ABSTRACT

To investigate bilateral masseter and anterior temporalis muscle activities during swallowing, chewing and maximum intercuspitation (MI) in skeletal open and deep-bite groups using electromyography (EMG) method.

Surface EMG recordings of the masseter and anterior temporalis muscles were obtained from subjects having skeletal open-bites (8 male, 8 female, mean age 12.6±2.5 years) and skeletal deep-bites (10 male, 5 female, mean age 11.6±2.1 years) during swallowing, chewing and maximum intercuspitation by using surface disc electrodes. Peak-to-peak amplitude values were measured in microvolts (uV). The mean value of the three recordings was calculated for each function. Statistical analysis of the data obtained was conducted using repeated measurement analysis of variance and Duncan's tests.

The masseter and anterior temporalis muscle activities were found distinct in all functions (P<0.01). This difference can be generalized as masseter muscle activity was higher than the anterior temporalis muscle. During swallowing, masticatory muscle activities were found similar in open/deep-bite groups. During chewing, masseter and anterior temporalis muscle activities were found statistically different in open/deep-bite groups (P<0.05). In MI, the interaction between muscle type (masseter and anterior temporalis) and groups (open and deep-bite) were distinct (P<0.01).

EMG activities of the masseter and anterior temporalis muscles are distinct during different functions and in subjects with different vertical facial patterns.