I needed major dental work, so I spent literally a couple of days doing online research about dentists in Mexico. I then contacted some RVers who had blogs indicating they'd gone there for their dental work.
I know a lot of people have had work in Mexico and are happy with the results, but to me, the risks outweigh the savings. I read about people with every imaginable disaster possible, including one who caught meningitis and almost died. I saw xrays of people who'd had the screws put into their mouths crooked (for implants). I also read about not being properly shielded for xrays and using unsanitary instruments as well as bad water. I also read stories of people who thought they had good results and found out a year later they didn't when their inexpensive crowns fell off or cracked. I talked to a local dentist (after the fact, so they weren't trying to get my business) who had a patient come to him for help after having Mexican dental work and had to be sent to an oral surgeon, who then told him he couldn't help as the damage was too great. They ended up in a major city for the work at a huge cost.
Be aware that a lot of the reviews on Trip Advisor and such are faked by the dental clinics.
Everyone has to do their own thing, but I'm glad I had my work done by a competent local dentist who was there afterwards in case I had any problems. I have no affiliations with anything dental, and I think the costs here can be too high, but I enjoy getting my medical treatment from a first-world country where things are regulated, which they aren't in Mexico. Saving money isn't worth it if you're in pain afterwards.