Craniofacial Diagnostic Imaging

TMJ Tomography

This is an image of the temporomandibular joint (TMJ) taken from the lateral aspect on a Quint-Sectograph x-ray unit. A Sub-Mento-Vertex (SMV) x-ray is used to make this image. This is an image of the base of the skull. From the SMV the angles of the condyles can be calculated for accurate cuts along the long axis of the condyles. This is called corrected tomography.

In a full TMJ series there are usually three views with the patient jaw closed and one image with the jaw fully opened. The three closed views are 3mm apart from each other and the image slice thickness is 2mm. Cross-sectional images are made on both joints because the side that the patient is experiencing pain on is not necessarily the side with the worst problem.

Occasionally, an anterior-posterior (AP) cut is prescribed. AP TMJ tomograms are sometimes referred to as frontal or coronal views. These terms refer to the same type of image. The AP views excel in showing bony changes to the superior surface of the condyle.

It is important to remember that an x-ray is a two dimensional view of a three dimensional structure. This imaging method often shows it best if there is concern that there may be changes to the bone shape and surface. The lateral TMJ views show the relationship between the condyle and the fossa. The AP views are taken with the jaw of the patient protruded to pull the condyle out past the eminence.

CDI questions? Call (585) 427-2510 .