【摘要】 <正>一般认为氟化物的防龋机理之一,是由于氟离子与牙釉质表面的羟基磷灰石Ca₅（PO₄）₃OH中的羟基发生交换反应: 由于氟离子与氢氧离子电荷相等,离子半径也非常接近,极易发生交换反应。生成氟磷灰石Ca₅（PO₄）₃F有较强的耐酸性,故有防龋作用。如忽略磷、钙、羟基和氟离子以外的其他离子的作用,则氟-羟基磷灰石的组成为:更多还原

【Abstract】 This paper describes a method for the determination of fluoride, phosphate, and calcium in teeth. The whole tooth is crushed and ground to a fine powder ( which can pass through a 60 mesh sieve). Using a flotation method, the whole tooth powder is separated into enamel ( density 2.9-3.0 ) and den tine ( density 2.14), while the cemen-tum ( density 2.03 ) discard.The fluoride in the sample (enamel and dentine) was isolated by diffusion ( in a cell of Conway-type ) and determined with the fluoride ion selective electrode after the pH of the diffusate was adjusted to 5.5. The phosphate and calcium in the residual solution after diffusion of hydrogen fluoride was determined by a colorimetric procedure employing the molybdovanadophosphoric acid, and by an EDTA titration procedure after extraction of phosphate.Fluoride of teeth ( enamel and dentine ) after the use of fluoridated water supply for seven years(1972)and before that nonfluoridated water supply ( 1965) in Guangzhou was determined. The results of the analyses of over 80 samples are presented in tabular form. It has been shown that the boys who drink fluoridated water have significant incre-.ase in the fluoride content of primary teeth, and gives a calcium to phosphorus weight ratio of about 2 : 1.更多还原