Research Of Restoration Of Tooth Enamel Caries By Hydrolysis Of α-TCP

Dental caries is a common and frequent disease in department of stomatology, with gradually damage of oral hard tissue. The crown is affected first, if dosn't treat timely, the whole teeth will lost at last. At the early stage of dental caries, the enamel surface damage is began with by demineralizing and dissolving, active and positive treatment can prevent it from developing further.A novel method involved the hydrolysis of a-TCP was developed to repair the early enamel lesions in this work. The properties of calcium deficient hydroxyapatite coating (CDHA) was charactered and studied on different experimental conditions. Cytotoxicity of a-TCP and its hydrolysis solution was evalued. A tooth brace was designed to medicate on enamel surface and gingival edge. So the convenient method of repairing caries lesions has application prospect.The results showed that the acid treatment improved the surface energy and hydrophilicity, and enhance the surface polarity, which are beneficial to generating and growing crystal. It was observed that after the hydrolysis of a-TCP for 6 h at 37℃, a hydroxyapatite coating with the thickness of about 20 urn was obtained on the enamel surface. The coating shows a tight contact to the substrate with a nearly perpendicular growth to the enamel surface. The microhardness and wear-resistance of the coating were determined by the Vickers microhardness tester and toothbrushing machine, respectively. The results indicated that the coating exhibites good wear-resistance and the Vickers microhardeness similar to the natural enamel. The best conditions of preparing CDHA coatings at 37℃was: the ratio of materials to water were 0.5 g/50 mL～0.5 g/100 mL; reaction time was 2～4 h; the initial pH walue was 8～10. The cytotoxicity of a-TCP and its hydrolysis solution was all under grade I by cell relative growth rate method using L929 cell, in accordance with criterion on biomaterials.The hydrolysis of a-TCP has been suggested to be a gental, effective and convenient method for popularizing the restoration and prevention of early enamel caries, combining the tooth brace which can detain the outflow of liquid medicine and stop diluting by saliva, especially suit for liquid, gel, and paste medicine used on tooth enamel and edge of gingiva.