Development of a New Diagnosis Method for Incipient Caries in Human Teeth Based on Thermal Images under Pulse Heating

A new noninvasive diagnosis method based on the pulse heating thermographic NDT was proposed for incipient caries of human teeth. Experiments were conducted to study 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 with 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. A coefficient of the temperature descent was obtained from sequential thermal images. It was found that the degree of the demineralization, i. e. the degree of incipient caries was evaluated from the temperature descent coefficient. Further the proposed technique was applied to the detection of natural incipient caries in an extracted human molar tooth. It was found that natural incipient caries was also clearly identified in the thermal images.