Antimicrobial activity of submicron glass fibres incorporated as a filler to a dental sealer

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.

Mechanical performance of a biocompatible biocide soda-lime glass-ceramic

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).

Antibacterial and antifungal activity of a soda-lime glass containing copper nanoparticles

A low melting point soda-lime glass powder containing copper nanoparticles with high antibacterial (against gram-positive and gram-negative bacteria) and antifungal activity has been obtained. Sepiolite fibres containing monodispersed copper nanoparticles (d(50) approximately 30 +/- 5 nm) were used as the source of the copper nanoparticles. The observed high activity of the obtained glass powder, particularly against yeast, has been explained by considering the inhibitory synergistic effect of the Ca(2+) lixiviated from the glass on the growth of the colonies.

The antibacterial and antifungal activity of a soda-lime glass containing silver nanoparticles

The antibacterial and antifungal activity of a low melting point soda-lime glass powder containing silver nanoparticles has been studied. Nano-Ag sepiolite fibres containing monodispersed silver nanoparticles (d(50) approximately 11 +/- 9 nm) were used as the source of silver. This powder presents a high antibacterial (against gram-positive and gram-negative bacteria) as well as antifungal (against I. orientalis) activity. The observed high activity against yeast has been explained by considering the inhibitory effect of the Ca(2+) lixiviated from the glass on the growth of the yeast colonies.