Papers by Author: T. Watanabe

Abstract: There is little information concerning the physical properties of various commercialized water-based temporary filling materials. In this study, the setting characteristics of 5 water-based temporary filling cements, i.e., Caviton, HY-seal, Lumicon, Cavit-G, and Cavit-W, were examined. Reinforced plastic pipes were filled with the test materials, and the specimens were then immersed in distilled water at 37°C. Setting time of each specimen was determined by a penetration test using a Vicat penetrometer; and setting layer depth was measured with micrometer calipers. Cavit-W exhibited the fastest setting time, whereas Caviton and HY-seal demonstrated the slowest setting time. These results indicate that the setting properties of these materials used in this study were significantly different for each material, which showed some changes on the surface and the internal part after the start of water absorption.

Abstract: The purpose of this study was to evaluate the physical properties of the composite membrane before and after soaking in simulated body fluid (SBF) and discuss both degradation and maintenance of their properties. Before and after soaking in SBF, some deposits were found on the preexisted apatite crystals, and Ca and P were mainly detected by energy dispersive X-ray analyzer (EDX). Our results suggest that the composite membrane consisting of apatite and the biodegradable PLGA copolymer would have excellent biocompatibility and maintain adequate physical properties for in vivo use.

Abstract: It is well known that bone morphogenetic protein (BMP) induces bone formation and requires for carriers. Poly-lactic acid / poly-glycolic acid (PLGA) is frequently used as the carriers of BMP. We developed a biodegradable composite PLGA membrane, which was containing oriented needle-like apatite with BMP. The composite membranes were implanted into the thigh muscle pouch of 3-week-old-mice. At 3 weeks after implantation, the implanted area was observed by optical microscopy. The composite membrane containing oriented needle-like apatite with BMP induced new bone formation. It seems that this composite membrane might be a scaffold of BMP and promoting the healing of bone defects.

Abstract: Sm2Fe17Nx compound is a prospective candidate as a material for high performance permanent magnets because of its good intrinsic magnetic properties with a Curie temperature of 747K, a room-temperature anisotropy field of 14T and a room-temperature saturation magnetization of 1.5T. However, Sm2Fe17Nx compound decomposes to
-Fe and Sm nitride above 873K and conventional powder metallurgy processing techniques fail to meet the processing requirements. Shock consolidation is a viable alternative to process this compound. Fully dense Sm2Fe17Nx bulk materials were fabricated by cylindrical explosive consolidation technique using water as a pressure transmitting medium. Explosive consolidation is performed under cold state and fully dense materials can be obtained without any degradation of the characteristics of the powder states. Sound compacts were obtained without any cracks or teas, and the value of (BH)max of Sm2Fe17Nx compact is 23.8 MGOe.