Transcranial radiography and linear tomography: a comparative study

There is continual controversy concerning the use of radiographs to determine the position of the mandibular condyle within the glenoid fossa for the diagnosis and treatment of temporomandibular disorders. This study compared joint space measurements from transcranial radiographs and linear tomographs with the anatomic joint space to determine whether condylar position could be accurately recorded radiographically. Anterior, superior, and posterior joint space dimensions were measured from projected radiographs with a sonic digitizer, whereas anatomic joint space dimensions were recorded from the thickness of polyether impressions of the joint space. Posterior/anterior joint space ratios were used to classify relative condylar position as anterior, concentric, or posterior. The Pearson correlations (alpha = 0.05) were calculated to determine the consistency between radiographic and anatomic joint space ratios. The corrected and standard transcranial projections did not accurately reproduce the anatomic joint spaces or the relative condylar positions. Only the corrected tomographic projection accurately reflected the condyle-fossa relationships.