The Antimicrobial Activity of Zinc Oxide Nanoparticles incorporated into Alginate Impression Material: An In vitro Study

Abstract

Background and aim: In dental clinics, disinfecting alginate impression materials is a critical practice to prevent cross-infection. Recently, zinc oxide nanoparticles (ZnO NPs) have been explored for their potential antimicrobial properties, making them promising additives for dental materials. This study investigates the antimicrobial activity of ZnO NPs incorporated into alginate impression materials and assesses the impact on material flow. The objective of this in vitro study was to evaluate the antibacterial and antifungal efficacy of ZnO NPs when incorporated into alginate impression material and to examine its effect on the material's flow properties.

Materials and methods: Zinc oxide nanoparticles were incorporated into an irreversible hydrocolloid alginate impression material at varying concentrations. The antimicrobial properties were assessed using the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) for antifungal activity against Candida albicans, and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for antibacterial activity against Staphylococcus aureus. The well-diffusion test was employed to observe zone inhibition. The flow properties of the modified alginate were evaluated using a standardized flow test. Scanning electron microscopy (SEM) was utilized to observe the morphological characteristics and nanoparticle distribution in the alginate matrix. Data were analyzed using one-way analysis of variance (ANOVA) and Duncan's multiple range test, with a significance level set at P ≤ 0.05.

Results: The results showed that the MIC for ZnO NPs against Candida albicans was 5% by weight, and the MFC was 10% by weight. For Staphylococcus aureus, the MIC was also 5%, with the MBC at 10%. The incorporation of ZnO NPs resulted in a significant reduction in the flow of the alginate material. SEM images revealed a random distribution of ZnO NPs within the alginate matrix, suggesting uniform incorporation.

Conclusion: The incorporation of zinc oxide nanoparticles into alginate impression materials conferred both antibacterial and antifungal properties, with effective antimicrobial activity observed at concentrations as low as 5%. However, the addition of ZnO NPs led to a decrease in the material's flow, which may affect the handling characteristics of the alginate. Clinically, the antimicrobial properties of ZnO NP-enhanced alginate could reduce the risk of cross-contamination in dental settings, but the alteration in flow must be considered when selecting or modifying impression materials for clinical use. Future studies should focus on optimizing the concentration of ZnO NPs to balance antimicrobial efficacy with material performance.

Keywords: Alginate impression material; antimicrobial activity; zinc oxide nanoparticles.

Figure 1

Means, ± sd and Duncan’s test for the antifungal activity of different concentrations of zinc oxide nanoparticles on Candida albicans (zone of inhibition in millimeters)

Figure 2

The ZnO nanoparticle of concentrations (1.25% and 2.5%) for agar well-diffusion test for Candida albicans

Figure 3

The ZnO nanoparticle of concentrations (5%, 10%, and 15%) for agar well-diffusion test for Candida albicans

Figure 4

Means, ± sd and Duncan test The zone of inhibition of various ZnO-NP concentrations added in the alginate impression medium against Staph aureus

Figure 5

The ZnO nanoparticle concentration-dependent agar well-diffusion test for S. aureus susceptibility to the alginate impression material

Figure 6

Means, ± sd and Duncan’s multiple range test for the flow test

Figure 7

Scanning electron microscopic pictures of the control sample

Figure 8

Scanning electron microscopic images of the alginate sample with 5% ZnO