A Study Of Using Botulinum Toxin To Treat Temporomandibular Joint Osteoarthritis In Rabbit

Objective To test the therapeutic efficacies of botulinum toxin on temporomandibular joint osteoarthritis (TMJOA)in rabbitMethods 30 adult rabbits were used to estabish animal models of TMJOA by collagenase injection method and divided into control and experimental group .Each group was subdivided into 4-week, 8-week and 12-week group ,The additional 5 rabbits were served as normal control group .Botulinum toxin was injected into the bilateral masseter muscles (MM) and temporalis muscles (TM)of rabbits in experimental group.The MM and TM of control group were treated with physiological saline by the same means.At the end of 4weeks 8weeks and 12weeks, Electromyography(EMG) of anterior temporalis(TA),posterior temporalis(TP) and MM of 5 animals in each group was recorded during postural position and clenching .The rabbits of control and experimental group were killed after EMG examination.The TMJ samples were stained and observed separately with light microscope,scan electron microscope.Rusults By the end of 4weeks,8weeks and 12weeks ,The EMG activity of MM, TA and TP of control group during postural position was significantly higher than that of normal control group(p<0.05),but lower during maximal clenching(p<0 05) In experimental group EMG activity of MM,TA and TP during postural position and clenching was significantly lower than that of normal control group by the end of 4weeks and 8weeks(p<0.05) .By the end of 12weeks, the EMG activity of the two group has no significently difference (p>0.05). By the end of 4weeks,samples of control group showed apperently OA changes, but that of experimental group showed slightly change of OA .By the end of 8weeks,OA change was more significantly in control group ,but in experimental group the joint sample was found repairment .By the end of 12weeks ,samples of control group showed serious degenerative change, That of experimental group were close to normal construction .Conclusion Masticatory muscle dysfunction was present during the developing of TMJOA .Botulinum toxin can significantly improve the function of masticatory muscle,and promote self-repair of TMJ .It was proved to have significantly therapeutic efficacies on TMJOA and that these extend beyond it'smuscle-relaxing effects.