咬肌内注射A型肉毒毒素和曲安奈德对大鼠下颌骨发育影响的实验研究

Effect of intramuscular injection of botulinum toxin type A and triamcinolone to the masseter muscle on the development of mandible： an experimental study

目的 探讨咬肌内注射A型肉毒毒素和曲安奈德对大鼠下颌骨发育的影响.方法 取28日龄雄性Wistar大鼠为实验对象,随机分为4组：A型肉毒毒素组（B组,n=8）、曲安奈德组（T组,n=8）、A型肉毒毒素＋曲安奈德组（BT组,n=8）、对照组（C组,n=6）,每组大鼠取右侧咬肌并向肌内注射相应的药物,左侧注射等量的生理盐水,空白对照组仅麻醉;大鼠75日龄时行头颅CT平扫＋三维重建,测量各组大鼠下颌骨长度、高度等线距后处死,切取双侧咬肌称其质量.结果 注射侧咬肌质量B组、BT组小于对照侧;B组注射侧下颌骨长度Ⅲ（下颌角至下颌中切牙牙槽骨前下点的距离）、下颌骨高度Ⅱ（冠突到下颌角最下点的距离）小于对照侧;BT组注射侧下颌骨高度Ⅱ小于对照侧;B组的下颌骨高度Ⅱ小于其他3组,BT组小于C组;下颌骨高度Ⅲ（髁突到下颌角最下点的距离）B组和BT组小于C组.结论 幼龄大鼠咬肌内注射A型肉毒毒素,成年后下颌骨高度减小,下颌骨长度、下颌间距无明显影响;注射曲安奈德对大鼠下颌骨发育影响不明显.

Objective To evaluate the effect of intramuscular injection of botulinum toxin type A and triaincinolone to the masseter muscle on the development of mandible. Methods Thirty 28-days-old Wistar rats were divided into four groups ： botulinum toxin type A group （ B group, 8 rats） , triamcinolone group （ T group, 8 rats） , botulinum toxin type A and triamcinolone group （ BT group, 8 rats） , control group （ C group, 6 rats）. The right side of masseter muscle was injected with the drugs corresponding to its group and the left side of masseter muscle was injected with saline. The control group was only anaesthetised. CT scan and 3D reconstruction were taken when the rats were 75 days old. Seven cephalometric points were digitized and selected 7 linear distances were measured. The rats were killed with an overdose of 10% chloral hydrate after CT scan. Masseter muscles of each side were obtained and weighted immediately. Results Significant atrophy of masseter muscles Were observed in the B group and BT group. Mandibular length Ⅲ （ Go-Iia）, mandibular height Ⅱ （Cor-GoT） on the right side was less than that on the left side in B group. Mandibular height Ⅱ on the right side was less than that on the left side in BT group. The variances of mandibular height Ⅱ and mandibular height Ⅲ （ Con- GoT） on the fight side between 4 groups were significant. Conclusion Changes on mandibular height after intramuscular injection of botulinum toxin type A to the masseter muscle were seen. But alterations of mandibular length and bigonial width were not found. Cephalometric changes were not obvious on the triamcinolone group.