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

这样，本例胎儿显示21三体的若干征象：包括鼻骨发、牙发、小颌和尿。

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

探讨颌恒切牙先天缺失情况,与牙颌畸形的关系以及尖牙近远中径的变化。