Los Algodones, Mexico, population 4,000, is home to about 350 dentists geared to foreign patients. Their treatment comes at a huge discount—70% or more—from what Americans pay at home, a reality that many patients call an indictment of U.S. healthcare. But U.S. medical authorities warn that Los Algodones is a medical Wild West, an unregulated environment where substandard providers can do not have the same oversight that exists in the United States.