Dentinal microgrooves fabricated via femtosecond laser Gaussian/Bessel beams

Femtosecond laser processing offers considerable potential for precision dental treatment and restoration, yet the ablation characteristics of different beam types in dentin remain insufficiently understood. This study compared Gaussian- and Bessel-beam processing for the fabrication of dentinal microgrooves. Gaussian-beam processing produced well-defined microgrooves with depths of up to 2179µm. Combining axial focal-position adjustment with array scanning enabled controllable three-dimensional fabrication, with a strong linear relationship between microgroove width and depth (R²=0.992). The maximum depth was approximately 1 order of magnitude greater than that obtained using fixed-focus processing. In contrast, under the available laser power and optical configuration, Bessel-beam irradiation at a nominal incident fluence of 2.829J/cm² did not produce stable deep ablation. The resulting morphology was mainly associated with cumulative energy deposition rather than efficient material removal. These findings clarify the different processing behaviors of Gaussian and Bessel beams in dentin and provide practical guidance for fabricating deep dentinal microstructures. This work may support the further development of femtosecond-laser techniques for precision dental treatment and restoration.