Physico-chemical Property And Biocompatibility Of The Hydroxyapatite Coating For Rapid Tooth Enamel Restoration

Objective: To discuss different performance of hydroxyapatite coating fabricated by twodifferent methods, looking for a proper repairing coating used in oral cavity. Thebiocompatibility (BC) of hydroxyapatite coating for rapid tooth enamel restoration hadbeen preliminary qualified by the Ames test, the delayed-type hypersensitivity test andthe subcutaneous implant test which providing experimental basis for the material’sclinical practice.Methods:(1) Searching for the recipes of the microwave accelerated synthesis methodand the ageing method to synthesize HA paint; X-Ray Diffraction (XRD), scanningelectron microscope (SEM) and vickers hardness tester (VHT) were used to characterizeHA coating. The effects of the two synthesis Methods on the performance of the coatingwere preliminary studied.(2) Four different bacterial strain including TA97、TA98、TA100and TA102were used forcarrying on the Ames tests. Whether existence of mutagenicity for the hydroxyapatitecoating for rapid tooth enamel restoration were discussed according to the test standard ofYY/T0127.10-2009.(3) According to the GB/T16886.10-2005,30guinea pigs randomly divided into threegroups. The samples were prepared and tested with the delayed-type hypersensitivity testto evaluate allergenicity.(4) To evaluate whether existence of deleteriousness and pungency for the hydroxyapatitecoating for rapid tooth enamel restoration, the subcutaneous implant test were discussedaccording to the YY/T0127.8-2001.Results:(1) After mixed with firming agent, HA power synthetized by the microwaveaccelerated synthesis method and the ageing method can be transformed into HAcoatings (HA-1and HA-2) on the surface of enamel after treated by acid.(2) The number of anaplasia bacterial colony and spontaneous anaplasia is similar in testteam while the number of anaplasia bacterial colony in positive control group is twicemore than negative control group, and the result is negtive which shows there is no mutation effect on the Salmonella typhimurium by using hydroxyapatite coating for rapidtooth enamel restoration.(3) In the tests of the delayed-type hypersensitivity test,9guinea pigs were founderythema in positive control which is about90%sensitization rate. However, noerythema was found in test team which is similar with the negative control which showsthere is no obvious sensitization rate for the aforementioned hydroxyapatite coating forrapid tooth enamel restoration.(4)In the subcutaneous implant test, lots of inflammatory cells in both groups wereinfiltrated when4W, inflammatory cells decreased gradually and there was no obviousinflammation until12W which indicated that no toxic action would happened in the tissueafter the implantation of this material.Conclusion: In conclusion, after mixed with firming agent, HA power synthetized byboth the microwave accelerated synthesis method and the ageing method can besuccessfully transformed into HA coatings (HA-1and HA-2) on the surface of enamelafter treated by acid. Compared with the the former, the ageing method shows moreadvantage. According to the test index of the Ames test、 the delayed-typehypersensitivity test、the subcutaneous implant test, the hydroxyapatite coating for rapidtooth enamel restoration have good biocompatibility which is correspond to the relevantstandard that can be expanded to many other fields.