Antibacterial Effect of Experimental Orthodontic Elastomeric Ligature Coated with Zinc Oxide Particles

Objectives. This study aimed to evaluate antibacterial activity of elastomeric ligatures coated with Zinc oxide particles against Streptococcus mutans. Methods. ZnO particles grafted with (3-Aminopropyl) trimethoxysilane (APTMS) were prepared in situ. The ATR-FTIR spectrum was used to analyze the APTMS grafted on ZnO surfaces. Two concentrations of ZnO-APTMS, i.e., 5 and 10 wt%, were coated on orthodontic elastomeric ligatures by the dip coating method. Antibacterial property of the ZnO-APTMS coated elastomeric ligatures against S. mutans ATCC25175 were investigated by the agar diffusion test. The effect of ligature aging on antibacterial property was evaluated by the direct contact test, in which the growth of bacteria was determined by the turbidity after exposed to the samples that had been immersed in distilled water for 0, 3, 7, 14, 28 days. The drop plate test was also performed to determine the inhibitory and the bactericidal effects. Results. The analysis of ATR-FTIR spectrum confirmed that APTMS was successfully grafted on ZnO surfaces. The agar diffusion test could not demonstrate the antimicrobial effects of the ZnOcoated elastomeric ligatures. However, results from the direct contact and the drop plate tests showed the inhibitory effects on bacterial growth compared to the positive controls (p < 0.05). The inhibitory effect of the ZnO-coated elastomeric ligatures was observed even after they had been immersed in distilled water for 28 days. Conclusions. The surface coating elastomeric ligatures with 5 and 10 wt% ZnO-APTMS exhibited antibacterial activity against cariogenic bacteria, S. mutans. The bacterial inhibitory effect was prolonged until 28-day.