Abstract

Mandibular movement is considered to be a fundamental factor in the study, analysis, and treatment of occlusion. For many years, dentists have realized that dental health depends upon the compatibility of mandibular movements and occlusion. This realization has led to the development of new methods and techniques for recording accurately and scientifically the movements of the mandible. In order for this data to be of scientific value, it must be stored in a usable form which is easily available for analysis.

The purpose of this research project was to develop a procedure for storing and recalling mandibular-movement information. Before such data can be stored, it must be translated into a common language. This translation was accomplished with the use of photography and a computer system.

Left and right recorded blocks for 10 patients (obtained by Lee's recording technique1) were photographed in three views: lateral "x-y", lateral "x-z", and protrusive "x-y". These photographs were projected (magnified = 6X) onto graph paper and the mandibular movement pathways traced thereon. A procedure was used which allowed the three tracings for one side to be aligned on one piece of graph paper so that the hinge-axis point for all three was on a collinear plane. To verify the reliability of this method, left and right recorded blocks for one patient were photographed on three separate occasions. These were then projected and traced.

A computer program was then designed to allow these tracings to be entered into computer memory. This was done via the Computek 531 computer tablet. The hinge-axis point was marked so that its position could be recalled from computer memory whenever necessary. A RMS (root-mean-squared) deviation test was done to determine mean deviations for the three tracings of each side for the one selected patient. The maximum deviation was found to be 0.363 mm.

Two programs were developed to show what could be done with the computerized data. 1) Angle-of-eminentia analysis showed a prevalence for steeper starting-movement angles than the overall angle of eminentia. 2) Bennett angle determination showed starting variations from 0.00° to 44.27°. All data was developed to correlate the angles with the movement of the hinge-axis point from centric relation.

Accurate marking of the hinge-axis point is of particular importance for future analysis of mandibular movements. This reference landmark has not been emphasized in many previously published studies. Nor has angle determination been done in conjunction with a known movement from centric relation. The method described in this thesis makes these landmarks and tracings readily available for reference and comparison. This process of computerizing the recorded information makes it possible to analyze mandibular movements on a numerical basis. It is felt that this modality is a valuable, forward step towards combining mandibular movement data from many research endeavors, the end product of which will provide more meaningful and scientific analysis of mandibular movements. It is predicted that other diagnostic factors (e.g. tooth interferences, muscle spasms, periodontal pocket locations, etc.) will also be translated into this common language, and then be analyzed, compared, and correlated with mandibular recording data.

1. Lee, Robert L.; "Jaw movements engraved in solid plastic for articula tor controls. Part I. Recording apparatus." J. Pros. Dent., Vol. 22, No. 2:209-224, August 1969.

Department

Dentistry

School

Graduate School

First Advisor

Lloyd Baum

Second Advisor

Jere R. Chrispens

Third Advisor

Virgil M. S. Lau

Fourth Advisor

Walter H. B. Roberts

Fifth Advisor

William S. Seibly

Sixth Advisor

Edwin F. Shryock

Seventh Advisor

Jack L. Tomlinson

Eighth Advisor

Judson Klooster

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

1973

Date (Title Page)

6-1973

Language

English

Library of Congress/MESH Subject Headings

Mandible -- physiology; Computers

Type

Thesis

Page Count

ix; 85

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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