I've been to Tijuana for eye care, Costa Rica for dental work and our neighbor and various other people we know have had dental work done in Mexico. I've been pleased with the work done at a significant savings, the Dr's trained in the US, the offices were clean and modern. Others have been pleased also.
Now, nmnita gave you good advise. It is a foreign country, and even if Dr's or dentists stand by their work and many don't, it costs money to go back. If you have insurance that will pay, make that your first option. I chose Costa Rica to get dental implants, my insurance paid nothing. The price my fancy Scottsdale periodontist quoted for two implants was more than the trip to Costa Rica, the work, hotel and meals. I know patients are supposed to pay for her Mercedes, the family vacation to the Bahamas, and her kids private school tuition, but I chose not to.
Instead I had an awesome time in Costa Rica, got world class dental implants and met many Americans who were there for dental work. When not sitting in the waiting room, we'd go out for dinner and tours of the island.
Do your research, read all you can about the dentist, then decide, based on what you know. Good luck.