The Influence of pH of Saliva on the Release of Nickel and the Surface Roughness of Stainless Steel as Medical Devices

Metal is common as medical devices. Stainless steel (SS316L) has low carbon composition in order to increase corrosion resistance. The release of stainless steel ions can occur due to corrosion and affect the surface roughness. This study determined the influence of pH level of saliva on the concentration of nickel ions release and the surface roughness of SS316L. Twelve specimens of SS316L sized (10x10x1)mm were divided into 3 groups (artificial saliva with pH 3, 5, and 7). Samples were stored in the incubator at 37°C for 14 days. The concentration of nickel ions released was measured using atomic absorption spectrophotometry (ppm). The surface roughness was measured before and after the immersion using surface roughness measuring instrument (µm). The result showed the concentration of nickel ion released (ppm) were 0.099±0.023 (pH 3), 0.045±0.020 (pH 5), and 0.000±0.000 (pH 7). While the surface roughness (µm) were 0.22±0.06 (pH 3), 0.12±0.04 (pH 5), and 0.1±0.03 (pH 7). One-way ANOVA proved that the pH level of saliva significantly influenced the concentration of nickel ions and the surface roughness (p <0.05). It can be concluded that the lower pH level of saliva, the higher concentration of nickel ions released and the rougher the surface of SS316L.