A bizarre ritual, but necessary. You usually need a few dozen intact collected teeth for practicing root canals in Endo class, circa 2nd year. Depending on the regional board exam, you are likely to need a couple "good" ones for 4th year clinical boards. You can drop off a collection jar (maybe w some dilute bleach water in it) at a dental office; ask nicely and they will save for you (every dentist remembers doing the same during their own school days) -- maybe wherever you've been shadowing. If the school doesn't state otherwise you can just wait till 2d year and worry about it then. No matter how you store them, any teeth you collect now will be suspect by the time you reach 4th year boards (get brittle over time; & last thing you need is to fracture a tooth during your board exams). So don't feel like you need to stockpile hundreds before school.