Many schools will want you to continue collecting teeth throughout your 4 years. We were asked to get some last year just so we could work on identifying teeth in dental anatomy. Now we are supposed to be collecting teeth for our endo class next year, and then the endo part of the WREB is done on extracted teeth. I would drop off jars at more than just oral surgeons if you can. You will want a variety of teeth (more than likely), and most OMS do 3rd molar extractions. I had my oral surgeon fill a jar for me. He had it filled with 120 teeth in about 2 weeks... 100 which were wisdom teeth. I would recommend dropping a jar off at a periodontist as well, and a general dentist (only if they do a good amount of extractions). Periodontists may not collect that many for you because a lot of the teeth they section, but the ones they do collect, won't be third molars. I had a periodontist collect about 15 anteriors for me last year. So that's just something to keep in mind.