The best way to instill the habit of brushing teeth in children is to have them learn by example. Once children have watched their parents perform this twice-daily ritual and get the hang of it, parents should encourage their kids to brush their own teeth.
First, children should learn to dab only a pea-sized amount of toothpaste on their soft-bristled toothbrushes. They should then concentrate on gently brushing back and forth on the inside surface of each tooth, where bacteria-laden plaque is most likely to accumulate. After that, the outer surfaces should be brushed with the brush turned at an angle along the gumline. Before rinsing, children should try some tongue-brushing to introduce an element of fun into the process.
P.S. Parents should floss for their children beginning at age four. By the time they reach age eight, most kids can begin flossing for themselves