Abstract

Evaluation of the cephalograms of 150 patients showed a wide range in the angulation of the lower border of the mandible to the various facial planes. The degree of this angulation did not always correspond with the severity of malocclusion. Group I represents normal occlusions, Group II comprises malocclusions.

A new reference line is submitted for the investigation of its advantages in cephalometric roentgenography. The mandibular radius drawn through the geometric center of the condyle to the point gnathion is correlated with several indices of facial growth, namely (1) ANB difference, (2) upper facial:lower facial height and (3) PoNB distance in mm. These correlations are compared with similar correlations of the mandibular plane.

The following conclusions were drawn from this investigation

  1. The angles formed by the mandibular radius and the various facial planes have approximately 25 percent smaller standard deviations than the corresponding angles formed by the mandibular plane.

  2. The mandibular radius was highly correlated (corr. coeff. .80, level of sig. 0.000) with the mandibular plane.

  3. Correlations of the mandibular radius with the upper facial height:lower facial height ratio appeared better (Group I .75, Group II .87) than similar correlations of the mandibular plane (Group I .68, Group II .72).

  4. Correlation of the mandibular radius with the ANB angle appeared better (Group I .51, Group II .38) than that of the mandibular plane (Group I .42, Group II .27).

  5. Correlations of the mandibular radius with the PoNB distance in Group II seemed better (.38) than similar correlation of the mandibular plane (.27). This was not seen in Group I.

The above comparison of correlations suggests that the mandibular radius could better evaluate antero-posterior and vertical dysplasias. Also comparison of correlations with PoNB suggests that in considering the influence of rotation of the mandible on pogonion, the mandibular radius would be a better guide.

An analysis is developed on the basis of the Frankfort-mandibular radius angle measurement, for the estimation of the effects of a change in the anterior vertical height, on the ANB discrepancies and on pogonion.

LLU Discipline

Orthodontics

Department

Dentistry

School

Graduate School

First Advisor

Howard W. Conley

Second Advisor

Alden B. Chase

Third Advisor

John P. DeVincenzo

Fourth Advisor

Benjamin W. Oesterling

Fifth Advisor

Edwin F. Shryock

Sixth Advisor

Roland D. Walters

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

1968

Date (Title Page)

6-1968

Language

English

Library of Congress/MESH Subject Headings

Cephalometry

Type

Thesis

Page Count

viii; 57

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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