Eat healthy foods Fruits, vegetables, nuts, cheese and milk are foods for strong, healthy teeth. Foods with a lot of sugar are can be bad for teeth. Sugars in food stick to the teeth and bacteria (germs) gather in the sugar and cause plaque. Plaque can melt the surface of teeth and cause decay. Brushing and flossing teeth keeps them clean and healthy. Brushing and flossing removes bits of food and plaque. Plaque is germs which can make teeth rot or decay. After each meal is a good time to brush or floss teeth but they should be brushed at least twice each day. Water Drink plenty of water during the day to help wash your teeth.