INTRAPULPAL TEMPERATURES DURING PULSED ND-YAG LASER TREATMENT OF DENTIN, IN-VITRO

LASERS ARE BEING USED FOR SOFT TISSUE REMOVAL, caries removal, and tre atment of root surface sensitivity. One concern for laser safety is th at the heat produced at the irradiated root surface may diffuse to the pulp causing irreversible pulpal damage. To test this heat diffusion, copper-constantan thermocouples were inserted into the radicular pulp canals of extracted teeth. Simulating direct exposure which might occ ur during gingival excision, superficial caries removal, and modificat ion of the dentin surface for treatment of root surface sensitivity, a 2 mm(2) area of the external root surface was uniformly irradiated wi th a pulsed Nd:YAG laser using a 320 mu m diameter fiber optic contact probe. Power was varied from 0.3 to 3.0 W with frequencies of 10 and 20 Hz. Temperature changes during cavity preparations using a high spe ed handpiece with air coolant were also recorded. Repeated measures AN OVA (P less than or equal to 0.05) indicated that intrapulpal temperat ures increased as a function of power, frequency, and time. Intrapulpa l temperatures decreased as remaining dentin thickness (0.2 to 2.0 mm) increased for each laser parameter. Irradiation of dentin using a Nd: YAG pulsed laser, within the treatment times, powers, and frequencies with adequate remaining dentin thickness, as outlined in this paper, s hould not cause devitalizing intrapulpal temperature rises.