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

Poser, Timothy

Abstract

The submentovertex (SMV) projection demonstrates the base of the skull and is used to evaluate the position and orientation of the mandibular condyles. Three reference or baselines have been advocated for SMV cephalometric analyses: trans-porionic, trans-foramina spinosa and transmid- condylar. Midlines are typically constructed as perpendiculars to these reference lines and are used to complete the SMV analyses. The aim of this investigation was to evaluate the efficacy of reference line choice among three reference lines used for SMV analysis for determination of mandibular condyle position and angulation. One hundred-two SMV cephalometric radiographs were analyzed to determine the angular position of the condyles as well as condyle-to-midline distances. The paired t-test was used to compare the mean linear and angular measurements for the four techniques employed. The hypothesis that there is no difference in linear measurements from midline to the center of mandibular condyle among the four methods used to establish submentovertex midline was rejected because all methods were statistically different except the "condylar" and "cervical" midlines. The hypothesis that there is no difference in the mediolateral angulation of the mandibular condyles among the four methods used to establish submentovertex midline was also rejected because statistically significant differences resulted among several methods for measuring condylar angulation. The trans-spinosal reference line appeared to be a very reasonable choice for SMV analysis. It was concluded that the choke of reference lines for submentovertex radiograph analysis is important in evaluating mandibular condyle position and angulation. Choice of techniques of establishing midline, however, do not effect measurements of condylar angulation as much as condyle-to-midline position measurements.

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