화학공학소재연구정보센터
Materials Science Forum, Vol.423-4, 321-326, 2003
Development of functionally graded implant and dental post for bio-medical application
The polymer-ceramics (1) and metal-ceramics (2) FGMs were fabricated for bio-medical application and the effect of gradient structure was evaluated. (1) Dental post, which is inserted in root canal after endodontic treatment to restore mastication function by setting a crown on the core part, often causes the fracture in dentin around the apex of post by imposition of impact force. Functionally graded post made of composite resin was fabricated by laser lithography, one of the photo-curing type CAD/CAM systems. The elastic modulus changed gradually from 10.6GPa in core part to 2.9GPa at the apex of post by decreasing the filler content of ceramic powders from 64% to 0% in polymer matrix. Stress analysis using finite element method showed the stress relaxation by further 30% in FGM, compared with the uniform composite resin. (2) Functionally graded implant with the gradience from titanium to hydroxyapatite (Ti/HAP) in longitudinal direction was made by spark plasma sintering (SPS) to optimize the mechanical properties and biocompatibility. The Brine] hardness decreased from 61 in Ti to 15 in HAP, which contributes for stress relaxation in the implanted region of bone. The new bone formed in bone marrow of femora of rats after 8 weeks showed the thin and smooth external form, directly contact to the implant surface, in HAP rich region and the thick, wavy form, less contact to implant, in Ti rich region. Maturation of bone is more advanced in HAP rich region. The gradient functions in both mechanical properties and biochemical affinity to osteogenesis contribute to the efficient biocompatibility.