engleski

The effect of magnesium on the development of biologically inspired titanium-based surface produced by powder metallurgy technique

Background: Magnesium enhances osteoinduction, osteoconduction and osseointegration of implanted material by interacting in important intra- and intercellular osteogenic processes in the alveolar bone during a new, perimplant bone formation. However, because of its poor corrosion resistance and high chemical reactivity, it can not be used as a pure magnesium. Powder metallurgy technique is one of possible production strategy how to incorporate magnesium in titanium matrix. In that way produced, innovative titanium- magnesium composite material can develop a biologically inspired titanium- based surface by releasing magnesium, increasing porosity and developing a favorable surface chemistry in order to improve the process of osseointegration. Aim: The aim of the present study is to quantify the amount of in vitro released magnesium from the surface of an innovative titanium- magnesium composite material and to determine physical properties and the chemistry of the surface after 42 days of immersion in simulated body fluid. Material and methods: Two groups of experimental innovative titanium-magnesium composite were produced by means of powder metallurgy technique: 1 mass% of magnesium in titanium matrix and 2 mass% of magnesium in titanium matrix. Specimens were prepared using standard metallographic methods, ground and polished. In vitro static immersion test was performed for 42 days using Hank’s balanced salt solution as a simulated body fluid at 37 ºC in thermostat. The test was carried out in triplicates. The blank test solutions were set and treated in identical manner. The mass concentration of released magnesium ions in the simulated body fluid was measured using inductively coupled plasma mass spectrometry and the amount of released magnesium per cm2 of tested surface was calculated from obtained data. The surface topography was observed by means of scanning electron microscopy using back- scattered electron and secondary electron detectors at the magnification of 50 and 200 times and the electron beam acceleration voltage of 20 kV. Energy dispersive spectroscopy was used in order to determine the chemical microanalysis of the surface. X-ray diffraction analysis was performed for identification of crystal phases formed on the surface after immersion time. Basic statistic method was used to find mean value and standard deviations of the amount of released magnesium. The difference between the tested groups was evaluated by means of Student-t statistical test. Results: Mean value for the amount of the released magnesium after 42 days of immersion in Hank’s balanced salt solution from the material with 1 mass% of magnesium was 448.66 ± 23.42 μg/cm2 and from the material with 2 mass% magnesium was 503.11 ± 18.92 μg/cm2. Student t statistical test showed that there wasn’t statistical significant difference (p<0.05) between the amount of released magnesium from two tested materials and p value was 0.124878. Scanning electron micrographs at the magnification of 50 and 200 times using secondary electron detector showed homogeneously distributed micropores and back- scattered electron detector clearly visualized dual chemical composition. By means of energy dispersive spectroscopy atoms of Mg and O, besides those of Ti, on the surface, were identified predominantly. X-ray diffraction analysis revealed formation of MgO crystals on the surface during the immersion time. Conclusions and clinical implications: Based on the in vitro study performed, one can conclude that magnesium can be released from innovative titanium- magnesium composite in surrounding area resulting in a porous surface topography and forming of MgO crystals on the surface. Such an effect may induce a favorable biological effect during the process of osseointegration of implants made of tested material. To determine the biological effect of releasing of magnesium in vivo, further research is needed.

titanium ; magnesium ; powder metallurgy ; dental implants

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