With the old way of floating teeth with just the file back and forth, some horses do not need sedation, but no sedation means a twitch.
The new science of Equine dentistry, with drills and bits, should only be done by a licensed Veterinarian, and this procedure is done with sedation. I would not have it done without sedation. If your equine dentist recommends no sedation he or she is most likely not a veterinarian, as administering sedation can only be done by a vet. While dentistry on a horse is expensive, a dental problem can be about 10x more.