Cytotoxicity Comparison of Different Common Bracket-Wires Combinations Used in Orthodontic Treatment

摘要

Since metallic ions are vital for adverse biologic effects such as allergy, cytotoxicity, mutagenicity and carcinogenicity, the corrosion of alloys is the key importance of its biocompatibility. The purpose of this study was comparing the cytotoxicity generated by different combination of common orthodontic bracket and wire after 7, 15 and 30 days. The materials include 5cm of 16 2 inch stainless steel, nickel titanium and beta titanium wires were coupled to central incisor to second premolar stainless steel brackets. To examine cytotoxicity, human gingival fibroblasts directly exposed to different couples. Cell culture was added to the plate of 6 wells containing the specimens and incubated in 5% carbon dioxide at 37°Cand cell viability for each pair corrosion products compared by MTT test. One-way ANOVA and RM ANOVA analysis were used and p value <0.05 was considered significant. The analysis showed different range of cytotoxicity between various combinations and days, respectively (P<0.05). Post-hoc pairwise comparison illustrated cytotoxicity decreased with time (P<0.001) and in comparison of different combinations, Beta-Titanium wire with Stainless steel bracket generates the highest cytotoxicity and had significant differences with stainless steel brackets-stainless steel wires (P=0.007) and nickel titanium wire and brackets was in between with insignificant differences (P=0.369 with Beta-Titanium combination and P = 0.069 with stainless steel combination). Coupling titanium alloys with stainless steel alloy remarkably increased the corrosion of stainless steel alloy induced localized cytotoxic effects.