That's a lot of time to do some amazing things! Aside from 100+ shadowing hours and researching, do stuff that sticks out that people don't usually do. Work on making connections to influential people. 1 year is more than enough time to both become a certified EMT and also take a dental assisting course (possibly certify dental assistant but that depends on your state). See if you can shadow at a dentist over break who is a faculty at your state dental school, so he can write you a recommendation letter. Lastly, don't be afraid to ask people for what you want and take big steps. I got to write for the ASDA, submit a patent on viral therapy on cancer, and go to hang with the (now former) surgeon general and get a rec. letter from him by asking around and taking big steps. If it's hard for you to find a fancy job or anything, you can always volunteer places/start your own clubs at your college.
Good luck