Hydroxyapatite coatings have been used on metallic substrates in a variety of applications, including modifying the surface of human implants, bone osseointegration and biological fixation. In this paper, the effects of various kinds of metallic substrate on clinical and pathological results of in vivo tests are presented. Four kinds of endodontic implants i.e, stainless steel, cobalt base all...

The effect of prior air exposure on rupture life of superalloys is reported. Oxygen is identified as a damaging species leading to severe losses in both rupture life and ductility. Similar embrittlement is observed in pure nickel and a mechanism is proposed in terms of reduced grain boundary mobility. Two cobalt base alloys and an oxide dispersion strengthened nickel base alloy do not embrittle...

Materials used for biomedical applications cover a wide spectrum and must exhibit specific properties. The most important property of materials used for fabricating implants is biocompatibility, followed by corrosion resistance. The main metallic biomaterials are stainless steels, cobalt alloy, and titanium and titanium alloys. Stainless steel was the first metallic biomaterial used successfull...

Diffusion characteristics of cobalt atoms were investigated using radioactive isotope method in phase-hardened Fe-18wt.%Mn-2wt.%Si alloy. The observed significant increase of diffusion coefficient of cobalt atoms under the cyclic γ-ε-γ martensitic transformations was due to the action of two independent mechanisms - an athermal one and a thermally activated one. The first one arose from the dir...

Nickel-metal hydride batteries (Ni-MH) are storers of electrochemical energy, which have a higher specific storage capacity than lead or nickel-cadmium batteries. The demand for Nickel-metal hydride batteries is increasing rapidly since their market launch in the early 1990's. Today there is no suitable and sustainable recycling process to recover nickel, cobalt and rare-earth metals. The disca...

Mechanical properties of nickel-cobalt alloys (0-10% Co) electroformed with low internal stress in sulfamate-based solutions were investigated in as deposited and heat treated conditions. It was demonstrated that alloy properties can be modified by selecting deposition conditions and alloy composition. Recommendations on alloy selection are made based on application requirements. The higher str...

Bone loss around femoral hip stems is one of the problems threatening the long-term fixation of uncemented stems. Many believe that this phenomenon is caused by reduced stresses in the bone (stress shielding). In the present study the mechanical consequences of different femoral stem materials were investigated using adaptive bone remodeling theory in combination with the finite element method....

BACKGROUND Modular neck adapters for hip arthroplasty stems allow the surgeon to modify CCD angle, offset and femoral anteversion intraoperatively. Fretting or crevice corrosion may lead to failure of such a modular device due to high loads or surface contamination inside the modular coupling. Unfortunately we have experienced such a failure of implants and now report our clinical experience wi...

A 45 yr old male developed pulmonary fibrosis after 29 yrs of employment as a dental technician. He subsequently developed adenocarcinoma of the lung. Diffuse interstitial fibrosis was seen using light microscopy. Neutron activation analysis of non-neoplastic lung tissue demonstrated high levels of chromium and cobalt suggesting the possibility of a chromium-cobalt alloy pneumoconiosis.

Recently, concerns have been raised about the potential effect of head-neck junction damage products at the local and systemic levels. Factors that may affect this damage process have not been fully established yet. This study investigated the possible correlations among head-neck junction damage level, implant design, material combination, and patient characteristics. Head-neck junctions of 14...