Good job for looking into the profession this early in life (wanting to be a dentist for since you're 13 or 12?)
But here's where the reality comes in. It might make you sad or whatever.
There are schools that take applicants without an undergrad degree but you better be a goddam genius (like, winning the ISEF smart) AND escaped from NK. So look to college to get a degree. If you really dont want to get a degree, go Pharmacy or vocational schools. You can get an undergrad degree in 4 years, that's how long normal college students go to school for. You can get it in 3 or 5 years too depending on how much you enjoy your school (ehem, parties).
Im sorry to burst your bubble that any idiot can maintain an A in highschool. I did in all of my classes, and I slept through all of them. Hell, even college intro courses are cakewalks. The REAL test of your scientific knowledge will from higher level science courses, including Biochemistry, Microbiology, Molecular Biology, Organic Chemistry, Genetics, Anatomy and Physiology (may or may not include Physical Chemistry and Advance Inorganic Chemistry). Dental schools will also be looking at how well you did in those courses to determine how well you can handle pre-doctoral level courses.
My advice, worry about college first. Take your time and do college right. Whatever you do in college will effect the rest of your academic life, no more do overs. I had a friend who went into a 7 year MD program from high school and stop the program after 3 years and took her undergrad degree and is doing something else now. Explore all that the world has to offer. Dont get narrowsighted.
Now, excuse me while I go throw up.