Hi this was refreshing to read and I feel that you will come back to this dream or series of dreams when you realize some important changes in your life. When we grow a tooth on top of another it is to force out the old and bring in the new. I do not know if it was an incisor or not but also coming to mind is "eye tooth" or I tooth The new is a mirror image in that it is you "the aspect is you". I saw a similar image in real life yesterday as I was thinking and driving. I passed a truck with an add for a yogurt beverage that said the same thing.... that a particular aspect of another person i was concentrating on was so strong because that aspect is me.
This touched me in several ways because I had a similar dream last night where I saw teeth and a pair of lips attached to the arm of a person who was not me but shares my name, therefore it was like me looking in the mirror. The man in the mirror although portrayed as someone else was obviously me. Dreams are usually all about I.