Radiography of the Temporomandibular Joint

Abstract

A modification of the commonly employed lateral transcranial oblique technic is described. The conventional 15O/15[degree] orientation of the central ray is necessary to avoid anatomic obstructions, but this angulation is shown to be inappropriate in many cases because of wide variations in the angulation of the condyle in diff. subjects. In 26 mandibles a range of 0[degree] to 30[degree] and -17[degree] to 20[degree] was found in the inclinations of the condyles to frontal and horizontal planes respectively. It is for this reason that delineation is sometimes imperfect. In a series of 100 patients, clear radio graphic delineation adequate for diagnosis was obtained in 70. The ease with which spurious "retropositions" and "erosions" can be produced and detected in radiographs is described. The main purpose of the investigation was to establish norms for the radiographic appearance of normal and abnormal joints, and in particular to establish norms for condyle/fossa relations and for the dimensions of the inter-articular space. In a survey of 60 normal adults, the avg. dimensions of this space were 3.0 mm. superiorly, 2.0 mm. anteriorly, and 2.5 mm. posteriorly. A standardized method of measuring these dimensions. and hence of comparing them in different patients, is illustrated.