Abstract:

  Background and Aim: Class II and Class III malocclusions have been reported to have a high incidence among the antero-posterior jaw anomalies. This study is aimed to evaluate the relation between the antero-posterior discrepancies and morphology of the cervical vertebra.

  Materials and Methods : This case control study evaluated 89 patients(aged 17 to 30 years old). The samples were matched based on vertical dimension indices such as SN-MP, MM, and Jarabak index. ANB index was used to divide the samples into 2groups as follows 1- Control group consisting of 39 subjects with normal growth pattern(ANB2+2 2- Case group with 20 Class II (ANB>4) subjects and 30 Class III (ANB<0) subjects. . Cervical vertebra morphology was assessed on lateral cephalograms and anomalies such as posterior arch deficiency and fusion were detected. Data were analyses by Binary logistic Regression ,T test and Independent sample test.

  Results : The prevalence of fusion was 35.9% in control group (normal growth pattern), 55% in Class II, and 73.3 % in Class III. The difference was statistically significant between control group and Class II malocclusion as well as Class III malocclusion .(p<0.003) (p<0.01). There was no significant difference in prevalence of fusion between Class II and Class III malocclusion groups. The prevalence of posterior arch deficiency was 5.5%, 15%, and 16.7 % in normal growth pattern, Class II, and Class III groups respectively. The difference.(p<0.8. p<0.9. p<0.5)

  Conclusions: There was a significant relation between anteroposterior discrepancies and cervical vertebra anomalies ,especially for C2 and C3 .