Tooth decay happens when plaque or bacteria come in contact with the tooth and is allowed to sit. The bacteria, once fed with sugars, will begin eroding the enamel.
Causes of tooth decay include:
Adults tend to get cavities around old fillings, which may be cracked, rough around the edges or loose in the tooth. Another common form of tooth decay in adults is root cavities. These are likely to occur in adults who have receding gums due to age or periodontal disease. As the gum line recedes, the tooth root becomes exposed. Since root tissue is softer than enamel, it decays more easily.