Biocompatibility of copper-based shape memory alloy

Aim or Purpose: To represent biocompatibility of CuAlNi shape memory alloy manufactured by continuous casting. Materials and Methods: Test samples were cut by electro erosion into discs shape. After polishing and cleaning, samples were UV sterilized for 1h. For the indirect test, discs were incubated in DMEM for 24h at 37°C in humidified 5% CO2 atmosphere (0.2 g/ml), and supernatant was collected the next day. Human gingival cells (HGCs) were isolated by outgrowth method from gingival tissues of healthy donors. HGCs were seeded in 96 well plates, and the next day undiluted material extract was added in corresponding wells. For the assessment of mitochondrial activity of HGCs after 24 and 168h from exposure to material supernatant, medium was discarded, and medium containing 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide was added to each well and incubated. After 4h supernatant was discarded, and dimethyl sulfoxide was added to each well and optical density was measured. Cells cultured in growth medium alone were used as control. Results: After 24h mitochondrial activity was increased in test group (HGCs exposed to material supernatant) in comparison to control group (untreated HGCs). After 168h of exposure to extracts mitochondrial activity was still higher in test group in comparison to control. T-test of paired samples showed that there was not statistically significant decrease in mitochondrial activity during time (p=0.642). Conclusions: Although Cu-based alloys are controversial in terms of their biocompatibility, our study justified that biocompatibility depends on the manufacturing process and surface modification but not directly from the content of Cu.