Effect of Mandibular Distraction Osteogenesis on Suprahyoid Muscles in Rabbits

Abstract

Recently, a surgical treatment to increase the airway capacity in patients with obstructive sleep apnea syndrome (OSAS) has been emphasized. However studies of changes in the surrounding soft tissue are rare.In this study, we compared the results of histological assessment, especially muscular neovascularization, by dividing Japanese white rabbits into 3 groups: a group in which anterior mandibular distraction osteogenesis was performed, a group in which the mandible was fixed after osteotomy with immediate anterior shifting, and a group in which the mandible was fixed after osteotomy without anterior shifting after osteotomy. To evaluate the geniohyoid and digastric muscles parallel to the shift direction via the hyoid bone, frozen cross sections of these muscles were prepared for hematoxylin and eosin (H-E)/alkaline phosphatase(index of neovascularization) (ALP) staining and immunohistological staining with anti-MHC-d antibody(index of muscular proliferation). On H-E staining, the sarcoplasmic area in the distraction osteogenesis group was significantly larger than in the osteotomy group. On ALP staining, the vascular endothelial cell count and area per blood vessel were significantly greater in the former. Immunohistological staining with anti-MHC-d antibody showed a positive reaction in an area adjacent to the wound site of the digastric muscle. However, there was no positive reaction in any other region or geniohyoid muscle specimen.
In the distraction osteogenesis group, the increase in the rabbit geniohyoid muscle tissue volume was less marked than in the osteotomy group, suggesting that distraction osteogenesis induces an increase in the number of neogenetic vascular endothelial cells and their dilatation.