A METHOD FOR DETERMINING THE DISTRIBUTION OF FLUORIDE IN HUMAN DENTAL PLAQUE in vivo AND THE EFFECT OF SOME FACTORS ON THE FLUORIDE DISTRIBUTION

建立了一种测定牙菌斑中氟化物和矿物质含量的方法。在单次900 ppm氟化物冲洗前、冲洗后10 min和24 h，以及浸泡在含有3%尿素和100 ppm氟化物的实验溶液中后，使用特殊装置从同一受试者重复收集菌斑样品，每天两次，共4天。将样品冷冻干燥，然后包埋在甲基丙烯酸酯混合物中，并使用超薄切片机从表面朝向牙釉质切成3 μ m或6 μ m厚的切片。在几个分层的菌斑样品中收集较厚的切片用于化学分析，并且较薄的切片用于确定菌斑体积。将每个牙菌斑样品置于氯仿中以提取甲基丙烯酸酯。将沉积物中的氟、钙和磷提取到酸性缓冲溶液（pH5.2）中。用氟电极测定氟，钙和磷的浓度分别用光谱和比色法测定。结果以每单位菌斑体积表示。本方法允许检查氟，钙和磷分布在斑块沿着其整个厚度的斑块。冲洗后10分钟，整个样品中的氟化物含量显著增加，表明氟化物已迅速渗透到牙菌斑中。升高的氟浓度在24 h内几乎降至基线水平。一个高度显着的相关性被发现之间的氟化物和矿物质的牙菌斑暴露于氟化物溶液。钙和磷之间的相关性显着高于尿素处理过的斑块比样品暴露的氟不含尿素。结论：这项技术将是有用的，以评估氟和矿物质的行为在菌斑/釉质界面，和抗龋效果的氟化物应用。

A method for the determination of the fluoride and mineral profiles within dental plaque formed in vivo has been developed. Plaque samples were repeatedly collected using special devices from the same subject, before a single 900 ppm fluoride rinse and, 10min and 24h after the rinse, and also after immersed in an experimental solution containing 3% of urea and 100 ppm fluoride twice a day on 4 days. The samples were freeze-dried and then embedded in a methacrylate mixture and were sliced from the surface towards the enamel into 3 mum or 6 mum thick sections using an ultra microtome. The thicker sections were collected in several layred plaque samples for the chemical analysis, and the thinner sections were used for determination of plaque volume. Each plaque sample was placed in chloroform to extract the methacrylate. Fluoride, calcium and phosphorus were extracted from the sediment into an acid buffer solution (pH5.2). Fluoride was determined using a fluoride electrode, and concentrations of calcium and phosphorus were determined by sectroscopical and colorimetrical techniques respectively. Results were expressed per unit of plaque volume. The present method allowed examination of fluoride, calcium and phosphorus distribution in plaque along its entire thickness of plaque. Fluoride content significantly increased throughout the sample 10min after rinsing, indicating that fluoride had rapidly penetrated into the plaque. The elevated fluoride concentrations diminished almost to baseline levels within 24 h. A high significant correlation was found between fluoride and minerals in the plaque exposed to the fluoride solutions. Correlation between calcium and phosphorus was significantly higher in the urea treated plaque than the sample exposed fluoride without urea. It is conclued that this technique will be useful for evaluating the fluoride and mineral behavior in the plaque/enamel interface, and the anti-caries efficacy of the fluoride application.