Experimental Substantiation of Possibility to Early Detect the Enamel Caries Lesion Using Terahertz Spectroscopy

The possibility of using terahertz spectroscopy in time domain for early noninvasive detection of caries lesion of the human tooth enamel is considered. The samples of human teeth with different enamel state (different degree of demineralization) are investigated in vitro. A state of the enamel demineralization was simulated by etching the samples with weak acids (the 1 % nitric acid and the 6 % acetic acid). The complex amplitude spectral factors of terahertz radiation reflection from the enamel samples are recorded. A method is developed for reconstruction ofpermittivity profile for the medium under study on the basis of the complex amplitude spectral reflection factor of the investigated medium. The permittivity profiles are reconstructed for the enamel samples with different degree of demineralization. As a result of experimental studies, the qualitative interconnection is determined between the terahertz opticalcharacteristics of enamel and the concentration of mineral substances contained in it, which is the evidence that the development of a novel method for early noninvasive diagnostics of caries lesion of human tooth using terahertz spectroscopy is possible.

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