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The Correlation Between Surface Electromyography and Bite Force of Mastication Muscles in Asian Young Adults

Yen, Cheng-I MD*; Mao, Shih-Hsuan MD*; Chen, Chih-Hao MD*; Chen, Chien-Tzung MD; Lee, Ming-Yih PhD

doi: 10.1097/SAP.0000000000000468
Research Papers

Background Mastication function is related to mandible movement, muscle strength, and bite force. No standard device for measuring bite force has been developed. A linear relationship between electromyographic activity and bite force has been reported by several investigators, but data on the reliability of this relationship remain limited in Asian young adults.

Aim and Objectives The purpose of this study was to develop a clinically applicable, reliable, quantitative, and noninvasive system to measure the kinetic mastication function and observe the correlation between surface electromyography (sEMG) and bite force.

Materials and Methods The study group consisted of 41 young healthy adults (24 men and 17 women). Surface electromyography was used to evaluate bilateral temporalis and masseter muscle activities, and an occlusal bite force system was used concurrently to measure the bite force during maximal voluntary biting. Bilateral symmetry was compared, and the correlation between EMG and bite force was calculated.

Results The sEMG signals were 107.7 ± 55.0 μV and 106.0 ± 56.0 μV (P = 0.699) on right and left temporalis muscles and 183.7 ± 86.2 μV and 194.8 ± 94.3 μV (P = 0.121) on right and left masseter muscles, respectively. The bite force was 5.0 ± 3.2 kg on the right side and 5.7 ± 4.0 kg on the left side (P = 0.974). A positive correlation between sEMG and bite force was observed. The correlation coefficient between the temporalis muscle and bite force was 0.512, and that between the masseter muscle and bite force was 0.360.

Conclusion No significant difference between the bilateral electromyographic activities of the temporalis and masseter muscles and bilateral bite force was observed in young healthy adults in Taiwan. A positive correlation between sEMG signals and bite force was noted. By combining sEMG and bite force, we developed a clinically applicable, quantitative, reliable, and noninvasive system for evaluating mastication function by using characteristics of biofeedback.

From the *Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan, ROC; †Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital at Keelung, Keelung, Taiwan, ROC; and ‡Graduate Institute of Medical Mechatronics, Chang Gung University, Taoyuan, Taiwan, ROC.

Received September 19, 2014, and accepted for publication, after revision, December 17, 2014.

Conflicts of interest and sources of funding: none declared.

Reprints: Chih-Hao Chen, MD, Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, 5 Fu-Hsin St, Kwei-Shan, Taoyuan 333, Taiwan, ROC. E-mail: Ming-Yih Lee, PhD, Graduate Institute of Medical Mechatronics, College of Engineering, Chang Gung University, 259 Wen-Hwa First Road, Kuei-Shan, Taoyuan 333, Taiwan, ROC. E-mail:;

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