Changes in temporomandibular disc position during growth in young Japanese.

Purpose: To detect the initial changes in temporomandibular disc position during growth with MRI examination in a prospective longitudinal study of a young Japanese population.
Methods: Forty-four temporomandibular joints in 22 healthy asymptomatic volunteers, mean age 11.8 years, age range 9-16 years, were examined by MRI. They were re-examined 2-3 years later. The mean age and age range at the second examination were 14.5 years and 12-19 years, respectively. The discs were assessed at three different locations by oblique sagittal planes at the lateral, central and medial parts, and the displacement was evaluated as a partial anterior or total anterior position.
Results: Six joints already had a partial anterior position of the disc at the initial examination and no developmental change in disc position was observed during the examination period. Nine joints developed partial disc displacement during the examination period. Every partial displacement was observed at the lateral part of the disc. One joint developed a total anterior position from the lateral to the medial images.
Conclusions: Initial changes in the disc position are likely to start from the lateral part of the joint in the early teenage years and are often asymptomatic.