Background: The aim of this study was to compare electromyographic data of two groups of patients (open and deep skeletal bite) before and after surgical orthodontic treatment. Methods: All patients who underwent orthognathic surgery at the Department of Orthodontics (University of Milan) were subjected to periodic electromyographic evaluation of the masticatory muscles (masseter and anterior temporal muscles) and to electrokinesiographic evaluation of mandibular movements. The sample comprised 72 patients (35 open skeletal bite patients and 37 deep skeletal bite patients) at the end of craniofacial growth. The electromyographic instruments used in the study included a Freely and a K6-I electromyograph. Statistical evaluation was carried out with Student's t tests for independent samples. Results: Lots of differences between open and deep skeletal bite patients have been underlined by the analysis of the electromyographic data obtained. These results have been obtained with both electromyographic systems. Muscular activity in microvolts is higher in deep skeletal bite patients at the beginning of the treatment than in open bite ones, but during the following phases of the treatment, the two values became similar. Conclusions: Morphologic differences between open and deep bite patients can also be demonstrated by instrumental examinations, and their correction after surgical treatment is observable on electromyographic and electrognatographic exams.
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