Effect of neurectomy and chemodenervation of the masseter muscle on mandibular bone mineral density

Abstract

Objective To evaluate the effect of neurectomy and chemodenervation of the masseter muscle on mandible bone mineral density.Methods Thirty 28-day-old Wistar rats were divided into four groups:operation groups 1 and 2,botulinum toxin group and control group.The main trunk and initial branches of masseteric nerve on the right side were resected in the operation group 1.The nerve was exposed,but not resected in the operation group 2.The right side of masseter muscle was injected with botulinum toxin type A and the left side was injected with sterile saline in botulinum toxin group when the rats were 28 days old.The control group was only anaesthetised.Bilateral mandibles of all four groups were scanned by GE lunar prodigy bone densitometer when the rats were 75 days old.Results BMD was (0.184±0.012) g/cm2 on the left side and (0.184±0.026) g/cm2on the right side in operation group 1.BMD was (0.179±0.022) g/cm2 on the left side and (0.173±0.019) g/cm2 on the right side in operation group 2.BMD was (0.165±0.061) g/cm2 on the left side and (0.158±0.051) g/cm2 on the right side in botulinum toxin group.BMD was (0.196±0.026) g/cm2 on the left side and (0.185±0.022) g/cm2 on the right side in control group.The variance of BMD between two sides of each group was not significant difference.The variances of BMD among the right side of the four groups were not significant difference.Conclusions No pathological changes in mandibular bone mineral density after denervation and chemodenervation of the massetermuscle are observed in this study. Key words: Mandible; Neurectomy; Botulinum toxin type A; Bone mineral density(BMD)