Biocompatible liquid-infused titanium minimizes oral biofilm adhesion in flow chamber and 3D implant-tissue-biofilm in vitro models.

Biomedical implants are susceptible to bacterial colonization, which can lead to challenging implant-associated infections. In particular, dental implant abutments - which are continuously exposed to bacteria within the oral cavity - stand to greatly benefit from strategies which inhibit the development of bacterial biofilms. Liquid-infused titanium surfaces have demonstrated excellent biofilm repellency, but to date have not been analyzed with substances suitable for medical device approval in terms of biocompatibility under conditions mimicking the environment of dental implant abutments. In this study, different medical-grade lubricants coated onto laser-structured titanium were screened for stability and water-repellency - with the results suggesting that unmodified structured titanium coated with silicone oil was the most promising combination of materials. When analyzing biofilm formation, the coated surfaces showed a statistically significant reduction in oral commensal Streptococcus oralis biofilms grown under static conditions as well as oral multispecies biofilms grown under salivation-resembling flow conditions. This biofilm-reducing effect was also observed when the coated surface interfaced with a 3D implant-tissue-oral-bacterial-biofilm (INTER(b)ACT) in vitro model, which allows for the direct interaction of human tissue and oral multispecies biofilm at the implant interface. Importantly, this biofilm reduction was not due to toxicity of the coated surfaces, but is most likely attributable to inhibition of bacterial attachment. Additionally, the surfaces were not cytotoxic, without altering adjacent soft tissue or causing elevated pro-inflammatory cytokine secretion. These findings highlight the promise of biocompatible liquid-infused titanium surfaces as biofilm-repellent implant abutment modifications and provide the basis for further investigations in targeted pre-clinical studies.