The aim of this laboratory study is to analyze, compare, and contrast qualitatively and quantitatively the surface roughness and metal ion leaching of two brands of orthodontic precipitation hardening 17-4 stainless steel (SS) brackets exposed to salt water and commercially available NaF-based oral rinses. A total of 60 SS maxillary premolar orthodontic brackets from two brands (Victory Series™, and Mini Diamond Twin™) were assigned to three groups (n = 10). The brackets were immersed in NaF-containing oral rinses (Listerine™ or Orex™), or salt water rinse for 28 days. Microhardness (Vickers hardness number, VHN) and surface roughness (Ra) before and after immersion in oral rinses were evaluated using a non-contact optical profilometer. Inductively coupled plasma mass spectrometry (ICP-MS) was used to analyze the ion leaching into oral rinses. The local surface changes and elemental analysis of corrosion-free and corrosion spots after immersion were assessed and compared using scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (EDS). Data analysis was performed using Statistical Package for the Social Sciences software using one-way analysis of variance, the Tukey’s post hoc test, and paired t-test (α = 0.05). The VHN of the brackets was significantly different at baseline and after immersion in the oral rinses (P < 0.05). The mean Ra before immersion in oral rinses for the two groups of the orthodontic brackets was significantly different (P < 0.01). The brackets immersed in salt water for Victory™ (0.65 ± 0.07 µm) and Mini Diamond™ (0.76 ± 0.08 µm) demonstrated significantly lower roughness values than NaF-based oral rinses (Listerine™ or Orex™) (P < 0.01). However, the difference in Rabetween the bracket systems was significant only for Listerine™ and Orex™ rinses (P > 0.01). The ICP-MS analysis showed significant differences for Cu and Zn ions in Listerine™ and all ions except Ni for salt water oral rinses. On the contrary, the comparison between the bracket systems for the metal ions showed no significant difference in the Orex™ group (P > 0.05). Salt water oral rinses demonstrated significantly fewer surface changes than NaF-containing oral rinses. The leaching of the metal ions was significant for Fe2+ and Cr3+ but did not vary considerably for Ni2+ between the evaluated oral rinses.
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