Imparting Antimicrobial Efficacy: Novel Polymer-Coated MgO Nanoparticles Transform Dental Composites

Failures of resin composite restorations can be caused by bacterial microleakage, which can lead to localised demineralisation of the tooth structure at the tooth-restoration interface. The objective of this study was to assess the antimicrobial activity of zein-coated magnesium oxide nanoparticles incorporated into conventional, flowable and bulk-fill resin composites.

A total of 288 composite specimens were prepared, with 96 discs fabricated from each type of composite. The groups were further subdivided by weight concentrations of zein-coated magnesium oxide nanoparticles (0.0%, 0.3%, 0.5% and 1.0%). The antimicrobial activity of the composite specimens was evaluated by agar diffusion and modified direct contact tests against Streptococcus mutans, Staphylococcus aureus, Enterococcus faecalis, and Candida albicans. The values of the inhibition zones and optical density readings were investigated by one-way analysis of variance (ANOVA), followed by a Dunnett post hoc test and a t-test at P < .05.

With the direct contact assays, all composites at all nanoparticle concentrations had significant antimicrobial activity when compared to the control. For the agar diffusion tests, the diameters of the inhibition zones were proportional to the increase in the nanoparticles' concentration.

The zein-coated magnesium oxide nanoparticles have great potential for developing new resin composites with superior antimicrobial properties, which would aid in combating microbial invasions and preventing secondary caries.