atlas,
Well, I think I'm well-suited to respond to this one.....you see, I went to med school for two years after college but then withdrew to pursue my initial love of dentistry. Much of this was based on lifestyle issues. Here's my 2 cents:
During school: As far as the "basic science" years go (i.e., first two years), dental school is just as intense if not MORE SO than med school (I've got buddies in dental and used to compare my med studies w/them). Dental students take essentially the same science classes as med students (and, at some schools, actually take it w/them, eg Columbia). Yes, some of the classes are condensed/more focused than the med school versions, but you have to remember that dental students have LOTS of additional laboratory courses and hours added on top of it all. So basically, life sucks for those 2 yrs. During the clinical years though (final 2), dental students are better off as they don't get "abused" as much as med students do in the hospital. One thing I hated about medicine was its very heirarchical nature and rigid, almost 'caste-like' system. It's gotten better, but when you're a third yr. med student out on the wards you're basically at your residents whim (although there are plenty of cool residents who aren't so anal). For dental students, clinics are more of an 8-5 sort of deal w/no "call" really (in general) or reporting to the hospital at 5 in the morning. Plus, you're viewed more as a future colleague rather than incompetent trainee....As for residency, w/the exception of oral surg. all of the dental specialties are much shorter than med ones. And they're not nearly as intense as far as hours go. Again, I'm tallking overall and not looking at fields like psych or family practice.
As for when you're out and practicing....Dentists enjoy a MUCH better lifestyle in my opinion. Unless you're an oral surgeon, I've yet to hear of a dentist who works more than 36 hrs. a week, with most of the ones I've met working only 4 days/wk, and this includes specialists. Again, you could go into psych or something and have a pretty chill schedule, but w/the vast majority of medical specialties you'll be working at a LOT more hours than that. Plus, you'll be on a call schedule of at least q7 or something. I was working with a pediatrician for the last two years and she worked 4 days/wk from 9-6 and then was also on call every other weekend (and always got called in numerous times). With dentistry, you also enjoy much more autonomy and have less HMO bureacracy crap to deal with it (although it's creeping in...). Plus, salary wise dentists make as much, if not more than, most physicians. Sure, a cardiac surgeon or radiologist can easily rake in 300-400+ soon after residency, but they also spent many more years finishing their programs and will be working many more hours. For me, making 200 or so per year down the line but only working 30-35 hrs. per week and having time for a life outside of dentistry is much more important. Plus, I'll still have the gratification of knowing that I'm making a difference in peoples' lives....
Honestly, many of med school classmates secretly tell me that they're jealous of my choice to switch to dentistry considering the lifestyle differences they're becoming aware of. Not to say that this should be your only factor of course...I'm sure there are just as many disgruntled dentists out there as there are residents and physicians. But if you're truly interested in dentistry and want to have a better shot at a well-balnced life and minimize burn-out potential, I'd stick with the DDS/DMD! I'd be happy to talk to you about this in more detail if you want, I only scratched the surface here and could go on forever w/specific details.....
hope this helps!