Insurance is just once small part of the expenses. A dentist will have more expenses having to pay staff, cover benefits, pay the electric bill, etc. Unless you own your own practice as a doctor, which is really not common at all these days, your expenses will be much higher as a dentist. Even if you do own your own medical practice, it's not likely you will have the equipment in your office like a dentist would.
As for lifestyle, it depends on what kind of medicine you practice and where. Some smaller towns have more flexible work schedules for doctors, but then again, they will make less money too. If you go into general practice, you won't be doing hospital rounds often, if at all, so that gives you more office hours. My GP doesn't work on Fridays, and works 8-3 the rest of the week....except she is generally there well past 3 most days.
In that case, I work 8-3 also but generally leave at 5.
