# Additive Manufacturing for Surgical Planning and Education: A Review
## 2 Workflow
### 3D Printing and Post-Processing
However, the level of intricate detail achieved with MEX is usually lower than that of other techniques. Unlike PBF and inkjet methods, MEX-produced parts require additional support structures. Post printing, models often undergo surface smoothing and excess material removal through post-processing. The extent of post-processing depends on the printer type, quality, and materials used [16]. Figure 4: Heart models manufactured via 3D-printing SLA method [13]. Material jetting (MJT) involves an inkjet print head forming small droplets from a liquid resin. This method uses a soluble support material that is relatively easy to dissolve or a waterjet blast-off. The biggest advantage of this technology is that it can print in multiple materials, including full-color and clear models or models with both soft and hard materials [15]. Figure 6 depicts such a case of a colored 3D-printed model of a tumor next to the spine printed with material jetting. As this review looks into the diverse landscape of 3D-printing technologies in the medical field, it is imperative to explore potential future trends that could shape the trajectory of these innovations. In the sector of vat photopolymerization (VPP) and particularly Stereolithography (SLA), advancements in material science are anticipated, leading to the development of cost effective and versatile photopolymers. The ongoing research aims to overcome limitations related to material costs and post-processing steps, potentially expanding the range of applicable materials and minimizing the need for sacrificial support structures. Additionally, the integration of real-time imaging and diagnostic data into SLA processes may further enhance the precision and customization of 3D-printed medical models. Figure 5: 3D printed prosthetic socket and arm produced using PBF. Figure 6: A colored 3D-printed model of a tumor next to the spine printed with material jetting. On the other hand, Direct Ink Writing (DIW) 3D printing is believed to be witnessing an evolution towards more sophisticated bioinks and materials suitable for intricate tissue-engineering applications. Predictions include the emergence of bioinks with enhanced biocompatibility and biomimicry, allowing for the fabrication of patient-specific scaffolds that closely mimic the natural tissue environment. As the understanding of regenerative medicine advances, DIW is likely to play a pivotal role in producing functional tissues and organs for transplantation, pushing the boundaries of personalized medicine. Regarding Powder Bed Fusion (PBF, ongoing research seeks to refine the surface finish of printed objects, potentially reducing the need for extensive post-processing. Future trends may also involve the development of new materials for PBE, expanding its capabilities beyond metals, plastics, and ceramics. The medical field could witness increased adoption of PBF for the production of patient-specific implants with improved surface quality. Also, Material Extrusion (MEX) is expected to undergo advancements in filament materials, potentially introducing new biocompatible polymers with improved structural properties. Future trends may focus on enhancing the precision and intricacy achievable with MEX, making it a more viable option for certain medical applications. Research efforts may also target the development of more efficient support structures, reducing post-processing requirements. What is more, Material Jetting (MJT) is likely to witness increased integration of multi-material capabilities, enabling the creation of highly complex and customizable medical models. Future trends may involve the refinement of soluble support materials, streamlining post-processing steps and making MJT even more user-friendly. The expansion of color capabilities in 3D-printing models, as demonstrated in Figure 6, could become more widespread, enhancing the visual representation and educational value of printed medical models. Thus, the future of 3D-printing technologies in the medical field looks promising.