Abstract
Objective: This study was performed to investigate the changes in temperature induced by an Er:YAG laser irradiation and to find the means to minimize potential thermal damage due to temperature rise after irradiation. Background Data: Intrapulpal temperature rise was found to last after irradiation at times, although the addition of appropriate water spray during tooth ablation by Er:YAG laser produced efficient ablation with little thermal damage. Methods: To investigate intrapulpal temperature change, each extracted tooth specimen was embedded into a resin block and temperature-measuring probes were placed on the irradiated and the opposite pulpal walls. An Er:YAG laser irradiation was performed at 300 mJ/pulse and 20 Hz, with a water flow rate of 1.6 mL/min for 3 sec. Each lasing was followed by (1) no application of post-irradiation water spray, (2) post-irradiation water spray for 1 sec and (3) for 2 sec. Results: No significant temperature change was found on the irradiated pulpal wall during Er:YAG laser, while there existed significant temperature rise on the irradiated pulpal wall after irradiation. However, the addition of water spray for 1 or 2 sec after irradiation significantly decreased intrapulpal temperature compared to no application of post-irradiation water spray. There were no significant differences between the 1- and 2-sec groups. Conclusion: It is suggested that the addition of water spray for 1 or more seconds after irradiation reduces post-irradiation temperature rise, possibly leading to thermal damage on the dental pulp tissue.
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