Anterior and posterior lingual depressions of the mandible.

Both posterior and anterior lingual depressions occur in the mandible. The posterior lingual mandibular depressions appear to be more common than had been previously reported. This probably due to one or both of the following causes. Shallow lesions are difficult to diagnose radiographically since an appreciable depth of lingual cortical plate must be resorbed before they can be visualized. As these may be active lesions, a slow resorptive process could place the patient into middle age or beyond before the lesion is clinically diagnosed. It is suggested that posterior lingual mandibular depressions may be benign, self-limiting lesions that are caused by a slow resorptive process resulting from pressure of unknown origin. The anterior lingual mandibular depressions are variable findings in dried mandibles that appear grossly as round or oval smooth depressions with intact buccal and lingual cortical plates and, radiographically, as ill-defined radiolucent areas with no radiopaque borders. They are usually located in the incisor-lateral-canine area and are usually bilateral. It is suggested that these depressions may be developmental anomalies related to the buttons of Gaughran or that they may simply be anatomic variants. They differ from posterior depressions in both gross and radiographic appearance, which suggests the existence of two distinct entities.