Nope. It's a fine choice, but dentures are no problem to dive with. Just use plenty of denture adhesive each morning. I make sure that I get there with plenty by packing a tube in checked luggage and another in my 3-1-1 bag for carry-on. Then I keep one tube in my room and the other in a pocket on my dive bag. I guess it can be purchased there, but I avoid shopping.
I tried that years ago, but then they sent their lab work to Mexico City and would take longer than the week I wanted to spend there. I already had my uppers from a Texas dentist, but did the lowers with a Cancun dentist.
Many years later, I was wondering how many I had left on my original plates, so priced a new set with the same office - which had relocated from the market area to a shopping mall closer to the tourist island. The quote was cheap enough so I went with the new set. They even cleaned my old set which I keep as a spare even tho the fit was a little different. Wonderful staff, all very friendly and helpful, etc. I did have a problem in that this trip they required I come back for a second fitting totaling three visits, so I had to travel from Coz to Cancun and back missing a dive day - but they failed to warn me about that in advance. I could have handled that with the first night in Cancun, second fitting the second day of trip, then a third visit at the end of the trip to pickup the dentures at the end of the trip, or maybe they did tell me and I forgot? Couldn't ask for a nicer staff anyway. See
Cancun Cosmetic Dentistry