RAMAN-SPECTRA OF HUMAN DENTIN MINERAL

Human dentin mineral has been investigated by using micro-Raman spectr oscopy. Fluorescence and thermal problems were largely avoided by prep aring dentin samples by grinding and ultrasonic agitation in acetone. The Raman spectral features were consistent with those of impure hydro xyapatite containing CO3 and HPO4. While spectral differences between enamel and dentin were clearly observable as changes in the bandwidth of the PO43- v(1) band and the intensities of the OH-, CO32- and HPO42 - bands, the technique could not detect spectral differences between c oronal and root dentin. NaOCl, NaF and APF-gel treatments caused measu rable changes in intensities of the bands due to CO32- and HPO42-; the results were found to be useful for band assignments. After NaOCl tre atment, the Raman bands, presumably due to amide and HPO42-, were lost , but the band intensity of the CO32- v(1) bands increased by 35-60%. This increase coincided with the appearance of a new broad band (250-3 00 cm(-1)). The same treatment on enamel caused no increase in the CO3 2- v(1) band intensity. This NaOCl-induced carbonate could be removed within 20 h in a 1000 ppm NaF solution. These findings indicate that t he carbonate ions induced by the NaOCl treatment are presumably in or on the mineral surface. After 3 min of APF-gel treatment on NaOCl- pre treated dentin, the intensities of the hydroxyapatite phosphate bands dropped by approximately 20%, and newly formed CaF2 and HPO4 bands bec ame observable.