Effect of Fluoride Exposure on the Mechanical Properties of NiTi Orthodontic Archwires: An In Vitro Study

Background Fluoride-containing mouth rinses are widely used in orthodontic patients to prevent enamel demineralization. However, fluoride exposure may influence the mechanical properties of nickel-titanium (NiTi) orthodontic archwires, potentially affecting their clinical performance. This study aimed to evaluate the effect of a 905 ppm fluoride-containing mouth rinse on the mechanical properties of NiTi orthodontic archwires. Methodology An in vitro experimental study was conducted using 35 NiTi orthodontic archwires (0.014″), divided into experimental, control, and baseline groups. The experimental group was exposed to a fluoride-containing mouth rinse (905 ppm fluoride, corresponding to approximately 0.2% sodium fluoride) for 1, 1.5, and 2 hours, followed by storage in artificial saliva for 10, 15, and 20 days. Mechanical properties were assessed using a universal tension-compression testing machine. Statistical analysis was performed using the Mann-Whitney U test, with significance set at p-values <0.05. Results No statistically significant differences were observed in force at breakage between groups (p = 0.740). However, a statistically significant reduction in elasticity was identified following fluoride exposure, particularly with longer exposure duration and storage time. Conclusions Fluoride exposure did not affect the force at breakage of NiTi archwires but significantly reduced their elasticity. The effect increased with prolonged exposure, suggesting a cumulative influence of fluoride on the mechanical behavior of orthodontic archwires. Further in vivo studies are required to determine the clinical relevance of these findings.