Molecular structural analysis of noncarious cervical sclerotic dentin using Raman spectroscopy

Molecular structure of the sclerotic dentin in noncarious cervical lesions (NCCLs) including both the inorganic phase and organic phase was investigated using Raman spectroscopy. It was found that NCCL sclerotic dentin was hypermineralized with the mineral/matrix ratios 2-3 times higher than those of normal dentin, which was caused by both the increase of mineral content and decrease of organic matrix (collagen) content in the sclerotic dentin. For the inorganic phase, the phosphate band (PO43-, nu(1), symmetric stretching vibrational mode) in NCCL sclerotic dentin was shifted from 960 to 963 cm(-1), and the width of this band was decreased from 16.4 to 10.4 cm(-1), indicating that the degree of mineral crystallinity in NCCL sclerotic dentin was higher than that of normal dentin. In addition, the carbonate content in the mineral of NCCL sclerotic dentin was less than that of normal dentin. As compared to the inorganic phase, the changes within the organic phase were not dramatic. However, the changes in collagen cross-link density along with other spectral changes were still detectable. There was a noteworthy reduction in the ratio of nonreducible to reducible cross-links in the NCCL sclerotic dentin, indicating that cross-link breaks occurred in the collagen matrix of the lesions. Copyright (C) 2009 John Wiley & Sons, Ltd.