Effects of build orientation on 3D-printed Co-Cr-Mo: surface topography and L929 fibroblast cellular response

Abstract

Selective laser melting (SLM) is increasingly being used for the fabrication of cobalt chromium customised medical devices. The purpose of this study was to determine the effect of surface topographies from SLM parts on the in-vitro biological responses of mouse fibroblasts (L929). Fibroblast cells were cultured for 3 days on SLM and on conventionally cast Co-Cr-Mo surfaces and their proliferation, morphology, viability and cytotoxicity investigated. SLM processing parameters were used to manufacture discs with different microlevel surface topographies. Our analysis showed that the SLM implants met basic biocompatibility requirement on all surfaces. The effect of the SLM processing parameters was characterised by an improvement in cell viability with increasing surface roughness. The number of viable cells on all the SLM Co-Cr-Mo either equaled or was higher than those on the reference cast sample. A statistically significant difference (p < 0.05) was found between the cell viability on two SLM specimens (Ra = 29.25 and 20.62 μm) and reference cast (Ra = 4.32 μm). In comparison to a polymeric negative control, the absorbance measurement on Co-Cr-Mo surfaces was in the range of 60 to 80% of the control and the cytotoxicity was comparable to the cast sample. The surface roughness amplitude parameters were found to discriminate cell viability and cytotoxicity better, confirming that fibroblast cell growth on SLM surfaces was more influenced by the amplitude rather than by the organisation or morphology of the surface. It is concluded that SLM processing significantly affects surface topography which in turn influences the L929 fibroblast cellular response.