To study the influence of botulinum toxin on masticatory muscle activity in temporomandibular joint model osteoarthritis(TMJOA).
30 adult rabbits were examined with EMG, and TMJOA was established by collagenase injection, then divided into experimental group and control group. EMG of masticatory muscles was recorded during postural position and clenching at the end of 4 weeks, 8 weeks and 12 weeks. Botulinum toxin was injected into the masseter muscle and temporal muscle in the experimental group. Those of the control group were only with TMJOA. All data were analyzed with group t test in SPSS 11.0.
During postural position, EMG activity of masticatory muscles in the control group was significantly higher than that of the normal at each examination(P<0.05). EMG activity in th experimental group was lower than normal at the end of 4 weeks and 8 weeks(P<0.05), but at the end of 12 weeks, the two groups showed no difference(P>0.05). During clenching, EMG activity in the control group was lower than normal at each measurement(P<0.05), EMG activity in the experimental group was lower than normal at the end of 4 weeks and 8 weeks(P<0.05), but showed no difference at the end of 12 weeks.
Botulinum toxin can change and improve masticatory muscle function of TMJOA in rabbit.