Location of the apex of the lower central incisor

Clinicians have always had difficulty finding the apex of the lower central incisor on a lateral cephalometric radiograph. This study was undertaken to define the radiographic anatomy surrounding the true apex. Standard cephalograms were taken of 38 skulls with metallic markers in the socket apex of 1 lower central incisor. Similar cephalograms were taken with the lower central incisor apex positioned in the central ray of the x-ray source. The comparison of the marked apices in the complete skulls and their separate mandibles showed that there was no distortion. Measurements from the markers to the lingual and labial symphyseal borders located the apices labial of center.