Detection and Characterization of Human Teeth Caries Using 2D Correlation Raman Spectroscopy

 Carious lesions are formed by a complex process of chemical interaction between dental enamel and its environment. They can cause cavities and pain, and are expensive to fix. It is hard to characterize in vivo as a result of environment factors and remineralization by ions in the oral cavity.  The development of a technique that gives early diagnosis which is non-invasive, is of crucial importance for publichealth. Raman spectroscopy is a technique that can fulfil these requirements. The main goal of this work was to use Raman spectroscopy to differentiate between normal and carious human teethinvivo. The samples used in this study were collected by traditional human teeth.  An in vivo Raman spectroscopy system andspecialized fiber optic probe has been designed to obtain spectra from tissue. Theseprobes are filtered to reduce the background signal from the fiber optics and the collection fiberutilizes beam steering to optimize the collection effectiv.  In order to detect any demineralization and carious versus sound pit and fissure enamel, the spectral data sets are analyzed by the proposed scheme to demonstrate the utility of generalized 2D correlation spectra. Potential applications of this 2D correlation approach are then explored. The Raman spectra in the normal tissue showed thepresence of vibrational bands in 437.87 cm-1, 581.89 cm-1, 953.89 cm-1 and 1054.73 cm-1 with smaller intensity than in the carious spectra. Image construction from the peak intensity produced chemical maps of apatite concentration. Such two-dimensional correlation spectra emphasize spectral features not readily observable in conventional one-dimensional spectra.No correlation is observed in mode-to-mode intensity fluctuations indicating that the changes inmode intensities are completely independent. Theoreticalcalculations provide convincing evidence that the fluctuationsare not the result of diffusion, orientation or local electromagnetic field gradients but rather are the result of subtle variations ofthe excited-state lifetime, energy and geometry of the molecule and producing a signature response for carious detection.