Just like you, horses need regular visits from the dentist.
Apollo got a full dental exam and had his teeth floated (the sharp edges filed off) and is so much happier now. He had a lot of sharp points on his teeth that were making his cheeks sore, so now he can chew and wear a halter comfortably.
If you've never seen a horse get their teeth worked on before, here's a look at what it involves:
The horse starts off by getting a sedative. Not enough to knock them out (although Apollo did almost tip over when it kicked in, straight sideways like a cartoon horse), but enough to keep them from panicking over the work being done in their mouth.
Then they get a special contraption strapped to their head that is essentially a vice to keep their mouth open. The vet ratchets it to be just open enough to reach back, but not so much that it makes their jaw tired.
The vet then files down the points and other spots where the horse's teeth have worn unevenly. This can be done with a hand file or a power file. There are pros and cons to each, but an experienced operator can do an excellent job with either tool.
When they're done, the horse gets to "sober up" for a while.
Although I'd seen this done numerous times, this was the first chance I'd been given to feel the teeth before and after. The difference was amazing!