Three-Dimensional Printing of Bone Repair and Replacement Materials

Abstract

Solid freeform fabrication techniques such as direct write technology can be used to fabricate tissue-engineering scaffolds in 3 dimensions with high levels of reproducibility and precision. These can comprise complex structures made of osteoconductive, remodelable lattices to conduct bone ingrowth and solid barriers to prevent soft tissue invasion. As such, they act as a combination of bone graft and barrier membrane. Results from animal studies have shown that these structures fill rapidly with healing bone and can conduct bone across critical-size defects to fill large defects in rabbit skull. Results indicate that this technology can be used to produce both off-the-shelf and custom-fabricated bone graft substitutes. These may initially be used to restore alveolar ridge defects, but could also be used, in the future, to repair or replace complex craniofacial bone defects such as cleft palate defects. In the more distant future, these technologies could be combined with controlled-release bioactive substances such as growth factors and pharmaceuticals to regenerate complex structures comprising multiple tissue types.

Biomaterials for Craniofacial Bone Engineering

“…It is well understood that porosity reduces compressive strength of the scaffold and results in increased difficulty in reproducible scaffold fabrication (Bose et al, 2012). However, recent advances in 3-dimensional printing techniques, such as robocasting, have enabled scaffold manufacture with highly controlled pore architecture and morphology (Ricci et al, 2012). A study from the National Institute of Dental and Craniofacial Research demonstrated that the combination of titanium dioxide with a hydroxyapatite-gelatin macroporous scaffold had comparable strength relative to natural calvarial bone in a study of rat critical-sized calvarial defects (Ferreira et al, 2013).…”

“…The degradation pattern of a scaffold should occur at an appropriate pace specific to the host tissue; for example, degradation occurring within 3 to 6 mo would be acceptable in the craniofacial skeleton, where there is lower mechanical demand, but inappropriate following spinal fusion (Bose et al, 2012). The ability of the scaffold to fully resorb and remodel completely is especially important for pediatric craniofacial applications, where the skull must be able to develop and mature during normal growth of the immature pediatric skeleton (Patel and Fisher, 2008;Ricci et al, 2012). porosity Interconnected porosity is another key factor in scaffold design.…”

“…Both Zn and Si doping can promote type 1 collagen gene expression and extracellular signal-regulated kinase secretion that positively regulates angiogenesis, osteoblast differentiation, and morphogenesis (Ricci et al, 2012;Shie et al, 2012).…”

Progress in organ 3D bioprinting

“…Comparing with the traditional metal or polymethyl methacrylate (mechanical and semimechanical) bone repair materials, most of the 3D printed bone repair materials have two obvious characteristics: one is made of biodegradable polymers, and the other is having go-through channels or pores. The predefined channels in the 3D printed construct are useful for nutrient supply and metabolite elimination for the in-growth of osteoblasts [69][70][71][72][73] . Some of the bone repair materials have showed good osteogenic effects and bone formation capabilities.…”

3D bioprinting for tissue engineering: Stem cells in hydrogels

“…hilst 2D printing has had a big influence on everyday living, the advent of additive processing technology in 1986 [1] has seen an explosion in innovative ways of producing 3D structures, such as electronic devices [2] , aircraft parts [3] , medical devices [4] and tissue mimics [5][6][7] . For clinical applications, early designs based on creating sacrificial moulds as templates for the biomaterials [8] were quickly superseded by aqueous systems that could directly print biological materials [9−11] .…”