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Rodriguez-Salvador and Ruiz-Cantu
Extrusion 3D printing is a contact dispensing system synthetic biomaterials are cheaper and can be customized
(nozzle in contact with the substrate) where continuous regarding their shape, mechanical and chemical properties
strands of material are forced thought a micro-nozzle (strength, pore characteristics, and degradation rate) for
from a movable head onto a platform. The print head specific applications. Nevertheless, they require chemical
can move in three axes xyz . This printing method can modifications to improve cell adhesion. Given this, it is
[23]
be used for creating scaffolds with defined architectures necessary to combine different types of materials to meet
from biocompatible materials and cell-laden hydrogels. the tissue requirements in terms of porosity, surface area,
Different extrusion systems have been used for 3D and mechanical strength. Asa’ad et al. established
[33]
printing such as pneumatic pressure, piston, and screw biodegradable synthetic polymers that hold potential in
driven. For the pneumatic pressure and piston systems, bone tissue engineering applications due to their low
the material is usually loaded into a syringe and dispensed cost and ability to be produced in large quantities with
with the respective methods . The screw-driven method a long shelf life, especially when compared with natural
[24]
has a separate reservoir with or without temperature biomaterials.
control. This method is usually used for highly viscous
materials. The material is transported from the reservoir 2. Methodology
to the printhead by pressure then the screw assists the
deposition process . The methodology applied in the current study was adapted
[25]
During the bioprinting process, biocompatible from the competitive technology intelligence approach of
[1]
materials (bioinks) are used to facilitate the printing and Rodríguez-Salvador et al. , and it consists of a hybrid
act as matrices for printed cells . The bioink should act model that combines a virtuous knowledge cycle with
[26]
as a cell carrier during the printing process and allow expert feedback, comprising of the following:
the cells to grow and secrete their own emulate the • Planning process: The main goals, activities, and
extracellular matrix (ECM) post-printing. The bioinks participants are stated. In this research, the principal
can be natural, synthetic materials or combinations of purpose was to identify S&T trends in 3D bioprinting
both. Polymeric hydrogels, highly hydrated 3D polymeric for dental tissue and bone applications.
networks, are one of the most viable classes of bioinks • Selection of primary and secondary information
due to their structural similarities to natural tissue and sources: Primary information mainly consists of expert
can offer a synthetic surrogate of ECM . Hydrogels participation. In this case, distinguished dentists,
[27]
can facilitate matrix remodeling, cell migration, and cell- periodontists, and experts in 3D printing and 3D
cell interactions necessary for the normal development bioprinting were consulted. They kindly asked to remain
of functional tissue . The bioink properties that need anonymous. Secondary sources encompass explicit and
[28]
to be considered for deciding if it is suitable for printing documented knowledge through papers, patents, reports,
to include viscosity, shear-thinning, viscoelasticity, and websites. In this case, Web of Science, Scopus,
cytocompatibility, gelation kinetics, and biodegradation. EBSCO Health and Science Direct were analyzed.
These properties will determine the fidelity, stability, and • Information collection: To gather information from
functionality of the final cell-laden construct . Important databases, it is important to establish a proper search
[29]
efforts of S&T are being devoted to the development of strategy, including the terminology that defines the
methods that enable printing and to the production of field under analysis and the query for information
bioinks and biomaterial inks that can produce scaffolds retrieval. The terms that define 3D bioprinting and
that can mimic the functions of the human body . dental domains were identified from a literature
[30]
review and the experts consulted. Different queries
1.2.1 Importance of Scaffolds in Dental Applications were designed and tested according to each database
Scaffolds play a key role in obtaining functional tissues. consulted. Boolean operators and inclusion and
They are designed to ECM by providing structural exclusion terms were used for this task. The time frame
support that stimulates attachment, proliferation, and for gathering the information was a 6-year period
differentiation . Dentistry applications of scaffolds are from 2012 to 2018 (when this research concluded).
[31]
recently being investigated with the aim of enhancing the • Analysis: It consists of the transformation of
regeneration of tissue and alveolar bone. information into intelligence. In this case, a statistical
Recently, Sharma et al. identified a variety of analysis combined with manual examination was
[32]
biomaterials that can be used to develop either natural or developed. Given the novelty of this domain, and
synthetic scaffolds. As they indicate, natural scaffolds offer after a cleaning a deduplication process, only a few
good cellular compatibility but have some disadvantages, documents were identified, coming out to <100.
such as limited range of mechanical properties and a lack Experts participated throughout the entire process to
of control over pore size. In addition, they specify that validate collection up to the final analysis.

International Journal of Bioprinting (2019)–Volume 5, Issue 1 3