ABSTRACT
In this study a phosphate-free glass-ceramic porous scaffold was synthesized by a three-step methodology involving slurry preparation, induction of porosity by surfactant-assisted foaming following by freeze-drying and sintering. This inorganic scaffold was characterized by X-ray diffraction, scanning electron microscope (SEM), degradation and bioactivity. Thermal treatment at 750 °C showed two new crystalline phases, combeite and nepheline, into the glassy matrix responsible for its properties. The cell response of the scaffold was also evaluated for using as a bone graft substitute. A commercial Biphasic Calcium Phosphate, BCP, scaffold was assessed in parallel as reference material. Microstructures obtained by SEM showed the presence of macro, meso and microporosity. The glass-ceramic scaffold possesses an interconnected porosity around 31% with a crack-pore system that promote the protein adsorption and cell attachment. Glass-ceramic scaffold with high concentration of calcium ions shows an antimicrobial behavior against Escherichia coli after 24 h of contact. Nepheline phase present in the glass-ceramic structure is responsible for its high mechanical properties being around 87 MPa. Glass-ceramic scaffold promotes greater protein adsorption and therefore the attachment, spreading and osteodifferentiation of Adipose Derived Stem Cells than BCP scaffold. A higher calcification was induced by glass-ceramic scaffold compared to reference BCP material.
Subject(s)
Bone Substitutes/chemistry , Ceramics/pharmacology , Escherichia coli/drug effects , Mesenchymal Stem Cells/cytology , Tissue Scaffolds/chemistry , Bone Regeneration , Calcium/chemistry , Cell Adhesion , Cell Proliferation , Cells, Cultured , Ceramics/chemistry , Escherichia coli/growth & development , Freezing , Hot Temperature , Humans , Materials Testing , Microscopy, Electron, Scanning , Porosity , Tissue Engineering/methods , Tissue Scaffolds/microbiology , X-Ray DiffractionABSTRACT
Two types of antimicrobial glass fibers containing ZnO and CaO, with diameters ranging from tens of nanometers to 1 µm, were successfully fabricated by a laser spinning technique. The antimicrobial performance was corroborated according to ISO 20743:2013, by using gram-negative (Escherichia coli) and gram-positive (Streptococcus oralis, Streptococcus mutans and Staphylococcus aureus) bacteria, and yeast (Candida krusei) (more than 3 logs of reduction). The metabolic activity and endosomal system of eukaryotic cells were not altered by using eluents of CaO glass submicrometric fibers and ZnO fibers at 1 : 10 dilution as cellular media (viability rates over 70%). A dental material was functionalized by embedding ZnO nanofibers above the percolation threshold (20% wt), creating a three-dimensional (3D) fiber network that added an antimicrobial profile. This new ZnO glass fiber composite is proved non-cytotoxic and preserved the antimicrobial effect after immersion in human saliva. This is the first time that a fiber-reinforced liner with strong antimicrobial-activity has been created to prevent secondary caries. The potential of developing new fiber-reinforced composites (FRCs) with antimicrobial properties opens up an extensive field of dental applications where most important diseases have an infectious origin.
Subject(s)
Anti-Infective Agents/chemistry , Dental Materials/chemistry , Glass/chemistry , Resin Cements/chemistry , Animals , Calcium Compounds/chemistry , Candida , Composite Resins , Dental Stress Analysis , Escherichia coli , Humans , Methacrylates/chemistry , Mice , Microbial Sensitivity Tests , NIH 3T3 Cells , Oxides/chemistry , Saliva/chemistry , Saliva/drug effects , Staphylococcus aureus , Streptococcus mutans , Streptococcus oralis , Zinc/chemistry , Zinc Oxide/chemistryABSTRACT
A biocompatible soda-lime glass-ceramic in the SiO2-Na2O-Al2O3-CaO-B2O3 system containing combeite and nepheline as crystalline phases, has been obtained at 750°C by two different routes: (i) pressureless sintering and (ii) Spark Plasma Sintering. The SPS glass-ceramic showed a bending strength, Weibull modulus, and toughness similar values to the cortical human bone. This material had a fatigue limit slightly superior to cortical bone and at least two times higher than commercial dental glass-ceramics and dentine. The in vitro studies indicate that soda-lime glass-ceramic is fully biocompatible. The in vivo studies in beagle jaws showed that implanted SPS rods presented no inflammatory changes in soft tissues surrounding implants in any of the 10 different cases after four months implantation. The radiological analysis indicates no signs of osseointegration lack around implants. Moreover, the biocide activity of SPS glass-ceramic versus Escherichia coli, was found to be >4log indicating that it prevents implant infections. Because of this, the SPS new glass-ceramic is particularly promising for dental applications (inlay, crowns, etc).
