Polarization-sensitive optical coherence tomography (PS-OCT) is 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 axes, is useful for enhancing the image contrast of the artificial caries and minimizing the interference of the strong reflections at surface interfaces. Using the perpendicular-axis signal, the mean reflectivity increase from day 0 to day 14 is 5.1 dB (p<0.01, repeated-measures analysis of variation, Tukey-Kramer). For imaging lesions underneath the sealants, the mean reflectivity of the enamel underneath 250, 500, 750, and 1000 µm of composite is calculated for demineralized and control samples. The artificial lesions can 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 allow 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 demonstrates that PS-OCT can be used to track lesion progression on occlusal surfaces nondestructively with or without sealants.