Disc movements over the condylar head. Radiographical study on autopsy materials.

A radiographical study has been performed to evaluate the movement of the disc posterior band over the condylar head during mandibular opening. Six formal free embalmed subjects were selected as 'normal'. Micro stainless steel balls were used as landmarks both into the bone and into the disc for X-ray identification. The data was processed at each phase of movement in selected planes. The true coordinates of each disc landmark gave the potential to calculate the linear length of their path and any distance change between them. It can be concluded that there is a 5% width reduction during the opening movement and it also suggests strongly that a fair amount of translation movement between the disc and the condyle occurs in the lower compartment.