Monitoring of artificial incipient enamel lesions with polarization-sensitive optical coherence tomography (Conference Presentation)

Abstract

The detection of incipient carious lesions is crucial for the preservation of dental hard tissue with preventive therapies. Optical coherence tomography (OCT) based imaging has been proofed to be a valuable methodology for the depth-resolved detection of alterations at dental hard tissue. Due to changes of birefringent properties at carious lesions, the measurement of polarization properties with polarization-sensitive OCT (PS-OCT) provides an additional contrast that could enhance the detection of incipient carious lesions. The aim of the present study was to monitor changes of polarization properties during the initial demineralization process by means of PS-OCT. Therefore, 18 bovine enamel palates were demineralized up to 7 weeks in an artificial demineralization model using lactate acid and buffer solution to mimic natural caries progression. The palates were stored at pH 5.5 and 35°C with constant fluid movement. In order to detect changes of depolarization at different stages of demineralization, the degree of polarization uniformity (DOPU) was calculated from PS-OCT measurements, performed under wet and dry conditions. In addition, polarization microscopy and micro-computed tomography of thin sections were analyzed to assess lesion depth and mineral loss. Our main finding is that consecutive stages of demineralization are correlated to an increasing DOPU contrast between sound enamel and the lesion area, where the lesion area is connected to decreasing DOPU values. Our results show that PS-OCT based imaging of birefringence changes is sensitive to very early stages of the demineralization process and adds a valuable contrast for the detection and monitoring of incipient enamel lesions.