I like this post, but I definitely took a different mentality and route. I realized very quickly in dental school that I didn't want to be a GP, but didn't know what specialty/area I wanted to pursue. Throughout dental school I began to narrow down the fields I could see myself in (and once you hit dental school you'll def. be able to do this) and kept narrowing til I chose my particular route. The specialties are all so drastically different that you will be suited for some, and completely opposed to others. I liked pedo and OS...but just couldn't stand endo and ortho.
Specialization def. has its pro's and con's...and the VAST majority of dental students do not go on to specialize (the numbers are higher now than recent years but I think it tends to trend with the economy). It is for the most part, guaranteed more money...but you're sacrificing (in many cases) a lot of the best parts of general dentistry for some people (relationship building with patients, broad scope of practice, EASY money, etc).
My best advice is to take Dental School like you're going to specialize (GPA, Externships, Extra-c's), but don't make final decisions until you get into your 3rd year.
You'll also want to keep that information to yourself...it is good advice to be vague about your future with your classmates and family members even. I saw many folks in my dental school who regretted announcing their intentions early on.
Specializing is like an incoming career path/major in UG...a lot happens in 4 years...there will be small changes and big changes...you really don't know til you get there
PS - I made a lot of generalizations here...of course there are exceptions to every rule