Application of Spatial Frequency Domain Imaging in Early Detection of Dental Caries

This study employed Spatial Frequency Domain Imaging (SFDI) at a wavelength of 530 nm and a spatial frequency of 0.4 mm^-1 to measure the reduced scattering coefficient (μ_s') of artificially demineralized dental tissues across various demineralization durations. Scanning electron microscope and polarized light microscope were utilized to detect surface morphology and demineralization depth. Results show that μ_s' of dental tissue increases nonlinearly with demineralization time. μ_s' of human dental tissue increased from 0.403 to 0.897 mm^-1 in 72 h, while that of bovine dental tissue increased from 0.604 to 1.420 mm^-1. The demineralization depth of bovine dental tissue increased from 0 to 169.83 μm. Artificial caries models with various demineralization durations showed a positive nonlinear correlation between μ_s' and depth of demineralization, with a correlation coefficient of 0.9673. It demonstrates SFDI's capability for nondestructive detection of early caries.