1995 Volume 6 Issue 1 Pages 8-15
Recently, it has been demonstrated that the soft and hard tissue can be ablated with minimal thermal damage by Er: YAG laser irradiation. However, there are a few studies about the effects of the Er: YAG laser on the bone tissue.
The purpose of this study was to investigate the morphological changes of the bone structure by Er: YAG laser irradiation. Twenty extirpated mandibula were used. Er: YAG laser was irradiated on the buccal surface of the rat's mandibula under the conditions; wavelength; 2.94μm, output; 5mJ/pulse, energy density; 16J/cm2. In the ten of the sample mandibula, a continuous water flow was maintained at the bone surface that allowed a gentle water trickle during laser irradiation. The other half mandibula were irradiated without any such water flow. Histological and scanning electron microscopical studies were perfomed. Er: YAG laser beam produced defect without signs of serious thermal injuries in both cases. Undesirable thermal effects like surface-cracking and carbonization were not obseved. Histological examinations revealed presence of the thin basophilic line at the bottom and along the wall of defects. These was minimal evidence of thermal damage on the surrounding tissue. Combining the Er: YAG laser irradiation with a water flow produced encouraging results. The application of water to the irradiated bone surface increases ablation efficiency with less thermal damage. These results suggest that the Er: YAG laser should be used with a water flow if vital bone are subjected to testing. The mechanism of the Er: YAG laser in this study has not been clarified yet. Therefore more resarch is necessary before Er: YAG laser may be used in the clinical field in the future.
