Pulsed Nd : YAG laser irradiation of the tooth pulp in the cat: I. Effect of spot lasing

Background and Objective: The purpose of the present study was to evaluate physiologically pulpal nerve responses and to elucidate histopathologically the pulp tissue reactions to "spot irradiation" with a pulsed Nd:YAG laser . Study Design/Materials and Methods: Antidromic compound action potentials a nd the pulpal blood flow (PBF) were recorded from the canine tooth of a sod ium pentobarbitone-anesthetized cat. The laser irradiation-induced pulp tis sue changes were histologically investigated. Results: The coronal antidromic compound action potentials disappeared in a ll the teeth tested during lasing, and the time needed to erase them was si gnificantly shortened with increases in lasing power (P < 0.05), The radicu lar PBF increased when spot irradiation was performed, and the coronal PBF also temporarily increased with low-powered lasing, Histologic investigatio n revealed that spot irradiation with the laser produced severe damage in t he pulp tissue in a dose-dependent manner. Conclusion: The present study suggests that spot irradiation with a pulsed Nd:YAG laser risks producing nerve injury and irreversible tissue damage in the pulp with lasing for the purpose of desensitizing hypersensitive denti n, Lasers Surg. Med. 26:398-404, 2000. (C) 2000 Wiley-Liss, Inc.