Despite great strides in decay prevention, one in four young children develops signs of tooth decay before they start school. Half of all children between the ages of 12 and 15 have cavities. ?Dental care should begin as soon as a child?s first tooth appears, usually around six months,? ?Teeth can be wiped with a clean, damp cloth or a very soft brush. At about age 2, you can let kids try brushing for themselves -- although it?s important to supervise.?