This logo is a combination between tooth and face. It represent a stetic and dental care
Ok...I'm just going to say it. If you google "tooth logo" the exact shape of your tooth comes up about every other one. =(
I think someone already suggested that a tooth for a dentist is too obvious and way to overdone. Unless you are doing it in a super creative and unique way, it's not going to wow ya know!
These logos look forced- you may be holding on to an idea that isn't working, and you are trying to force it to work. That's when you have to step back and sketch, brainstorm, word map- whatever works for you and then go back to the computer fresh.
That's just my two cents. Good luck!