Invasive cervical resorption is a relatively uncommon form of external root resorption. There may be no external signs, and the resorptive condition is often detected by routine radiographic examination. Where the lesion is visible, the clinical features vary from a small defect at the gingival margin to a pink coronal discoloration of the tooth crown, resulting in ultimate cavitation of the overlying enamel. The condition is usually painless unless pulpal or periodontal infection supervenes. Radiographic features of lesions vary from well-delineated to irregularly bordered mottled radiolucencies, and these can be confused with dental caries. A characteristic radiopaque line generally separates the image of the lesion from that of the root canal, because the pulp remains protected by a thin layer of predentin until late in the process. Histopathologically, the lesions contain fibrovascular tissue with resorbing clastic cells adjacent to the dentin surface. More advanced lesions display fibro-osseous characteristics with deposition of ectopic bonelike calcifications both within the resorbing tissue and directly on the dentin surface. Secondary invasion of microorganisms into the pulp or periodontal ligament space will elicit a normal inflammatory response.