Drug repositioning promises the advantages of reducing costs and expediting approvalschedules. An induction of the anesthetic and sedative drug; midazolam (MDZ), regulatesinhibitory neurotransmitters in the vertebrate nervous system. In this study we show the potentialfor drug repositioning of MDZ for dentin regeneration. A porcine dental pulp-derived cell line(PPU-7) that we established was cultured in MDZ-only, the combination of MDZ with bonemorphogenetic protein 2, and the combination of MDZ with transforming growth factor-beta 1. Thedifferentiation of PPU-7 into odontoblasts was investigated at the cell biological and genetic level.Mineralized nodules formed in PPU-7 were characterized at the protein and crystal engineeringlevels. The MDZ-only treatment enhanced the alkaline phosphatase activity and mRNA levels ofodontoblast differentiation marker genes, and precipitated nodule formation containing a dentinspecificprotein (dentin phosphoprotein). The nodules consisted of randomly orientedhydroxyapatite nanorods and nanoparticles. The morphology, orientation, and chemicalcomposition of the hydroxyapatite crystals were similar to those of hydroxyapatite that hadtransformed from amorphous calcium phosphate nanoparticles, as well as the hydroxyapatite inhuman molar dentin. Our investigation showed that a combination of MDZ and PPU-7 cellspossesses high potential of drug repositioning for dentin regeneration.
In this study, in vitro experiments were conducted using an acid erosion model to investigate and compare changes in enamel demineralization over time in different age groups. A total of 34 human extracted teeth with no caries were used, 17 of which came from subjects in their 20s at the time of extraction and 17 from subjects in their 60s. To measure the depth and the volume of enamel demineralization, the teeth were immersed in demineralization solution (0.1 N HCl) for durations of 30 seconds, two minutes, one hour and five hours. In terms of the results, one important finding was that on the outermost layer of the enamel exposed to the acidic solution, an acid resistance layer was observed after only 30 seconds of exposure and after up to five hours of exposure. Detailed investigation of this hypermineralized layer revealed that the molar ratio for Ca/P was 1.16 ± 0.02, the width of the layer was 0.9 ± 0.2 m, and dense depositions of large and small quadrilateral crystals were observed. Another important result is that the volume of enamel lost per second of exposure to the demineralization solution initially declined exponentially over time, with the largest rate of loss observed at 30 seconds of demineralization, after which the demineralization time increased and a tendency was seen for a state of equilibrium to be reached. Based on the results of this study using an acid erosion model, we conclude that while the demineralization solution penetrated into the interior of the enamel even after only a few seconds of exposure, minerals eluted from the crystals were confirmed to have been remineralized. In terms of age, enamel demineralization was not considerably influenced by age since no statistically significant differences in demineralization depth or volume were observed between the 20s and 60s age groups.
Background:Volatile sulfur compounds (VSCs) produced inside the mouth are a well-known cause of halitosis. Recent studies have suggested that VSCs modify the pathology of periodontitis by encouraging the migration of bacterial toxins associated with increased permeability of gingival epithelia, and enhancing the production of matrix metalloproteinases in gingival connective tissue. Nonetheless, the effects on the enamel of direct exposure to VSCs within the oral cavity remain unclear.In the present study, we observed the effects of VSCs in the form of hydrogen sulfide (H2S) on enamel surfaces and determined their effects on restorations.Materials and Methods:Extracted human tooth and bovine tooth samples were divided into the H2S experimental side and the control side. We observed the effects of H2S on enamel surfaces using electron microscopy and conducted a shear test.Results:We found that exposure to H2S obscured the enamel surface's crystal structure. The surface also exhibited coarseness and reticular changes. Shear testing did not reveal any differences in bond strength.Conclusions:Our findings suggested that H2S occurring inside the mouth causes changes to the crystal structure of the enamel surface that can lead to tooth wear, but that it does not diminish the effects of dental bonding in adhesive restorations.
This study was designed to evaluate the volume of alveolar bone augmentation after immediate implant placement using demineralized bone. We examined the collagen matrix of demineralized bone and biologically active substances contained therein. Rat maxillary first molars were extracted, and the animals were divided into five groups as follows: tooth extraction only, implant into the mesial root socket, implant and other root sockets covered with demineralized bone sheet, implant and other root sockets filled with demineralized bone powder under the sheet, and implant and other root sockets covered with demineralized bone sheet from which proteins were extracted. We ascertained whether biologically active substances are contained in extracted proteins. Biologically active substances were detected in extracted proteins. Conditions using demineralized bone sheet with biologically active substances significantly augmented the height of the alveolar bone. Such resorbable membranes containing biologically active substances hold promise as clinical agents for bone augmentation upon implantation.
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