Correlation Study On Head Posture, Cervical Vertebrae Posture And Craniofacial Structure In Children And Adults With Angle Class Ⅲ Malocclusion

Class III malocclusion is not a very rare dental anomaly. It has great unfavorable effects on the function, oralfacial aesthetics and psychology. Craniofacial growth prediction of class III malocclusion is very important for the correct diagnosis and treatment. The material consisted of 52 children and 45 adults with class III malocclusion. 33 children and 31 adults with normal occlusion were selected as control. The craniofacial structure, cervical inclination and head posture of the samples were analysed basing on natural head position cephalograms. The relationship between craniofacial structure and head posture was investigated in order to get some reference for facial growth prediction, diagnosis and prognosis.Results:1. Significant correlation was found between SN-VER, SN-OPT, SN-CVT and SNA, SNB, SN-MP, SN-PP, SN-OP, NSAr+S-Ar-Go+Ar-Go-Me, NSGn both in children and adults with class HI malocclusion.2. Significant difference could be seen in head posture variables between high and low angle class III malocclusion children. The same difference existed in adults with class III malocclusion. The craniovertical angle and craniocervicalangle of the low SN-MP angle samples were smaller than that of the high angle samples. The head posture of high SN-MP angle sample had an extended appearance; and the low angle samples could be expected to have flexed head postion.3.No significant difference had shown in head posture variables between children and adults with class III malocclusion and low SN-MP angle; between children and adults with high angle, there was no significant difference either. Significant difference could be seen in SN-CVT, CVT-HOR, OPT-CVT between children and adults who had normal SN-MP angle; and no significant difference had shown in SN-VER, SN-OPT, OPT-HOR between them.Conclusions:Head posture was particularly related to the morphology of mandible. Significant correlation could be seen between head posture and the variables which indicated the tendency of facial development and the direction of mandibular growth. The study on head posture of class III malocclusion might afford usable reference for facial growth prediction. The analysis based on lateral cephalometric radiographs in natural head position could make the diagnosis of malocclusion more reasonable.