Nd:YAG laser transmission through enamel and dentin

摘要

Abstract: Laser energy transmission through enamel and dentin may effect pulpal safety. In this research, energy transmission was measured by placing enamel and dentin samples directly on an optical detector (both specular and diffuse transmission). Recently-extracted non-carious third molars were cut at thicknesses of 0.5, 1.0, 1.5, and 2.0 ($POM 0.25) mm. Laser exposure was effected using a pulsed contact-delivered infrared Nd:YAG laser with 320 $mu@m fiberoptic probe, moved continuously across the surface for 30 seconds per measurement. Transmitted energy was measured following every 50 pulses; three replications were performed per treatment condition. Power was applied on enamel and dentin at 8 parameters: 0.3, 0.5, 0.7 and 1.0 W with frequency of 10 Hz and at 1.0, 2.0, 2.5, and 3.0 W with frequency of 20 Hz (total measurements n $EQ 864). Multifactor ANOVA confirmed that transmission through enamel was greater than through dentin. Energy transmission increased with both power and frequency. In enamel, transmission decreased as thickness increased. The most significant determinant of energy transmission was the incident surface energy per pulse. Means for samples 0.5 mm thick, at 1 W, 10 Hz: in enamel, 53% of the laser energy was transmitted through the sample, compared with 14% through dentin. For samples 2.0 mm thick: in enamel, 38% of the laser energy was transmitted compared with 17% in dentin.!22