Dental materials incorporated with nanometals and their effect on the bacterial growth of Staphylococcus aureus

Abstract

Purpose: The purpose of this study was to investigate the effect of different commercially used dental materials (RelyX Luting Plus and Dyract Extra) mixed with either a metallic ionic solution or a colloidal suspension of metallic nanoparticles. Both the solution and the suspension contained a mixture of silver, copper, and lithium ions. Methods: The metal/ion-incorporated dental materials were prepared into disk-shaped samples and tested against the growth of Staphylococcus aureus. The susceptibility of bacteria against the antibacterial dental disks was tested using two methods: counting the colony-forming units per milliliter and disk diffusion (Kirby–Bauer). The incorporated materials (Dyract and Rely cement) were tested for ion release using flame atomic absorption spectroscopy. Results: Assessment showed efficient antibacterial activity of metal ion–incorporated Rely luting cement, exhibited by the formation of inhibition zones larger than those formed by the standard antibiotic, as well as a reduction in bacterial number of sevenfold after incubation for 24 hours. Dyract material incorporated with nanoparticles showed no significant clear zones and had no inhibiting effect on bacterial colony numbers after incubation for 24 hours. The release of silver, copper, and lithium metal ions depended on the type of both dental material and the incorporated nanoagents. The metal ion–incorporated Rely Plus cement released the highest levels of metal ions, which was attributed to its antibacterial efficiency. Conclusion: Rely Plus cement incorporated with the nanoparticle suspension demonstrated high antibacterial potency, due to the release of the highest concentrations of silver, copper, and lithium metal ions. This work is the first direct comparative study of dental materials with different forms of nanomixtures (metallic nanoparticles and soluble metallic ions) and their antibacterial effects after incubation with bacterial culture for 24 hours.