Production and characterization of hybrid Ti64 dental implants using sponge replica method

Trabecular dental implants have attracted increasing attention in recent years due to their low density and structural similarity to natural bone, which supports osseointegration. Among candidate materials, Ti-6Al-4V alloys are widely used owing to their biocompatibility, high strength, corrosion resistance, relatively low elastic modulus, and chemical stability. In this study, porous Ti-6Al-4V foams were produced via the sponge replica method using polyurethane templates with different pore sizes (20, 25, and 30 ppi). Processing parameters such as powder size, dispersant content, and pH were optimized to ensure homogeneous slurry distribution. The effects of sintering temperature (1170 °C, 1200 °C, 1250 °C, 1280 °C)) on microstructural evolution and mechanical properties were investigated. Hybrid structures combining porous and bulk Ti-6Al-4V materials were also produced and characterized. Comprehensive analyses (XRD, SEM, EDS, mechanical tests, and SBF bioactivity) showed that sintering at 1250 °C yielded the best performance, with maximum compressive strength of 40.2 MPa and Young's modulus of 858.9 MPa for 30 ppi foams. In-situ TiC formation reinforced the structure up to 1250 °C but caused degradation at 1280 °C due to particle coarsening. Hybrid structures exhibited excellent metallurgical bonding with an average compressive shear strength of 835.5 MPa, with failure occurring in the porous region rather than at the interface. Surface treatment with 5 M NaOH at 60 °C for 24 h enhanced bioactivity, with SBF tests showing Ca/P ratios of 1.66 after 28 days, close to the theoretical 1.67. These results demonstrate that porous Ti-6Al-4V foams with sufficient mechanical strength and bioactive surfaces can be successfully produced for potential implant applications. Furthermore, hybrid structures combining porous and bulk Ti-6Al-4V were also achieved, exhibiting strong interfacial bonding and reliable mechanical integrity.