To become a dentist, you will complete dental school, not medical school. In the USA, dental school and medical school both take four years to complete once you have completed your four-year...
If you completed your bachelor's degree, and are accepted to a medical school, it will take four years and an additional three to eight years to fulfill the residency and internship requirement...
It would take four years for the bachelor's degree with completion of all prerequisite coursework required by medical schools and four years of medical school. Thus, eight years beyond high school...