I'm not sure I'd be comfortable getting dental work or medical care in Mexico, but I have gotten prescription meds from across the border at a significant savings. No Rx required. They're sold OTC.
I haven't had to do it for a couple of years, but I'd do it again if I needed to. I don't know if they have a limit on how many you can bring across the border because some friends were the ones who brought them back. In fact, they make regular runs to get meds for family members and friends.
The meds I got are PRN (for migraines), they come 5 to a bottle, and I got 5 bottles. Apparently there wasn't a problem with that amount. I also got some topical meds. All the meds worked as well as what I get in the US and pay mucho dinero for.