Three-dimensional measurements on the mandible of patients with hemifacial microsomia

Hemifacial microsomia (HFM), which involves multiple sites with different levels of severity, is the second most common congenital craniofacial deformity after cleft lip and palate. However, three-dimensional (3D) measurements of mandibular deformities have not yet been studied in detail. The objective of this study is to investigate the method of 3D measurements of mandibular deformities in HFM patients.

A total of 48 HFM patients were included in this study. All clinical treatment for patients was performed in the Plastic Surgery Hospital of the Chinese Academy of Medical Sciences at Peking Union Medical College from June 2006 to June 2020. The patients' 3D computerized tomography scan data were processed using medical imaging software, following four iterative steps: 3D reconstruction, mirroring, differential analysis, and partition.

The characteristics of the mandibular bone in HFM patients are mainly presented as follows: (1) compared to the normal side, the part of the bone body that extends from the ascending ramus to the pogonion (Po-NB) is analyzed using a dynamic process: less fullness-fullness-more fullness; (2) absences were frequently observed among the angular zones, that is, the height of the ascending ramus is deficient.

HFM is a complicated condition with numerous variations in clinical presentation. We employed both 3D image reconstruction and computerization image processing techniques to investigate asymmetrical mandibular deformity in HFM patients in detail and with great accuracy. This will be of great use to clinicians for disease management.