Hello, Tufts D23 here! The same is true for my class, with almost half of us (including myself) having an M.S. degree. However, there are also many of my classmates who came straight from undergrad and quite a few people who took a gap year and worked as a dental assistant, etc. So to answer your question, I do not think they prefer M.S. degree students per se. I believe that TUSDM looks closely at the experience that each applicant has, whether it be from undergrad, a graduate program, or from a dental office - and how the applicant's background will positively contribute to the class dynamic and success.