DEAR DOCTOR K: What is tooth decay, and how does it happen?
DEAR READER: Tooth decay is a disease of the mouth that can lead to cavities and infection. But before we start talking about sick teeth, let's talk about healthy teeth. Each tooth has one or more roots that are anchored in the bones of the jaw. Since those roots are inside the jaw bone, they are invisible. The part of the tooth that we see, sticking out above the gumline, is the crown. The crown of the tooth is covered with a hard, whitish material called enamel.