[Significance of the CO2-laser angle, oral cavity endoscopes]

The CO2-laser ray guided at 90 degrees to the surface creates a crater of typical "v" shape. If the guide angle of the ray deviates therefrom and the smaller the angle of incidence than 90 degrees, destruction becomes the more astymmetric, the crater takes an ever more flattened eliptical shape. The lack of tissue becomes even more superficial, thus removal of a circumscribed pathological area requires the sacrifice of more ambient healthy tissue. Consterning the possible angle of incidence of the laser ray instrumental measurements were carried out. It has been ascertained that in the pharinx third of the mouth cavity behind the plain corresponding to the premolars, as a rule, only guide angles below 50 degrees, in the middle third of the mouth cavity corresponding to the area between the front teeth and the molars guide angles between 50-70 degrees, and in the front third mostly a ray guiding below 90 degrees are possible. In the middle and rear third of the mouth cavity the ideal rey-guiding at 90 degrees can be obtained but with reflection, certain areas even cannot be treated directly, are visible but in mirrors. By transforming the hand piece of the laser apparatus endoscopes with fixed mirror and rotating mirror have been constructed. By means of the endoscope with fixed mirror already all parts of the mouth cavity have been rendered accessible while the rotating mirror model became suitable even to admit the laser ray to the surfaces at the ideal angle of incidence of 90(2).