Rotational and Translational Loading of the Temporomandibular Joint

ABSTRACT

Following an introduction to the functional properties of a three-dimensional instantaneous helical axis pertaining to circular (rotatory) and linear (translatory) motions of the mandible, this feasibility study applied the concept of a mandibular average finite helical axis to the maneuver of cyclic opening and closing of the mouth in three healthy subjects. Through the accelerations and decelerations of a mandibular incisor point (instead of a mandibular condylar point) as well as the laws of physics, the kinetic reaction forces and reaction pressures in the upper and lower cavities of the temporomandibular joint (TMJ) were estimated over opening-closing distances of five and ten mm from centric occlusion. The translatory reaction pressures in the upper TMJ cavity (17–29 mm Hg) exceeded the rotatory reaction pressures in the lower TMJ cavity (5–12 mm Hg). The estimated reaction pressures were in close agreement with synovial fluid pressures measured in vivo in the TMJ of humans and pigs, and the biologic significance of frequent and/or prolonged increased TMJ hydrostatic pressures is discussed.

Additional information

Notes on contributors

L.V. Christensen

Dr. Larry V. Christensen received his D.D.S. degree from The Royal Dental College in Copenhagen, Denmark, his M.S. degree from Marquette University in Milwaukee, Wisconsin, and his Ph.D. degree from the The University of Gothenburg in Göteburg, Sweden. He has published more than 100 scientific articles, primarily on temporomandibular disorders and has lectured worldwide.

D.C. McKay

Dr. Duane C. McKay received his D.D.S. degree and Certificate in Prosthodontics from The University of Southern California in Los Angeles, California. Dr. McKay maintains a private practice in Los Angeles, California and has lectured worldwide.