Metal ion quantification in the saliva of patients with lingual arch appliances using silver solder, laser, or TIG welding

Objectives Quantify metal ion release in the saliva, considering that orthodontic appliances with soldered or welded parts may suffer corrosion and release metal ions into saliva, which can trigger adverse effects, such as hypersensitivity. Methods Sixty-four patients were distributed into four groups: G1 (control), G2 (silver-soldered lingual arch), G3 (laser-welded lingual arch), and G4 (TIG-welded lingual arch). Saliva samples were collected at four different points and were analyzed for ion release with ICP-MS. Results For Cr, Fe, Cu, and Sn ion concentrations among groups, there was no difference along collections and no statistically significant difference throughout collections for any group ( P > 0.05, with release values between 3.3 and 4.2 μg/L for Cr, 201 and 314.8 μg/L for Fe, 23.1 and 40.7 μg/L for Cu, and 13 and 27.7 μg/L for Sn). For Ni, G4 showed an increased ion release at T2 (14.3 μg/L) and T4 (34.5 μg/L), values with an interaction effect ( P 0.05). For Zn ions, there was a statistic difference from G4 to G1 and G2 ( P = 0.007 and P = 0.019), with median values ranging from 741.7 to 963.4 μg/L for G4, and for Ag ions, from G4 to G2 and G3 ( P