2008 Volume 51 Issue 2 Pages 156-162
The aim of the study was to assess the effects of Er: YAG laser irradiation equipped with a cone-shaped tip (300μm inner-diameter) on root canal walls of extracted human teeth and on bovine dentin slices. Human teeth mechanically prepared using K-files were irradiated by Er: YAG laser at the output powers of 30 mJ and 40 mJ without air and water cooling. Subsequently, the samples were split longitudinally and observed under a scanning electron microscope (SEM). SEM showed the crater formation with the removal of smear layer and open dentinal tubules, free of melting, crack, and carbonization. The size of open tubules by laser was smaller than that by chemical irrigation using EDTA. In addition, Er: YAG laser was applied to bovine dentin surfaces with a thickness gauge (50, 100, or 150μm) between the tip and dentin slices. Laser microscopic analysis revealed that the ablation effect of Er: YAG laser largely decreased by distance between the tip and dentin wall. These results indicate that the Er: YAG laser in conjunction with a cone-shaped tip is a suitable tool for removing the smear layer in root canals. Moreover, it was suggested that in the apical third of the root canal the use of a tip which fits the size of enlarged canals is necessary for the efficient cleaning of the mechanically prepared canal wall.
