| 摘要 |
Glassy coatings are made by curing in situ a coating of a sol gel, xerogel or heat-consolidated gel composition comprising a hydrolysable silicic ester, 1-4 moles water per mole of silicon and a solvent e.g. alcohol, filled with a filler such as kaolinite or with fiat plates (1-2 mu m x 10-5 mu m) of mica, which may be coated with TiO2, Cr2O3 or Fe2O3 applied by CVD. The silicic ester may be silicon tetrahalide or tetraalkoxysilicon. Further fillers are laponite, zeolite, talc, vermiculite. The mica or talc may be coated with silane. The composition may also contain a metal alkoxide capable of participating in forming glass structures with the silicic ester, e.g. alkoxides of Na, Zr, Al and Ti. The composition may be cured to form the glassy coating by the use of laser radiation or a butane gas flame. Use is made of very miniature flames so as to avoid vital tissue when curing on a tooth. Part of the silicic ester may be replaced with other glass formers such as boron-based sol gels. The coating may be applied to teeth as a dental fissure sealant or varnish to protect restorations, or as an inherently coloured cosmetic coating, or as a prophylactic coating. in an application for slow drug release the coating may be charged with a drug, eg for treating dentine hypersensitivity or peridontal disease.
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