Abstract
ObjectivesThis study aimed to investigate the three-dimensional (3D) mandibular asymmetry in craniofacial microsomia (CFM) and its association with the Pruzansky–Kaban classification system.Materials and methodsCone-beam computed tomography images of 48 adult CFM cases were collected. The asymmetry of the mandibular body and ramus was analyzed with 3D landmarks. The mirrored mandibular model was registered on the original model, yielding a color-coded distance map and an average distance (i.e., asymmetry score) to quantify the overall mandibular asymmetry.ResultsThe lengths of the mandibular body and ramus were significantly shorter on the affected than the contralateral side (p < 0.001). The ANB (p = 0.009), body and ramal lengths (both p < 0.001), and body and ramal length asymmetry (both p < 0.05) were significantly different between mild (types I/IIA) and severe (types IIB/III) cases. The mandibular asymmetry score correlated with mandibular body length asymmetry (r = 0.296, p = 0.046). CFM mandibles showed high variability in shape asymmetry.ConclusionsCFM patients showed distinct body and ramal length asymmetries. In severe cases, mandibles were smaller, more retruded, and more asymmetric in length. The mandibular shape asymmetry was highly variable regardless of the Pruzansky–Kaban types, being a determinant in the extent of overall mandibular asymmetry.Clinical relevanceThe 3D morphologic analysis provides better insights into real mandibular asymmetry. Although the Pruzansky–Kaban classification was applied, high individual variability of the mandibular morphology still existed within the types. Therefore, individualized analyses and treatment plans for CFM patients are highly recommended.
Highlights
Craniofacial microsomia (CFM) is the third most common congenital craniofacial anomaly after cleft lip and palate and craniosynostosis, with an incidence ranging from 1:3500 to1:5600 in live births [1, 2]
This system was developed based on two-dimensional (2D) radiography, it can be applied in modern three-dimensional (3D) images [4]
For adults with unilateral CFM, the lengths of the mandibular body and ramus were significantly shorter on the affected side than on the contralateral side
Summary
Craniofacial microsomia (CFM) is the third most common congenital craniofacial anomaly after cleft lip and palate and craniosynostosis, with an incidence ranging from 1:3500 to1:5600 in live births [1, 2]. The Pruzansky–Kaban classification system, which is based on the severity of temporomandibular joint and mandibular deformity, is the most commonly used tool in planning interventions [20, 21]. This system was developed based on two-dimensional (2D) radiography, it can be applied in modern three-dimensional (3D) images (i.e., computed tomography [CT] or cone-beam CT [CBCT]) [4]. In addition to a schematic description of the mandibular deformity that this classification system provides, understanding the etiology, growth patterns, and 3D morphology of the mandibular malformation is necessary for an optimal treatment plan for the asymmetry. The outcome of the 2D studies, has been inconclusive because of overlapping structures, magnification variability, or image distortions that can lead to misinterpretations [24]
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