Pleliminary investigationof orthodontic treatment and its mechanic basis in patients with skeletal Angle class III malocclusion combined with open bite

Abstract

：Objective To analyze themechanic basis of orthodontic correction of preadolescence skeletal class Ⅲ malocclusion combined with open bite, and to summarize helpfulexperiences for clinical practice. Methods There were 8 preadolescent patients with severeskeletal class Ⅲ malocclusion combined withopen bite [age ranged from 7 to 9 years, mean (7.9±0.8) years]. All the patients hadindication of orthognathic surgery, but rejected surgical therapy. The patients receivedface mask traction, rapid maxillary expand, molar occlusal splint and fix appliancetreatment, and were followed up for two years after the treatment. Lateral cephalometricfilms performed at the beginning and end of treatment were compared using traditionalcephalometric analysis. Results All the patients get remarkable and stable improvement inocclusion, oral function and facial aesthetic after the treatment. The changes includedthe anterior movement and (5.3±1.7)° anticlockwise rotation of the maxilla (P<0.01),(2.6±0.5)° downward-backward rotation of the mandible body (P<0.01) and increase ofmandible ramus length, and (5.7±0.4)° inclination of lower incisors when measured to theNB line (P<0.01). Meanwhile, the direction of the facial growth was maintained.Conclusion With the most of mechanic basis of dento-maxillofacial orthopedics, the facialgrowth direction of the patients with skeletal class Ⅲ malocclusion combined with open bite can be guided, and stable and estheticscurative effect can be achieved.