Technique for temporomandibular joint radiographs

Abstract

A simplified TMJ radiographic technique that does not use a head positioner has several disadvantages. Due to the lack of control of head position, nondiagnostic TMJ radiographs cannot be corrected. On the other hand, if a newly designed head positioner is used, three-dimensional control of the head position permits the control of the superimposition of bony structures on the TMJ space, decreased radiation, and improved quality of the resultant TMJ radiographs. An experiment was performed on a skull using the auditory axis (a rod passing through both auditory meatus) as a means of recording the head position. The bony structures were superimposed on the TMJ radiograph, and their positions were controlled by specific changes in head position. Qualitative comparisons were made as to the relative effect of specific changes in head position on the location of these superimposed bony structures. Specific changes in head position were recommended in order to improve nondiagnostic TMJ radiographs. The TMJ head positioner permits pinpoint aiming of the central x-ray beam so that the radiated area can be reduced by a factor of 4. Marked reduction in the radiated area not only is beneficial to the patient, but it also increases the contrast and quality of the TMJ radiograph due to the decrease in background fogging caused by x-ray scatter. Practical suggestions were made for darkroom procedures and chemistry in order to produce consistently good results. Several practical examples were shown in order to illustrate the quality that can be obtained with a TMJ head positioner and recommended darkroom procedures.