## 4 Conclusions  
This study investigated the surface modification of Ti-6 Al-4V alloy through electrical discharge machining (EDM) to enhance its suitability for orthopedic and dental implant applications. The influence of dielectric fluid composition and tool polarity was comprehensively analyzed across surface morphology, wettability, roughness, microhardness, and biocompatibility. The results confirmed that EDM effectively tailored the physicochemical and mechanical properties of the alloy, leading to modified surface features. Such modifications may favor biological interactions and support implant integration. Furthermore, the absence of cytotoxic effects observed in the LDH assay suggests initial biocompatibility, although this potential should be further investigated through complementary biological studies. Overall, the findings validate the proposed approach and highlight EDM as a promising technique for optimizing titanium-based biomaterials used in implantable medical devices. Through optical microscopy (OM) and scanning electron microscopy (SEM) analyses, it was observed that machining with the fluorine-containing dielectric fluid (DF1-F) in negative polarity resulted in surfaces with more reentrances and irregularities, while positive polarity produced flatter surfaces, albeit with deep and wide cracks and an increased concentration of debris. Additionally, the DF2-Ca fluid produced surface features such as open pores, tiny droplets, and encrusted elongated structures, highlighting the influence of polarity and dielectric composition on surface morphology. Surface roughness measurements showed that samples treated with DF1-F in negative polarity exhibited the highest roughness values, contributing to improved cell adhesion potential for biomedical applications. The roughness values were consistent with the morphological observations, indicating that negative polarity enhances surface irregularities, which are beneficial for osseointegration. Vickers microhardness testing showed that all recast layers exhibited higher hardness compared to untreated titanium. Samples processed with DF2-Ca in positive polarity displayed the highest microhardness among all tested conditions, demonstrating significant mechanical strength improvements, particularly in the recast and heat-affected zones, which enhances the durability of biomedical implants. Contact angle measurements revealed that the DF2-Ca dielectric fluid significantly increased surface wettability, achieving superhydrophilic behavior. The DF1-F fluid also displayed a very low contact angle under anodic polarity, indicating improved hydrophilicity, which contributes to tissue integration in medical applications. Biocompatibility results based on the LDH assay indicated that all surfaces remained non-cytotoxic. Finally, the most promising EDM conditions identified in this study are as follows:  
a. DF1-F with negative polarity: This surface exhibited the highest surface roughness, high hardness from the heat-affected zone (HAZ) to recast layer, good wettability, in addition to non-cytotoxicity, suggesting good biocompatibility. b. DF2-Ca with positive polarity: In this case, the modified layer was thicker, presenting the highest hardness. Additionally, precipitates of calcium compounds were formed on the surface, leading to a superhydrophilic and non-cytotoxic surface, which may indicate excellent biocompatibility. These findings highlight the great potential of Ti-6 Al-4V alloy processed via EDM for the development of biomaterials intended for bone implants and prostheses. Conceptualization, B.A.B.d.S. and H.d.S.C. ; methodology, B.A.B.d.S., E.C.S.C., L.Y.C.M., R.M.S. and W.L. ; software, E.C.S.C. and W.L. ; validation, L.Y.C.M., R.M.S. and K.C.P. ; formal analysis, B.A.B.d.S. ; investigation, B.A.B.d.S. ; resources, K.C.P. ; data curation, B.A.B.d.S. ; writing--original draft preparation, B.A.B.d.S. ; writing--review and editing, R.M.S. and H.d.S.C. ; visualization, E.C.S.C., L.Y.C.M. and W.L. ; supervision, H.d.S.C. ; project administration, R.M.S.