Infrared absorption bands of enamel and dentin tissues from human and bovine teeth

The chemical components present in the hard tissue such as water, phosphate, carbonate and organic material strongly absorb infrared radiation. The research in dentistry area has a fundamental interest in identifying the chemical origin of all the bands present in the infrared region to study the chemical and thermal action on the hard dental tissues. To improve this technique it is: important to identify chemical alterations in the tissues and characterize their properties in a more natural form. Transmission and reflection spectra in the infrared range from 2.5 mum to 25 mum of the enamel and dentin tissues from human and bovine teeth were acquired. Sliced samples were used for the transmission spectra, polished blocks and natural surfaces for the reflection spectra. Tissue spectra were registered between 4000 and 400 cm(-1) in a FTIR Spectrometer. No differences were found between the mineral matrix of human and bovine tissues, only differences in intensity among bands were observed. Regarding the organic matrix, the bands observed in the dentin were not observed in the enamel tissue and, as the same, the bands observed in the enamel tissue were not observed in the dentin tissue with a significant intensity. Using infrared spectroscopy of sliced samples or blocks forms it is possible to characterize the chemical and optical alterations produced in the dental hard tissues by either thermal or chemical treatment, or an association of the two treatments, Therefore this technique can be used in dental research that study the effect of laser irradiation on hard tissues and the acid attack produced by intraoral bacteria.