咬肌肌内注射A型肉毒毒素对大鼠下颌骨发育的影响

目的 探讨咬肌肌内注射A型肉毒毒素对大鼠下颌骨发育的影响.方法 以28日龄Wistar大鼠为实验模型,于右侧咬肌肌内注射A型肉毒毒素,左侧注射等体积的生理盐水,空白对照组仅麻醉;75日龄时行头颅CT平扫+三维重建,测量两组大鼠下颌骨长度、高度及间距后处死,称量双侧咬肌质量,并取咬肌和下颌骨标本行组织学检查.结果 大鼠的咬肌质量肉毒毒素组右侧为(0.4575±0.0940)g,空白对照组右侧为(0.8899±0.1030)g,差异有统计学意义(P<0.05);肉毒毒素组右侧下颌骨高度Ⅱ为(10.8±0.8)mm、下颌骨高度Ⅲ为(9.5±0.6)mm,空白对照组右侧下颌骨高度Ⅱ为(12.5±0.6)mm、下颌骨高度Ⅲ为(10.7±0.4)mm,两组比较差异有统计学意义(P<0.05);下颌间距肉毒毒素组为(11.6±0.6)mm,空白对照组为(12.4±0.6)mm,差异无统计学意义(P>0.05).结论 幼龄大鼠咬肌肌内注射A型肉毒毒素,成年后下颌骨高度降低,下颌骨长度和下颌间距无明显影响.

Effect of botulinum toxin type A injection into the masseter muscle on mandibular development in rats

Objective To investigate the effect of Botulinum toxin type A (Botox) injection into the masseter muscle on mandibular development in rats. Methods 12 28-day-old Wistar rats were divided into two groups as Botox group( n = 6) and control group( n = 6) which received anesthesia only. InBotox group, Botox was injected into the right masscter muscle, while only sterile saline into the leftmuscle. When the rats were 75-day-old, CT scan and 3D reconstruction were performed for cephalometry.The masseter muscles at both sides were weighed. Histologic study of masseter muscle and mandible was also performed. Results The weight of right masseter muscle was (0.4575 ± O.0940) g in Botox group,and (0.8899±0.1030 ) g in control group ( P < 0.05 ). The mandibular height Ⅱ and Ⅲ was ( 10. 8 ±0.8) mmand (9.5 +0.6) mm in Botox group and (12.5 +0.6) mm and (10.7 +0.4)ram in control group, respectively( P < 0.05 ). The intergonial distance was (11.6±0.6) mm and (12.4±0.6) mm in Botox and control group, respectively (P> 0.05). Conclusions When the rats receive Botox injection into the masseter muscle at young age, the grown-up rats have a decreased mandibular height, but the mandibular length and intergonial distance are not affected.