Mexican dentists studied in dental colleges that trained students in modern dental procedure. The same novacaine that was used in the U.S. was used there. The high speed drills, the same type chairs, sinks, and the same dental materials that are available in the United States are available there. Some of the resort area dentists treated patients from the Europe, the United States, and Canada on a regular basis.
I would not recommend going there for minor procedures. I had my mercury Amalgam fillings replaced with a resin composite for about $100. per tooth, each molar had multiple filling surfaces. The composite fillings implaced in my front teeth (in the U.S.) as a child are seem good more than forty years later; although somewhat discolored.