Study On The Adsorption And Lubricating Properties Of Salivary Pellicle On Three Dental Restorative Materials

The tooth is an important organ for mastication in human body. Its main duty is to cut and minify the food then effectively reduce the burden of other digestive organs. Furthermore, people often regard teeth as an important symbol of a fitness because it is closely related to the breath, pronunciation and facial aesthetics. Physiological wears, pathological reasons and accidental injury often cause dentition defect or tooth excessive wear, and then break normal teeth occlusal relationship, lower the quality of human life. Once defected, permanent teeth are not regenerated, dental restorative materials are used as substitute of human teeth. The frequently-used dental restorative materials include macromolecular materials, metal, ceramic. The color of metal alloy is very different from human tooth, so it limited the use of this kind of material. Resin and ceramic dental restorative material were widely used. The service life of dental materials is influenced by their tribological property which received wide attention of scholars. But in vitro simulation experiment mostly ignored the effect of human natural saliva in the mouth, the understanding of the adsorption and lubricating properties of saliva on dental restorative material is not clear. Therefore, making deep study about the adsorption and lubricating properties of human whole saliva on resin and ceramic has very strong theoretical guidance significance for evaluating, improving, developing dental restorative materials.This study selected human tooth enamel, methyl acrylic resin teeth, Vita Enamic, IPS e.max Press as research objects, nano-scratch tester, nano-indent tester, AFM, contact angle tester, zeta potential tester were used to study the adsorption and lubricating properties of saliva on different materials. The main results and conclusions were as follows:(1) A method based on nano-scratch technology for evaluation of shear adhesion energy between salivary pellicle and matrix was proposed. The normal load is a key factor of this method. It was conformed through progressive approaching method. The optimal one we used was the smallest force that could remove the salivary pellicle, repetitive shear adhesion energy result could be got at this load.(2) After 1min saliva adsorption treatment, salivary pellicle was formed on both enamel and resin surfaces. The shear adhesion energy and adhesion force of salivary pellicle with resin were both less than enamel. The results of wear tests showed that the reduction rate of wear volume of resin after saliva-adsorption treatment was far less than enamel. This means that the salivary pellicle on resin was easier to be destroyed when met same external forces, so the lubricating property is poorer.(3) Salivary pellicle was formed on both e.max and Enamic ceramic surfaces after 1min saliva-adsorption treatment. Shear adhesion energy between salivary pellicle and e.max was similar with enamel. Adhesion force between salivary pellicle and two ceramics was far bigger than resin. The electrostatic interaction between salivary protein and ceramic lead to higher adhesion strength, so the salivary pellicle can resist external force then lower the wear of ceramic surfaces.