I would like to address this topic as a person who has been involved with equine dentistry for over 11 years.
I practice dentistry in Alberta and I work in conjunction with veterinarians. There recently was a political struggle in Alberta between the Alberta Veterinary Medical Association and equine dentists. The AVMA proceeded with legal action against an equine dentist starting in 2001. The Justice ruled that equine dentistry is NOT THE PRACTICE OF VETERINARY MEDICINE IN ALBERTA.
The AVMA then appealed this decision to the Alberta Court of Appeal and again lost their case. The next step for the AVMA was to make an application for an appeal to the Supreme Court of Canada, where their case was dismissed. So the practice of equine dentistry is still not, and never was, the practice of veterinary medicine.
There are a number of veterinarians in Alberta who are more than willing to work together with an equine dentist to provide this much needed service.
The issue that I think needs to be discussed is the one of sedation. The only way that a horse can be sedated legally in Alberta is: by a vet, by an AHT under supervision of a vet, or by the owner of the animal with a prescription from a vet. If someone is sedating your horse in Alberta who isn't one of the above, they are breaking the law. If you live in other places you should check into the legality of having a non-veterinarian sedate your horse.
I know for a fact (because I have first hand knowledge of it) that there is a lot of incompetent dentistry being performed in the field by vets and dentists alike. It truly is a "buyer beware" market. There is no set standard anywhere in Canada for anyone practicing equine dentistry. Just because one is a vet doesn't mean that they are qualified to perform competent dentistry.
Balance and whole mouth function are paramount to the horse's ability to eat efficiently, perform, and live a comfortable dental-pain free life. The basic things like sharp edges, wolf teeth, and retained caps are just scratching the surface of what the best treatment for each horse may be.
The other point that I would like to make is that it is (or at least should be) up to the horse owner to educate themselves about proper dental care for their horses. There is a lot of fiction and little fact in this section of horse care.
If your dental practitioner isn't explaining what they are doing and why, then you may not be getting the best service.
You should discuss with them things like whole mouth balance, TMJ function, proper radius on molar arcades, proper incisor profile, table angles, and a long term treatment plan for each horse. We must remember that horses are individuals and a "rubber stamp" approach to dentistry isn't an effective treatment.
There are several issues involved with the situation and it is up to the horse owner to sort through them and get the best possible care for their horse.
Good Luck, Shorty