Therefore, dogs' teeth are
tubules is the basic event that elicits dentinal pain (Figure 3). The direct exposure of the dentin allows for more rapid movement of fluid. Heat, cold, dessication, and dental probing can all displace fluid and therefore elicit pain. In this theory, it is A fibers (nerve fibers that have the fastest rate of transmission of nervous impulses) that are activated by fluid movement.
formed properly and immediately.6 Even under ideal conditions, vital pulp therapy has a poorer prognosis than standard root canal therapy.7-10 Traumas, such
as uncomplicated crown fractures, attrition, and abra- sion, will result in inflammation that is reversible or irre- versible depending on the degree of inflammation and treatment (if any). Over time, the tooth may respond to inflammation by increasing the dis- tance between the injury and the pulp (tertiary dentin) or
Figure 3. Diagram illustrating move- ment of fluid in the dentinal tubules (blue arrow), resulting from the dehydrating effect of a blast of air from an air syringe (red arrow). This process creates deformation of the odontoblasts and associated nerve fiber (yellow arrow), creating pain.
January/February 2012 Today's Veterinary Practice 41
Proper Therapy for Endodontic Disease