Aim: The parameters of the laser-used cavity preparation and roughening procedures are important for their effects on hard tissue. We aimed to analyze the in vitro ablative and etching effect of the Erbium Chromium, Yttrium Scandium Gallium Garnet (Er, Cr: YSGG) laser on the human dentin using scanning electron microscopy (SEM), comparing six different laser parameters in this study. Materials and Methods: Seven non-carious, sound-extracted human third molar teeth were used. To abrade the teeth and expose the dentine, a diamond bur was used. The laser was applied to the dentin surface of the teeth with 1–6-Watt (W) power, and a tooth was left for control. All examples were evaluated with a SEM. Results: SEM observation of the irradiated dentin showed that different energy parameters did not give the same results because of the presence of induced alterations (microcracks, melting, flakes) resulting from the thermal effect. It was observed that the effect created by using 1-2 W created indentations similar to chemical etching. Hard tissue ablation was also observed at 4-5 W parameters, and tissue melting and crack formation was observed at 6 W parameters. Since the study focused on morphological changes, statistical analysis was not performed. Conclusion: Lower energy levels (1-2 W) are advised for etching, while higher levels (4-5 W) are suggested for cavity preparation in dentin. Avoidance of energy levels exceeding 6 W is recommended. Further studies with increased variables and sample sizes are needed on this topic.