Abstract: Objective To measure the morphological chin characteristics of skeletal Class Ⅰ adult females with congenital absence of mandibular incisors by conebeam computed tomography, and investigate the effect on chin morphology. Methods According to the inclusion criteria, CBCT data of 113 adult female patients before treatment were selected, and were divided into study group (60 cases) and control group (53 cases) for the measurement and statistical analysis of line, space area and volume. Results There were statistically significant differences in chin, mandible development and facial aesthetic evaluation between the study group and the control group. In the study group, the comprehensive and transverse length of the mandible, the alveolar bone width between the lower canines, the volume of the alveolar process above the chin process, the development of the mandible in front of the mental foramina and the sagittal sectional area of the mandible were weaker than those of the control group. The Po point was relatively far from the facial plane. Conclusion Congenital absence of mandibular incisors impacts the development of mandible, mainly on the transverse growth of lower anterior alveolar process and the overall development of the mandible. The chin volume is not significantly affected, but the convexity increases relatively, which results in a better evaluation for the facial profile.

Key words: chin, congenital absence of mandibular incisors, three-dimensional morphology