Study on the Protein Adsorption and Bacterial Attachment to Synthetic Hydroxyapatite

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It is well known that primitive formation of plaque is a phenomenon initiated by protein adsorption and bacterial attachment onto tooth surface. This phenomenon is significantly influenced by physicochemical characteristics of tooth, protein and bacterial surface, and by electrostatic interaction between tooth, protein and bacteria.We succeeded to measure zeta potentials (mobility) of synthetic hydroxyapatite (HAp), protein and bacteria, and to analyze physicochemically the phenomenon of protein adsorption onto HAp. We also analyzed qualitatively the elements existing on bacterial surface by using X-ray photoelectron spectroscope, moreover observed the surface morphology of bacteria by atomic force microscope to discuss with electrochemical characterization of bacteria.We concluded that; 1) It was possible to measure not only zeta potentials for HAp but also protein and bacteria as a living colloid. With regard measuring apparatus of zeta potential, it was convenient for HAp to employ Lazer Zee Model-501 provided by the Pen-Kem Co., and for protein and bacteria to use LEZA 600 and ZETASIZER-4 provided by the Otsuka Electronics Co. and the Malvern Co. 2) Surface characteristics of HAp and enamel were altered by treatments of fluoride or fluorosurfactant to affect protein adsorption. The protein adsorption is decreased by slight changes of hydrophobicity of HAp surface, while increased adsorption of protein is enhanced by extreme changes of hydrophobicity of HAp surface. 3) There were no changes of zeta potentials for oral bacteria between pH 5.0 and 9.0. However, the bacteria were divided two groups by the data of zeta potential; one group for stabilized negative zeta potential and another group for near the O of zeta potential. Zeta potential of bacterial surface was dependent on not only the presence of phosphate ion on the bacterial surface but also the length of glycoprotein and smoothness of ridge of bacterial surface.