Antibacterial and physical properties of resin cements containing MgO nanoparticles

Cariogenic bacteria and dental plaque biofilm at prosthesis margins are considered a primary risk factor for failed restorations. Resin cement containing antibacterial agents can be beneficial in controlling bacteria and biofilm. This work aimed to evaluate the impact of incorporating magnesium oxide nanoparticles (MgONPs) as an antibacterial filler into dual-cure resin cement on bacteriostatic activity and physical properties, including mechanical, bonding, and physicochemical properties, as well as performance when subjected to a 5000-times thermocycling regimen. Experimental resin cements containing MgONPs of different mass fractions (0, 2.5%, 5%, 7.5% and 10%) were developed. Results suggested that the inclusion of MgONPs markedly improved the materials' bacteriostatic effect against Streptococcus mutans without compromising the physical properties when its addition reached 7.5 wt%. The mechanical properties of the specimens did not significantly decline after undergoing aging treatment, except for the flexural properties. In addition, the cements displayed good bonding performance and the material itself was not prone to cohesive fracture in the failure mode analysis. Furthermore, MgONPs possibly have played a role in decelerating material aging during thermocycling and enhancing bonding fastness in the early stage of cementation, which requires further investigation. Overall, developing MgONPs-doped resin cements can be a promising strategy to improve the material's performance in inhibiting cariogenic bacteria at restoration margins, in order to achieve a reduction in biofilm-associated secondary caries and a prolonged restoration lifespan.