A Three-Dimensional Volumetric Classification of Mandibular Hypoplasia in Hemifacial Microsomia.

Authors

Yuki Akiyama, Teruyuki Niimi, Yasunori Akiyama, Ken Kitagawa, Chisato Sakuma, Nagana Natsume, Ryosuke Miwa, Yoshio Akiyama, Masaaki Ito, Masahiro Umeda, Eiichiro Ariji, Yoshiko Ariji, Akira Arasaki, Nagato Natsume

Published in

Congenital anomalies. Volume 66. Issue 1.

Abstract

Hemifacial microsomia (HFM) is characterized by mandibular hypoplasia with complex three-dimensional (3D) craniofacial deformities. Conventional classification systems are mainly based on two-dimensional morphology and provide limited information on the regional distribution of mandibular deficiency. This study aimed to develop a novel 3D volumetric classification method using anatomically and biologically relevant reference planes.3D mandibular models were reconstructed from craniofacial computed tomography data using Aquarius Net software. Plane A was defined by the mental protuberance and the most lateral prominent points of the bilateral mandibular angles, and the coordinate system was standardized by rigid transformation so that Plane A became parallel to the horizontal CT plane. Plane B, defined by the origins of the external and internal oblique lines, isolated the posterior mandibular ramus (Region T). Additional planes (C-F), based on landmarks including the condyle, mandibular angle, mandibular foramen, and mandibular notch, subdivided Region T into four subregions (r + 1 to r + 4). Volumetric ratios were compared between seven unilateral HFM patients and seven controls with symmetrical mandibles. Intraobserver reliability was assessed using intraclass correlation coefficients (ICC [1, 1]). Exploratory volumetric analysis suggested greater volume reduction in the superior ramus region, including the mandibular condyle; however, no between-group differences remained statistically significant after Bonferroni correction for the five regional comparisons. Intraobserver reliability was excellent, with ICC values ranging from 0.9601 to 0.9960 in the HFM group. This 3D volumetric classification system enables region-specific assessment of mandibular hypoplasia in HFM and may support surgical planning and evaluation.

PMID:
42994984
Bibliographic data and abstract were imported from PubMed on 07 Nov 2026.

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