Abstract

The rotation of the maxillary molars is considered important in the orthodontic treatment of malocclusions. In this study a computer analysis program was developed to examine the rotations of maxillary molars, mandibular molars, and maxillary first premolars in casts of permanent dentitions with acceptable occlusions. Ninety three sets of untreated "acceptable occlusion" models from the collection of the Foundation for Orthodontic Research (FOR) were scanned on a flat bed scanner at 600 dots per inch (dpi). The images were analyzed using custom software on a computer. Measurements were made by relating maxillary first permanent molars to the midline, the archform, the opposite canine, and the mandibular first permanent molars. The mandibular first molars and maxillary first premolars were also analyzed and their rotations measured. The mean rotations of the maxillary first molars, measured as the angle between a line joining the tips of the buccal cusps and a line tangent to the appropriate archwire form, from Ricketts Pentamorphic Arches, at the first molars, were 0.59 and -0.72 degrees (positive values represent mesio-lingual rotations) for the right and left, respectively. For the mandibular molars, these means were 6.34 and 8.40 degrees, respectively. The mean differences in rotation between buccal cusp tips of maxillary and mandibular first molars in occlusion were 5.75 and 9.12 degrees for the right and left, respectively, with the mandibular being more mesio-lingually rotated. The differences between left and right were significant for all measurements. The present study brings into question the suitability of our present "straight wire" prescriptions in producing similar occlusions. It also suggests that scanning models for computer analysis may be a practical and precise way to measure similar rotations in untreated normal and treated occlusions.

LLU Discipline

Orthodontics

Department

Dentistry

School

Graduate School

First Advisor

Joseph M. Caruso

Second Advisor

M. Toufic Jeiroudi

Third Advisor

James F. Farrage

Fourth Advisor

Craig A. Andreiko

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

1995

Date (Title Page)

6-1995

Language

English

Library of Congress/MESH Subject Headings

Dental Occlusion; Orthodontics, Corrective; Malocclusion

Type

Thesis

Page Count

2 iii; 18

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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