It has been reported that CO2 laser energy can be utilized to etch enamel. However, consistency of etching has been a significant problem. This research was designed to ascertain which exposure parameters result in consistent etching of enamel. Fourteen non.carious teeth were selected and a 2x4 gridwork was cut into the buccal surfaces creating eight discrete windows for laser exposures. Four teeth served for the initial pilot project. Two windows were lased at each combination of exposure parameters. Laser exposures were at .01, .02, .05, or .10 sec. at 2, 5, 10, or 15 Watts (W) with a model 20C Pfizer CO2 laser. A 1.0mm focal spot was used throughout. Following SEM examinations, it became clear that etching occurred only at .05 and .10 sec. at 10 and 15W. Ten teeth were used for the main project at .05 and .10 sec. exposures at 10 and 15W. Ten windows were lased for each combination of exposure parameters. SEM analysis was accomplished at 100X and 1,200X. 10/10 laser exposures at .05 sec./15W, .10 sec./10W and .10 sec./15W resulted in etched enamel. Statistical analysis showed a significant difference in etching between the .05 sec.10W group and the higher exposure parameters (p= .003). The results indicate that CO2 laser energy can consistently etch enamel at .10 sec. at 10 or 15W and at .05 sec. at 15W with a 1.0mm focal spot
