Objective: This study aimed to evaluate the chewing muscular dynamics and correlate the side of the masticatory movement that is more vertical and/or more horizontal established by the photomeasurement Masticatory Functional Angle (MFA) to the muscular activity behavior, showed in the surface electromyography and in the radiographic images.
Material and method: Seventeen people were selected of both genders, with the average age of 25 years, without signs or apparent symptoms of masticatory muscular disorders. The teleradiographies were done in lateral norm and surface electromyography of the masseter muscles, anterior portion of temporal and supra-hyoids in rest position and maximal bite. The bite force measured with a metallic transducer that was connected to a force sensor (Strain Gauge) to measure the deformation of the material model SF4 (EMG SYSTEM DO BRASIL). A mandibular goniometer of the EMG System of Brazil was used to measure the opening size.
Results: The comparison and correlation were established between the groups with MFA>5 degrees and MFA<5 degrees by the test "t" of Student or test of Mann-Whitney conform the distribution was normal or not, respectively. The results showed significant differences between groups, although without sexual dimorphism, to masseter muscle in maximal bite.
Conclusion: In conclusion, the anatomic-physiological aspects of temporomandibular disorders are related to the asymmetrical mandible function.