Studies on Adhesion Properties of Shellac to Bovine Enamel

Though an attempt to apply a natural resin shellac in the dental field has been made in recent years, almost no study have concerned its adhesive strength to the tooth surface or its persistency. In the present study, therefore, the adhesive strength of shellac to the enamel surface, the influence of etching treatment on the adhesive strength and possible changes in the adhesive strength following thermal loading due to thermal cycle were examined by means of compressive shear bond strength test. By using a test material composed of shellac in alcohol solution and bovine extracted tooth, the adhesive strength of shellac at varied concentrations was examined with the results as below. The adhesive strength with no etching treatment was about 5MPa irrespective of the shellac concentration used and no significant difference was observed between the examined groups. When an etching treatment was applied, however, the adhesive strength significantly increased in almost all experimental groups with the maximum value of 13.7±1.5MPa. Though a decreased adhesive strength was observed in all groups examined after thermal loading due to thermal cycle, the rate of decrease however tended to be relatively small in experimental groups at a shellac concentration ranging 0.1 to 1%. In particular, the rate of decrease was the smallest in 0.1% shellac group(11.4%) and the adhesive strength of 10.6 1.9MPa was maintained even after thermal cycle. Based on the above evidences, an practical adhesive strength was suggested to be successfully maintained to some extent of period when it is applied to human oral cavity

VoxBlastによるX線マイクロCT断層像の三次元再構築と解析 : 卵巣摘出マウスの腰椎に対するラロキシフェンの効果について

To evaluate the skeletal efficacy of raloxifene on the osteoporosis in ovariectomized mice model, the sixth lumbar vertebrae was scanned by X-ray micro-CT, and these resulting 8-bit gray-scale images were analyzed by using commercial three-dimen. sional (3-D) reconstruction software (VoxBlast^ Mac, VayTek, Inc., USA). In this paper, it is described how to use VoxBlast software practically for processing sequential datasets from CT scanners. Furthermore, we demonstrate in 3-D visualization that new trabecular bones buik compact bridge constructions in the lumbar vertebrae after the treatment with raloxi fene

キトサンオリゴ糖の創傷治癒促進作用

Chitosan is a natural macromolecule that can be obtained by deacetylation of chitin in concentrated alkaline solution, and it has been known to exhibit various pharmacological actions, including facilitative effects on wound healing. Chitooligosaccharides are oligosaccharides composed of two to seven glucosamine residues, which are the basic molecules of chitosan. Systemic administration of chitooligosaccharides facilitates wound healing, but its mechanism remains largely unknown. The present study was investigated the effects of systemic administration of chitooligosaccharides on healing of the oral mucous membrane in vitro and in vivo. Human gingiva-derived fibroblast were incubated with 0.25-1.0% of chitooligosaccharides, and the cell number was counted after 24, 48, 72, 96, 120 and 144 hours. In addition, to determine whether systemic administration of chitooligosaccharides facilitates healing of mouse oral mucous membrane damaged by neodymium YAG laser irradiation, the oral mucous membrane was sampled at certain times after laser irradiation and was analyzed histologically. The results were as follows: 1. With 0.5-0.75% of chitooligosaccharides, the number of fibroblasts increased during the early stages of incubation, but with high concentrations of chitooligosaccharides, the number of fibroblast decreased. 2. Systemic administration of chitooligosaccharides facilitated proliferation of fibroblast, while continuous high-dose administration suppressed proliferation. The above findings clarify that chitooligosaccharides facilitate the proliferation of fibroblast in vitro and that systemic administration facilitates wound healing in vivo. In addition, there appear to be optimal doses in both in vitro and in vivo applications

止血剤処理がワンステップ型ボンディングシステムの象牙質接着に及ぼす影響

Vascular endothelial growth factor (VEGF) is a major angiogenetic factor in both developmental and wound healing processes. Recent studies have shown the expression of VEGF mRNA in lung, kidney, heart, ovary and various organs. In order to clarify the role of VEGF in developing human tooth germ, the expression of VEGF and VEGF receptors (KDR/Flk-1 and Flt-1) were investigated on the mandibular deciduous central incisors by immunohistochemistry. At fetal 12 weeks, immunoreactivity of VEGF was detected on many cells in the enamel organ, dental papilla and dental follicle. Immunoreactivity of VEGF in the dental papilla at fetal 14 weeks was localized at undifferentiated cells in adjacent inner enamel epithelium. As compared with immunoreactivity of VEGF at inner enamel epithelium, that of preameloblasts was weak at fetal 18 weeks. At fetal 21 weeks, ameloblasts and odontoblasts were positive for and VEGF. Immunoreactivity of KDR/Flk-1 was similar to that of VEGF. However, it was not visible at ameloblasts and odontoblasts. Immunoreactivity of Flt-1 was not detected in tooth germ except endothelial cells penetrating dental papilla and dental follicle. It was localized on stratum intermedium and outer enamel epithelium at fetal 21 weeks. These results suggest that VEGF, KDR/Flk-1 and Flt-1 are involved in the angiogenesis on developing tooth germ. In addition, VEGF, KDR/Flk-1 and Flt-1 may have an important role in the proliferation and differentiaton of ameloblasts and odontoblasts in human tooth germ morphogenesis

Effects of Intravenous Administration of Chitosan Oligosaccharide on the Wound Healing Process of Oral Mucosal Injury in Mice

Chitosan is a natural macromolecule obtained by deacetylating chitin in a concentrated alkaline solution. Chitosan is pharmacologically active, having been shown to accelerate wound healing, inhibit tumor growth, and lower serum cholesterol. A low molecular weight from of chitosan, chitosan oligosaccharide, has also been developed, and its pharmacological activities are currently being investigated. However, the pharmacological actions that occur when chitosan oligosaccharide is administered systemically have not been fully elucidated. We previously investigated the effects of oral administration of chitosan oligosaccharide on wound healing of the oral mucosa in vitro and in vivo, and here, we investigated the effects of intravenous administration of chitosan oligosaccharides on healing of oral mucosal injury in mice. An Nd-YAG laser was used to damage the oral mucosa, and then various concentrations of chitosan oligosaccharide were intermittently administered intravenously. As a control, one group of mice under-went the wounding process, but received no chitosan. After a certain period, the damaged oral mucosa was excised, and tissue sections were prepared for morphological observation. When compared to controls, animals treated with chitosan oligosaccharide demonstrated faster resolution of tissue unevenness and new capillary vessel formation, and greater fibroblast induction and subsequent collagen fiber production. Hence, intravenous administration of chitosan oligosaccharide might accelerate wound healing after oral mucosal injury