Mechanical and biological properties of 3D-printed porous titanium scaffolds coated with composite growth factors

Background Osseointegration is considered a prerequisite for predicting implant success, and structure, biocompatibility, and properties of the implant are important parts of the factors that influence osseointegration. The focus of current research is on how to increase the strength of osseointegration on the implant and shorten the osseointegration time. Methods In this research, different porous scaffolds, including uniform, radial-gradient, and axial-gradient porous,were designed and fabricated. Their mechanical properties and biocompatibility were comprehensively evaluated through mechanical tests and in vitro cellular experiments. A porous scaffold exhibiting optimal properties was identified through preliminary experiments. Subsequently, three different sets of composite scaffolds were developed, consisting of the selected scaffold modified with chitosan microspheres loaded with Bone Morphogenetic Protein-2 (BMP-2), Platelet-Derived Growth Factor-BB (PDGF-BB), or a combination of both. The biological responses to the composite scaffolds were systematically examined through in vitro and in vivo experiments. Results Finite element analysis indicated that the maximum equivalent stress of all three porous implants was lower than that of solid implants, while the maximum equivalent stress in the cortical bone of the porous group was higher than in the solid group. Compression tests confirmed that the elastic modulus of all three porous scaffold structures falls within the range of natural human bone. In vitro cell experiments showed that the radial gradient porous group scaffolds had the highest cell count and Alkaline phosphatase activity. The composite scaffolds exhibited superior wettability and water absorption properties compared to the non-coated scaffolds. Cell and animal experiments demonstrated that the titanium scaffolds co-modified with BMP-2 and PDGF-BB showed greater cell proliferation and new bone formation compared to scaffolds with single-factor coatings and uncoated scaffolds. Conclusions Radial-gradient porous scaffolds exhibit compatible elastic modulus, excellent cell compatibility, and osteogenic potential, making them promising candidates for bone tissue engineering applications in dentistry. Furthermore, the composite scaffolds incorporating BMP-2 and PDGF-BB-loaded chitosan microspheres demonstrated enhanced osteogenic differentiation compared to single-factor modified porous scaffolds, providing experimental evidence for the clinical application of novel implants.