Many dental practitioners continue to use radiographic or magnetic resonance imaging (MRI) findings in the temporomandibular joint (TMJ) as the sole m
eans of establishing that there is pathology present that requires treatment. These findings include the position of the intra-articular disc in relation to the mandibular condyle, the location of the condyle relative to the glenoid fossa, the depth of the glenoid fossa, and flattening of the condylar surface. In this study the MRIs of two groups of asymptomatic general population individuals differing in age by 20 years were analyzed for these factors.
In both groups, condylar position was characterized by great variability. Whereas those dentists who use condylar position as a criterion of pathology believe that the condyle should be centered in the glenoid fossa, this study found only 49% of the subjects had condyles in that position and, of these, an absolute centric position was present in less than 4%. In females, a posterior position was present in 52%, while in men, 57% were in a centric position. Neither age nor gender had any influence on location of the condyle.
In three-fourths of the subjects the intra-articular disc, described in textbooks as normally having its posterior band at the twelve o’clock position, was in a more forward position. This anterior location was twice as frequent in females as in males, in conjunction with the more common finding of TMJ clicking in women. The depth of the fossa was decreased in both age groups.