The most likely location for a cavity to develop in your child's mouth is on the chewing surfaces of the back teeth. Run your tongue over this area in your mouth, and you will feel the reason why: These surfaces are not smooth, as other areas of your teeth are. Instead, they are filled with tiny grooves referred to as “pits and fissures,” which trap bacteria and food particles. The bristles on a toothbrush can't always reach all the way into these dark, moist little crevices. This creates the perfect conditions for tooth decay.
What's more, a child's newly erupted permanent teeth are not as resistant to decay as adult teeth are. The hard enamel coating that protects the teeth changes as it ages to become stronger. Fluoride, which is found in toothpaste and some drinking water — and in treatments provided at the dental office — can strengthen enamel, but, again, it's hard to get fluoride into those pits and fissures on a regular basis. Fortunately, there is a good solution to this problem: dental sealants.