Abstract

This study mainly examined neuromuscular function, occlusal index, and centric relation-centric occlusion (CR-CO) discrepancy of 23 orthodontically treated patients. Phase I, craniofacial anomalous, and orthognathnic surgery cases were excluded from the study. Record taking was done in 2 sessions: (1) at the time of deband and (2) 3-4 months later. Records taken at each session included facial and intraoral photographs, impressions, CR wax bites, a facebow, and surface EMG (sEMG) recordings.

For the sEMG recordings, electrodes were placed on the upper hyoid, masseter, and anterior temporalis muscles. Subjects were asked to perform numerous tests; these included baseline, clenching to test isometric function, mandibular movements to test isotonic function, chewing, swallowing, and phonetic. The isometric and baseline recordings were used in this study.

The CR bites were taken three times to check for reproducibility. The casts were then mounted in this CR position. The occlusal index was calculated for both CR and CO relationships. The Mandibular Position Indicator (MPI) was used to determine hinge axis location in all three planes and the discrepancy between CR and CO heights.

Differences in the parameters between the first session (post-treatment 1 or PT1) and the second session (post-treatment 2 or PT2) were compared. Possible correlations among the various parameters were likewise investigated.

The CO occlusal index (TCOOI) was found to be statistically significantly higher than the CR occlusal index. Yet all the occlusal indices were less than 50%. Although the CR occlusal index (TCROI) and the CO occlusal index (TCOOI) both usually improved from PT1 to PT2, the change was not clinically or statistically significant.

The masseter and upper hyoids appeared to have greater physiologic adaptive capacity than does the anterior temporalis.

Increased occlusal support usually resulted in improved isometric masseter sEMG values. Isometric function of the masseters with and without support increased from PT1 to PT2.

The MPI showed the most change in the transverse dimension and CR-CO discrepancy in all the subjects.

Overall, a vast range of neuromuscular adaptation was found. Such individualistic behavior necessitates the measurement of these parameters on an individual basis to best determine treatment needs.

LLU Discipline

Orthodontics and Dentofacial Orthopedics

Department

Orthodontics and Dentofacial Orthopedics

School

Graduate School

First Advisor

Ivan Dus

Second Advisor

Joseph M. Caruso

Third Advisor

Jay Kim

Fourth Advisor

R. David Rynearson

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

2000

Date (Title Page)

6-2000

Language

English

Library of Congress/MESH Subject Headings

Dental Occlusion; Esthetics, Dental; Dental Occlusion, Centric

Type

Dissertation

Page Count

x; 67

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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