Showing 5 results for M. H. Fathi
M. H. Fathi, Gh. Feizi, Sb. Moosavi, Gh. Gahanshahi, M. Salehi, A. Saatchi and V. Mortazavi,
Volume 20, Issue 1 (7-2001)
Abstract
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 alloy, plasma sprayed hydroxyapatite coated stainless steel, plasma sprayed hydroxyapatite coated cobalt base alloy were prapared and implanted in mandibular canine of
cats. After a healing period of 4 months, investigation by SEM and histopathological interpretation and evaluation showed significant differences in tissue response and osseointegration between coated and non-coated metallic implants. It was concluded that the results were affected by the kind of metallic substrate .
Keywords: Hydroxyapatite coating, Dental endodontic implant, Osseointegration, Corrosion, Stainless steel,
Cobalt base alloy
B. Mostaghaci, M. H. Fathi, M. Sheikh-Zeinoddin, and S. Soleimanianzad,
Volume 27, Issue 2 (1-2009)
Abstract
S. Salehi, M. H. Fathi, K. Raeissi,
Volume 29, Issue 1 (Jun 2010)
Abstract
The addition of ZrO2 particles to the HA coating has received considerable attention because ZrO2 particles increase the bonding strength between HA coating and substrate. In this study, nanostructured hydroxyapatite (HA)/yttria stabilized zirconia (YSZ) coatings were prepared by a sol–gel method. It was found that at 950ºC, the dominant phases were HA and tetragonal (t)-zirconia in 3YSZ, cubic (c)-zirconia in 8 YSZ and t-c-Zirconia in 5YSZ phases with the small amounts of β-tricalcium phosphate (β-TCP) and CaZrO3. The crystallite size of the coating was about ~20-30 nm for tetragonal and cubic zirconia grain size and 40-80 nm for hydroxyapatite grain size. Crack-free and homogeneous HA/YSZ composite coatings were obtained with no observable defects. In vitro evaluation in 0.9% NaCl showed that Ca2+ dissolution rate of composite coatings was lower than that of pure HA coatings. The decrease in electrochemical performance of these coated samples in comparison with the uncoated type 316L St.St could be associated with chloride ion and water penetration into the coating, transport of ions through the coating, and the subsequent electrochemical reactions at the coating–metal interface.
H. Edris , M. H. Fathi,
Volume 29, Issue 2 (Dec 2010)
Abstract
Fabrication of biomaterials with ability to form a bond with bone tissue for bone skeletal system repair is one of the biomaterial science aims. Bioactive glasses containing CaO-SiO2-P2O5 are among the most important groups used in biomedicine and dentistry such as bone defect repair and maxillo-facial reconstruction. The aim of this work was preparation and characterization of nano particle bioactive glass with optimum bioactivity. Bioactive glasses with three different compositions (45S, 49S and 58S) were prepared via sol- gel technique. X- ray diffraction (XRD) technique and X- ray fluorescent (XRF) method were utilized for the phase analysis and also to investigate the chemical composition of the obtained bioactive glass nanopowders. Transmision electron microscopy (TEM) and Scanning electron microscopy (SEM) were utilized to study the structure, morphology and particle size of synthesized bioactive glass nanopowders. In order to investigate the bioactivity, the prepared bioactive glasses were immersed in the simulated body fluid (SBF) solution at 37◦C for 30 days. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were utilized to recognize and confirm the apatite layer on the prepared bioactive glass nanopowders. TEM images showed that the prepared bioactive glasses had the particle sizes less than 100 nanometers. SEM, FTIR and XRD confirmed the formation of bone-like apatite layer formed on the bioactive glass nanopowders surface, confirming the bioactivity of synthesized bioactive glass nanopowders. It was concluded that the amount of apatite on the 45S bioactive glasse was greater in comparison with 49S and 58S bioactive glasses. It is notable that by optimizing the chemical composition, bioactive glass nanopowder could be used in applications such as repair of bone defects and bone replacement.
M. Mazrooei Sebdani, M. H. Fathi ,
Volume 31, Issue 2 (Dec 2012)
Abstract
Despite excellent bioactivity of bioactive ceramics such as hydroxyapatite, their clinical applications have been limited due to their poor mechanical properties. Using composite coatings with improved mechanical properties could be a solution to this problem. Therefore, the strength of metal substrate and the bioactivity of the improved composite coating combined could yield suitable results. The aim of this work was fabrication and characterization of hydroxyapatite-forsterite-bioactive glass nanocomposite coating. The sol-gel technique was used to prepare hydroxyapatite-forsterite-bioactive glass nanocomposite in order to coat on 316L stainless steel (SS) by deep coating technique. The X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and energy dispersive X-ray analysis (EDX) techniques were used to investigate the microstructure and morphology of the prepared coating. The results obtained from XRD analysis showed that the suitable temperature for calcination is 600 °C. At this temperature, the homogenous and crack-free coating could attach to the 316L SS substrate. The crystallite size of composite coatings determined via AFM was lower than 100 nm. Overall, the results obtained from this work indicate that hydroxyapatite-forsterite-bioactive glass nanocomposite coating can be a good candidate for biomedical applications.
