INTRODUCTION: Studies describe the role of the buccinators muscle as controlling the bolus during mastication. Little is known, however, about its behavior in subjects with different dental and skeletal standards, which would contribute to the development of orthodontic and orthognathic treatments. OBJECTIVE: The purpose of this study was to investigate the electromyographic activity of the buccinator muscle, in subjects Class III Angle, during mastication. MATERIAL AND METHOD: The sample was composed by 32 healthy subjects, without Temporomandibular Disfunction, during mastication, being 16 Class I and 16 Class III. In order to guarantee the reliability of the caption of the signal, differential electrode were used, as well as function tests, correlation and normalization of data. As the data revealed a non-normal distribution (Shapiro-Wilk test), the median test was carried out, establishing then the level of significance in 5%. RESULT: In the comparison of the normalized data of the variable Root Means Square (RMS) (µV), from the active period, no significant differences were found (Classe I: 0,469 ± 0,355; Classe III: 0,531 ± 0,355 - p: 0,4812). Nonetheless, in comparison to the variables RMS (µV) from the inactive period (Classe I: 0,359 ± 0,355; Classe III: 0,641 ± 0,355 - p; 0,0016), duration of the active period (ON) (Classe I: 0,313 ± 0,180; Classe III: 0,687 ± 0,180 - p: 0,0368) and the result between the RMS of the inactive period and the RMS of the active period (RIA) Classe I: 0,391 ± 0,355; Classe III: 0,609 ± 0.355 - p: 0,0137) significant differences were found. Conclusion: Based in the results of the data analysis, we could to comprove the existence of exacerbated activity of the buccinator muscle in Angle's Class III subjects.
Buccinators; electromyography; Angle Class III malocclusion; mastication