Pulpal effects of a high rep rate Nd:YAG laser

Molar teeth in male rats were used in this study to assess the effects of enamel surface treatments of pulp survivability. The occlusal surfaces of the first and third molars in each quadrant were treated with an Nd:YAG laser (Pulsemaster, Incisive Technologies, Inc.) using a 300-mum contact tip fiber, in a figure-8 motion, for a 30 sec ablation time. The second molars were not treated. Energy parameters/animal were as follows: (1) 0.6 W, 30 mJ energy, and 20 Hz, (2) 1.2 W, 30 mJ energy, and 40 Hz, (3) 1.8 W, 30 mJ energy, and 60 Hz, (4) 2.4 W, 30 mJ energy, and 80 Hz, (5) 0.6 W, 60 mJ energy, and 10 Hz, (6) 1.2 W, 60 mJ energy, and 20 Hz, (7) 1.8 W, 60 mJ energy, and 30 Hz, (8) 1.0 W, 100 mJ energy, and 10 Hz, and (9) 2.0 W, 100 mJ energy, and 20 Hz. Animals were sacrificed at two time periods (1 and 6 weeks, postoperatively). SEM analysis of enamel was performed at 2000x magnification to observe the parameter difference in surface quality. Microscopic examination of the histological samples was accomplished at 250x magnification. Surface analyses of tooth structure revealed a wide dispersion of enamel roughness, ranging from slightly etched to moderately cavitated. Power levels above 2.4 W exhibited significantly more roughness than lower energy parameters. Efforts were made to correlate the pulp biology effect with enamel surface condition to determine a safe threshold for survivability of the pulp tissue.(ABSTRACT TRUNCATED AT 250 WORDS)