In any examination for the soundness of a horse, an important factor is the determination of its age. Since this is a very controversial subject, the examination of the teeth is one of the most useful guides. For general purposes, the Incisor teeth and especially the lower ones are the ones which are used. In the newly – erupted, unworn tooth, the enamel is deeply folded into a funnel – like depression or infundibulum passing down into the central regions of the tooth.
This cup like depression holds black decaying feed in it and so always appears discoloured. The tooth crown is covered with cement which also extends down into the infundibulum. When the tooth comes into wear the cement on the biting surface of the crown is worn off first and then the enamel is worn away to expose the underlying dentine.
A short time after the tooth has come into wear, the infundibulum is surrounded by 5 rings of alternating cement / enamel / dentine. Enamel is the hardest of the three components and always stands proud of the other two since it is worn away more slowly. (See diagram below. The cross sections through the tooth will also represent the structure of the tooth – table when the tooth has worn down to the level indicated.)
As in all mammals the horse has two sets of teeth i.e. milk teeth and permanent teeth. The time of tooth eruption is the most valuable criterion for age estimation. Up to 5 yrs of age the eruption of milk teeth, their casting and their replacement by permanent teeth rarely varies beyond a couple of months and so age is determined with some degree of accuracy.
1. Infundibulum (Cup)
2. Remains of Infundibulum (Mark)
3. Central Enamel
4. Peripheral Enamel
5. Central Enamel
6. Peripheral Cement
8. Pulp Cavity Containing Nerves and Blood Vessels
9. Dental Star
12. Root Canal