The aim of this study was to examine calbindin D-28k immunoreactivity in odontoblasts to know whether the expression of this protein is affected by cavity preparation. The cavity was prepared in human third molar under the local anesthesia and then filled with temporally material. After that, the cavity teeth were extracted within 1 week. Extracted teeth without cavity preparation were used as a control. After fixation with Zamboni fixative, the teeth were demineralized in 4.13% EDTA solution, frozen-sectioned, and processed for calbindin immunoreactivity and hematoxylin-eosin stain. The distribution of calbindin D-28k immunoreactivity in odontoblasts was observed under the light microscopy. In the teeth without cavity, almost all of odontoblasts showed the immunoreactivity. However, odontoblasts underneath the cavity were immunonegative for calbindin D-28k in the cavity-prepared teeth. These findings may suggest that the expression of calbindin D-28k in odontoblasts was suppressed by inflammation following cavity preparation.
Objectives: Bone substitute comparable to autologous bone has been clinically desired. The purpose of the present study was to examine effects of demineralized dentin matrix (DDM) on regeneration in surgical bone defect. Material and Methods: Rabbit upper right incisors were extracted and demineralized and then, dentin slices in 8µm thickness (DDM) were prepared. Two surgical bone defects were created on the skull of each rabbit. Autologous DDM was mixed with autologous platelete-rich plasma (PRP) and applied to the bone defect (experimental site) whereas autologous PRP was applied to another bone defect (control site). To keep the space of the bone regeneration, each bone defect was covered with two methylcellulose membranes. The rabbits were sacrificed 4 weeks and 8 weeks after the surgery. Subsequently, radiographical and histomorphometrical analyses were performed. Results: In the soft X-ray photographs the experimental site was more radiopaque than the control site at 4 and 8 weeks. Similarly, bone mineral density of the experimental site was higher at both time points. Histologically, bone formation was induced along with DDM and newly-formed bone in the experimental site was extensive and matured, compared to the control site. Histomorphometrically, at 4 weeks, bone volume and the parameters of bone formation and resorption of the experimental site were higher than the ones of the control site. Conclusion: The present results indicate that DDM is effective as a bone substitute accelerating bone repair.
Thin carbonate-containing apatite (CA) film was coated on titanium fiber mesh using molecular precursor method. Thin CA coating was produced by the immersion of titanium fiber mesh into the molecular precursor solution. The efficacy for CA coating was evaluated by electron probe micro analysis. The principle of the molecular precursor method is the application of an alcoholic precursor solution of a Ca-EDTA complex on the substrate and then firing the materials at around 600oC for 2 hours. One-time coating was not sufficient inside the titanium fiber mesh. Three-time coating produced better CA deposition not only the surface are of titanium fiber mesh but also the inside area of titanium fiber mesh. This was due to the improvement of penetration of molecular precursor solution into titanium fiber mesh. It revealed that molecular precursor method is useful for coat CA film inside the porous scaffold material such as titanium fiber mesh.
Mesenchymal stem cells are important for tissue engineering therapy because they can be seeded in scaffold materials, proliferated and differentiated into osteoblasts. The purpose of this study was to evaluate gene expressions of human mesenchymal stem cells cultured for 14 days in osteogenic differentiation medium that contained ascorbic acid, β-glycerol phosphate and dexamethasone, using 2.9k DNA microarray. It became evident that 198 genes were more than 10-fold up-regulated, but 395 genes were less than 0.1-fold down-regulated with respect to control genes. These 593 genes had wide varieties of biological significance. While ossification-related sialoprotein precursor and osteopontin genes were significantly up-regulated, cartilage-related chondroitin sulfate proteoglycan 2 and aggrecan 1 genes were also up-regulated. Some genes related to angiogenesis, TGF-beta receptor signaling pathway and cell differentiation were also considerably up-regulated. It was concluded that osteogenic differentiation medium differentiated mesenchymal stem cells into not only osteoblasts but also chondroblasts to facilitate endochondral ossification with vascular invasion in gene expression levels. The list of genes presented here could be used as a database for ossification studies of human mesenchymal stem cells that might be clinically useful.