The fluorescence background in Raman spectra of sound enamel

Raman spectroscopy is constantly being developed for the detection of early dental caries. The Raman spectrum background can indicate fluorescent compounds in the enamel which appear e.g. in the caries lesion. However, an in-depth analysis of the results of studies regarding sound enamel is necessary to successfully use fluorescence background in the Raman spectrum of teeth, especially in the detection of very early stages of caries. The purpose of this study was to assess the influence of organic compounds in healthy human enamel on the background intensity in Raman spectra. Raman spectroscopy and cone-beam computed tomography confirmed that the enamel was healthy. Scanning electron microscopy analysis indicated that the area of Raman imaging is smooth, without defects and cracks. Raman spectroscopy results were compared with DIAGNOdent pen 2190. The correlation between the spectroscopic results and DIAGNOdent results was evident. Moreover, Raman spectroscopy showed that the additional layer on the enamel surface could not be related to the presence of porphyrins in caries but to organic compounds in plaque or calculus. This conclusion was confirmed by EDS analysis. The results showed that background in Raman spectroscopy may be useful in dental research. However, it should be treated very cautiously as fluorescence can be related to organic compounds which occur in plaque, not in the carious lesion.