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.

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Augmentation of alveolar bone after tooth extraction is beneficial for subsequent prosthetic treatment. Simvastatin, a therapeutic drug for hypercholestemia, stimulates BMP-2 expression in osteoblasts and local application of simvastatin augments bone. The purpose of the present study is to examine whether local application of alpha-tricalcium phosphate containing simvastatin augments the bone of the tooth-extracted site. Porous α-TCP rods containing different doses of simvastatin (0, 0.25, 0.50, 1.0mg) were prepared. The right mandibular incisors of rats were extracted. The tooth sockets were filled with one of the rods in the experimental groups and were not filled with the material in the control group. Animals were sacrificed at 4 and 8 weeks and the tooth-extracted sites were analyzed with soft X-ray photography, dual-energy bone absorptiometry and micro CT, and histologically examined. Bone mineral content and bone width of the tooth extracted site were significantly higher in 0.5mg and 1.0mg groups at 4 weeks and in 1.0mg group at 8 weeks than those of the control and 0mg groups. Histologically, extensive new bone formation was observed outside of the socket walls in simvastatin-applied experimental groups. The present results indicate that local application of simvastatin with α-TCP would be potential to preserve alveolar ridge after tooth extraction although further studies are required.

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The purpose of the present study was to examine effects of hydroxyapatite fiber material (HF) on the socket healing after tooth extraction. Right mandibular incisors of 12-week-old male Wistar rats were extracted and the sockets were filled with 60mg HF or left empty. The animals were injected with fluorescence dyes for histomorphometrical analysis and they were sacrificed at 0, 2, 4, 8 and 12 weeks after tooth extraction. Socket healing was radiologically evaluated with micro CT and dual energy x-ray absorptiometer and histologically examined. Although there was no significant difference in mineral apposition rate, the bone volume and bone mineral content of the experimental group were higher than those of the control group at all time points (p<0.05). The amount of HF in the socket gradually decreased from 4 weeks to 8 weeks, and disappeared almost completely at 12 weeks. HF not only allowed but also promoted the bone healing of the socket and it could be applicable for alveolar bone preservation after tooth extraction.

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Hyaluronic acid is a biological material thought to facilitate cell migration, proliferation, and tissue repair in vitro. This study biomechanically evaluated the effect of hyaluronic acid on the quality of bone repair around pure titanium implants inserted into pre-drilled cavities measured on the basis of removal torque strengths.
Methods: Screw-shaped pure titanium mini-implants (measuring 6 mm in length and 1.2 mm in diameter), which had been developed for orthodontic use, were placed with and without hyaluronic acid into 1.0-mm and 1.2-mm-diameter pre-drilled cavities of the bilateral hind leg femurs of beagle dogs, aged 3 years, who had been anesthetized by the intravenous injection of sodium pentobarbital. At 3, 6, and 9 weeks post-insertion, biomechanical evaluations, which were made according to the removal torque strengths, were performed.
Results: The differences in the removal torque strengths between the implants with and without hyaluronic acid and controls at 3, 6, and 9 weeks after the operation were not significant.
Conclusions: Although these results did not indicate that hyaluronic acid itself markedly contributes to strengthening the interface between the implant and bone at an earlier stage, these findings did suggest that it may be useful as an exogenous matrix that can be added to various bioactive substances around the implant-tissue interface.

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