Date of Award

Spring 1995

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Dentistry

First Advisor

Ferguson, Donald J.

Second Advisor

Schuckit, William I.

Third Advisor

Kittleson, Russell T.

Abstract

Articulators vary widely in the accuracy with which they reproduce the movements of the mandible. It is highly desirable that dental articulators will accurately mimic mandibular movements and produce appliances which require minimal time for chairside adjustment. With the relatively recent advent of arthroscopic surgery in conjunction with TMJ imaging, knowledge of the functioning TMJ continues to expand and articulator designs are beginning to replicate the functional TMJ anatomy. The Polycentric Hinge Articulator (POLY) was built with cylinderically shaped condyles and trough shaped fossas which, in the opinion of the designers, results in a polycentric hinge joint rather than a simple hinge joint. Designers claim that the POLY articulator more accurately replicates mandibular movement and that clinicians using the new device will spend less chairside time adjusting appliances fabricated in the laboratory on their articulator. The present investigation was initiated to test how accurately vertical mandibular movements are replicated using two different articulator systems; the Polycentric Hinge and the SAM-2. Both the POLY and SAM-2 cast mountings utilized arbitrary hinge axis location and centric relation bite registrations. Twenty adult subjects volunteered to participate in the study at Marquette University, School of Dentistry. All subjects demonstrated no signs or symptoms of TMD. Maxillary "cone-splint" appliances were fabricated on each articulator utilizing centric relation cast mountings. The same splint base used for building the cones was shared between the two articulators. Cone-to-tooth gap distances were measured for each of the individual five cones using a stainless steel feeler gauge. No statistically significant differences (p>.05) were found in cone-to-tooth gap distances measured from maxillary conesplint appliances fabricated on the POLY and the SAM-2. However, all POLY mean cone-to-tooth gap distances (except cone#2) were smaller than the gaps observed with cone-splints fabricated on the SAM-2 articulator. Results of this study do not substantiate the contention that an articulator which imitates the morphology of the TMJ/Jaw complex in man will more accurately replicate mandibular opening movement.

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