Depends on the dentist. I had one where I shadowed over 50 hours for through an internship. This was nice because then you get to follow treatment plans from beginning to end. For now, since you are in high school, just start with a couple sessions to get a feel for it. You will have LOTS of time to shadow in college. On your application, there is room to place ten different dentists for shadowing. You also don't need to fill all the spots but look at the schools pre-requisites for shadowing to see how many hours to shoot for (see UoP's website for pre-reqs). But shadow several general dentists because then you get the feel for how different offices run. Then add a few specialties, but dental schools like most of your shadowing to come from a general dentist. And to answer your other question, job shadowing is a must to be admitted into dental school. Also, do not stress! You have loads of time right now. It is good you are preparing. Job shadowing is fun if you let it be. Do not be scared to ask to shadow a doctor. Some doctors don't want shadows, so don't get discouraged if they reject you and just move on to the next one. The fact that you are planning so early says a lot, so enjoy the fun pre-dental ride. Also, job shadowing can get boring. Don't let that deter you. It helps to pass the time by asking questions. I'm sure actually learning/performing the procedures is much different from watching
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