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15 February 2006 Characterization of early dental caries by polarized Raman spectroscopy
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Proceedings Volume 6137, Lasers in Dentistry XII; 613706 (2006)
Event: SPIE BiOS, 2006, San Jose, California, United States
The early approximal caries lesion in enamel is observed clinically as a white spot and is difficult to detect and/or monitor with current methods available to dentists. New methods with high sensitivity and specificity are required to enable improved early dental caries diagnosis. Using unpolarized Raman spectroscopy to examine unsectioned teeth, peak intensity changes in the phosphate (PO43-) vibrations (ν2, ν3 and ν4) were observed between spectra of sound and carious enamel. However, there is little change in the ν1 vibration with this approach. In contrast, when tooth sections were examined by unpolarized Raman spectroscopy, marked changes in the ν1 peak at 959 cm-1 were noted between healthy and carious enamel. These differences suggest that sampling orientation play a role in understanding the spectral changes. Using polarized Raman spectroscopy to examine unsectioned samples, cross polarized measurements from sound enamel exhibited significant reduction of the ν1 peak compared with parallel polarized measurements. A similar reduction was observed with carious enamel, however, the reduction was not as prominent. By calculating the depolarization ratio of the area under the ν1 peak, sound enamel can be clearly distinguished from demineralized regions. The spectral changes observed are attributed to changes in the structure and/or orientation of the apatite crystals as a result of the acid demineralization process.
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Lin-P'ing Choo-Smith, Alex C.-T. Ko, Mark D. Hewko, Cecilia C. S. Dong, Blaine M. Cleghorn, and Michael G. Sowa "Characterization of early dental caries by polarized Raman spectroscopy", Proc. SPIE 6137, Lasers in Dentistry XII, 613706 (15 February 2006);

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