Ex vivo detection and characterization of early dental caries by optical coherence tomography and Raman spectroscopy

Early dental caries detection will facilitate implementation of nonsurgical methods for arresting caries progression and promoting tooth remineralization. We present a method that combines optical coherence tomography (OCT) and Raman spectroscopy to provide morphological information and biochemical specificity for detecting and characterizing incipient carious lesions found in extracted human teeth. OCT imaging of tooth samples demonstrated increased light backscattering intensity at sites of carious lesions as compared to the sound enamel. The observed lesion depth on an OCT image was approximately 290 m m matching those previously documented for incipient caries. Using Raman microspectroscopy and fiber-optic based Raman spectroscopy to characterize the caries further, spectral changes were observed in PO43- vibrations arising from hydroxyapatite of mineralized tooth tissue. Examination of various ratios of PO43- v(2), v(3), v(4) vibrations against the v(1) vibration showed consistent increases in carious lesions compared to sound enamel. The changes were attributed to demineralization-induced alterations of enamel crystallite morphology and/or orientation. OCT imaging is useful for screening carious sites and determining lesion depth, with Raman spectroscopy providing biochemical confirmation of caries. The combination has potential for development into a new fiber-optic diagnostic tool enabling dentists to identify early caries lesions with greater sensitivity and specificity. (c) 2005 Society of Photo-Optical Instrumentation Engineers.