Bacteria that accumulate on the surface of dental prostheses could lead to systemic disease. If you want your prosthetics to resist bacteria, then, you have to start with the right materials. But those materials should not compromise the strength of the prosthetic.
A team of researchers from Brazil recently investigated the growth of Staphylococcus aureus and Pseudomonas aeruginosa on the surface of autopolymerizing (AP) and heat-polymerizing (HP) acrylic resins incorporated with nanostructured silver vanadate (b-AgVO3) as well as the effect of that nanomaterial on the impact strength of those resins.
The researchers prepared 216 circular specimens measuring 9 x 2 mm for microbiologic analysis and 60 rectangular specimens measuring 65 x 10 x 3.3 mm for mechanical analysis for each resin, according to the percentage of b-AgVO3: zero percent control group; 0.5%; 1%; 2.5%; 5%; and 10%.
After a biofilm had formed, the researchers measured the metabolic activity of the bacteria using the 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) reduction assay. They also determined the number of viable cells by counting colony-forming units per milliliter (CFU/mL).
Furthermore, the researchers used confocal laser scanning microscopy to complement the analyses and evaluated the mechanical behavior by impact strength assays. They then analyzed the data by 2-way analysis of variance followed by the Tukey honestly significant difference post-hoc test.
Adding the 5% and 10% b-AgVO3 significantly decreased the metabolic activity of P aeruginosa for both resins. The HP resin promoted a greater reduction in metabolic activity than the AP resin. No difference was found in the metabolic activity of S aureus according to the XTT. The CFU/mL totals for both bacteria also dropped significantly when 5% and 10% b-AgVO3 were added.
However, the researchers found that the 5% and 10% concentrations of b-AgVO3 significantly reduced the impact strength of the resins because the system was weakened by the presence of clusters of b-AgVO3. Since the addition of b-AgVO3 can boost the antibacterial activity of acrylic resins but reduce their impact strength, more efficient addition methods should be investigated, they concluded.