Not in itself. However, if you eat a lot of sugar in the form of sweets (candy), you may not eat enough of all the other foods needed to provide your body with the nourishment it needs. Sugar can cause dental decay if you eat sweets or drink sugar-sweetened drinks between meals. You need to clean your teeth afterwards in the conventional way or by eating a piece of specific dental chewing gum. Otherwise the sugar sticks to your teeth causing plaque and decay.