ATR-FTIR and Raman spectroscopy of primary and permanent teeth

BACKGROUND: Valuable structural and chemical properties can be obtained for dentin and enamel by vibrational spectroscopy. A better understanding of structural and chemical changes in deciduous dentition will contribute to improved dental restoration procedures for adolescents. OBJECTIVE: ATR-FTIR and Raman spectroscopy were applied to study human permanent and primary teeth. Slices were prepared from 10 German, 10 Turkish and 25 Jordanian teeth. METHODS: Raman images were collected at 785 nm excitation. FTIR images were collected using a germanium ATR accessory and focal plane detector. Average Raman and infrared spectra were calculated for analysis. RESULTS: Our results showed that (i) the mineral to matrix ratio is lower in primary teeth than in permanent teeth, (ii) the carbonate to phosphate ratio was higher for primary teeth, (iii) crystallinity was lower in primary teeth, and (iv) collagen cross-links occurred to be higher in primary teeth. FTIR and Raman data confirmed the results of each other. Band deconvolution of the infrared band near 870 cm-1 reveals evidence for A2-type carbonate substitution on hydroxyapatite of primary teeth spectra in addition to the A and B type carbonate substitution that are also found in permanent teeth. CONCLUSIONS: Beside chemical and structural differences found between primary and permanent teeth, variations between the origin and age of the specimens were observed which requires further systematic investigations.