Reactions to Bioabsorbable Suture Thread Embedded in Rat Subcutaneous Tissue

We examined the subcutaneous tissue reactions in rats to bioabsorbable suture thread using histopathological methods. Using Wister rats, Vicryl®, a bioabsorbable suture thread, was embedded into the subcutaneous tissue and histopathological examination was carried out after 4 weeks. Cholesterin crystals were used for the control. Furthermore, immunohistochemistry for CD68 was done. Histopathological examination showed proliferation of granulation tissues inboth experimental and control groups. The majority of cells in the granulation tissues were macrophages and giant cells. Fibroblasts were also observed in the proliferating granulation tissues surrounding the embedded bioabsorbable suturethread. Immunohistochemistry revealed that macrophages and giant cells were positive to CD68. The results suggest that the embedded bioabsorbable suture thread is not only fabricated to undergo absorption but also for phagocytosis bymacrophages and foreign body giant cells

焼結ルチル二酸化チタン上の骨芽細胞様細胞の増殖およびアルカリホスファターゼ活性

The purpose of this study is creation of biomaterials from titanium dioxide (TiO2). This TiO2 has known for photocatalysis and osteogenesis. For the purpose of applying this function to orthodontic brackets and coating materials for implant, the relationship between surface of sintered and cell proliferation were examined. In addition, crystal structure and the surface property of sintering TiO2 were investigated. TiO2 were sintered at 1300°C for use as samples. We examined surface roughness, x-ray diffraction and scanning electron microscopy to make observations of the surface properties and texture. Moreover, mouse osteoblast-like cell line, MC3T3-E1 was cultured on sintered TiO2 in order to evaluate the cell proliferation and ALP. For the samples sintered at 1300°C, the crystalline phase of rutile-type TiO2 was confirmed.5000-fold magnified SEMimages of the surface of the unsintered samples, needle-like TiO2 crystals were pressure welded and showed mutual overlap, with pores occurring among the crystals. Sintering at 1300°C produced numerous small pores. Rutile TiO2 as a starting material was sintered at 1300°C and subjected to a cell culture experiment in which MC3T3-E1 cells were cultured on the sample, followed by viable cell counting and cell morphology observationon days 7, 14, 21, and 28 of culture. In the test of cell proliferation, sintered at 1300°C samples was found to remarkable cell proliferation even after time had passed. ALP activity of cells on 1300°C TiO2 sample, the values were 110% and 126% on days 14 and 28 of culture, respectively. These changes were calculated using polystyrene dish as the reference condition. Thus, TiO2 sintered at 1300°C showed good compatibility and increase in the ALP activity in MC3T3-E1 cells

Histochemical Characteristics of Tertiary Dentin Due to Calcium Hydroxide Paste in Rats

Calcium hydroxide is mainly used for dental pulp capping and it is thought that it induces hard tissue formation far better than other materials. Experimentally verifying this fact, Nishikawa et al revealed that bone-like dentin corresponding to tertiary dentin is rapidly formed when calcium hydroxide is applied directly to the pulp. Utilizing the same experimental system, histochemical study of the newly formed hard tissue (reparative dentin) was carried out and the results thereof were reported. Thick and irregular reparative dentin was formed in the pulp cavity and partial narrowing of the root canal was observed in m-CT. Histopathologically, the irregular reparative dentin increased its thickness obliterating the root canal having a diff erent Azan staining of aniline blue compared to primary dentin. Numerous cellular inclusion bodies were also trapped inside the thick dentin. Furthermore, with Schmorl’s thionine picric acid staining,thick reparative dentin was noted around the pulp cavity and dentin. The dentin was densely stained with picric acid with diff erent staining ability from the surrounding dentin. In addition, it was clearly confi rmed that many cells were trapped in reparative dentin. The results of the experiment suggest that the characteristics of the newly formed reparative dentin is comparable to tertiary dentin

マウスにおける実験的に発生させた歯根膜ポリープへのGFP移植骨髄由来細胞の移動と分化

Perforation of floor of the dental pulp is often encountered during root canal treatment in routine clinical practice of dental caries. If perforation were large, granulation tissue would grow to form periodontal polyp. Granulation tissue consists of proliferating cells however their origin is not clear. It was shown that the cells in granulation tissue are mainly from migration of undifferentiated mesenchymal cells of the bone marrow. Hence, this study utilized GFP bone marrow transplantation mouse model. The floor of the pulp chamber in maxillary first molar was perforated using ½ dental round bur. Morphological assessment was carried out by micro CT and microscopy and GFP cell mechanism was further assessed by immunohistochemistry using double fluorescent staining with GFP-S100A4; GFP-Runx2 and GFP-CD31. Results of micro CT revealed alveolar bone resorption and widening of periodontal ligament. Histopathological examination showed proliferation of fibroblasts with some round cells and blood vessels in the granulation tissue. At 2 weeks, the outermost layer of the granulation tissue was lined by squamous cells with distinct intercellular bridges. At 4 weeks, the granulation tissue became larger than the perforation and the outermost layer was lined by relatively typical stratified squamous epithelium. Double immunofluorescent staining of GFP and Runx2 revealed that both proteins were expressed in spindle-shaped cells. Double immunofluorescent staining of GFP and CD31 revealed that both proteins were expressed in vascular endothelial cells in morphologically distinct vessels. The results suggest that fibroblasts, periodontal ligament fibroblasts and blood vessels in granulation tissue were derived from transplanted-bone marrow cells. Thus, essential growth of granulation tissue in periodontal polyp was caused by the migration of undifferentiated mesenchymal cells derived from bone marrow, which differentiated into fibroblasts and later on differentiated into other cells in response to injury.2016博士（歯学）松本歯科大