Improved Mechanical Properties and Bioactivity of Silicate Based Bioceramics Reinforced Poly(ether-ether-ketone) Nanocomposites for Prosthetic Dental Implantology.

Polyether-ether-ketone (PEEK) biomaterial has been increasingly employed for orthopedic, trauma, spinal, and dental implants due to its biocompatibility and in vivo stability. However, a lack of bioactivity and binding ability to natural bone tissue has significantly limited PEEK for many challenging dental implant applications. In this work, nanocomposites based on PEEK reinforced with bioactive silicate-based bioceramics (forsterite or bioglass) as nanofillers were prepared using high energy ball milling followed by melt blending and compression molding. The influence of nanofillers type and content (10, 20 and 30 wt.%) on the crystalline structure, morphology, surface roughness, hydrophilicity, microhardness, elastic compression modulus, and flexural strength of the nanocomposites was investigated. The scanning electron microscopy images of the nanocomposites with low nanofillers content showed a homogenous surface with uniform dispersion within the PEEK matrix with no agglomerates. All nanocomposites showed an increased surface roughness compared to pristine PEEK. It was found that the incorporation of 20 wt.% forsterite was the most effective in the nanocomposite formulation compared with bioglass-based nanocomposites; it has significantly improved the elastic modulus, flexural strength, and microhardness. In vitro bioactivity evaluation, which used biomimetic simulated body fluid indicated the ability of PEEK nanocomposites loaded with forsterite or bioglass nanofillers to precipitate calcium and phosphate bone minerals on its surface. These nanocomposites are expected to be used in long-term load-bearing implant applications and could be recommended as a promising alternative to titanium and zirconia when used as a dental implant material.

A review on alloy design, biological response, and strengthening of ß-titanium alloys as biomaterials.

From the past few years, developments of ß-Ti alloys have been the subject of active research in the medical domain. The current paper highlights significant findings in the area of ß-Ti alloy design, biological responses, strengthening mechanisms, and developing low-cost implants with a high degree of biocompatibility. It is evident that an astonishing demand for developing the low modulus-high strength implants can be fulfilled by synchronizing ß stabilizer content and incorporating tailored thermo-mechanical techniques. Furthermore, the biological response of the implants is as important as the physical properties that regulate healing response; hence, the optimum selection of alloying elements plays a curial role for clinical success. The paper also presents the evolution of patents in this field from the year 2010 to 2020 showing the relevant innovations that may benefit a wide range of researchers.

Surface Morphology and Mechanical Properties of Polyether Ether Ketone (PEEK) Nanocomposites Reinforced by Nano-Sized Silica (SiO2) for Prosthodontics and Restorative Dentistry.

In the field of orthopedics and traumatology, polyether ether ketone (PEEK) serves a significant role as a suitable alternative to traditional metal-based implants like titanium. PEEK is being used more commonly to replace traditional dental products. For bonding with various adhesive agents and preserved teeth, the surface alteration of PEEK was investigated. The aim of this research was to understand how different types and contents of nano-sized silica (SiO2) fillers influenced the surface and mechanical properties of PEEK nanocomposites used in prosthodontics. In this work, PEEK based nanocomposites containing hydrophilic or hydrophobic nano-silica were prepared by a compression molding technique. The influence of nano-SiO2 type and content (10, 20 and 30% wt) on surface properties of the resultant nanocomposites was investigated by the use of scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), surface roughness analysis, and contact angle measurement. The crystalline structures of PEEK/SiO2 nanocomposites were examined by X-ray diffraction (XRD) spectroscopy. Mechanical properties were measured by microhardness, elastic compression modulus, and flexural strength. All nanocomposites showed increased surface roughness compared to pure PEEK. SEM images revealed that nanocomposites filled with low content hydrophobic nano-SiO2 showed uniform dispersion within the PEEK matrix. The introduction of 10 wt% of hydrophobic nano-SiO2 to the PEEK matrix improved elastic modulus, flexural strength, and microhardness, according to the findings. The addition of nano-SiO2 fillers in a higher weight percentage, over 10%, significantly damages the mechanical characteristics of the resultant nanocomposite. On the basis of the obtained results, PEEK/SiO2 nanocomposites loaded with low content hydrophobic nano-SiO2 are recommended as promising candidates for orthopedic and prosthodontics materials.

Ni-free, built-in nanotubular drug eluting stents: Experimental and theoretical insights.

Stents used for cardiovascular applications are composed of three main elements; a metal, polymer coating and the specific drug component. Nickel-based metals and polymer coatings currently used in the stent market have increased the recurrence of in-stent restenosis and stent failure due to inflammation. In this study, a Ti-8Mn alloy was used to fabricate a nanostructured surface that can be used for drug eluting stents to overcome the hypersensitivity of metals that are currently used in stent making as well as introducing a new built-in nano-drug reservoir instead of polymer coatings. Two different systems were studied: titanium dioxide nanotubes (NTs) and Ti-8Mn oxides NTs. The materials were characterized using field emission electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), roughness, wettability and surface energy measurements. Nanoindentation was used to evaluate the mechanical properties of the nanotubes as well as their stability. In-vitro cytotoxicity and cell proliferation assays were used to study the effect of the nanotubes on cell viability. Computational insights were also used to test the blood compatibility using band gap model analysis, comparing the band gap of the materials under investigation with that of the fibrinogen, in order to study the possibility of charge transfer that affects the blood clotting mechanism. In addition, the drug loading capacity of the materials was studied using acetyl salicylic acid as a drug model.

A new look at biomedical Ti-based shape memory alloys.

Shape memory alloys (SMAs) are materials that exhibit a distinct thermomechanical coupling, one that gives rise to a wide variety of applications across a broad range of fields. One of the most successful roles is in the construction of novel medical implants. Unfortunately, concerns have been raised about the biocompatibility of the most popular SMA, nitinol (NiTi), due to the known toxic, allergenic and carcinogenic properties of nickel. Given the unique capabilities of SMAs, it is apparent that there is a need for a new class of alloys - alloys that exhibit the full range of shape memory abilities yet are also free of any undesirable side effects. This article reviews the literature surrounding SMAs and identifies the metals Ti, Au, Sn, Ta, Nb, Ru and Zr as candidates for the production of thoroughly biocompatible SMAs. Hf and Re are also promising, though more research is necessary before a definitive statement can be made. Further, the Ti-(Ta,Nb)-(Zr,Hf) alloy system is particularly suited for orthopaedic implants due to a reduced Young's modulus. However, concerns over this system's shape memory properties exist, and should be taken into consideration. Alternate alloy systems that demonstrate higher bulk moduli may still be considered, however, if they are formed into a porous structure. Due to the nature of the alloying components, blended elemental powder metallurgy is recommended for the manufacture of these alloys, particularly due to the ease with which it may be adapted to the formation of porous alloys.