Craniomaxillofacial Characteristics Of Adult Skeletal ClassⅢ Patients And Discriminant Analysis Of Surgical And Non-surgical Treatment

Orthodontic treatment planning is based on the patient’s chief complaint, malocclusiontype, malocclusion formation mechanism as well as the patient’s potential for growth anddevelopment and other factors. Skeleton Class Ⅲmalocclusion is more common inclinical. The incidence rate is4%to14%in China, Japan and South Korea. Adults’growth and development has almost stopped, so its treatment planning is different fromthe teenagers. Through X-ray cephalometry technology, understanding adult skeletalmalocclusion deformity proportions, different vertical facial types in the morphologicalcharacteristics of hard and soft tissues of the maxillofacial help clinicians diagnose andmake treatment planning. Through retrospective study of surgical and non-surgicalpatients with craniofacial characteristics, indicators and formulas discriminate surgical andnon-surgical treatment, to provide a reference for clinicians in the development of thecorrection program. Those are the purpose of what this research.This study includes three parts:1. The analysis of adult skeletal class Ⅲ malocclusion deformity composition.152adultpatients were analysed in the sagittal, vertical and transverse. The results show that the deformity of adult skeletal class Ⅲ malocclusion are mainly maxillary developmentnormally associated with protrusive mandibular in sagittal（43.42%）. In vertical,average angle patients were accounted for54.61%. And about30%of them werehigh-angle. Most of the patients’ face were symmetry. But the chin point deviationfrom the midline were in accounting for36.84%of the total.2. Characteristic differences among the three different vertical facial skeleton types ofadult Skeleton Class Ⅲ patients with the maxillary,teeth and soft tissue.The152patients were were divided into high angle group(46)、anerage angle group(83) and thelow-angle group(23) according to the degree of the mandibular angle. The resultsshowed: patients with high-angle have maxillary rectraction and mandibularprotrusion,upper front teeth protrusive, the lower front teeth lingual inclination. Softtissue characteristics is mainly reflected in the length of anterior lower1/3faceincreased, the facial profile convexity increased significantly； the lip-chin angledecreased．3. Astudy on the surgery indications of adult patients with skeletal class Ⅲ malocclusion.152class Ⅲ adult patients were selected,including89treated with only orthodonticstreatment. Stepwise discriminate analysis was applied to classify the variables that bestseparate the groups. The equation wasY=-9.13+0.233Holdaway-angle+0.145Wits-0.093ArGoMe+0.054L1-MP+15.665(Sco-Go ratio）. The classification results was90.75%. The Wits appraisal,gonial angle,theconcavity of the lower face, the inclination of the lower incisors and the midlinedeviation of the mandibular were concerning to the treatment plan.