Horse's teeth don't get cavities ... unless, I guess, their owners feed them candy bars all their lives ... but they do get oddly-shaped as the horse ages.
Horse teeth never really stop growing but their constant grazing wears their teeth down unevenly. In the wild, an older horse's teeth become uneven, it begins to have trouble chewing and digesting its food, and subsequently weakens, feeding the carnivore next up the food chain.
In captivity, we have our horses' teeth "floated."
See Diagram One. When one side of the teeth/tooth doesn't grind down on its own, we have the vet come in and reduce the long side so that Horse's teeth meet efficiently again.
The picture is a rendition of not MY horse's tooth, but of a tooth I saw extracted from a mare whose teeth were "floated" the same day the vet came out to do Dink's teeth. The mare had a loose tooth, which the vet pulled out almost with his bare hands. It looked very much like my image -- a low inner side, and a high outer side.
Floating reduces the high side to match the other, as per the red line.
Interesting process: the vet injects the horse with an anesthetic. The horse, in a matter of seconds, begins to look sleepy, and then rearranges his limbs as though he is a sodden drunk. At that point, Horse couldn't give a shit what you want to do with his mouth, which is prime for the vet to bring out his power files and saw/file down those crags of tooth.
Horses have no nerves to their teeth, so the noise of the drill/rasp might annoy them, but they're in no pain.
Dink had no loose teeth, and his teeth were not in too bad a shape. But this was a necessary maintenance operation, and I must say that in subsequent days, I took pleasure in hearing his teeth grind properly as he snarfed his food. It's a sound that I should have missed months before, and just didn't. But I know it now, and won't overlook it again.
There is no post-operative trauma with this procedure, and the next morning, Dink was raring to go.
He yawns after we ride ... I wonder if he is as tired as I am?