I have a good friend (and know a few others) in dental school, so I can give you some info about US programs.
It is 4 years, including summers, after a BS degree (sometimes people get in after 3 years of undergrad, but not usually). Obviously, you'd have to make sure you had the proper pre-reqs (lots of science: 2 organic chems, biochem at some schools, anatomy & phys, etc). It's also ridiculously difficult to get into dental school since there are so few of them, so getting in with some local dentists to volunteer, observe, etc is a good idea ASAP.
It is VERY intense. I will say that. It's an 8a-5p M-F situation for sure in the 1st 2 years, and pretty close to that in the next 2. It gets less structured when you hit final year and do mainly clinicals. I know that many people do it with families, but it's all about scheduling. My friend says everyone she knows leaves class at 5, goes home and eats dinner, and then studies alone until about 10pm. You need to have at least 3 hours of studying per night. Sometimes the people with kids take a long dinner and study late with their spouse so there aren't many distractions. The weekends are lifesavers.
That said, once those 4 years are over, you can go right into practice (as long as you don't specialize). And, you have manageable hours, can take off fridays, long vacations, etc. Depending on the age of your kids, I would say go for it. If it were me, I'd do prep work and lay down foundation to build up my resume (volunteer at dental clinics, observe dentists and oral surgeons, take some art/sculpting classes, etc) and apply when my kids were in school so being away during the day wouldn't be as big of a deal. I wouldn't try to go with a baby, though I know people do.
