Effect of cerium oxide nanoparticles on the antimicrobial properties and retentive strength of glass Ionomer cement for orthodontic band cementation

Objective: This study aimed to investigate the antimicrobial effects and retentive strength of glass ionomer cement (GIC) containing cerium oxide nanoparticles (NPs) when used for cementing orthodontic bands, as well as to evaluate the cytotoxicity of these nanoparticles.Methods: Cerium oxide nanoparticles (NPs) were incorporated into glass ionomer cement (GIC) at concentrations of 1%, 2%, and 4%. Disc-shaped specimens were prepared for each concentration, along with a control group without nanoparticles. Antibacterial activity was evaluated against Streptococcus mutans using the direct contact test. The lowest concentration of cerium oxide NPs that thoroughly eliminated bacterial growth was identified and then compared with the control group in the retentive strength test. In addition, cytotoxicity of cerium oxide NPs was assessed on gingival fibroblast cells using the MTT assay. The difference in retentive strength between the two groups was evaluated using an independent samples t-test at the significance level of P<0.05.Results: The direct contact test showed that a 1 wt% concentration of cerium oxide NPs was sufficient to eliminate all Streptococcus mutans. Incorporating 1 wt% cerium oxide into GIC did not significantly affect its retentive strength (P=0.31). Cytotoxicity testing indicated that cerium oxide NPs have relatively low toxicity, with an IC₅₀ (half maximal inhibitory concentration) value of 1000 μg/mL.Conclusions: GIC containing 1 wt% cerium oxide NPs demonstrated significant antibacterial activity against Streptococcus mutans, maintained acceptable retentive strength, and exhibited relatively low cytotoxicity.