Effect of Nd: YAG Laser on Human Dentin Fluid Flow

Objectives: The aim of the current investigation was to assess the rate and magnitude of dentin fluid flow of dentinal surfaces irradiated with neodymium-doped yttrium aluminum garnet (Nd:YAG) laser. Materials and Methods: Thirty extracted intact molars were sectioned, mounted and irradiated with Nd:YAG laser at 2-W power setting. The samples were automatically irradiated at sequential runs until dentin surfaces were completely irradiated. Samples were divided into 3 groups; group 1: the dentinal-fluid flow was measured over 5 minutes after irradiation, group 2: dentinal-fluid flow was measured over 10 minutes after irradiation and group 3: teeth were immersed in 1% sodium hypochlorite, then irradiated and dentinal-fluid flow was measured over 10 minutes after the end of irradiation. Dentinal-fluid flow was measured using fluid-flow apparatus. The rate, magnitude and direction of dentin-fluid flow were recorded at baseline and after irradiation. Results: Non-parametric Wilcoxon Signed Ranks repeated-measure t-test and KruskalWallis ANOVA test revealed a statistically significant increase in fluid flow after laser treatment. However, no significant differences were found between the groups. The samples demonstrated a baseline outward flow followed by inward flow due to irradiation followed by increased outward flow. Conclusions: Nd:YAG laser at 2-W power setting has significantly increased dentinal-fluid flow rate. The removal of smear layer with sodium hypochlorite prior to irradiation did not have any effect on the fluid flow rate.