Date of Award
Spring 1990
Document Type
Thesis - Restricted
Degree Name
Master of Science (MS)
Department
Dentistry
First Advisor
Ferguson, Donald J.
Second Advisor
Austin, B. P.
Third Advisor
Donegan, Sara J.
Abstract
The use of premolar extractions as a viable form of orthodontic therapy has been an accepted mode of treatment for many years. Today, the orthodontic community has been questioned about this form of treatment and assertions have been made that as a result of extraction therapy, the temporomandibular joints are being adversely affected. Relative to extraction therapy, the purpose of this study was to evaluate the temporomandibular joints in terms of joint space ratios, often referred to as condylar position or condylar displacement. In addition. the purpose of this study was to evaluate jaw muscle function in terms of electromyography (EMG) of voluntary isometric contractions - a method not previously applied in this context. The experimental subjects (N=29) were patients who had undergone orthodontic treatment in combination with extraction of maxillary and/or mandibular premolars. The control subjects (N=28) were healthy dental students with no orthodontic/extraction experience. Corrected axis sagittal TMJ tomograms were used to determine the narrowest linear distance between the anterior and posterior outlines of the TMJ condyle and TMJ fossa, expressed as the joint space ratio. No significant statistical differences (P>0.05) between control and experimental ratios. Bipolar surface EMG of the masseter and anterior temporalis muscles was used to determine the isometric contraction velocities of these muscles until 50% and 100% (maximum) voluntary isometric contraction effort (teeth clenching). There were no significant statistical differences (P>0.05) between control and experimental subjects. In addition, EMG was used to determine the relative contribution of the masseter and anterior temporalis muscles to the bite force developed during brief maximum voluntary teeth clenching, expressed by the activity index. There were not significant differences (P>0.05) between control and experimental subjects. The results of this investigation do not support the contention that extraction of premolars combined with orthodontic therapy will lead to irreparable damage of the temporomandibular joints and the jaw elevator muscles.
Recommended Citation
Kundinger, Kim Kathleen, "An Evaluation of the Masticatory System Following Orthodontic Treatment Involving Premolar Extractions" (1990). Master's Theses (1922-2009) Access restricted to Marquette Campus. 5247.
https://epublications.marquette.edu/theses/5247