Effects of Different Archwires Induced to Corrosion in HGFs Culture

Objectives: To compare the cytotoxicity of stainless steel (G1), nickel-titanium (G2=Ni-Ti), copper-nickel-titanium (G3=Cu-Ni-Ti) archwires induced to corrosion or not and respectively group (G4) in culture with human gingival fibroblasts (HFGs) according to standard of ISO 10993-5-Biological evaluation of medical devices-Part 5: Test for in vitro cytotoxicity.
Methods: HGFs were subculture at 1x10⁵ células/mL. Comercial orthodontic archwires (5 mm) were induced to corrosion or not with hydrochloric acid-artifical saliva (pH:5.3) for 24 hrs by agitation at 37 C, 5% CO₂ and 95% of relative humidity. The archwires were inoculated in direct contact and incubated for 24 hrs. The relative viable cell number were calculated with MTT method at 570 nm. The experiments were perfomed by triplicated from three independent experiments. Data were analized with Shapiro-Wilks normality test and ANOVA pos-hoc Tukey test. Significance were consider at p<0.05.
Results: A significant difference of (p<0.05) was found between group 2 and 3 induced to corrosion. It was observed that the three groups showed significant differences decreasing cell viability compared to G4, however G3 was the most cytotoxic decreasing cell viability up to 40 % in 24 hrs. Non differences were observed in conventional archwires.
Conclusions: The oral buccal acid can cause corrosion and ions detachment that will alter the cellular viability of the periodontal support tissues. In orthodontic treatments it is common to use metal alloys that will necessarily be subjected to corrosion for prolonged periods of treatment, however the non-cytotoxic orthodontic wires could be considered.