Abstract
The aim of this study was to clarify the working mechanism of intra-canal irrigation by pulsed lasers. Using a high-speed camera, vapor and cavitation bubbles induced by Er:YAG laser were visualized in a water environment and in a glass root canal model. In addition, the motion of glass-bead tracers was captured in the root canal model. The vapor bubbles produced by a cone-shaped tip and flat one were different in shape and lifetime. In the root canal model, the vapor bubbles grew up and down along the canal wall, followed by the repeated formation and collapse of many smaller cavitation bubbles. The analysis using tracers showed rapid agitation caused by laser irradiation. These results suggest that the mechanism of Er:YAG laser in root canal irrigation might be attributed to high-speed fluid motion due to bubble formation and collapse. An Er:YAG laser with a cone-shaped tip may be promising for intra-canal irrigation.
