The Effect of TiN-Coating on Cytotoxicity of Electroplated Stainless-Steel Wire

Objectives:This study was performed to investigate whether TiN coating could reduce the cytotoxicity of electroplated orthodontic stainless-steel wire which had been known to be cytotoxic. Methods:Nickel plating was done on stainless-steel wire using a electroplating technique. Some of the electroplated wires were coated by TiN film and 4 groups of specimen were prepared (Non-coated elecroplated wire, TiN coated elctroplated wire, Titanium which was known to have no cytotoxicity, Copper which was known to have high cytotoxicity). Each wire was incubated for 72 hours on the medium. The release of the metal ion was measured by ICP-AES. The incubated medium was diluted 75%, 50%, 25% and added on each microplate with Balb/c 3T3 mouse fibroblast for MTT analysis and compared with medium only. Results:1. The results of ICP-AES analysis showed that lots of nickel ions were isolated from non-coated wires but not isolated from TiN coated wires. 2. The inverted microscope showed that there was a decrease in cell count in non-coated wires but no significant change in TiN coated wires. 3. The results of MTT analysis showed that there was no difference in the absorbency value between TiN coated wires and medium and between titanium and medium but the absorbency value of non-coated wires and copper were lower than that of medium only at all dilution and showed statistically significant differences (p<0.001). 4. Assessment as per ISO 10993, part 5, non-coated wires and copper investigated corresponded to "moderately cytotoxic"and "highly cytotoxic"; whereas titanium and TiN coated wires were alloted to"non-cytotoxic". Conclusions:The results of the present study indicate that the cytotoxicity of the electroplated orthodontic wire can be changed from"moderately cytotoxic"to"nontoxic"by TiN coating and electroplated wire can be used clinically without the concern of cytotoxicity.