| Description |
Calcium-phosphate bioceramics have long been attempted as replacement bone substitutes due to their resemblance to the mineral component of natural bone tissue, and because their dissolution byproducts can elicit new bone growth. Many studies have demonstrated that fluoridated hydroxyapatite, or fluorapatite (FA), is resorbed more slowly in-vivo than hydroxyapatite (HA) due to its higher thermochemical stability. Further, the release of F- ions supports more rapid osteogenic-cell differentiation and proliferation over HA. For assessing the bone regenerative properties, porous scaffolding was fabricated from FA powder that was synthesized through wet chemical methods. The scaffolding was produced using the ceramic gelcasting process in combination with the polyurethane (PU) foam method where the degree of crosslinking and polymer concentration was varied. Colloidal techniques were used to optimize the rheology of 50wt% FA aqueous suspensions. Prior to making the scaffolding, the gel-casting procedure was optimized through the creation and characterization of eight prototypical batches of gel-cast pieces created with different initiator and monomer concentrations. It was found that the density and mechanical strength of gel-cast FA ceramics improved with monomer and initiator concentration. The gel-casting procedure was then combined with the PU foam method to produce scaffolding, which was 40-80% porous and resembled human trabecular bone. Characterization of the FA scaffolding is discussed in terms of its viability for clinical bone repair in orthopedic application. The average pore size of the scaffolding was determined through micro-CT imaging, and were large enough (>300μm) for vascularization according to the literature. The mechanical strengths of the porous scaffolding could not be determined due to insufficient testing methods. The effective porosity and dye-permeability of the scaffolding were determined to assess pore interconnectivity, which was higher for scaffolding created with lowerdensity foam. |
