A reassessment of the mandibular transverse horizontal axis therory

1. Within the limits of accuracy imposed by individual operators, equipment, and patient variations, a single transverse horizontal axis can usually appear to be located. 2. Location of a kinematic axis is worthwhile clinical procedure to transfer an arc of rotation in the sagittal plane from the patient to an articulator. 3. Past experiments have been useful, but none have proved or disproved the presence of colinear or noncolinear condyle arcs. Only the arc of the rigid clutch and its associated mechanism is located. Such an apparent arc may result from the resolution of compound condylar movements. 4. The right angle-nonright angle concept is misleading and generally is not applicable to clinical procedures. 5. The anatomic asymmetries of the axis transfer procedure may result in cast dislocations that may produce undesirable alterations in esthetic tooth positions. 6. The single transverse horizontal axis as a fact in articulating instruments and as a theory in the human craniomandibular complex. 7. The terms "transverse horizontal mandibular axis" and "intercondylar axis" should not be confused or used as synonyms. The term "transverse horizontal mandibular axis" ("hinge axis") should be used instead of "condylar" or "intercondylar" axis.