When teaching your children good dental habits you want to start sooner then latter. 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. Your child dental care should begin as soon as the first tooth appears, usually around six months. Teeth can be wiped with a clean, damp cloth or a very soft brush. At around the age of two, you can let your child/children try brushing their teeth themselves, although it is still important to supervise them..