# Morphological Evaluation of Cranium Facial Asymmetry in Class III Malocclusion Patients
## 4 Discussion
### Research Methods  
In orthodontic practice, maxillofacial morphology is often diagnosed with lateral and postero-anterior cephalometric radiographs. In the lateral cephalometric examination, the anteroposterior positioning of the maxillary and mandibular bones and the inclination of the maxillary and mandibular anterior teeth can be easily determined. The postero-anterior cephalometric radiographs can be used to evaluate the amount of mandibular deviation and inclination of the occlusal plane due to the position of Menton. However, detailed mandibular morphology and diagnosis of deviation are often unclear from lateral and postero-anterior cephalometric measurements alone. Axial cephalometric measurements are useful for evaluating cranial morphology, the position of the mandible relative to the maxilla, and detailed morphological features of the mandible, as well as for determining the factors contributing to mandibular deviation. In the surgical treatment of facial asymmetry, axial cephalometry radiographs are important for proper diagnosis and treatment planning regarding the amount and direction of mandibular displacement and postoperative stability [30]. The foramen ovale, which was used as the reference point for the axial cephalometric radiographs in this study, is considered to be relatively unaffected by cranio-maxillofacial deformity because of its stable shape [31]. In addition, skeletal mandibular prognathism cases were used in this study. Facial asymmetry is more common in patients with skeletal mandibular prognathism than in patients with skeletal maxillary prognathism [32], and it has been reported that it is often accompanied by lateral mandibular deviation, a horizontal as well as anteroposterior abnormality [33; 34]. In assessing facial symmetry, the American Association of Oral and Maxillofacial Surgeons criteria define facial asymmetry as a mandibular midline deviation of 3 mm or more [19]. [PERSON] et al. reported that the critical distance between facial symmetry and asymmetry was approximately 4 mm from the median sagittal plane [6], and [PERSON] et al. reported that the mean distance of Menton from the median sagittal plane was 3.45 to 4.89 mm on cephalograms of patients whose orthodontists judged that they needed surgical orthodontic treatment because of facial asymmetry [20]. Therefore, in the material of this study, cases in which Menton deviated more than 4 mm laterally to the mid-sagittal plane on the postero-anterior cephalometric radiographs were considered as the facial asymmetry group. Although this study used two-dimensional materials such as cephalometric radiographs,in recent years, three-dimensional information has been increasingly used for diagnosis and treatment in the field of dentistry. Particularly in the treatment of jaw deformities, the use of CT images has made it possible to evaluate the morphology and structure of the jawbone, which are difficult to quantify and analyze with two-dimensional images such as the cephalometric radiographs and orthopantomographs used in this study. As a future challenge, it is necessary to evaluate the relationship between cranial deformity and mandibular morphology in three dimensions.