摘要
降低牙矿物质的溶解度是防止龋齿的重要方法之一 .氟对于羟基磷灰石 ( HAP)溶解度影响的研究已有报道 ,然而氟对于牙矿物质中的其它基本无机成分 ,如二水磷酸氢钙 ( DCPD)等溶解度的影响则研究较少 .本文以 XRD、SEM等为表征手段 ,研究了 37℃下 DCPD在不同浓度的 Na F溶液中水解时的 p H、氟离子浓度变化规律及转化产物 ,并与 HAP在相同条件下的结果进行对比 .以恒 p H的方法对 DCPD、HAP及其转化产物的溶解性质进行比较 .实验结果表明 ,DCPD在 Na F溶液中水解的产物随着氟浓度的提高依次为 :无水磷酸氢钙 ( DCPA)、DCPA+氟基磷灰石 ( FAP)、FAP、FAP+Ca F2 .恒定 p H测定的溶解曲线表明 ,经氟处理后的磷酸钙盐的抗酸能力得到了显著的改善 .
Decrease of the solubility of the mineral phases of teeth will aid in preventing caries. The effect of fluoride ion on the solubility of hydroxyapatite (Ca 10 (PO 4) 6(OH) 2, HAP) has been well reported. However, the effect of fluoride ion on the solubility of the calcium hydrogen phosphate (CaHPO 4·2H 2O, DCPD) was not very clear. DCPD is one of the precursors of hydroxyapatite and the important inorganic compositions in teeth as well. The purpose of this study was to investigate the hydrolysis characteristic of DCPD and HAP in NaF solutions. The variations of pH of DCPD hydrolysis in NaF solutions of concentration ranging from 1×10 -6 to 5 000×10 -6 were determined by a pH electrode under 37 ℃. The crystal structure and morphology of the hydrolysate was determined using XRD and SEM, respectively. When the fluoride ion concentration in the solution was lower than 5 000×10 -6 , the pH at equilibrium decreased with the increase of fluoride ion concentration in the solution. However, due to the formation of CaF 2, pH increased to a high value when the fluoride ion concentration in the solution was 5 000×10 -6 . The XRD diffraction patterns indicated that with the increasing of fluoride ion concentration hydrolysate was CaHPO 4, CaHPO 4+Ca 10 (PO 4) 6F 2, Ca 10 (PO 4) 6F 2, and Ca 10 (PO 4) 6F 2+CaF 2, respectively. At low fluoride ion concentration the fluoride uptake was very close to the whole amount of the fluoride in the initial solution. A pH stat method was used to assess the dissolution properties of DCPD and its hydrolysate. From the solution curves it can be concluded that the calcium phosphates became more resistant to acid than they did before the fluoridation.
出处
《厦门大学学报（自然科学版）》
CAS
CSCD
北大核心
2001年第1期52-58,共7页
Journal of Xiamen University：Natural Science
基金
国家自然科学基金! ( 2 98730 39)
福建省自然科学基金! ( E0 0 10 0 0 3)
国家教育部留学回国人员基金
