We applied hyperspectral imaging (HSI) system to distinguish early caries from sound and pigmented areas. It will provide a theoretical basis and technical support, for research and development of an instrument that could be used for screening and detection of early dental caries.

Eighteen extracted human teeth (molars and premolars), with varying degrees of natural pathology and no degree of decay involving dentin were obtained. HSI system with a wavelength range from 400 to 1000nm was used to obtain images of all 18 teeth containing sound, carious and pigmented areas. We compared the spectra of the wavebands at both 500nm and 780nm from the different tooth states, and the reflectance difference between sound versus carious lesions and sound versus pigmented areas, respectively.

There was a slight difference in reflectance between carious areas and pigmented areas at 500nm. A substantial difference was additionally noted in reflectance between carious areas and pigmented areas at 780nm.

The results have shown that the interference of tooth surface pigment can be eliminated in the near-infrared (NIR) waveband, and the caries can be effectively identified from the pigmented areas. Thus, it could be used to detect carious areas of teeth in place of the traditional visual inspection method or white light endoscopy.

The NIR diffused light signal enables the identification of early caries from pigment and other interference, providing a reasonable detection tool for early detection and early treatment of teeth diseases.