Cytotoxicity of ions released from 17-4 precipitation hardening stainless steel orthodontic brackets in artificial saliva

Objective: 17-4 precipitation hardening (PH) stainless steel has a low nickel content, which can reduce the risk of allergic reactions. It also has good mechanical properties against the stress caused by the archwire slot brackets in orthodontic treatments. The main focus of this study to evaluate the metal ions released into artificial saliva from different orthodontic brackets with the same 17-4 PH stainless steel and to examine the in vitro cytotoxicity of the metal. Methods: Material properties were analyzed by energy dispersive spectroscopy. The 3-(4,5-dimethylthiazol-2-y1)2,5-diphenyltetrazolium bromide (MTT) assay method was used to examine the cytotoxicity of Gemini and Synergy brackets. Results: The cytotoxicity test on all the orthodontic brackets showed a mean cell viability value above 80% in each immersion group, which means that this material is not cytotoxic to the human immortalized keratinocyte cell line. Conclusions: The results showed cell viability in the extracts of both groups of brackets, and there was no statistically significant difference between the groups (p>0.05).