Shigeaki Kurata

Enhanced Hydrolytic Stability of Dental Composites by Use of Fluoroalkyltrimethoxysilanes

The hydrolytic stability of a group of experimental composite materials was evaluated. Seven distinct composites were formed by the mixing of a resin monomer mixture with silica filler that had been pre-treated with one of 7 different ethanol solutions. In one case, the filler was treated with an ethanol solution that contained only 3-methacryloyloxypropyltrimethoxysilane. In 5 cases, it was treated with solution containing a mixture of 3-methacryloyloxypropyltrimethoxysilane and one of the following hydrophobic fluoroalkyltrimethoxysilanes: trifluoropropyl-, nonafluorohexyl-, tridecafluorooctyl-, heptadecafluorodecyl-, and henicosafluorododecyl-trimethoxysilane. The tensile strength, after being immersed in water for 1800 days, of 2 of the experimental composites, whose pre-treatment regimen had included a fluoroalkyltrimethoxysilane, was significantly higher than that of the composite whose pre-treatment regimen had not included a fluoroalkyltrimethoxysilane. Moreover, there was no significant difference between the tensile strength of fresh samples of these 2 composites and the tensile strength of identically produced samples that had remained under water for 1800 days or that had been subjected to 30,000 cycles of thermal stress.

Synthesis of Collagen-Like Sequential Polypeptides Containing O-Phospho-L-Hydroxyproline and Preparation of Electrospun Composite Fibers for Possible Dental Application

A synthetic route is described for collagen-like polypeptides constructed from O-phospho-L-hydroxyproline [Hyp(PO(3)H(2))] residues. Using the synthetic polypeptides and a natural protein, gelatin, fine fibers and their network structures (ESNWs) were prepared via electrospinning. The composite ESNWs can induce the mineralization of calcium phosphate. The phosphoryl groups of the Hyp(PO(3)H(2)) residues affect both the crystalline phase and amount of the calcium phosphate, depending on the chemical structure in the repeating sequence. The composite ESNWs can be developed as a biocompatible replacement of the extracellular matrix of hard tissues, and thus can be applied as dental materials for restoration of dental cavities or as a sealant for pits and fissures.

Changes of protein profiles during pollen development in Lilium longiflorum

Pollen proteins of Lilium longiflorum were examined at different developmental stages (young, mature and cultured) using two-dimensional differential gel electrophoresis. Quantitative changes of six proteins (MP1–MP6) during pollen development were observed in the acidic and low molecular weight region. After water absorption on the culture medium, the quantities of all six proteins were drastically changed. Mass spectrometric analysis revealed that MP2, MP3, MP4 and MP6 are late embryogenesis abundant (LEA) (D-7) protein, profilin 3, profilin 1 and enolase, respectively. The remaining two proteins (MP1 and MP5) could not be identified by mass spectrometric analysis. Immunogold electron microscopic examination showed the presence of these proteins in different regions: MP1 around lipid bodies, suggesting possible involvement in lipid metabolism, MP4 near actin in the cytoplasm, indicating the possibility of its interaction with actin in the regulatory pathways of pollen, and MP2 and MP6 in the cytoplasm.

Study on antibacterial dental resin using tri-n-butyl(4-vinylbenzyl) phosphonium chloride

The antibacterial properties of a polymeric phosphonium salt were studied to determine its suitability as an additive to develop an antibacterial dental resin. The phosphonium salt monomer studied was tri-n-butyl(4-vinylbenzyl)phosphonium chloride (VP), and acrylic acid (AC) and methacryloyloxyethyl trimethyl ammonium chloride (MA) were used as controls. The antibacterial activity of these monomers and their corresponding polymers (PVP, PAC, and PMA) against Streptococcus mutans (S. mutans) was examined. When incubating S. mutans in a medium containing 10 μmol/mL for 24 hours, the antibacterial activity of PVP against S. mutans was high, while the antibacterial activity of PMA and VP was lower. AC, PAC and PMA exhibited the lowest antibacterial activity. The mechanical properties of the copolymers of methyl methacrylate, 2-hydroxyethyl methacrylate, and VP decreased as VP content increased, and were lower than those of poly(methyl methacrylate).

Chiral Biomineralization: Epitaxial and Helical Growth of Calcium Carbonate Through Selective Binding of Phosphoserine Containing Polypeptides, and the Dental Application onto Apatite

Hiroyuki Yamamoto, Mina Yamaguchi, Tetsunori Sugawara, Yukie Suwa, Kousaku Ohkawa, Hisaaki Shinji and Shigeaki Kurata Institute of High Polymer Research, Faculty of Textile Science and Technology, Shinshu University, Ueda 386-8567, Japan, E-mail hyihpr2@giptc.shinshu-u.ac.jp 2 Department of Pediatric Dentistry and Department of Dental Materials, Kanagawa Dental College, Yokosuka 238-8580, Japan, E-mail yamagumi@kdcnet.ac.jp

Cytotoxic effects of polybasic acids, poly(alkenoic acid)s, and the monomers with various functional groups on human pulp fibroblasts

This study evaluated the cytotoxicity of various polybasic acids, poly(alkenoic acid)s, and the monomers with various acidic functional groups such as carboxyl, phosphoryl, and sulfo group. The cell growth of fibroblasts cultivated in medium containing polybasic acids and polymers up to the concentration to 5 mmol/L was not significantly different compared with that of control without their acids. On the other hand, the cell growth fibroblasts cultivated in medium containing 1 mmol/L of the monomers with acryloyloxy and phosphoryl or carboxyl group decreased remarkably compared with that of the control and the cells were probably lifeless. Those exposed to the monomers with a ether bond and a carboxyl group or a amide bond and a sulfo group was not significantly different compared with that of control.

Scanning tunneling microscopic observation of dental structures of a permanent tooth

Abstract An application of scanning tunneling microscopy to biological research is presented on observation of micro-structures of a permanent tooth. This observation provides micro-structural images of cross-sectional surface of thin-sliced samples of dentin and enamel of a human permanent tooth within a nanometer region under atmospheric conditions at room temperatures. The scanning scale used in this study is in 313–10,000 nm for measurements of dental specimens. Several tunneling microscopic images of the dental