Annotation

Lingual Tubercles and the Maxillary Incisor-Canine Field .1~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ G. RICHARD SCOTT

Anthropology Program, University of Alaska, Fairbanks, Alaska 99701, USA TABLE

J Dent Res 56(10): 1192 October 1977. Regionalization of tooth form in the human dentition stimulated DAHLBERG (JADA 32:676, 1945) to develop a general field model to help explain the occurrence and evolution of morphologic tooth crown traits. The four types of teeth (incisors, canine, premolars, molars) were viewed as morphogenetic fields with the expression of a crown trait on one member of a field related developmentally to the expression of that same trait on another member, e.g. hypocone expression on M', M2, and M3. The canine, as the single member of its own field, was considered a stable tooth with crown form and morphology largely independent of the influences of adjacent morphogenetic fields. Although the maxillary canine is not known for its crown complexity, it does exhibit a lingual tubercle in frequencies ranging from 50 to 90% in 15 samples from world-wide populations (SCOTT, Am J Phys Anthrop, 35:294, 1971). This tubercle emanating from the basal cingulum varies in size from a small groove to a large cusp with a free apex. The maxillary incisors also exhibit tubercles on the internal cingulum although the form is frequently expressed as one or more ridges rather than freestanding tubercles. Because of the general similarities in form and in the position on the tooth crown, tests of association were undertaken to determine if lingual tubercles of the maxillary central incisor (I1) and canine (C) share in common an underlying developmental basis. To test for association, seven samples from U.S. Southwest Indian populations (n = 446) and one American white sample (n =83) were classified for lingual tubercle expression on II and C. Ranked scales were employed for classifying expression so it was possible to compute rank order correlation coefficients (Kendall's tau) to ascertain the significance and degree of correlation. The tau values and associated probabilities shown in the table indicate that the null hypothesis of no association between lingual tubercle expression on II and C can be rejected. Seven of the 8 samples show a significant degree of inter-trait association with five of the seven significant at the 0.01 level. Only the Yuman sample shows nonsignificant association, but the correlation is still positive with a tau value only Received for publication February 25, 1977. Accepted for publication March 31, 1977.

RANK ORDER CORRELATIONS BETWEEN LINGUAL TUBERCLES OF THE MAXILLARY CENTRAL INCISOR AND CANINE Group

No. Individuals

Yuma Papago Navajo (Ramah) Navajo (Tuba City) Navajo (Keams Canyon) Hopi (Oraibi) Hopi (Keams Canyon) American white

tau

p

444

0.174 0.229 0.207 0.286

0.10-0.20

Lingual tubercles and the maxillary incisor-canine field.

Annotation Lingual Tubercles and the Maxillary Incisor-Canine Field .1~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ G. RICHARD SCOTT Anthropology Program, Uni...
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