The impact of silver nanoparticles integration on biofilm formation and mechanical properties of glass ionomer cement.

Objectives: To study the effect of silver nanoparticles incorporation to glass ionomer cement (GIC) on the Staphylococcus aureus biofilm in terms of bacterial growth and evaluate the incorporating effect on hardness and compressive strength.

Methods: Silver nanopowder was added in concentration 0, 1, 3, and 5 wt% to the conventional powder of GIC Fuji IX GP and then the powder is added to the liquid and mixed together with the recommended Powder/liquid ratio of 3.6:1 g. One hundred and twenty disc and cylindrical-shaped specimens were prepared using teflon molds. The specimens were put in tissue culture plate wells contained S. aureus in brain-heart infusion broth. The plate was incubated at 37°C for 24 h. Specimens were then washed, fixed, dehydrated, and air dried. The spatial distribution of biofilm was examined via scanning electron microscope. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were also evaluated. After setting, the specimens were stored in distilled water for 24 h before testing for microhardness and compressive strength.

Results: Scanning electron photomicrographs of biofilm formed on the control GIC, showed a consistent biofilm with a thick sheet of cells, whereas those formed were less dense at 3 wt% and below the detection limit at 5 wt% silver nanoparticles. MIC and MBC of S. aureus were 25 and 50 µg/mL, respectively. The microhardness and compressive strength values of tested groups showed a nonsignificant decrease from the control group, P = .58 and .82, respectively.

Conclusion: Incorporation of silver nanoparticles with GIC can limit S. aureus biofilm formation with an insignificant effect on mechanical properties and noticeable influence on its coloration, which restrict its usage in areas where esthetic is not of major concern.

Clinical Significance: As the modification of GIC with silver nanoparticles improved the antibiofilm properties without altering its mechanical properties, it could be used as a restoration of root carious lesion mainly in nonesthetic areas, a base under composite restorations in deep posterior cavities and as a core material in caries susceptible patients.