WET VERSUS DRY ENAMEL ABLATION BY ER-YAG LASER

The purpose of this study was to observe tooth structure and pulpal temperature changes in extracted human teeth subjected to a pulsed Er:YAG (2.94-mu-m) laser. Two teeth were irradiated while dry and three teeth while moistened by a fine water mist. When the dry teeth were irradiated, there was minimal enamel ablation. SEM of the resulting surface showed rounded fragments of enamel rods, enamel melting, cracks, and smooth-edged voids. Intrapulpal temperature measured by thermal sensor rose more than 27-degrees-C. When the laser application on the teeth was pulsed with a constant fine water mist, enamel and dentin were efficiently ablated. SEM of the resulting surfaces showed fissures and conical craters with sharp enamel projections remaining. Intrapulpal temperatures rose an average of 4-degrees-C. These results indicate that pulsed Er:YAG (2.94-mu-m) used with a water mist removes enamel and dentin without producing significant pulpal temperature changes.