Hey TRON,
Most schools encourage getting letters from dentists or anyone working in the field. It is a good idea to get one since that illustrates your passion and experience in dentistry. However, it is also important to get really good letters of recommendations from professors as well. I think it is a good idea to get a couple from science profs, one from a non-science prof and one from a dentist. Some schools have weird recommendation policies like Columbia: even though they accept recs from dentists, they still want three science profs to write you letters. Hope this helps.
-DesiDentist
