Abstract

The Mayo Indian of Sonora, Mexico, was selected for a study of dental morphology. The objectives of the investigation were to determine the extent to which the Mayo conformed to the four criteria of the Mongoloid dental master pattern, and to compare eight other specific tooth morphologic characteristics with like studies on Mongoloid and non-Mongoloid peoples. Plaster casts were made on a sample of forty-one Mayos.

The results of the study indicate that Mayos exhibit a 46 percent frequency of shovel-shape maxillary incisors, classifying "moderate shovel" and "shovel" together. The maxillary central-lateral width difference of 1.5 mm is small compared with 2 mm for Whites. Carabelli's anomaly of the maxillary first molars of the cusp type (slight and pronounced tubercle) appear in only 12 percent of the observations. Mandibular tori were seen in only one of the forty-one subjects, and these were quite small. "Winging" of maxillary central incisors was observed in 17 percent of Mayos. The mandibular molar cusp pattern formula found was Y5, [+]4, [+]5 for M1 M2 M3. The cusp pattern for maxillary molars was 4, 4-, 3[+]. Degree of occlusal wear, although classified primarily in the "slight" and "moderate" categories was judged to be somewhat excessive considering the young age of the subjects. The buccolingual diameter ratio of the maxillary second premolar and first molar was 83 percent.

Mandibular arch length in Mayos was smaller than for Aleuts and Navajos, but not significantly so. Maxillary arch length and width, and mandibular width were greater for the Mayo than those reported for Aleuts, Navajos, Swedes, and American Whites. The Mayo maxillary incisors are significantly larger than the Aleut incisors, but not larger than the Navajo. All subjects studied were classified in Angle's Class I. None of the Mayo subjects exhibited missing mandibular incisors.

Conceivably the Mayo master pattern includes three of the four Mongoloid master pattern traits in attenuated form, plus a low incidence of torus mandibularis.

LLU Discipline

Orthodontics

Department

Orthodontics and Dentofacial Orthopedics

School

Graduate School

First Advisor

Thomas J. Zwemer

Second Advisor

Gayle H. Nelson

Third Advisor

Lloyd Baum

Fourth Advisor

Howard W. Conley

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

1965

Date (Title Page)

6-1965

Language

English

Library of Congress/MESH Subject Headings

Orthodontics -- Mexico -- familial & genetic

Type

Thesis

Page Count

49 pg.

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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