Morphological Study on Preparation of Root Canal Orifices by Er : YAG Laser

Abstract

Abstract : The purpose of this study was to evaluate the cutting ability of root canal orifices and walls as well as the exposure of root canal entrances by a Er : YAG laser beam. For this study, 42 human extracted teeth and the prototype Er : YAG laser device were used. The laser parameter was fixed at 8 Hz and 250^mJ/_pulse. The exposure time of a laser beam was 60 seconds in a single root case and 120 seconds in multiple root cases. Keeping the laser tip of holotube type on the root canal orifices, the laser irradiation was carried by the non-contact method. The evaluation of this research was done by the examination of X-ray pictures as well as the LM and SEM pictures. The results were as follows :

 The root canal orifices and walls of all specimens could be clearly exposed at the parameter of 8 Hz and 250^mJ/_pulse for 60 seconds and 120 seconds laser irradiation. In the cases of the curved root canals, the possibility of the perforation of the root canal wall was observed radiographically. So, it was mentioned that it was necessary to decrease the irradiation time or power in the curved root canals. The root canal surface lased by a Er : YAG laser beam showed the smooth surface with a LM and the scale-like structure with a SEM. Of course, there were little debrisses on the root canal surface. In some cases, the zip formation on the root canal wall close to the orifices could be observed with the radiographic examination.