What courses do I need to become an orthodontist?

I am going into my grade 12 year, and I plan to apply to university and eventually get my bachelor of science. I am not sure what courses I should be taking to get into such a program, and I am not sure where I should look online to find that information. Can anyone help me? (If it matters, I hope to apply to Western, University of Toronto, and University of Waterloo)