Evaluation of cytotoxicity of electroplated stainless steel orthodontic wire

Lee, Gye Hyeong; Cho, Jin Hyoung; Lee, Ki Heon; Hwang, Hyeon Shik

Abstract

The purpose of this study was to examine the cytotoxicity of orthodontic wire which had an increased diameter through electroplating, and to evaluate its possible clinical applications. First, nickel plating was carried out on the commercially available stainless steel wire using an electroplating technique. For the comparison of the electroplated wire with ready made stainless steel wire and titanium or copper, each wire was incubated for 72 hours in a medium. The release of the metal ion was measured using ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrophotometer). Balb/c 3T3 mouse fibroblast was put on a microplate and placed in an incubated medium of 75%, 50%, and 20% dilation. An MTT analysis was used to compare with the medium only. The change in absorbency value of each wire group and the difference of absorbency value according to the change of dilution was measured. The results of ICP-AES analysis showed that great amount nickel ion was isolated from electroplated orthodontic wires and great amount copper ion was isolated from copper. The results of the MTT analysis showed that there was no difference in the absorbency value of titanium at any dilution. However, the electroplated wires (p < 0.001), the stainless steel wires (p < 0.05) and the copper (p < 0.001) were statistically significantly lower than those of medium only at all dilutions. Assessment as per ISO 10993, part 5, showed that electroplated wire was alloted to "moderate cytotoxic", the titanium and stainless steel wire were "non-cytotoxic". The results of this study indicate that the electroplated orthodontic wires need additional efforts to decrease cytotoxicity for their clinical applications.