I've done little experiments at a time when I was insured just to see where an American dentist was coming from just by mentioning that I've had a lot of dental work done there including two crowns for $90 apiece. He immediately told me that he needed to replace the fillings and crowns both as they were substandard work and were leaking. So I went and got a second opinion from another dentist (without telling him where I got the dental work) and he said that both the fillings and crowns were fine......That was over 20 years ago and I still have those crowns and fillings.
So I say propaganda, in some cases, when it comes to getting dental work and what would be prescription medicines from across the border. (You don't need prescriptions for most medicines there) I would certainly consider taking advantage of the better facilities there if the price were right and they were approved by the American insurance carriers whether I used insurance or not.
But you're talking to someone who ate off Thai street vendors for 5 months with no problems whatsoever. I do stay away from drinking the tap water in TJ though including iced drinks.