Wide-field Raman Imaging of Dental Lesions

Objectives: Visualization of the mineralization status of enamel would be invaluable for early detection because caries are associated with changes in the mineralization of teeth. The capability of imaging mineral distribution over larger fields of view in a shorter time would enhance the translational prospect of Raman imaging for detecting dental caries and for surveying the success of remineralization treatments.
Methods: Human teeth were obtained under the approval of the Institutional Review Boards of CWRU. A custom wide-field Raman imaging system was integrated to acquire 2D images of mineral distribution of teeth. The system was mainly composed of a 785nm laser sources, a CCD camera, and other necessary optics. By using lower magnification lens or additional defocalization of the laser beam, larger images can be acquired.
Results: Wide-field Raman images at the transition area between the enamel and the lesion indicated that the mineral Raman signal decreased (or increased) gradually from the sound enamel to the lesion area for teeth with hypomineralized (or hypermineralized) lesions.
Regardless of the nature of the lesion in teeth, hypo or hypermineralized, the wide-field Raman imaging is capable of detecting inherent differences in mineralization levels, and the qualitative discrimination was in agreement with the traditional point-and-shoot Raman mapping.
Conclusions: Wide-field Raman imaging can discriminate a sound enamel from a lesion in human teeth based on the contrast of the mineral Raman signal distribution. Wide-field Raman imaging is a promising method in early dental caries detection and can be applied in a fashion to check suspected locations.