So this fetus presented seeral signs of trisomy 21, including the hypoplasia of the nasal bone, hypodontia, micrognathia, and hypospadias.

这，例胎儿显示21三体若干征象：包括鼻骨发育不、牙发育不、小颌和尿道下裂。

Objective:To investigate the relationship among the congenital hypodontia of mandibular incisor and malocclusion and the variation of medial distal dimension of mandibular canine.

探讨下颌恒切牙先天缺失情况,与牙颌畸系以及下尖牙近远中径变化。