I say go for it.
We have been trying to crack in to this niche for almost two years with our http://patientboost.com/default.html service but it is a damn challenging market.
Its been at the top of my list of software I have basically no interest in working on yet feel like I could do a hell of a lot better at anyway. Of course, I haven't researched what's out there, there may already be much better options available.
Besides being ugly, my main beef is that I have watched her drag photos, one at a time, into their proper slots in my "file" from the incoming area, even though they were already clearly labelled as to what tooth they were pictures of. It's maddening. It's only a minute or two, and she doesn't take pictures every visit, but it's the kind of thing that just screams shoddy workmanship... and opportunity.
Are you certain that is a software problem? It could well be a user education problem, or a trust issue between dentist and program.
Having a good website will get you a competitive advantage in the market segment I'm a part of. (And my segment, people who don't want to deal with automated call systems or dead trees of phone numbers is growing every day.)
However if you are offering Cosmetic Dentistry, each new client can worth thousands of dollars and people will travel from their immediate surrounding to go reach your dentist practice.