Our aim was to determine the relation between the electromyographic activity of the sternocleidomastoid muscle and head posture in individuals with and without dentofacial deformity class II and class III. The study was approved by the Ethics Committee of the Institution involved (n° 2513/2007). Twenty-five patients with dentofacial deformity seen at the Craniomaxillofacial Surgery Outpatient Clinic of a public hospital participated in the study. Ten patients with a diagnosis of class II dentofacial deformity (mean age 24.4 years) were assigned to DG-II and 15 patients with a diagnosis of class III dentofacial deformity (mean age 24.1 years) were assigned to DG-III. The control group consisted of 15 volunteers (mean age 22.5 years) with no occlusal changes or clinical evidence of skeletal deformities. The participants were submitted to bilateral electromyographic evaluation of the sternocleidomastoid muscle during head rotation to the right and left. Photographic evaluation of head posture was later performed by analysis of the head-neck angle. The Spearman correlation test was used. In the control group, correlations occurred in the left sternocleidomastoid during right rotation of the head ( r = −0.54; p = 0.04), and in the right sternocleidomastoid during right rotation of the head ( r = −0.49; p = 0.07). No correlations were observed in DG-II. In DG-III, there was a correlation in the right sternocleidomastoid during left head rotation ( r = 0.59; p = 0.02). We conclude that in the control group and in DG-III there was a correlation in a negative and positive manner, respectively.

Conflict of interest: None declared.