The status of in vivo autofluorescence spectroscopy and imaging for oral oncology.

Autofluorescence spectroscopy and imaging have been studied for the early detection and classification of (pre)malignancies of the oral mucosa. In the present review we will give an overview of the literature on autofluorescence imaging and spectroscopy for various clinical questions. From the studies performed so far we hope to conclude whether autofluorescence spectroscopy and imaging are helpful in the diagnosis of lesions of the oral mucosa, and if this is the case: for which clinical questions they are suitable. A strong emphasis is put on in vivo human studies of the oral mucosa.

[Lasers in dentistry 8. Use of lasers in oral and maxillofacial surgery]. / Lasers in de tandheelkunde 8. Het gebruik van lasers bij mondziekten en kaakchirurgie.

Since the 1970's lasers are used in oral and maxillofacial surgery. The effect of a laser on tissue is determined by the wavelength of the laserlight and the tissue specific absorbtion. Lasers are used for evaporation, excision and coagulation of tissue. The CO2-laser, the Nd:YAG-laser and the Argonlaser are used for these purposes. Light and laserlight are used for the diagnosis of mucosal lesions. By using different excitation wavelength autofluorescence of lesions can be detected and analysed. An artificial neural network can be used to analyse these data. Photodynamic Therapy (PDT) is a cancer therapy based on the more or less specific absorption of a drug in tumour, that can be activated with light of a specific wavelength. Activation of this drug causes tumour destruction due to the formation of oxyginradicals. PDT is limited by the penetration of the activating light and is therefore only suitable for the treatment of superficial tumours.

Autofluorescence and Raman microspectroscopy of tissue sections of oral lesions.

Autofluorescence spectroscopy and Raman spectroscopy have been suggested for lesion diagnostics. We investigate the information contained in autofluorescence and Raman spectra recorded from oral tissue slices of various lesion types. Thirty-seven human oral mucosa lesions were biopsied and freeze-dried. Complete autofluorescence images and spectra were recorded from 20 microm sections. Raman spectra were acquired from the same positions for 12 of the sections. Cluster analysis was applied to find any relationship between spectral shape and lesion type or cell layer. Autofluorescence images showed high intensities for keratin layers and connective tissue, but hardly any for the epithelium. Autofluorescence spectra were centered around 520 nm and did not show specific spectral features. No clustering with regard to lesion type or cell layer was observed. Raman spectra allowed for reliable classification into cell layers, but differences between lesion types were not significant in this study. Autofluorescence spectra of freeze-dried oral mucosa sections did not contain useful information. A more comprehensive study is required for Raman spectra.