Sustained Fisetin Release Prevents Orthodontic Mini-Screw Failure

This study aims to develope a novel Ti6Al4V screw system coated with a poly(lactide-co-glycolide) (PLGA) film incorporating fisetin, and investigate the effectiveness of fisetin-releasing PLGA-coated Ti6Al4V screws in preventing peri-implantitis and improving long-term orthodontic mini-screw stability. This study used eight week old male Sprague-Dawley rats with approval from the Osaka Dental University (Approval No. 24-02011). Ti6Al4V screws were implanted 4 mm distal to the upper anterior teeth, and plaque retention was induced using a colored elastomeric ligature. The groups included T, TCL, TPF and TPFCL screw. Ti6Al4V screws were coated with PLGA (20 mg/mL) and fisetin (0.1 mg/mL) to create TPF screws. After 10 days, peri-implant plaque was stained with plaque-check gel BR and quantified using ImageJ. Screw mobility was measured with a Periotest M device. Microcomputed tomography assessed bone parameters. Tissues were decalcified, paraffin-embedded, and stained with H&E and TRAP. Sustained fisetin-release Ti6Al4V screws implanted in rats showed significant plaque deposition in the TCL and TPFCL groups after 10 days. Histological analysis revealed fisetin's ability to suppress inflammatory cell infiltration and bone resorption. Microcomputed tomography and TRAP staining indicated that fisetin-loaded screws preserved bone density, reduced osteoclast numbers, and improved screw stability. Our findings suggest that sustained fisetin-release Ti6Al4V screws inhibit inflammation and alveolar bone resorption, preventing screw movement, making them a promising strategy for preventing peri-implantitis in orthodontic treatments.