THERMAL EFFECTS OF CO2-LASER ON THE PULPAL CHAMBER AND ENAMEL OF HUMAN PRIMARY TEETH - AN IN-VITRO INVESTIGATION

Background and Objective: Thermal effects of direct exposure of the pulp chamber to CO2 laser irradiation were evaluated and potentially safe parameters for its clinical application were determined. Study Design/Materials and Methods: Using conventional methods, the pulp chambers of freshly extracted primary cuspids were exposed and then subjected to CO2 laser irradiation at the following parameters: 2, 4, 6, 8, 10, 15, and 20 Watts power settings; 0.76 mm diameter spot size; total energy densities between 4-1,058 J/cm(2) exposure time between .01-60 s. Exposures in the continuous wave mode were performed in some specimens. In others, single firings of a .01 s pulse duration and a 1 s pulse interval were conducted. Temperature measurements were conducted using a thermocouple and thermal camera. Results: Significant statistical differences in maximum temperature rise on enamel were observed in groups that received total energy densities greater than or equal to 8 J/cm(2) (P less than or equal to 0.01); within the pulp chambers these were observed in groups that used greater than or equal to 44 J/cm(2) (P less than or equal to 0.01). Conclusion: Parameters appropriate for pulpotomy were observed at energy densities up to 176 J/cm(2) in the continuous wave mode and 264 J/cm(2) using single pulses, wherein temperature rises below 5.5 degrees C were recorded on tooth surface. (C) 1995 Wiley-Liss, Inc.