Table 1 Definition of measurements
Measurements | Definition |
|---|---|
MRI | |
 C point | the center of the condyles |
 D point | the posterior marginal midpoint of posterior articular disc band |
 FHVL line | the line perpendicular to the FH line at C point |
 ∠CD-FHVL(°) | disc-condyle angle, whose normal range was from -10°to 10°, and any more than 10° was defined as ADD |
 C-HRP(mm) | the distance between C point and the horizontal reference plane (drawn by connecting the lowest point of articular nodule and the uppermost point of external auditory canal) |
 D-HRP(mm) | the distance between D point and the horizontal reference plane |
 C-VRP(mm) | the distance between C point and the vertical reference plane (drawn perpendicular to HRP at the highest point of articular fossa) |
 D-VRP(mm) | the distance between D point and the vertical reference plane |