Abstract: Objective To investigate whether there is an association between skeletal Class III and the cervical skeletal abnormalities by lateral cephalometric, panoramic radiographs, CBCT. Methods Select 249 patients with skeletal Class III who had accepted orthodontic-orthognathic surgery as the experimental group,120 were male and 129 were female;296 patients with Class I who had only accepted orthodontic treatment as the control group, 150 were male and 146 were female .All the patients’age were between 18-36.Record the data of the first four cervical fusion and posterior arch defects by the lateral cephalometric. The relationship between the abnormal cervical vertebra and skeletal Class III was analyzed by chi-square test. Results The occurrence rate of the cervical fusion in the experimental group was 71.84%(74 cases),while in the control group was 15.53%(16 cases).The occurrence rate in the experimental group was significantly higher than that of the control group(p<0.001);the occurrence rate of the posterior arch defects in the experimental group is 10.68%(11 cases),while in the control group was 4.85%（5 cases）.Conclusions? There is an obviously increasing occurrence rate of the cervical skeletal abnormalities in patients with skeletal Class III.

Key words: skeletal Class III, cervical vertebra, skeletal abnormalities