Non-invasive in vivo screening of oral malignancy using laser-induced fluorescence based system

About 4000 spectra from oral cavity sites have been recorded in vivo from 380 volunteers, under normal (n=133), potentially malignant (n=155), and malignant (n=92) conditions, by excitation with 325 nm CW He-Cd laser. The analyses of the spectra show that the overall spectra arise from about 7–8 bands from different molecular species. In healthy condition (from subjects with no abnormal oral conditions, including tobacco use), buccal mucosa, lip underside, and tongue bottom give spectra very similar to each other, while tongue top, tongue lateral, and palate give spectra different from these as well as from each other. Under potentially malignant and malignant conditions all sites give spectra which are noticeably different for different sites and under different conditions. It is therefore advisable to use separate reference data sets of normal, potentially malignant, or malignant conditions for different sites for optical diagnostic applications.