DETECTION AND QUANTIFICATION OF CALCIUM-FLUORIDE USING MICRO-RAMAN SPECTROSCOPY

Investigations on the caries-preventive effect of calcium fluoride hav e been seriously hampered by the lack of adequate detection techniques . In this paper, the micro-Raman technique is introduced as a suitable method for CaF2 quantification with a spot size typically 5 mum. Adva ntages of this measuring technique and associated problems are describ ed for CaF2 determination in the presence of large amounts of hydroxya patite. The data show that a comparative analysis of Raman intensities of calcium fluoride and phosphate ions of hydroxyapatite can be used for quantification of CaF2 concentrations. The intensity behaviour of the CaF2 and hydroxyapatite Raman lines is explained considering the a bsorption-scattering cross-sections of the two components. The ratio o f the Raman intensity (322 cm-1) of CaF2 to the phosphate Raman intens ity (432/447 cm-1) of hydroxyapatite was found to be related linearly to the ratio of the concentration of CaF2 to that of hydroxyapatite. A t present, the lower limit of CaF2 quantification is approximately 3 w t%. The technique has already been applied on fluoridated bovine ename l, and Raman emissions due to CaF2 or CaF2-like material formed on/in enamel have been detected for the first time.