The reliability of mandibular radiographic superimposition.

Using tracings from thirty pairs of serial cephalometric radiographs, the reliability of three outlines, commonly used for mandibular superimposition, was investigated. There were sizeable errors associated with all three groups, but tracings involving Björk's mandibular structures were found to be the least reliable. Despite the greater validity of the Björk structures for assessment of growth changes, in certain cases the use of the mandibular outline may be of greater value for the superimposition of tracings, especially when the time interval between the radiographs is short, or the patient has passed maturity and the growth rate has declined to a negligible level.