**4. Conclusions**

In this study, four of the most prevalent surface treating strategies for Ti were systematically compared: HA-blasting, SLA, SLA/AO, and SLA/MAO. After surface treatment, each of the specimens exhibited a substantially roughened surface structure due to the additional coating layer or carving process. Elemental components were analyzed by EDS and XRD, confirming that Ti, HA, and TiO2 layers were present, in agreemen<sup>t</sup> with previous research. Surface-treated Ti substrates exhibited higher hydrophilicity than that of pristine Ti substrates as a result of increased roughness and porosity. Furthermore, adhesion strength tests indicated that the HA coating layer was less stable than the TiO2 layer formed through AO and MAO. In vitro test results demonstrated the superiority of electrical treatments (SLA/AO and SLA/MAO) in enhancing cellular attachment and proliferation.

**Author Contributions:** Conceptualization, T.-S.J. and H.-D.J.; methodology, H.L., D.K., C.-B.Y., G.H.; validation, J.K., H.-D.J.; investigation, J.K., H.L., C.-B.Y., G.H.; resources, H.L., D.K., H.- D.J.; data curation, J.K., H.L., H.-D.J.; writing—original draft preparation, J.K., H.L.; writing— review and editing, J.K., H.L., H.-D.J.; supervision, H.-E.K., H.-D.J.; project administration, H.-D.J.; funding acquisition, H.-E.K., H.-D.J.; All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by The Catholic University of Korea, Research Fund, 2020 and the Basic Science Research Program [No. 2020R1F1A1072103] through the National Research Foundation of Korea funded by the Korea governmen<sup>t</sup> (MSIT).

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not included.

**Conflicts of Interest:** The authors declare no conflict of interest.
