Purpose: The aim of this study was to evaluate Nd:YAG laser irradiation for its potential usefulness to achieve in vivo human pulp anesthesia. Materials and Methods: Thirteen faculty members from the Tsurumi University School of Dental Medicine participated in this study, following review of the Nd:YAG laser irradiation test protocol by the University Human Subject Committee. Thirteen canines served as controls and 13 served for experimental tests. For heat application and measurement of pulpal response, an electrothermal stimulator was used (Unique Medical: UDH-104), which consisted of a heat probe and a pain thermometer. The buccal surface of each of control tooth was heated to 65°C with the tip of the heat probe, and each patient reported extreme sensitivity at that temperature. The gingivobuccal epithelium adjacent to each of the 13 experimental mandibular canines was coated with India ink and irradiated with an Nd:YAG laser for 30 s at 120 mJ, 10 pps. The degree of pulp sensitivity response was measured by the pain thermometer immediately before and after each Nd:YAG laser irradiation treatment. Results: Temperature sensitivity threshold increased significantly after each laser irradiation treatment (Wilcoxon signed-rank test). Conclusion: The thermal pain perception threshold level for each pulp was significantly increased immediately following Nd:YAG laser irradiation. After one week, the increased pain thresholds for each tooth returned to the pretreatment values. It is suggested that Nd:YAG laser irradiation has anesthetic effects on human pulp.
Keywords: Nd:YAG laser, pulp, anesthetic effect, thermal pain threshold, temperature sensitivity, pain thermometer