Relationship between cervical spine and skeletal class II in subjects with and without temporomandibular disorders

AIM. To assess changes of cranio-cervical structure and of hyoid bone position in skeletal Class II subjects with and without Temporomandibular disorders (TMD). MATERIAL AND METHODS. The cephalometric analysis of 59 subjects with skeletal Class II were evaluated and compared. The measurements considerated were: ANB as parameter of Class II and C0-C1 distance, C1-C2 distance, cranio-cervical angle and hyoid bone position for the cervical spine analysis. Patients were divided into two subgroups: patients with TMD (group A) and patients without TMD (group B). TMD were evaluated with the Diagnostic Criteria for TMD (DC/TMD). Descriptive statistics and Pearson and Spearman correlation analysis, with p-value <0,005, were performed. RESULTS. C0-C1 and C1-C2 distance values and hyoid bone position resulted within normal range in the majority of patients examined. Cranio-cervical angle was alterated in 33 patients. The reduction of this angle with the increase of the ANB value resulted statistically significant in the group A, according to Pearson correlation index. No other data was statistically significant. CONCLUSIONS. Significant relationship between skeletal Class II and cervical spine cannot be highlighted. The alteration of cranio-cervical angle seems to be mildly present, with backward counterclockwise rotation of the head upon the neck in the sample (group A and B). The presence of TMDs as key factor in changes of neck posture could explain the different result between the two groups about relationship between ANB and cranio-cervical angle. This result should be further analyzed in order to better understand if cervical spine changes could be related to mandibular postural ones in the cranio-cervical space or to temporomandibular joints retropositioning, more recognizable in Class II with TMD, which could determine functional changes in other structures of this unit; neck posture also could be the result of a compensatory/ antalgic mechanism in response to TMD