The condition is more common in Native Americans, American Indians and Eskimos than in Caucasians or Blacks and has a population-wide frequency of occurrence of about 25 percent. Hereditary factors have been implicated. Radiographically, the maxillary torus appears as a well-defined radiopacity situated at, or superior to, the apices of the maxillary teeth (Figure 61). On panoramic radiographs, it may be visualized in the midline and over the roots of the canines, premolars and molars.