Dual-topography electrical discharge machining of titanium to improve biocompatibility

Surface modifications of titanium are widespread in an effort to improve the osseointegration capabilities of the metal for orthopaedic and dental applications. Here, electrical discharge machining (EDM) was used to create modified, notably, dual-topography surfaces on titanium. By swapping conventional copper electrodes for a titanium electrode and water dielectric, modified surfaces free of trace element contaminants were produced. Three surfaces were produced by varying the peak currents at 10 A, 29 A and a uniquely hierarchical multi-current combination of 29 A followed by 2.4 A. The physicochemical properties of these surfaces were analyzed by scanning electron microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDX), and Auger Spectroscopy. These revealed the topography of the modified surfaces and a titanium oxide layer that was markedly thicker on the EDM samples compared to controls. In vitro cell testing was carried out with osteoblast-like MC3T3-E1 cells. Cell differentiation was increased in all EDM modified surfaces compared to controls and early differentiation was promoted on the dual-topography surface. The present study suggests the promise of dual-topography surfaces created using EDM for implant applications.