Effect of Silver Ion Surface Coating on Antimicrobial and Cutting Efficiencies of Nickel-titanium Rotary Files

Objective: Silver ions are well known to have effective antimicrobial activity against many microorganisms. This study aims to evaluate the antimicrobial and cutting efficiencies of nickel-titanium rotary file surface coated with silver ions by using the dip-coating method. Materials and Methods: A pilot study was performed before the endodontic file coating. The prepared coating solutions (silan and silver-complex systems) were applied to stainless steel plates by using the spin-coating method. The antibacterial activity of the coatings was researched against Enterococcus faecalis, which resulted in the selection of the coating solution with a 20% solid ratio and 2% silver content. Subsequently, the files were assigned to three groups based on the coating speed [group 1, 50 mm/min; group 2, 25 mm/min; and group 3, non-coated files (control)]. The cutting efficiency was evaluated by calculating the weight loss of the transparent acrylic blocks. The file surface and section was evaluated using scanning electron microscopy (SEM) and SEM-energy-dispersive X-ray spectroscopy before and after preparation. Data were statistically analysed with one-way analysis of variance and post-hoc Bonferroni test (p<0.05). Results: Significantly more debris was removed from Group 1. The cutting efficiency was not significantly different between groups 2 and 3. Groups 1 and 2 showed distinctive surface irregularities. Conclusion: The application of this antimicrobial surface coating was promising for improving antibacterial effectiveness of nickel-titanium rotary files. In addition, the thin film coating did not cause any negative effects on file cutting efficiency.