Yes, Algodones near Yuma, AZ is the place many people go to get dental work done. In reading RV blogs, I learned that many RV'ers walk across the border, with their RV parked on the US side.
The quality of work depends on the dentist, same as in the US. I have read about some RV'ers not being happy with the work, while some were just raving about the fancy machines that I have not seen in any US dental office I have visited. For example, one office has a CAD-Scan machine to take 3D images of patient's jaws as part of the implant procedure. It has a milling machine to make crowns the same day you walk in. The same office will do everything from implant surgery to teeth cleaning.
A worker at the megacorp where I worked took a vacation and went down to Algodones for several crowns, despite having dental insurance from work. He explained that paying 100% of the cost there was still much less than the out-of-pocket he had to pay in the US.
For more info, search the Web for "Algodones RV blog". To read about a particular dentist that one RV'er raved about, search the Web for "mobilecodgers Algodones dentist".
I do not want to provide the links directly because it would look like I am pushing something. If you are really serious about this, you have to do a bit of work and read some info to decide for yourself.
I myself have not gone down to Algodones although it's only 200 miles from my home, because we have not needed extensive work, and just a crown here and there. But for more major works, I would seriously look into it.