Not bad - almost too many concepts packed into one little logo on #1 and #2 - I had to concentrate and analyze for a minute until I captured what all you were trying to convey. Great idea, though. Maybe try simplifying a bit to two concepts - possibly drop the heart - and add a second color. Just some ideas...
Designs cleverly using negative space are thought to be more engaging and thus more memorable. It's not always a bad thing for the viewer to spend an estra moment more looking at the design. Since this design does not rely on negative space nothing is lost if the tooth is not seen right away.
I will consider ways to rework/improve the design.