Development of a new diagnosis method for caries in human teeth based on thermal images under pulse heating

A new diagnosis method based on the pulse heating thermographic NDT was proposed for the incipient caries of human teeth. Experimental study was made on the applicability of the proposed method to the quantitative evaluation of location and shape of the incipient caries as well as the quantitative diagnosis of the degree of incipient caries. The incipient caries were artificially introduced to the extracted human teeth in various severities. Impulse heat flux by the xenon flash lamp was applied to the surface of the tooth and sequential thermal images were taken by the high-speed infrared thermography. It was found that the caries were clearly identified as the localized high temperature region in the sequential thermal images. Coefficients of the temperature descent were obtained from sequential thermal images. It was found that the degree of the demineralization, i.e. the degree of incipient caries was evaluated from temperature descent coefficients.