Papers by Keyword: Bone Like Apatite

Abstract: Hydroxyapatite (HAp) is very attractive in medical field. The objective of this study is to produce HAp/Ti composite coating with Supersonic Free-Jet PVD (SFJ-PVD). The SFJ-PVD is a technique to deposit nanoparticles with supersonic gas flow and to form a thick coating film. In a gas evaporation chamber, a source material is evaporated to form nanoparticles in an inert gas atmosphere. The nanoparticles are then carried to a substrate in a deposition chamber with an inert gas flow through a transfer pipe. The gas flow is generated by the pressure difference between the chambers and accelerated to the supersonic flow of 4.2 Mach through a specially designed supersonic nozzle. With SFJ-PVD, we obtain a uniform high-density HAp/Ti composite coating. XRD analysis reveals that the composite coating is composed of Ti and HAp. An in-vitro study was carried out to investigate the bioactivity of the HAp/Ti composite coating under simulated body fluid.

Abstract: Previous studies have shown that hydroxyapatite increases the bonding strength of dental luting cement with human teeth by forming bone-like apatite when it is added to cement. However, due to the low solubility of the hydroxyapatite, its ability to form bone-like apatite decreases in protein-free acellular simulated body fluid with ion concentrations nearly equal to those of the human blood plasma. The purpose of this experiment was to increase the formation of bone-like apatite by mixing hydroxyapatite with β-TCP of high solubility. RelyXTM glass ionomer cement(3M/ESPE, USA) was used as dental luting cement. Film thickness, setting time, and compressive strength was measured for each group of 15% hydroxyapatite, 15% β-TCP, and 15% mixed hydroxyapatite and β-TCP (85:15). Every specimen of each group was immersed in the simulated body fluid for four week before measuring bonding strength, and then their sectional surface was observed under SEM. The most noteworthy result was that the group containing β-TCP produced more amount of bone-like apatite compared with the group composed of only hydroxyapatite.

Abstract: The mineral phase of bone and teeth is mainly hydroxyapatite. Currently there are numerous researches being conducted on the effect of the addition of hydroxyapatite to dental materials. Among them, several studied were published stating that the addition of hydroxyapatite to composite resin or glass ionomer cement resulted in an improvement in bonding strength and physical properties Therefore, this study will investigate the effect that the addition of hydroxyapatite to light curing glass ionomer cement has on bonding strength. Two different light curing glass ionomer cement products were selected (FujiⅡLC, GC Cor, Japan and Vitremer™ , 3M/ESPE, USA) and hydroxyapatite was mixed into the light curing glass ionomer cement at various concentrations to create hydroxyapatite-light curing glass ionomer cement mixture. In order to confirm that hydroxyapatite-light curing glass ionomer cement met the basic requirements of dental materials, sensitivity to ambient light, depth of cure, and flexural strength were tested. From the results of the above mentioned tests, the hydroxyapatite-light curing glass ionomer cement with the most superior physical properties for each product (15% HA-Fuji Ⅱ LC, 20% HA-Vitremer™)was bonded to the teeth and then immersed in artificial saliva(36.5°C) for four weeks. Finally the sectioned surface was observed under SEM after measuring the bonding strength. As the hydroxyapatite concentration increased, the depth of cure decreased. However flexural strength increased and there was not much change in the sensitivity to ambient light. Bonding strength, which was the main focus of this study, increased with the addition of hydroxyapatie and scanning electron microscope findings show a more cohesive type of fracture in the material with bone like apatite material formation along the tooth-material interface.