CEJ

The cementoenamel junction, abbreviated CEJ, is the anatomical boundary between the enamel covering the crown of a tooth and the cementum covering the root. It marks the transition from the anatomic crown to the root and is located in the cervical region of the tooth. In most teeth the enamel and cementum meet at the CEJ, but there can be variation: cementum may overlap enamel, or a small gap may exist between them.

Variations in CEJ anatomy are common and can differ among individuals and tooth types. The CEJ is a fixed landmark established during tooth development, and its position on the tooth surface does not change with age, though its clinical appearance can be altered by wear, recession, or restorative procedures. Clinically, the CEJ serves as an important reference point in dentistry, used to assess gingival recession, periodontal attachment loss, and the extent of root surface exposure during examinations.

The CEJ also has implications for dental health. When recession exposes dentin beyond the CEJ, sensitivity and caries risk can increase on the root surface. Although radiographs can sometimes help identify the CEJ, it is often inferred from surrounding structures because enamel and cementum can appear radiopaque on imaging.

Overall, the CEJ is a fundamental, stable landmark relevant to periodontal assessment, restorative planning, and the understanding of tooth anatomy. See also enamel, cementum, dentin, and periodontal ligament.