Nondestructive measurement of the inhibition of demineralization on smooth surfaces using polarization-sensitive optical coherence tomography

Background and Objective: The objective of this study was to test the hypothesis that the inhibition of demineralization in an in vitro simulated caries model by different fluoride agents could be monitored nondestructively using polarization-sensitive optical coherence tomography (PSOCT) on smooth enamel surfaces peripheral to orthodontic brackets. Materials and Methods: Sixty human molar samples used for this in vitro study were divided into four groups of fifteen. The groups consisted of a control, a fluoride releasing glass ionomer cement, an adhesive fluoride sealant, and fluoride in solution (2-ppm fluoride). The reflectivity from tooth surfaces was monitored using a PS-OCT system at different time points after exposure to a pH cycling demin/remin model at 3-day intervals for 15 days. Polarized light microscopy (PLM) was used to examine lesion depth after day 15. Results: PS-OCT was effective at measuring significant differences in the integrated reflectivity in depth between the control and fluoride groups (P < 0.001). The fluoride sealant demonstrated a greater protective effect than the fluoride in solution and the glass ionomer cement. Conclusions: These results suggest that PS-OCT is well suited for the nondestructive assessment of caries inhibition by anti-caries agents.