Facial soft tissue depth measured using ultrasonography: Towards facial approximation for Japanese crania

Abstract

The metric data on the facial soft tissue depth has been repeatedly reported for European or African people in response to the demand for 3D digital facial approximation using recently developed techniques. In contrasts, the metric data for Japanese has not been updated for half a century, regarding those which cover enough measurement points for facial approximation. This study aims to add and update the metric data on the facial soft tissue depth for Japanese and examine the correlation to body mass index and biological sex. Firstly, the facial soft tissue depths of the three cadavers were measured by the two methods using ultrasonography and needle puncture. Results show that the mean error was 0.8 mm, and the mean error rate 14.1% between the both methods, which were equivalent with those of the previous studies. Secondly, the facial soft tissue depth of 58 subjects were measured using ultrasonography at the 21 points of face. Results show that males were larger than females in the frontal, nasal, oral, and mental regions, and the reverse in the orbital, infraorbital, zygomatic, parotid-masseteric, and buccal regions. The subjects were divided into obese and skinny types according to the body mass index, and the obese type were significantly larger than the skinny type in 9 of 21 measurement points in males. As a result of the analysis of covariance, significant interaction between body mass index and biological sex was detected in lower lip margin. The comparison among world-wide populations shows that the previous report of “the facial soft tissue of Japanese is thinner than that of European and African people” was not confirmed in this study. The result of this study is expected to apply to the forensic facial approximation for Japanese crania in future.