Laser-induced thermal events in empty and pulp-filled dental pulp chambers

BACKGROUND AND OBJECTIVE: The purpose of this investigation was to evaluate: 1. thermal events during laser irradiation @2.1 microns of the pulp; 2. whether these effects are adequately modeled using an empty pulp chamber/root canal. STUDY DESIGN/MATERIALS AND METHODS: In extracted human teeth, pulpal access was prepared and thermocouples placed 2, 3 mm apical to the center of the irradiation spot. Pulp-filled or empty pulp chambers were irradiated using a Ho:YAG laser: Spot Size: 1 mm; Power: 1, 2, 3.5, 4.5 W; PRR: 5, 12 Hz; DURATION: 10 sec. Thermal measurements were repeated 3x. RESULTS: Thermal trends did not differ significantly and correlated positively with power (P < 0.01), PRR (P < 0.01), irradiation duration (P < 0.05). No significant difference was determined between temperatures in empty and pulp-filled chambers at all parameters at 5 Hz and at 1-2 W at 12 Hz (P < 0.05, 2-tailed Student's t-test). At 12 Hz and > 3.5 W, pulp chamber temperatures exceeded those in pulpal tissue (P < 0.05). CONCLUSION: Pulp tissues must be present to ensure clinical relevance of thermal measurements.