In vitro Evaluation of Corrosion and Cytotoxicity of Orthodontic Brackets

Abstract

The corrosion resistance of AISI 304 stainless steel (AISI 304 SS) and manganese stainless steel (low-nickel SS) brackets in artificial saliva was investigated. The cytotoxic effects of their corrosion products on L929 cell culture were compared by two assays, crystal violet, to evaluate cell viability, and MTT (3-[4,5-dimethylthiazol-2-yl]2,5-diphenyltetrazolium bromide), for cell metabolism and proliferation. The atomic absorption spectroscopic analysis of the corrosion products demonstrated that nickel and manganese ion concentrations were higher for the AISI 304 SS-bracket immersion solution as compared with the low-nickel SS brackets. Scanning electron microscopy and energy-dispersive spectroscopy demonstrated less corrosion resistance for the AISI 304 SS brackets. Although none of the bracket extracts altered L929 cell viability or morphology, the AISI 304 SS-bracket extracts decreased cellular metabolism slightly. The results indicated that the low-nickel SS presents better in vitro biocompatibility than AISI 304 SS brackets. Abbreviations used: AISI, American Iron and Steel Institute; EDS, energy-dispersive spectroscopy; OD, optical density; ISO, International Organization for Standardization; MTT, (3-{4,5 dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; NiSO(4), nickel sulfate; SEM, standard error of the mean; WHO, World Health Organization; and TNF, tumor necrosis factor.

In vitro oxidative stress induced by conventional and self-ligating brackets

“…16,29 It seems that corrosion extracts of stainless steel brackets do not alter viability in L929 cell culture but cause reduction of cellular metabolism. 30 This suggests that mitochondrial metabolism is the target of corrosion products. Nickel ions, when in the trivalent form, are exposed to mitochondrial redox metabolism, which leads to the formation of not fully reactive oxygen radicals.…”

Stainless Steel: Material Facts for the Orthodontic Practitioner

“…Several authors have evaluated the corrosion resistance of stainless steel in orthodontic wires and brackets [40][41][42][43] and have found that this alloy shows corrosion potential in different media, including the oral environment. House et al [44], in their review article, summarize corrosion types as follows:…”

Genotoxicity in oral epithelial cells in children caused by nickel in metal crowns

“…The most frequent mechanisms of adverse reactions induced by metals are: a) corrosion, which is dependent on the presence of oxygen, chlorides, and non-noble metal alloys in the oral cavity, and b) the gradual and continuous release of ionic components from dental materials. Such ionic components are absorbed in the human body, either through the digestive system, oral mucosa, skin, or airways (Eliades and Athanasiou, 2002;Costa et al, 2007). The most common adverse reactions are caused by metal toxicity, sub-toxic reactions, hypersensitivity, and allergic contact dermatitis (Pedemonte et al, 2006).…”