# Additive Manufacturing and Chemical Engineering: Looking for Synergies from a Bibliometric Study
## 4 Review of Research Focused on Additive Manufacturing and Chemical Engineering
### Additive Manufacturing and Biofabrication
#### 4.1.3 Bioprinting Applications
While the volatile organic compounds measurements for all materials were found to be below safety thresholds, and therefore not harmful, the particulate matter for White Resin and BoneSTN was found to be above the threshold value at PM\({}_{10}\), which could be harmful for long periods of exposure without personal protective equipment. Regarding implants, the selection of the most adequate material is also a critical task. Patient-specific composite bioimplants, consisting of crosslinked poly(trimethylene carbonate) (PTMC) networks and \(\beta\)-tricalcium phosphate (TCP), were tested in vivo in twelve Gottingen minipigs [108]. Histopathologic evaluation reveals that neat PTMC bioimplant surfaces were largely covered with fibrous tissue, while in the PTMC+TCP bioimplants, bones attached directly to the implant surface showed good osteoconduction and histological signs of osteoinductivity. However, these PTMC+TCP  
Figure 12: Examples of the applications of additive manufacturing in the medical field: (**a**) medical models; (**b**) implants; (**c**) tools, instruments, and parts for medical devices; (**d**) medical aids, supportive guides, splints, and prostheses; (**e**) scaffolds [105]. bioimplants were associated with a higher incidence of necrosis and infection. In the case of external prostheses and other auxiliary medical items, the selection of materials, additive manufacturing technologies, and post-processing alternatives have been investigated too. The cytotoxicity of 3D-printed dental splints made of several materials with different fabrication orientations and post-processing treatments (manual cleaning, automatic washing, or postpolymerization) was evaluated [109]. Whereas the manufacturing orientation did not affect toxicity, both the tested materials (Luxaprint OrthoPlus based on bisphenol A dimethacrylate and V-Print based on various acrylates) provided lower cytotoxicity when standardized washing and adapted post cure were considered. Lastly, the production of pharmaceutical drugs by additive manufacturing could significantly modify the global healthcare industry, potentially saving costs by minimizing the waste associated with unused or expired medicines. A notable advantage of employing additive manufacturing in the pharmaceutical sector lies in its ability to easily customize medication treatments to meet each patient's individual needs. Furthermore, there is the possibility of producing medicines on demand, and, this way, the long-term stability of drugs becomes less critical, as these could be printed as needed, enabling the design of more effective drugs with quicker onset by not requiring an extended shelf life [110]. The role of polymeric materials in the additive manufacturing of oral pharmaceutical dosage forms and appropriate characterization methods for understanding and optimizing additive manufacturing processibility and product performance have been reviewed [111]. Several polysaccharides, cellulose derivatives, and polymer-based surfactants were highlighted for their potential in specific additive manufacturing technologies to produce oral drugs. The most important polymer properties for melt-based additive manufacturing are thermal properties and melt rheology, while for solvent-based additive manufacturing, the rheology and surface tension of printing inks are critical. Most of the characterization techniques already used to assess product performance appeared equally suitable for assessing material suitability for drug printability. More specific examples of research have explored the combination of materials and additive manufacturing technologies for drug production. For instance, different ethylene-vinyl acetate copolymers were selected and loaded with 50% metoprolol tartrate to investigate the potential of fused filament fabrication to obtain 3D-printed tablets [112]. The drug-loaded filament with 18% vinyl acetate copolymer was the most promising printable formulation due to its appropriate mechanical and rheological properties.