Abstract
The manufacturing of ideal implants requires fabrication processes enabling an adjustment of the shape, porosity and pore sizes to the patient-specific defect. To meet these criteria novel porous hydroxyapatite (HAp) implants were manufactured by combining ceramic injection molding (CIM) with sacrificial templating. Varied amounts (Φ = 0–40 Vol%) of spherical pore formers with a size of 20 µm were added to a HAp-feedstock to generate well-defined porosities of 11.2–45.2 Vol% after thermal debinding and sintering. At pore former contents Φ ≥ 30 Vol% interconnected pore networks were formed. The investigated Young’s modulus and flexural strength decreased with increasing pore former content from 97.3 to 29.1 GPa and 69.0 to 13.0 MPa, agreeing well with a fitted power-law approach. Additionally, interpenetrating HAp/polymer composites were manufactured by infiltrating and afterwards curing of an urethane dimethacrylate-based (UDMA) monomer solution into the porous HAp ceramic preforms. The obtained stiffness (32–46 GPa) and Vickers hardness (1.2–2.1 GPa) of the HAp/UDMA composites were comparable to natural dentin, enamel and other polymer infiltrated ceramic network (PICN) materials. The combination of CIM and sacrificial templating facilitates a near-net shape manufacturing of complex shaped bone and dental implants, whose properties can be directly tailored by the amount, shape and size of the pore formers.
Highlights
The restoration of large bone defects represents one of the key issues in current orthopedic and trauma surgery [1,2]
We present the fabrication of porous HAp implants with adjustable porosities and pore sizes by combining injection molding with sacrificial templating
Porous hydroxyapatite (HAp) ceramics were fabricated utilizing ceramic injection molding combined with the addition of sacrificial templates
Summary
The restoration of large bone defects represents one of the key issues in current orthopedic and trauma surgery [1,2]. The most promising materials are calcium phosphate-based ceramics (such as bioactive hydroxyapatite or bioresorbable β-tricalciumphosphate) due to their chemical similarity to apatite, the natural bone mineral, and the ability to form a strong bonding to natural bone [1] To meet these biological and mechanical criteria, various fabrication techniques for porous hydroxyapatite (HAp) scaffolds were implemented including replica method [9,10,11,12], sacrificial templating [11,13,14,15], direct foaming [10,14,16], freeze casting [7,17], extrusion [18] and additive manufacturing [19,20,21,22]
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