雑種成犬の歯数変異に関する統計的調査

概要

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A statistic survey was carried out in 168 skull bones radiographically. This survey consists of two groups, only upper jaw 100 cases (The first survey) and 68 cases examined in upper and under jaws (The second survey) . The results obtained may be summarized as follows; The first survey- (1) Dental anomalies occurred in 9.0 per cent in upper jaw 100 cases, 8.0 per cent of those were congenital missing and supernumerary in one per cent. (2) The second and first premolar teeth were most commonly absent. (3) An extra-tooth was occurred in the anterior area of left first premolar. (4) There was not recognized statistical correlation between the numerial anomalies of teeth and the skull length. The second survey- (1) Dental anomalies occurred in 41.2 per cent in upper and under jaws of 68 cases, 38.2 per cent of those were missing and supernumerary in 2.9 per cent. There was no differences in sexes. (2) Dental anomalies occurred more frequently in the lower jaw than in the upper. (3) Mandibular second and first premolars were most commonly affected. (4) The extra were located on fourth molar portion of bilateral mandibula and between first and second premolar of the right maxilla. The findings of the present study were similar to the results reported by previous authors.
日本哺乳類学会の論文