The Influence of Fluoride-Containing Toothpaste on the Mechanical, Chemical, and Physical Properties of Niti Orthodontic Archwires

Introduction There is an ongoing discussion of the connection between the mechanical, chemical, and physical characteristics of nickel-titanium (NiTi) archwires and their exposure to fluoride agents. Aim The aim of this study is to evaluate how fluoride exposure influences the mechanical, chemical, and physical characteristics of NiTi archwires. Methods According to the study protocol, twenty round 0.014″ diameter NiTi archwires were tested. The study sample was divided into two groups. The study group was incubated for 240 minutes at 37°C in artificial saliva mixed with toothpaste containing 1448 ppm fluoride. The control group consisted of unused archwires that were not exposed to toothpaste. The physical properties were analysed using scanning electron microscopy, pictures were taken at 2,500×, 5000× and 10,000× magnification. The chemical properties were evaluated with Energy Dispersive X-ray Spectroscopy. The mechanical properties were measured during a tensile test using a universal 10 kN tensioncompression machine, equipped with a 250 N sensor from the same manufacturer. Data analysis was done using SPSS version 29.0. Results Physical properties analysis revealed that fluoridated archwires exhibit increased corrosion more irregular surface with dark and white spots, increased pitting and cracks. In contrast, unused wires show less surface irregularities than fluoridated archwires. The mechanical properties analysis revealed that the applied force remained consistent at the point of archwire breakage, with no statistically significant differences (p=0.772). However, the fluoridated archwires exhibited significantly the biggest decrease in elongation (42.2%) (p < 0.001). Moreover, in chemical properties analysis, the biggest decrease was noticed of titanium ions in fluoridated archwires group (19.23%). In addition, a decrease of nickel ions was also noticed (15.97%). However, both results were not statistically significant (p > 0.05). Conclusions Fluoridated archwires exhibited more corrosion, surface degradation, weakest elasticity, and decrease of titanium and nickel ions. Therefore, using fluoride toothpaste could affect the surface characteristics, decrease the mechanical and chemical properties of the NiTi archwire, and potentially contribute to prolonged orthodontic treatment.