Papers by Author: Nudthakarn Kosachan

Abstract: Calcium phosphate cement has been widely used as a bone substitute because of its chemical similarity to natural bone. In this study, calcium phosphate cement was prepared using dicalcium phosphate dihydrate (CaHPO₄.2H₂O) and calcium carbonate (CaCO₃) as starting raw materials. The cement pastes were mixed and the chemistry adjusted with two different aqueous solutions of sodium hydroxide (NaOH) and disodium hydrogen phosphate (Na₂HPO₄). Concentrations of the solution were varied in the range 0.5 to 5.0 mol/L with the ratio of solid/liquid = 2 g/ml. The cement paste was then poured into a silicone mold having a diameter of 10 mm and a height 15 mm. Setting times for the cement were measured using a Vicat apparatus. XRD, FT-IR, and SEM techniques were used to characterize properties and microstructure of the cement. From the experimental results, it is clear that different concentrations of Na₂HPO₄ and NaOH have affected the setting times of the cement. The relationship between concentration of NaOH and Na₂HPO₄ and setting time, including final properties of the cement, is discussed.

Abstract: Bioactivity of biomaterials is recognized to be of importance and the behavior of nanosized HA and β-TCP particles is described and compared. The study focuses on the influence of the phase transformation and grain size on the reprecipitation of calcium phosphate and the effect of immersion time in SBF on the surface characteristics of the samples. The HA and β-TCP samples were fabricated by mixing the powders in a ball mill, drying, uniaxial pressing and sintering at 1150oC for 240 minute using fixed heating and cooling rates. The densified samples were then immersed in a simulated body fluid (SBF) for controlled periods of time in order to investigate their bioactivities. Changes in the surface structure were examined to investigate and characterize phase formation and the chemical functionality of the samples.

Abstract: The composite, based on a polymer matrix such as Bisphenol A glycol dimethacrylate (Bis-GMA), urethane dimethacrylate (UDMA), and triethyleneglycoldimethacrylate (TEGDMA) and a reinforced-ceramic filler has been used in dental restorative materials. The light curing composite consists of Bis-GMA, TEGDMA, UDMA, Bis-GMA/TEGDMA, Bis-GMA/UDMA, or UDMA/TEGDMA polymer systems and a fumed silica filler with 35 weight ratio loading was synthesized using camphorquinone (CQ) and 2-(dimet6hyloamino)ethyl methacrylate (DMAEMA) as an initiator system. FTIR spectroscopy was used to determine the degree of conversion (DC) of the composites. Polymerization shrinkage and physical properties such as hardness strength and flexural strength were correlated with the composites containing different polymer systems.