Bioprinting and biomaterials for dental alveolar tissue regeneration

Abstract

Three dimensional (3D) bioprinting is a powerful tool, that was recently applied to tissue engineering. This technique allows the precise deposition of cells encapsulated in supportive bioinks to fabricate complex scaffolds, which are used to repair targeted tissues. Here, we review the recent developments in the application of 3D bioprinting to dental tissue engineering. These tissues, including teeth, periodontal ligament, alveolar bones, and dental pulp, present cell types and mechanical properties with great heterogeneity, which is challenging to reproduce in vitro. After highlighting the different bioprinting methods used in regenerative dentistry, we reviewed the great variety of bioink formulations and their effects on cells, which have been established to support the development of these tissues. We discussed the different advances achieved in the fabrication of each dental tissue to provide an overview of the current state of the methods. We conclude with the remaining challenges and future needs.

Keywords: bioink; biomaterials; bioprinting; dental tissue engineering; dentistry.

FIGURE 1

Anatomy of a tooth.

FIGURE 2

Three major bioprinting techniques (A) extrusion-based printers use mechanical or pneumatic dispensing systems to extrude the bioink, (B) to force bioink droplets out of the nozzle, inkjet printers use either a pulsed heater to heat the print head producing air bubbles or a piezoelectric actuator to generate localized pressure via ultrasonic waves, and (C) laser-assisted bioprinters (LABs) use a laser beam on an absorbing substrate to generate heat waves that dispense the bioink onto a substrate. Reprinted with permission from (Ostrovidov et al., 2019) ^© 2019 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim.

FIGURE 3

(A) Micro-CT image of a patient tooth, (B) with its 3D printed model with a fibrinogen-gelatin-hyaluronic acid-glycerol bioink loaded with hDPSCs. (C) Cross-sectional views of the construct stained with alizarin red S at different days of culture. The staining shows a spatial deposition of calcium, which corresponds to a spatial differentiation of hDPSCs that mimics the dental pulp complex, with an unmineralized central area (white dashed circles) similar to a pulp center and a mineralized outer area similar to a dentin region. (D) 3D printed triphasic scaffold of PCL-hydroxyapatite (HA) bioink used for PDL regeneration. Phase (A) A scaffold area with 100 μm microchannels and PLGA microspheres loaded with amelogenin was seeded with hDPSCs for dentin-cementum formation. Phase (B) A scaffold area with 600 μm microchannels and PLGA microspheres loaded with CTGF was seeded with hPDLSCs for periodontal ligament formation. Phase (C) A scaffold area with 300 μm microchannels and PLGA microspheres loaded with BMP-2 was seeded with hABSCs for alveolar bone formation. (E) Multimaterial bioprinting of a construct with a PCL bioink and a fibrinogen/gelatin/hyaluronic acid/glycerol/human demineralized dentin matrix (DDM 10%) bioink with hDPSCs for odontogenic differentiation. (F) Schematic showing the bioprinting strategy for the generation of dental pulp (fuchsia pink area) and dentin (light pink area) complexes, which were generated by depositing two different bioinks with hDPSCs in a printed PCL frame (white area). The whole construct was obtained by a layer-by-layer process. (G) Top view of 3D printed calcium silicate (CS) and strontium calcium silicate (SrCS) scaffolds used for bone regeneration (H) with alizarin red S staining at day 7 of culture. Sr promotes MSC osteogenic differentiation with increased calcium deposition. (A–F) adapted with permission from (Han et al., 2019)^©2019 The Authors (open access), (D) Reprinted with permission from (Lee et al., 2014)©Mary Ann Liebert, Inc, (G, H) adapted with permission from (Chiu et al., 2019) (open access).