Effects of a botulinum toxin type A injection on the masseter muscle: An animal model study.
BACKGROUND
The aim of this study was to investigate the effect of a botulinum toxin type A (BTX-A) injection in the masseter muscle using electromyography (EMG) in an animal model.


METHODS
Ten male adult (>3 months of age) New Zealand white rabbits were used. Muscle activity was continuously recorded from 8 hours before to 8 hours after BTX-A injection. The rabbits received unilateral BTX-A injections of either 5 units (group 1, n = 5) or 20 units (group 2, n = 5).


RESULTS
The masseter muscle activity of the rabbits was significantly reduced immediately after BTX-A injection (P < 0.05 for both groups). When the results from group 1 were compared with those from group 2, only the peak voltage was significantly decreased in group 2 (P = 0.013).


CONCLUSIONS
Masseter muscle activity measured by EMG was immediately decreased after a BTX-A injection.
Department of Oral and Maxillofacial Surgery, College of Dentistry, Gangneung-Wonju National University, Gangneung, Republic of Korea.
Si-Yeok
SY
Park
Department of Oral and Maxillofacial Surgery, College of Dentistry, Gangneung-Wonju National University, Gangneung, Republic of Korea.
Young-Wook
YW
Park
Department of Biomedical Engineering, Ulsan University, Ulsan, Republic of Korea.
Young-Jun
YJ
Ji
Department of Electronic Engineering, Gangneung-Wonju National University, Gangneung, Republic of Korea.
Sung-Wook
SW
Park
Department of Oral and Maxillofacial Surgery, College of Dentistry, Gangneung-Wonju National University, Gangneung, Republic of Korea.|Oral and Maxillofacial Surgery, Gangneung-Wonju National University-College of Dentistry, Gangneung, 210-702 Republic of Korea.
Seong-Gon
SG
Kim
Botulinum toxin type A; Electromyography; Masseter muscle; Peak voltage