When you eat sugar, the bacteria in your mouth make acid which rots the teeth. However, saliva can wash away the acid and any microscopic damage to the teeth will heal over the next few hours. But, if more sugar is taken in during this recovery period, the acid remains and decay may set in. Generally speaking, the mouth appears to be able to cope with sugar at meal times, so eat your sweets then. The worst thing you can so is eat something sweet when you go to bed, or have a sweet drink during the night. The saliva flow almost stops when you sleep, so the acid produced from anything sweet will just sit there and decay your teeth.

Bacteria only need minute amounts of sugar to make the acid; so slightly sweetened coffee is as much a feast as a Mars bar to them. Therefore you need to avoid sugar completely to avoid the acid forming on your teeth. Bacteria can't convert artificial sweeteners, which can be safely used in beverages between meals. At meal times enjoy fizzy drinks, squashes, cakes, sweets and biscuits, but find something savoury for between meal snacks.

Always check the label of proprietary foods for 'hidden sugars'. Most manufacturers will add sugar to their foods (e.g. tomato ketchup), but watch out especially for 'low fat' products which replace the fat with sugar to make it more palatable.

Dental disease can be prevented by avoiding sweet food and drink between meals, and by brushing your teeth really well with a fluoride toothpaste last thing at night.