John A. Matis

Abstract

The morphologic characteristics of the oral cavity in five contemporary Western Indian and Alaskan Eskimo groups have been investigated by the use of study models of the dental archs. The sample consisted of 216 individuals, including 44 Navajos, 43 Apaches, 40 Papagos, 42 Pimas and 47 Alaskan Eskimos.

The first purpose of the study was to determine the extent of investigator error. This was accomplished by remeasuring many morphologic traits of the dentition in 125 Indians which had previously been measured by different investigators using the same study models. It was found that investigator error can be significant, even in objective type measurement, confirming the work of Kuzma and Zwemer.

The second purpose of the study was to determine the possibility of differentiating between these five groups on the basis of their dentition. By utilizing nine separate measurements of the models, it was found that with a stepwise discriminate analysis, individuals within the four Indian tribes could be properly classified by group 60% of the time. The Alaskan Eskimo can be properly classified, by only the use of study models, 100% of the time in both group and sex. Overall, the sex of the individuals whose study models are measured, can be accurately determined at a 100% incidence.

The third purpose of this study was to determine to what extent the specific traits of the "Mongoloid Master Pattern", as proposed by Moorrees, are found in these five groups. The four Indian tribes had an average shovel depth of over 1 mm, with a high incidence of occurrence, to conform to the pattern. The Eskimos had comparatively less shovel, but a large smooth concavity on the lingual of the incisors, without mesial or distal marginal ridges. As Koski and Hautala (1952) found a 76% incidence of shoveling in their Caucasian sample, it would appear to be more proper to describe a larger depth of shoveling in Mongoloids rather than a larger incidence of occurrence, although it technically is true. All of the five groups studied closely approximated the mean Japanese interincisal width difference of 1.40 mm. The average American in the army, regardless of national, ethnic or social background, was found by Dietz to have a 72.3% incidence of occurrence of Carabelli's cusp. The five groups herein studied had an average incidence of 62%. Moorrees (1957) states, "The cusp of Carabelli is supposedly rare in Mongoloids" (p.38). As no figures or range is given for this "supposedly rare" condition, our findings of 62%, cannot be judged as conforming, or not conforming, to the Mongoloids as far as this trait is concerned. In our five groups, a rather low incidence of mandibular tori occurrence was found. Inasmuch as this trait has never been proven to be inheritable, the validity of this trait in the evaluation of a particular subgroup being derived from any specific original groups is questionable.

LLU Discipline

Orthodontics

Department

Dentistry

School

Graduate School

First Advisor

Alden B. Chase

Second Advisor

Lloyd Baum

Third Advisor

Howard W. Conley

Fourth Advisor

Walter H. B. Roberts

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

1967

Date (Title Page)

6-1967

Language

English

Library of Congress/MESH Subject Headings

Odontometry -- United States; Indians, North American; Eskimos

Type

Thesis

Page Count

viii; 49

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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