Histopathological changes in dental pulp irradiated by Er:YAG laser: a preliminary report on laser pulpotomy

OBJECTIVE: The effects of Er:YAG laser irradiation on the pulp tissue during a pulpotomy procedure were evaluated histopathologically. BACKGROUND DATA: The effects on pulp tissue during laser pulpotomy using Er:YAG laser irradiation are not clear. MATERIALS AND METHODS: Sixty mesial root canals of mandibular first molars in rats were divided into four groups. In three of these groups, root canals were irradiated using an Er:YAG laser at 2 Hz and 34, 68, and 102 mJ/pulse for 15 sec. Non-irradiated canals served as controls. The effects of laser irradiation on the remaining pulp tissue and periodontal tissues were evaluated at 0 days, 2 days, and 1 week after irradiation under light microscopy. RESULTS: At 1 week after treatment, no inflammation or resorption was observed in any cases in the control or 34 mJ/pulse-irradiated groups. However, moderate to severe inflammation was observed in 9 of 10 cases (90%) in the 68 and 102 mJ/pulse-irradiated groups. CONCLUSION: These results suggest that effects on pulp tissues during a pulpotomy procedure by Er:YAG laser irradiation are minimal, if appropriate parameters are selected, and this is a potential therapy for pulpotomy of human teeth.