What is an annular fissure?

An annular fissure is a groove-like defect (deep fold or invagination) of the enamel and dentin of a tooth that occurs during its enamel formation. It appears after the crown is completely formed and is typically seen in the cervical area of the tooth, where the enamel and cementum meet. Annular fissures are usually confined to the enamel but may extend into the underlying dentin. They can be caused by various factors such as nutritional deficiencies, genetic anomalies, and systemic conditions. Annular fissures are often associated with enamel hypoplasia, a condition where the enamel of the tooth is underdeveloped or absent in certain areas.