Research Progress on Antibacterial Coatings for Preventing Implant-Related Infection in Fractures: A Literature Review

Magnesium Infusion on Dental Implants and Its Impact on Osseointegration and Biofilm Development: A Review

Dental implants have gained global popularity as a treatment option for tooth loss. The success of dental implants depends on their optimal integration into the tissues of the alveolar bone and the periodontium. However, several factors can hinder the proper osseointegration of implants, with the growth of biofilm on the implant surface and subsequent peri-implant infections being significant concerns. To overcome this challenge, researchers have explored the incorporation of antimicrobial agents onto metallic implant surfaces to mitigate biofilm growth. Ideally these agents should promote osteogenesis while exhibiting antibacterial effects. Magnesium (Mg) has emerged as a promising dual-function implant coating due to its osteogenic and antibacterial properties. Despite several studies, the precise mechanisms behind osteoinductive and antimicrobial effect of Mg is unclear, as yet. This review aims to collate and discuss the utility of Mg as a dental implant coating, its impact on the osteogenic process, potential in mitigating microbial growth, and prospects for the future. A comprehensive literature search was conducted across several databases and the findings reveal the promise of Mg as a dual-function dental implant coating material, both as a standalone agent and in combination with other materials. The antibacterial effect of Mg is likely to be due to its (1) toxicity particularly at high concentrations, (2) the production or reactive oxygen species, and (3) pH modulation, while the osteoinductive effect is due to a complex series of cellular and biochemical pathways. Despite its potential both as a standalone and composite coating, challenges such as degradation rate, leaching, and long-term stability must be addressed. Further research is needed to understand the utility of Mg as an implant coating material, particularly in relation to its antibacterial activity, osseointegration, and longevity in the oral milieu.

Development and characterisation of antimicrobial epoxy resin

Surface contamination is an important, if under-discussed, route of infection transmission. In this study, we suspended chlorhexidine digluconate (CHX) in epoxy resin. CHX was found to be stably incorporated into the material, and its addition to epoxy resin was found to have minimal effects on the optical transparency of the material. After application of the epoxy resin to steel surfaces, time-of-flight secondary ion mass spectrometry revealed that CHX was uniformly present over the surface. Surfaces painted with CHX-resin were found to have significant, reproducible antimicrobial efficacy against E. coli, S. aureus, and C. albicans. We have shown that the addition of CHX has minimal effects on the adhesion of the epoxy resin to surfaces, as well as a high durability of the antimicrobial efficacy. We believe that this material has a wide array of applications, and could be utilised to confer significant, low-cost antimicrobial efficacy to existing surfaces, to prevent surface contamination, and to stop the transmission of infectious disease.

Biocompatibility Analysis of the Silver-Coated Microporous Titanium Implants Manufactured with 3D-Printing Technology

3D-printed microporous titanium scaffolds enjoy good biointegration with the residuum's soft and bone tissues, and they promote excellent biomechanical properties in attached prostheses. Implant-associated infection, however, remains a major clinical challenge. Silver-based implant coatings can potentially reduce bacterial growth and inhibit biofilm formation, thereby reducing the risk of periprosthetic infections. In the current study, a 1-µm thick silver coating was prepared on the surface of a 3D-printed microporous titanium alloy with physical vapor deposition (PVD), with a final silver content of 1.00 ± 02 mg/cm2. Cell viability was evaluated with an MTT assay of MC3T3-E1 osteoblasts and human dermal fibroblasts cultured on the surface of the implants, and showed low cytotoxicity for cells during the 14-day follow-up period. Quantitative real-time polymerase chain reaction (RT-PCR) analysis of the relative gene expression of the extracellular matrix components (fibronectin, vitronectin, type I collagen) and cell adhesion markers (α2, α5, αV, β1 integrins) in dermal fibroblasts showed that cell adhesion was not reduced by the silver coating of the microporous implants. An RT-PCR analysis of gene expression related to osteogenic differentiation, including TGF-β1, SMAD4, osteocalcin, osteopontin, and osteonectin in MC3T3-E1 osteoblasts, demonstrated that silver coating did not reduce the osteogenic activity of cells and, to the contrary, enhanced the activity of the TGF-β signaling pathway. For representative sample S5 on day 14, the gene expression levels were 7.15 ± 0.29 (osteonectin), 6.08 ± 0.12 (osteocalcin), and 11.19 ± 0.77 (osteopontin). In conclusion, the data indicate that the silver coating of the microporous titanium implants did not reduce the biointegrative or osteoinductive properties of the titanium scaffold, a finding that argues in favor of applying this coating in designing personalized osseointegrated implants.

Biodegradable implant of magnesium/polylactic acid composite with enhanced antibacterial and anti-inflammatory properties

Addressing fracture-related infections (FRI) and impaired bone healing remains a significant challenge in orthopedics and stomatology. Researchers aim to address this issue by utilizing biodegradable biomaterials, such as magnesium/poly lactic acid (Mg/PLA) composites, to offer antibacterial properties during the degradation of biodegradable implants. Existing Mg/PLA composites often lack sufficient Mg content, hindering their ability to achieve the desired antibacterial effect. Additionally, research on the anti-inflammatory effects of these composites during late-stage degradation is limited. To strengthen mechanical properties, bolster antibacterial efficacy, and enhance anti-inflammatory capabilities during degradation, we incorporated elevated Mg content into PLA to yield Mg/PLA composites. These composites underwent in vitro degradation studies, cellular assays, bacterial tests, and simulation of the PLA degradation microenvironment. 20 wt% and 40 wt% Mg/PLA composites displayed significant antibacterial properties, with three composites exhibiting notable anti-inflammatory effects. In contrast, elevated Mg content detrimentally impacted mechanical properties. The findings suggest that Mg/PLA composites hold promise in augmenting antibacterial and anti-inflammatory attributes within polymers, potentially serving as temporary regenerative materials for treating bone tissue defects complicated by infections.

Cell migration, DNA fragmentation and antibacterial properties of novel silver doped calcium polyphosphate nanoparticles

To combat infections, silver was used extensively in biomedical field but there was a need for a capping agent to eliminate its cytotoxic effects. In this study, polymeric calcium polyphosphate was doped by silver with three concentrations 1, 3 or 5 mol.% and were characterized by TEM, XRD, FTIR, TGA. Moreover, cytotoxicity, antibacterial, cell migration and DNA fragmentation assays were done to assure its safety. The results showed that the increase in silver percentage caused an increase in particle size. XRD showed the silver peaks, which indicated that it is present in its metallic form. The TGA showed that thermal stability was increased by increasing silver content. The antibacterial tests showed that the prepared nanoparticles have an antibacterial activity against tested pathogens. In addition, the cytotoxicity results showed that the samples exhibited non-cytotoxic behavior even with the highest doping concentration (5% Ag-CaPp). The cell migration assay showed that the increase in the silver concentration enhances cell migration up to 3% Ag-CaPp. The DNA fragmentation test revealed that all the prepared nanoparticles caused no fragmentation. From the results we can deduce that 3% Ag-CaPp was the optimum silver doped calcium polyphosphate concentration that could be used safely for medical applications.

Microwave-Assisted Hydrothermal Treatment of Multifunctional Substituted Hydroxyapatite with Prospective Applications in Bone Regeneration

Orthopedic bone graft infections are major complications in today's medicine, and the demand for antibacterial treatments is expanding because of the spread of antibiotic resistance. Various compositions of hydroxyapatite (HAp) in which Calcium (Ca²⁺) ions are substituted with Cerium (Ce³⁺) and Magnesium (Mg²⁺) are herein proposed as biomaterials for hard tissue implants. This approach gained popularity in recent years and, in the pursuit of mimicking the natural bone mineral's composition, over 70 elements of the Periodic Table were already reported as substituents into HAp structure. The current study aimed to create materials based on HAp, Hap-Ce, and Hap-Mg using hydrothermal maturation in the microwave field. This route has been considered a novel, promising, and effective way to obtain monodisperse, fine nanoparticles while easily controlling the synthesis parameters. The synthesized HAp powders were characterized morphologically and structurally by XRD diffraction, Dynamic light scattering, zeta potential, FTIR spectrometry, and SEM analysis. Proliferation and morphological analysis on osteoblast cell cultures were used to demonstrate the cytocompatibility of the produced biomaterials. The antimicrobial effect was highlighted in the synthesized samples, especially for hydroxyapatite substituted with cerium. Therefore, the samples of HAp substituted with cerium or magnesium are proposed as biomaterials with enhanced osseointegration, also having the capacity to reduce device-associated infections.