I think they beat you with clubs and then throw goat urine on you...but that may be something else I'm thinking about.
I'm an older applicant and a career changer. From what I've heard, it isn't really an issue. There are statistics that show the oldest and youngest ages of students in various schools and it really does range widely at times. I don't think there are that many 40 or 50 year olds applying, but there are stats that show a 41 year old at one school...I forget.
I think once you get over 40, they start to make it a concern, but other than that...you should be fine.
Age shouldn't matter- My class had students that began 1st yr of dental school in an age range of 21-40... and some of the older students did very very well. Just make sure your scores, grades, and coursework are competitive with the younger folk.
So I figure, the avg age I've seen for most schools is 24. Since most "traditional" applicants are 21ish when the graduate from college, there are obviously a good deal of us older folk out there in dental school. I think that career changers show serious commitment to dentistry considering the life changes that must be made to go back to school and drag family along with you (in a lot of cases) and that makes a big impression on adcoms. There are a lot of youngins that are committed to it, don't get me wrong, but this is just a plus for us considering the possible lack of upper level courses, clubs, activities, etc non-trads usually have compared to many traditionals. Maturity and real world experience can't hurt, either. Every dentist I talk to thinks it's a plus, and a dean of student affairs at Baylor didn't have a problem with my age - 27 (28 by the time school starts).
I think being slightly older, or making a career change after years of work, is looked favorably upon by admissions. I forget where I heard this from, but I was told they liked these applicants because they've already been out in the "real world," and know more of what they want in life - compared to the fresh, right out of college student who's had their nose in the book for the last four years. Also older applicants w/ families to support would probably be less likely to drop out of dental school because they're more committed, and have much more to lose than a traditional student.
Consider this: Even if you enter school at 40 and have your DDS at 44, you'll still have a good 20+ years of practice ahead of you.
I'm 34 and will be starting school at UNC this fall. I can't say that my age gave me any kind of advantage. Then again, I guess an argument can be made that someone who changes careers at my age is probably pretty serious about the new career path. It's certainly not easy to give up a good job in order to take on $150k in loans and pursue a new career...
I'll be 37 if/when I get accepted somewhere. Very humbling experience going back to school and taking pre-reqs. I think if I maintain my grades and score well on the DAT, I'll have alot to say and talk about during the interview of what I can contribute to the dental school. I think it is nothing but positive.
You would think that non-traditional students would have a strong sense of why dentistry over continuing to do what you were doing to get through life. It's likely not about the years in school or the expense as much as getting the chance to do what you are genuinely interested in doing. But you still have to be able to do the science and hand skills. It's a tricky balance of life experience versus my mind and body can still do prof school very well.