If you agree to take part in this study, a researcher may use fluorescence and/or widefield fluorescence imaging instruments to take pictures of several areas in the mouth. Then, the researcher may gently place point spectroscopy probe on 1-4 normal-looking areas and 1-4 abnormal areas. Different colors of light will be shone on the lining of the mouth through the probe. The light that returns from the tissue is collected through the probe and recorded on the computer.