Recently, it has been demonstrated that the hard tissue can be removed without thermal damage by excimer laser irradiation. KrF excimer laser produced defect with clean-cut margins on the teeth. But, our data demonstrated that thermal side effects of the ArF excimer laser was less than that of the KrF excimer laser. In addition to, we investigated the effects of the enamel and dentin by Er : YAG laser irradiation. Combining the Er : YAG laser with a water produced defect without signs of

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... thermal injuries. Undesirable thermal effects like surface-cracking and carbonization were not observed. These finding suggested that Er : YAG laser was superior to excimer laser in the case of removing the dental hard tissurs, clinically. Because, Er : YAG laser can use the fiber system and is not UV laser.