Healthy teeth, bones and gums need to be supported by a nutritious, well-balanced diet. A variety of foods from the five food groups helps avoid cavities and other dental problems. Many processed-food snacks such as granola bars are loaded with sugar that can cause cavities. For healthy teeth, children should only eat nutritious snacks like fresh vegetables, low-fat yogurt and cheeses. Fresh fruit is also good, but should be limited because fruit contains natural sugars.