I used to have a lot of battles with my son over brushing teeth. Sound familiar? First I bought him a Spiderman electric toothbrush, which helped, though he was still never keen. Then one day his breath smelled of something - not very pleasant - and I remarked on it. He immediately went to brush his teeth, unasked. Since then, I have occasionally pretended his breath smells and he goes off with great enthusiasm to brush his teeth. He now mainly does it unasked and unaided, morning and night - an incredible turnaround! It may not last (in the way of these things) but fwiw, I share it.