Imaging artificial secondary caries under composite sealants and restorations

Polarization Sensitive Optical Coherence Tomography (PS-OCT) was used to monitor the progression of simulated caries lesions on occlusal surfaces and image the lesions underneath composite sealants. The polarization sensitive system, recording images in both the parallel (∥) and perpendicular (τ)-axes, was useful for enhancing the image contrast of the artificial caries and minimizing the interference of the strong reflections at surface interfaces. Using the τ-axis signal, the mean integrated reflectivity increase from day 0 to day 14 was 5.1 dB (p<0.01, Repeated-Measures ANOVA, Tukey-Kramer). For imaging the lesions underneath sealants, the mean integrated reflectivity of the enamel underneath 250, 500, 750 and 1000 μm of composite was calculated for the demineralized and control samples. The artificial lesions could be detected under 750 μm of visibly opaque sealant, with a 5.0 dB difference from the control samples (t-test, p<0.001). Tooth colored sealants allowed deeper imaging depth. The artificial lesions could be detected under 1000 μm of sealant, with a 6.6 dB difference from the control samples (t-test, p<0.001). This study demonstrated that PS-OCT can be used to track lesion progression on occlusal surfaces non-destructively with or without sealants.