Laser induced molar tooth pulp chamber temperature changes.

Temperature changes in enamel tissue and the pulp chamber under the influence of a CO2 laser were measured by direct methods in vitro. X-ray diffraction analysis revealed alpha-Ca3(PO4), the high-temperature modification of enamel hydroxyapatite, thus indicating that the enamel melting temperature was above 1,000 degrees C in the interaction area of laser (continuous wave, 15 s exposure time, 1 mm spot size) and tissue. Powers of 0.5 and 1 W (continuous wave), 1.5 mm spot size, and 10 s exposure time vaporize and carbonize dentin tissue at the cavity bottom of class I preparation molars. The observed temperature rise of 4 degrees C indicates that thermal injury to the pulp tissue does not occur.