Tenoch24, if you can't write spanish very well you can enroll in an intensive writing course in a university. Since you'd be a citizen, the cost would be very low. It wont be a big problem since Mexican universities dont stress too much writing as in the US, except for programs in literature, philosophy, or law.

In Mexico you dont have to have a bachelor's degree to get into a dentistry or medical program. Students enroll after high school. However, admission for medical programs is very competitive and, like in the US, only a few students are admited each term, which may be every semester or year, depending on the school. For dentistry programs, it is not that hard to get into.

In your case that you have a bachelor's, the entrance exam would be easier, and you would have more chances of getting admitted. Medical and dentistry programs typically last 6-7 years for medical and 5-6 years for dentistry.

For any of these programs, you'll have to be able to read, learn, and memorize many shelves of books. So, start practicing your Spanish reading if you decide to study in Mexico.