Improvement of metallic implant biocompatibility by bioactive glass coating

The aim of this work was preparation, development and characterization of bioactive glass coating by sol–gel technique for improvement of biocompatibility of 316L stainless steel implant used in dentistry and orthopaedic surgery. Bioglass powder was made by sol–gel technique and thermal properties of the prepared powder were studied using differential thermal analysis (DTA). The prepared bioglass powder was immersed in the simulated body fluid (SBF) solution. Fourier transform infrared spectroscopy (FTIR) was utilized to recognize and confirm of the formation of apatite layer on prepared bioglass powder. Bioactive bioglass coating was performed on 316L stainless steel (SS) substrate by the sol–gel technique. Structural characterization techniques including XRD, SEM and EDX were used to investigate the microstructure and morphology of the coating. Electrochemical potentiodynamic polarization tests were performed in two different types of physiological solutions at 37 ◦C in order to determine and compare the corrosion behavior of the bioglass coated SS and uncoated specimens as an indication of biocompatibility. The formation of apatite layer confirmed the bioactivity of the bioglass powder and tests revealed that all the films signs of bioactivity. It was also found that at sintering temperatures above 900 ◦C, crystalline phase Ca2SiO4 was formed. Crack-free and homogeneous bioglass coatings were obtained with no observable defects. The bioglass coating also improved corrosion resistance of the 316L SS substrates such as the corrosion current density of coated samples in comparison with pristine samples was decreased.It was concluded that the sol–gel bioglass coating can improve the corrosion behavior of dental and orthopedic metallic implants and two goals including improvement of biocompatibility and bone osteointegration can be obtained simultaneously.