The upper and lower anterior teeth of 3 beagle dogs, were raised under strictly controlled conditions, were cut using air turbine handpiece or by Er:YAG laser irradiation. Changes in the pulp and dentin of these teeth were examined histopathologically under light microscope and scanning electron microscope (SEM). Influence of cutting with Er:YAG laser irradiation on pulp was little different from the cutting with the airturbine handpiece. Cutting with Er:YAG laser formed secondary dentin in approximately one week except one specimen showed edema. No dentin degeneration was showed on the surface irradiated with Er:YAG laser except in a few specimens. The tooth surfaces cut with Er:YAG laser displayed irregularities but did not have smear layers when observed by SEM, and showed intensely stained layers approximately 9 μm thick. On the tooth surfaces after cutting with the airturbine handpiece, smear layers and strae and collagen-like fibers as well as the images that might indicate denaturation of the dentin by heat were observed.