J.H.
With my son, who is 13 months old, I have made it a fun game. I showed him how I brush my teeth, then I hand him my toothbrush and let him brush my teeth. In the meantime, I use his toothbrush to brush his teeth. He thinks it's funny, and we both laugh. So now when I tell him it's time to brush his teeth, he gets excited and laughs. It may seem really silly, but it works for us.