Masticatory features, EMG activity and muscle effort of subjects with different facial patterns

P>It has been suggested that craniofacial morphology plays an important role in masticatory function, however, there are controversies and unsolved questions that still require elucidation. The aims of this study were to evaluate masticatory performance, mandibular movement, electromyographic (EMG) activity and muscle effort of masseter and anterior temporal muscles during mastication. Seventy-eight dentate subjects were selected and divided into three groups according to vertical facial pattern: brachyfacial, mesofacial and dolichofacial. Silicon-based material was used for chewing tests. Masticatory performance was determined by a 10-sieve method, and masticatory movements during mastication were assessed using a 3D mandibular tracking device. Electromyographic activities of masseter and anterior temporal muscles were evaluated during mastication, and muscle effort was calculated by the percentage of activity required for mastication based on maximum muscle effort. Data were analysed using anova and anova on-ranks tests. Dolichofacial subjects presented significantly poorer masticatory performance (6 center dot 64 +/- 2 center dot 04; 4 center dot 33 +/- 0 center dot 70 and 3 center dot 67 +/- 0 center dot 63), slower rate of chewing (1 center dot 34 +/- 0 center dot 27, 1 center dot 18 +/- 0 center dot 22 and 1 center dot 21 +/- 0 center dot 20 cycles per second) and larger posterior displacement during mastication (6 center dot 22 +/- 2 center dot 18; 5 center dot 18 +/- 1 center dot 87 and 5 center dot 13 +/- 1 center dot 89) than meso- and brachyfacial individuals, respectively. No statistical difference was detected among groups for the other masticatory movement parameters. There was no difference in absolute EMG amplitudes of masseter and anterior temporal muscles during mastication among groups, but the relative effort of both muscles was higher in dolichofacial, followed by meso- and brachyfacial subjects (masseter: 39 center dot 34 +/- 2 center dot 25; 36 center dot 87 +/- 4 center dot 05 and 33 center dot 33 +/- 4 center dot 15; anterior temporal: 38 center dot 12 +/- 1 center dot 61; 38 center dot 20 +/- 8 center dot 01 and 35 center dot 75 +/- 2 center dot 48). It was concluded that the vertical facial pattern influences masticatory performance, mandibular movement during mastication and the effort masticatory muscles required for chewing.