title: Ex vivo detection and characterization of early dental caries by optical coherence tomography and Raman spectroscopy.
abstract: 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 microm 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 PO4 (3-) vibrations arising from hydroxyapatite of mineralized tooth tissue. Examination of various ratios of PO4 (3-) nu2, nu3, nu4 vibrations against the nu1 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.
authors.affiliation: National Research Council Canada, Institute for Biodiagnostics, 435 Ellice Ave., Winnipeg MB, Canada R3B 1Y6.
authors.forename: Alex C-T
authors.initials: AC
authors.lastname: Ko
authors.forename: Lin-P'ing
authors.initials: LP
authors.lastname: Choo-Smith
authors.forename: Mark
authors.initials: M
authors.lastname: Hewko
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Leonardi
authors.forename: Michael G
authors.initials: MG
authors.lastname: Sowa
authors.forename: Cecilia C S
authors.initials: CC
authors.lastname: Dong
authors.forename: Peter
authors.initials: P
authors.lastname: Williams
authors.forename: Blaine
authors.initials: B
authors.lastname: Cleghorn
mesh_terms: D001641:Bicuspid / Q000473:pathology*; D003731:Dental Caries / Q000473:pathology*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005336:Fiber Optic Technology / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D066298:In Vitro Techniques; D055100:Optical Fibers; D011379:Prognosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D013059:Spectrum Analysis, Raman / Q000295:instrumentation* / Q000379:methods; D041623:Tomography, Optical Coherence / Q000295:instrumentation* / Q000379:methods