Intrinsic Antimicrobial Properties of a Novel Silorane-Based Material for Orthopedic Applications

One of many drawbacks of PMMA bone cement used to secure orthopedic implants is that its surface is highly susceptible to bacterial attachment and biofilm formation. In an effort to find alternative materials, we focused on silorane-based polymers previously developed for use in dental composites. Compared to PMMA, this composite has low shrinkage, low exothermic polymerization, low toxicity, and the potential for lower bacterial susceptibility. Building on this dental material's advantages, a novel silorane-based material for orthopedic use was developed utilizing a dual initiation system including a platinum catalyst and a surface-modified yttria alumino-silicate glass filler. In this study, we tested the silorane-based orthopedic biomaterial for any antibacterial properties while using PMMA cement as the control. Using a variety of models, both static and dynamic, we found a 60%-78% decrease in S. aureus adherence (p < 0.0001). In order to explore the sources of this antibacterial property, we used profilometry, EDS, and contact angle measurement to characterize the two materials' surfaces. In addition, MIC assays of the material's components and bacterial adherence assays on variations in the material's composition led to insight about which components had the largest effect. The properties and characteristics that lowered its bacterial susceptibility were identified as higher hydrophobicity, significantly lower surface roughness, and the presence of residual platinum following catalysis. Inclusion of the platinum-containing chemical initiator had a large effect in reducing bacterial adherence (p = 0.004). A silorane-based epoxy bone cement with substantial intrinsic inhibition of bacterial adherence may offer an effective way to reduce orthopedic periprosthetic infection without increasing antibiotic resistance.