The effect of the ethanolic extract of African leaves (Vernonia amygdalina Delile) on the corrosion rate and microstructure of stainless steel orthodontic wire

corrosion rate ethanolic extract of African leaves microstructural changes orthodontic wire stainless steel

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Vol. 58 No. 4 (2025)
Original articles
October 10, 2025

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Background: Stainless steel orthodontic wire is commonly used in orthodontic treatment but is prone to corrosion; therefore, an inhibitor is required. Purpose: This study aimed to evaluate the effectiveness of the ethanolic extract of African leaves (Vernonia amygdalina Delile) as a corrosion inhibitor for stainless steel wires. Methods: A laboratory experiment with a pre- and post-test control group design was conducted. Samples included one negative control (artificial saliva), one positive control (chlorhexidine), and two treatment groups (ethanolic extract of African leaves at 3.125 mg/mL and 6.25 mg/mL), totaling 28 samples. Immersion lasted 7 days at 37°C. Corrosion rates were measured by weight loss, and microstructural changes were analyzed using a scanning electron microscope. Results: The highest average corrosion rate was observed in the chlorhexidine group (0.98 ± 0.58 mils per year [mpy]), whereas the lowest was in the 6.25 mg/mL extract group (−0.04 ± 0.80 mpy). Scanning electron microscope analysis revealed notable microstructural differences: the artificial saliva group showed long scratches scattered across the surface and localized round porosity; the chlorhexidine group exhibited rough scratches and widespread porosity; in contrast, the African leaves groups displayed minor scratches and a thin layer presumed to be protective. Conclusion: The ethanolic extract of African leaves considerably affects corrosion rates and microstructural changes in stainless steel orthodontic wires.