Dr. Sue Kempson, also at Edinburgh, has shown through EM that peripheral cementum on the exposed crown of the tooth contains
small blood vessels and nerves. In short: the equine tooth is a much more sensitive living structure than many of us once
realized. It is not simply a block of wood that we may shape at will. It is normal for a horse to have sharp enamel edges
to properly masticate coarse feed materials. Transverse ridges on the occlusal surface of the teeth are normal structures
providing increased surface area and have a function in normal mastication. The curvature of the jaw (Spee's curve) is natural
and should not be mistaken for a high lower caudal molar. Molar table angles vary naturally between individuals and should
not be changed just to fit a mold of "the perfect mouth". While balance in the mouth is extremely important, a perfectly smooth,
level mouth often will not be the most functional for the horse.
One must be conscious at all times of the amount of tooth material that is removed, the amount of heat that an instrument
may create, as well as the longevity of the horses' dentition. It is not acceptable to create a "perfect" bite on a horse
in one session and expose sensitive dentin, causing dysphagia for several days or even weeks.
It is not acceptable to remove too much tooth material at one time, creating enough heat to destroy the sensitive pulp and
result in a dead or abscessed tooth in three or four years. These are problems that currently are being observed with the
improper use of power instruments.
So, what can you do to prevent these complications?
- Use water-cooled instruments.
- Be accurate. Reduce only the overgrowths and leave normal tooth structures alone.
- Reduce large overgrowths in stages. Take down a portion of the overgrowth, finish work in other areas of the mouth, then after
many minutes, return to reduce more of the large overgrowth.
- Realize that in the best interest of the horse and its health, a large overgrowth does not have to be corrected all at one
time. A malocclusion this severe most often took years to form, and it should be corrected over many visits spanning months
to years. A 2-cm overgrowth that is reduced 0.5 or 1 cm likely will be out of occlusion and no longer cause an obstruction
of lateral excursion. By partially reducing the overgrowth, you will provide the horse improved lateral excursion and the
ability to better use his mouth. The excessively worn opposing tooth will begin to recover, and the odontoblasts will deposit
additional secondary dentin allowing for more non-sensitive tooth material to be removed at another time.
Finally, a complete record of your findings and treatments on a dental form provides a good medical/legal record and helps
in itemization of all the work performed.
Dr. Johnson is owner of Advanced Equine Dentistry in Grass Lake, Mich. He graduated from Michigan State University in 1991 and has limited
his practice to equine dentistry since 1994. Dr. Johnson is an adjunct associate professor at Michigan State University, and
he lectures and teaches advanced dentistry courses internationally. He can be reached at (517) 522-4111 or via e-mail firstname.lastname@example.org