On the "Protostylid" of the Japanese

概要

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The protostylid of DAHLBERG (mesio-buccal prominence of DE JONGE) is closely associated with the buccal groove which separates the protoconid from the hypoconid. It is a prominence or ridge of enamel which is limited to the mesial part of the buccal surface of lower permanent molars and lower- deciduous second molars which ascends from the gingival end of the buccal groove and extends mesio-occulusally.On the protostylid of the Japanese, TAKABATAKE ('35) reported 3 instances as the surplus tubercle and SUGANUMA ('36) mentioned 13 individuals with the anomalous tubercles appear at the buccal surface of lower permanent molars and lower deciduous second molars.This paper offered the statistical data on the protostylid among the 108 dental casts (18-34 year-old males) of the Japanese.Of the 108 individuals, 20 (18.5%) had the protostylid in varying degrees of prominence on the lower permanent first molars. And of these 20 materials 13 (65%) had the cusp of Carabelli on the upper permanent molars.The frequency and the combination of occurrence of the protostylid are as. follows:* M1 is missing on the dentition.
日本人類学会の論文