ABSTRACT
INTRODUCTION: This study aimed to evaluate the metal ion release, cytotoxicity, and surface roughness of clinically used metal orthodontic appliances after immersion in different fluoride product solutions compared with those of new appliances. METHODS: Used fixed appliances were debonded from 36 patients after their treatmentâ¯was done. New appliances were as-received. Each used and new group comprised 36â¯sets of 20 brackets and 4 tubes that were divided into 3 groups by archwire type; stainless steel, nickel-titanium, andâ¯beta-titanium. The samples in each group wereâ¯divided into 3 subgroups and immersed in solutionsâ¯of fluoride toothpaste, 1.23% acidulated phosphate fluoride,â¯or artificial saliva without fluoride as a control group. The immersion times were estimated from the recommended time for using each fluoride product for 3 months. The samples were then immersed in Dulbecco's Modified Eagle's Medium for 7 days. The cytotoxicity test was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay using primary gingival fibroblasts. Chromium, nickel, and iron ion release were detected using inductively coupled plasma mass spectroscopy. The surface roughness of the brackets and wires was measured by a scanning electron microscope and a noncontact optical 3-dimensional surface characterization and roughness measuring device. The data were analyzed using the paired t test and 2-way analysis of variance. RESULTS: Used brackets demonstrated a significantly higher ion release, surface roughness, and cytotoxicity than the new brackets. Acidulated phosphate fluoride significantly increased the ion release and surface roughness; however, it significantly decreased cell viability, especially in the titanium molybdenum subgroup. CONCLUSIONS: Used brackets were significantly prone to further corrosion. Acidulated phosphate fluoride gel should not be used in orthodontic patients with fixed metal appliances.
