## 4 Discussion  
Earlier studies have reported surface damage when using Nd:YAG and CO\({}_{2}\) lasers, with no significant chemical alterations in zirconia and LD materials [42; 43; 44]. A study of materials similar to zirconia and LD glass ceramics by [PERSON] et al. [45] on the ablation characteristics of alumina and aluminum nitride (AlN) under _fs_-laser ablation found that the ablation characteristics of alumina were predominantly governed by intense thermal stress stemming from elevated temperatures, resulting in minimal melting. The ablation of AlN involved melting, followed by subsequent re-solidification [45]. Notably, despite undergoing laser ablation, the original chemical composition of both alumina and AlN appeared to remain unaltered, suggesting that the alterations induced by the _fs_ laser were primarily of a physical nature rather than chemically induced. Zirconia is known to undergo phase transformation from tetragonal to monoclinic phase at 1043 \({}^{\circ}\)C, accompanied by a 3% volumetric change in crystal structure [46]. This transformation leads to the formation of microcracks within the lattice. The mechanism of stress relaxation via phase transformation might create some microcracks that can propagate through fatigue, thus impacting the total lifetime of the crown and implants and preventing zirconia from failing under the localized compressive load. This mechanism helps explain how failure of veneers can occur by chipping without exposing the zirconia support layer. [PERSON] et al. [47] suggested that Nd:YAG dental laser welding should not be performed on tetragonal zirconia due to the risk of inducing phase transformation and microcrack formation within the material. A recent study by [PERSON] et al. [48] using X-ray diffraction analysis identified the presence of monoclinic crystals on surfaces treated with _ns_- and _ps_-pulse lasers. A study by [PERSON] et al. [34] used _fs_-laser micro-structuring on zirconia implant surfaces. Their chemical analysis revealed that the grooved and bored surfaces exhibited larger fractions of zirconium and oxygen compared to untreated control surfaces, whereas the presence of carbon and aluminum was found to be remarkably low. During _fs_-laser irradiation of zirconia, its tetragonal phase remains unaffected by laser irradiation, in contrast to its monoclinic phase, which can respond to light irradiation [34]. Recent studies have clearly demonstrated the advantageous characteristics of _fs_-laser pulses for resolving the monoclinic phase fraction in zirconia post-irradiation [25; 49]. Conversely, there are several studies that have reported different outcomes regarding the monoclinic phase of zirconia. Currently, the preferred parameters for laser processing have not been decisively established [50; 51; 52]. Additionally, _fs_-laser processing has been found to affect the surface roughness but not the crystal structure of zirconia derivatives, such as alumina-toughened zirconia ceramics, without affecting the chemical or phase compositions of these materials [30; 50]. Precise control over the chemical changes in materials, which may influence cell-surface interactions, has emerged as a primary focus in the advancement of new ceramic implant materials. Surface patterning techniques have enabled ongoing investigation into cell-biomaterial interactions, revealing that surface topography significantly influences cellular responses in biomaterials [53]. Cell-surface functions such as adhesion, migration, and proliferation are profoundly influenced by physical cues from the surrounding microenvironment [54]. Nevertheless, the specific responses of cells also depend on other factors, including cell type, size, the geometric configuration of the underlying topography, and the surface chemistry of ceramic materials. The influence of the ablation regimen used in the present study on cell behavior is a topic that should be addressed in future studies.