Fluoride helps make teeth strong and prevents decay. The American Academy of Pediatrics, the American Dental Association (ADA), and the CDC all agree that kids should use fluoride toothpaste for brushing, taking care not to swallow it.

Cavities break through the surface enamel of teeth, and they'll probably get bigger unless you close them off with fillings. Your dentist will numb your mouth before drilling around the cavity to prep it. A combination of strong materials or a white mix called a composite goes into the cavity soft and then hardens as it dries. You may feel pain or pressure when getting the numbing shot and during the drilling. Once set, fillings can last a long time but need replacing if they break or wear down.