Anthropol. Sci. 110(4),349-363, 2002 |
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| Kayoko Sasaki, Hitoshi Makiguchi, Kenji Yoshino, and Eisaku Kanazawa |
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| (Received
June 2, 2001; accepted June 28, 2002) |
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Abstract The dental morphology
of the outer enamel surface (OES) is basically determined by the form
of the dentino-enamel junction (DEJ) and the thickness of the enamel
substance covering the DEJ. In our series of studies of morphological
traits observed on the DEJ of deciduous molars (Sasaki, 1997; Sasaki
and Kanazawa, 1999, 2000), we demonstrated that the traits are observed
clearly on the DEJ as a distinct ridge or a process, even when they
are not distinct on the OES. In this paper, we report characters originating
from the buccal cingulum, the occurrence of occlusal ridges, and cusp
number on the OES and DEJ of the upper first deciduous molar. The
combined frequencies of (+) and (++) morphology of several traits
were as follows: buccal cingulum: 62.2% (DEJ) and 15.4% (OES), mesiobuccal
marginal ridge: 79.1% (DEJ) and 52.3% (DES), distobuccal marginal
ridge: 33.9% (DEJ) and 7.7% (OES), mesiobuccal tubercle: 86.7% (DEJ)
and 61.7% (OES), crista obliqa: 80.0% (DEJ) and 72.5% (OES), trigonal
hypocone crest: 36.4% (DEJ) and 4.6% (OES). The frequencies of trait
occurrence on the DEJ were higher than on the OES, because the original
characters were not obscured by the enamel. Although previous observers
had different opinions concerning the number of cusps of the upper
first deciduous molar, three or four cusps were found on the DEJ suggesting
that this tooth is more morphologically differentiated than the successional
first premolar tooth. The results of this study suggested that phylogenetically
conservative crown characters were retained more frequently in the
anterior molar of the primary dental series from dm1 to M2. Key Words: dentino-enamel junction, upper first deciduous molar morphology, primary dentition |
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| (C)Copyright
2002 The Anthropological Society of Nippon |
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