Morphological comparative study on ablation of dental hard tissues at cavity preparation by Er:YAG and Er,Cr:YSGG lasers

Objective: The purpose of this study was to evaluate morphologically the dental hard tissue ablation at the class V cavity preparation by two types of laser devices: Er:YAG and ErCr:YSGG lasers in vitro. Background Data: There have been no reports on the comparative study of dental tissue ablation at cavity preparation by Er:YAG and ErCr:YSGG lasers. Methods: Twenty-two extracted human mature molar teeth were used in this study and divided into two groups of 11 teeth each. The teeth of the Er:YAG laser-irradiated group were irradiated at the parameters of 250 mJ/pulse and 15 Hz with water spray, and those of the ErCr:YSGG laser-irradiated group were irradiated at the parameters of 5 W and 20 Hz with water spray. After cavity preparation, the teeth were dehydrated, coated with platinum, and examined by scanning electron microscopy. Results: Both of the laser devices were capable of ablating dental hard tissues, but similar, irregular, and rugged surface aspects with different depths were observed. Open dentinal tubules at the cavities prepared by Er,Cr:YSGG laser were more clearly visible than those prepared by Er:YAG laser. Smaller width and stripped surfaces were observed on the cavities prepared by ErCr:YSGG laser. Conclusion: The results suggested that there is little difference between the two types of lasers-Er:YAG and ErCr:YSGG lasers-morphologically for class V cavity preparation, because both lasers were capable of preparing class V cavities, and the morphological features of the irradiated surfaces were very similar.