Interaction of Carbon Dioxide Laser Radiation with Enamel and Dentin

Extracted human teeth were exposed to con-tinuous CO2 laser radiation at 10.61t. Ground sections showed disrupted enamel rods and incineration of odontoblastic processes in dentin. Microradiographs of enamel con-firmed the changes observed, which were probably due to high temperature elevation at the site of interaction together with heat flow from this region. Many attempts have been made to alter tooth enamel to increase its resistance to caries. If it were possible to eliminate the pits and fissures from the enamel surface by fusing or "welding " the enamel, the susceptibility of teeth to caries might be considerably de-creased. In a previous report, ' the gross and micro-scopic findings of the interaction of oral hard tissues and pulsed ruby laser radiation at 0.69344t was presented. Although the enamel surface appeared glazed, opaque, and hard, it was brittle, and true fusion of enamel was not accomplished. Other investigators2-4 who have used ruby laser radiation have reported similar findings. The purpose of these studies was to deter-mine the feasibility of fusing enamel by using high-power-density, continuous-wave (CW) radiation at 10.6Qt, as made available by CO2 lasers. The gross and microscopic findings of the interaction of CW radiation on calci-fied tissues was compared with short-pulse