[Effects of projection errors on the pantographic diagnosis of TMJ dysfunction]

Extraoral recording methods are bound to produce geometric projection errors. Mirror projections of the curvatures on both sides are a particular problem in clicking joints, thus complicating diagnosis. With the aid of magnetic resonance tomography it has been demonstrated in clinical examples that misinterpretations of the recordings can be avoided by means of computer-supported measuring systems providing accurate projection error correction. Furthermore, it is important that diagnosis be based not only on the usual sagittal plane recordings but also on additional information from the horizontal and frontal planes. Magnetic resonance tomography is then used to confirm the eccentric disc luxation established with the aid of the electronic recordings.