Innovations in bonding to zirconia-based materials. Part II: Focusing on chemical interactions

Stainless steels are widely used as orthopaedic and dental implant; however, bioadhesion in the case of thrombosis, inflammation, and infection is one of their major limitations. One way to tackle this problem is to graft the stainless steel surface with a zwitterionic polymer known for being anti-bioadhesive. Controlled atom transfer radical polymerization (ATRP) of zwitterionic poly(sulfobetaine methacrylate) (polySBMA) grafted from biomedical grade stainless steel surface was employed in this study. The interactions of polySBMA-grafted surfaces with biomacromolecules were demonstrated in vitro by the adhesion tests of plasma protein, blood cells, human MG63 osteoblast- and HT1080 fibroblast-like cells in biological complex media to evaluate their bioadhesive properties. Anti-microbial effects were also assessed for two most ordinary seen clinical bacteria, i.e., Escherichia coli and Staphylococcus epidermidis. Results showed that polySBMA-grafted surface exhibited evident bioadhesion resistance and con...

Zwitterionic-based stainless steel with well-defined polysulfobetaine brushes for general bioadhesive control.

Low-modulus Mg/PCL hybrid bone substitute for osteoporotic fracture fixation.

An interpenetrating polymer network (IPN) is a material containing two polymers, each in network form. In biomaterials used in dentistry, the IPN-like nanostructures are used in denture base polymers, denture teeth and fibre-reinforced composites. IPN structures provide the specific and desired properties for the resin system prior to and after polymerization. At adhesive interfaces, IPN polymers and composites provide good interfacial adhesion for adhering and veneering resin composites based on the so-called secondary-IPN bonding formation due to swelling of the IPN nanostructure. Good interfacial adhesion is a requirement for the success of modern adhesive dentistry.

Interpenetrating Polymer Networks (IPNs) in Dental Polymers and Composites

A series of castor oil based polyurethane/siloxane cross-linked films were prepared using castor oil, isophorone diisocyanate, and 3-aminopropyl trimethoxysilane by the sol-gel process. Fourier transform infrared (FT-IR) spectra reveal the cross-linking interaction between polyurethane and siloxane moieties, thereby shifting the peak position of characteristic N-H and C═O groups to higher wavenumber. (29)Si (silica) solid state nuclear magnetic resonance spectra were used to prove the formation of siloxane network linkage in the polyurethane system, thereby analyzing the Si environment present in the polyurethane/siloxane cross-linked films. The activation energy values at two stages (Tmax1 and Tmax2) for the degradation of polyurethane films were increased with increasing silane ratio. The calculated activation energy values for the higher silane ratio (1.5) are 136 and 170 kJ/mol at Tmax1 and Tmax2, respectively. From contact angle measurements, we observed that increasing siloxane cross-linking increased the hydrophobicity of the films. The optical transmittance obtained from ultraviolet-visible spectra indicated that the film samples are transparent in the region 300-800 nm. The moisture sorption/desorption isotherm curve shows a characteristic behavior of type III isotherm corresponds to hydrophobic materials. Dynamic mechanical studies show that the increase in storage modulus reveals siloxane cross-linking gives rigidity to the films. Atomic force microscopic images show that the introduction of siloxane changes the surface roughness of the polyurethane films. It is found that the siloxane cross-linking can be used to obtain hydrophobic surface films having good thermal stability and optical transmittance.

Physicochemical studies on polyurethane/siloxane cross-linked films for hydrophobic surfaces by the sol-gel process.

The aim of this investigation was to study the siloxane, SiOSi, film formation on Ti substrate by using mono-, bis- and tris-aminosilanes. The ultimate goal was to obtain a smooth, well-organized and stable siloxane film with suitable surface energy. Such films are expected to perform well in adhering resins to dental metal alloys when the films contain reactive functional groups. Aminosilanes were prepared as 0.5 vol.% solutions in dilute ethanol (50 vol.% ethanol in deionized water), with their natural pH of ∼ 9. The substrates were silanized in two ways: silane was allowed to react at room temperature or was cured for 1 h at 110°C. The surface characterization was carried out by reflectance–absorbance Fourier transform infrared spectroscopy (RA-FTIR), x-ray photoelectron spectroscopy (XPS), contact angle measurement and atomic force microscopy (AFM). Siloxane film thickness measurements were not made. According to spectral analysis, all silanes indicated covalent bond formation with titanium. SiOTi and SiOSi bonds were clearly seen in the spectra, suggesting that chemical retention had taken place. After curing at elevated temperature, the spectral bands seemed to be stronger than those on samples cured at room temperature. Curing of hydrolyzed silanes at elevated temperature seemed to enhance the siloxane layer formation, derived from aminosilanes, on the Ti substrate. This might have an influence on the hydrolytic stability of organosilane-promoted adhesion between Ti and dental resins. Copyright © 2004 John Wiley & Sons, Ltd.

S. Areva

Papers

Characterization of siloxane films on titanium substrate derived from three aminosilanes