Korean J Orthod.  1990 Mar;20(1):23-45.

The effects of facial denervation on facial muscles and bones in growing rabbits

• Park YG
• Lee KS

Abstract

It is the aim of this study to determine the effects of facial denervation on physiological properties of facial muscles and facial bones in growing rabbits. Experimental animals of fifty two Oryctolagus cuniculus rabbits were employed. Unilateral dissection of facial nerve was carried out on twelve rabbits, bilateral dissection of facial nerve was made on another twelve rabbits and the other twenty rabbits were on unilateral dissection of facial nerve for the histochemical analyses. Six rabbits on the bilateral surgical sham operations and six rabbits of non-intervention served the control groups. EMG records of the orbicularis oris, buccinator and masseter muscles as well as lateral and dorsoventral cephalometric films were taken and analyzed at 0, I, 2, 5 and 8 weeks respectively. The orbicularis oris, buccinator and masseter muscles of both sides were removed from the animals of the histochemistry group and muscle fibers were classified on the basis of histochemical staining for alpha-GPD, NADH-D and myosin ATPase. EMG activities of orbicularis oris and buccinator muscles were vanished immediately after denervation. Recovery of activities were detected one week after denervation in buccinator and five weeks in orbicularis oris muscles. Histochemical properties of masseter muscles remained as fast glycolytic through the experimental period. Orbicularis oris muscle fibers showed the gradual diminution of size and ratio of the slow oxidative fibers accompanied with atrophy, phagocytosis and vacuolation as well as the augmentation of fast oxidative glycolytic fibers. The buccinator muscle manifested the augmentation of fast oxidative glycolytic fibers at five weeks of experiment. Visual changes in morphology of craniofacial area were not evident, however it variety of subtle changes were apparent from statistical analysis of cephalometric measurements. It is concluded facial nerve regulates the physiological properties of facial muscles and interrelation between the function of the facial muscles and changes of facial bones would be in some degrees.

MeSH Terms

Animals
Atrophy
Denervation*
Facial Bones
Facial Muscles*
Facial Nerve
Masseter Muscle
Muscles
Myosins
Phagocytosis
Rabbits*
Myosins