MANDIBULAR CONDYLE POSITION - COMPARISON OF ARTICULATOR MOUNTINGS ANDMAGNETIC-RESONANCE-IMAGING

This study evaluated the reliability of jaw positions, the existence o f distinct jaw positions, and condyle-disk-fossa relationships in a sy mptom-free population by using articulator mountings and magnetic reso nance imaging (MRI). The subjects examined included 28 men, 22 to 35 y ears of age, all having Angle Class I molar relationships and no disce rnible TMJ dysfunction. Records taken included the following: an axiog raphic face-bow to locate retruded hinge axis position, an interocclus al registration of retruded position (RE), a series of interocclusal r egistrations for centric occlusion (CO), a leaf gauge-generated centri c relation (CR), a series of interocclusal registrations for CR, and M RI. The mandibular position indicator of the SAM articulator (Great La kes Orthodontics, Ltd., Tonawanda, N.Y.) was used to determine reliabi lity and existence of distinct jaw positions. Magnetic resonance imagi ng also evaluated jaw positions and anatomic relationships. The result s indicate: (1) The articulator analysis of CO and CR is statistically replicable. (2) A distinct jaw position could be demonstrated for CO that was separate from RE and CR. It was not possible to discriminate between RE and CR. (3) Condylar concentricity was observed in half of the sample and remained consistent in RE, CO, and CR. (4) Of the sampl e 13% demonstrated anteriorly displaced disks that were not influenced by posterior condyle placement. (5) The clinical concept of treating to CR as a preventive measure to improve disk-to-condyle relationships was not supported by this study.