Micro-Raman spectroscopic investigation of dental calcified tissues

The purpose of this study was to determine if dental calcified junctions (DEJs/CDJs) in human teeth contain different compositional phases compared to the adjacent dental calcified tissues. Peak positions and intensities were determined from micro-Raman spectra for PO(3-) (4) and the C--H modes and compared among the mineralized tissues and their junctions. Values of width were determined from the intersections of intensity regression lines through the junctions and in the adjacent tissues. The peaks were measured in 1-microm steps along a l00-microm line across the junction. High-resolution analysis revealed that PO(3-) (4) band peaks for dentin, the DEJ, enamel, the CDJ, and cementum were at the same position (959 cm(-1)), while for the C--H stretching mode a significant shift of 4.6 cm(-1) was found between enamel, the DEJ, and dentin. The mean width of the DEJ was 7.6 (+/- 2.8) microm using the PO(3-) (4) band and 8.6 (+/- 3.6) microm using the C--H stretching mode. Across the DEJ, the mineral content monotonically decreased from enamel to dentin while the organic component monotonically increased. The DEJ width was in agreement with prior nanoindentation studies. No width estimate was possible for the CDJ because the compositional differences between cementum and dentin were small.