A long, long time ago there was a wizard who accidentally invented a rather unusual spell. Whoever the spell was used on would get perfect teeth. As he didn't know what to do with this discovery, the wizard decided to use it on one of his toads. After the spell was cast, the toad became a very smiley happy amphibian. Not only could he now eat all sorts of foods, but he also started speaking. "I'm delighted with the change", repeated the toad, proudly, "I much prefer the consumption of candy to feeding on filthy flies". The wizard noticed that the toad was taking little care about choosing what to eat, and he kept telling the toad, "Look after your teeth, mr toad. brush them so you don't get a toothache. and, above all, don't eat so many sweets…"But the toad didn't pay much attention. He thought his teeth were too strong for him to have to brush them, and he liked sweets so much that he didn't even try to eat less. One day, a tooth started decaying and, gradually, the decay spread throughout his mouth. Before long, the toad discovered that there were holes in all his teeth, and they were starting to fall out. He decided to start looking after them, but by then it was too late. And when his last tooth fell out, he lost the ability to talk. Poor mr. Toad! If he hadn't lost that last tooth he could have told the wizard that if he gave him teeth again he would brush them every day. After all, there's nothing more disgusting than having to go back to eating bugs. Yuck! 
A nice way to explain to children the importance of brushing their teeth, and not eating too many sweets. 