Micro/nanostructured bioactive titanium implant surface with sol-gel silicate glass nanoparticles

Abstract

Andrew M. Shenoda, BDS/Maged A. Gadallah, MSc/Rahaf M. Darwish, MSc/Mona S. Saad, PhD/Mona K. Marei, PhD: Purpose: To develop a surface coating of sol-gel 70S30C bioactive glass (BAG) nanoparticles on titanium disks and dental implants and to characterize the results in terms of average surface roughness, adhesion strength, and coating stability upon implant insertion under clinical settings. Materials and Methods: BAG was prepared with the modified sol-gel technique, then milled into nanoparticles. The resultant powder was characterized in terms of phase structure, composition, and particle size. Titanium disks and dental implants were coated with BAG nanoparticles by electrophoretic deposition. Surface characterization of coated implants was conducted. Uncoated vs BAG-coated implants were examined for average surface roughness by a confocal laser scanning microscope. The pull-off test was conducted to measure the adhesion strength of BAG coating to the underlying disks. Coated implants were inserted under clinical settings into artificial and natural bone to measure the amount of coating loss and to evaluate the effect of insertion on coating thickness. Results: BAG nanoparticles had an amorphous structure, with a particle size of < 20 nm in diameter. Electrophoresis resulted in a continuous coating covering the whole implant surface. Microscopic analysis confirmed the porous nanostructure of BAG coating, which formed a homogenous surface with microcracks. BAG coating had a uniform thickness of 35.38 ± 4.67 μm. Average surface roughness was significantly lower for BAG-coated implants, with a reduction of surface irregularities (3.34 ± 0.45 μm for uncoated implants, 1.45 ± 0.23 μm for BAG-coated implants). Adhesion strength of 18.51 ± 3.37 MPa was recorded for BAG coating, and 66.23% ± 10.23% of the coating weight was found to remain on the implant surface after insertion into artificial bone. A reduction in BAG coating thickness occurred only in sites of high friction with bone after implant insertion into bovine bone. Conclusion: Coating titanium implants with 70S30C BAG nanoparticles is attainable through electrophoretic deposition and results in a homogenous coating layer with a moderately rough surface, considerable adhesion strength, and high coating stability observed during implant insertion.