Bioprinting of three-dimensional dentin-pulp complex with local differentiation of human dental pulp stem cells

Numerous approaches have been introduced to regenerate artificial dental tissues. However, conventional approaches are limited when producing a construct with three-dimensional patient-specific shapes and compositions of heterogeneous dental tissue. In this research, bioprinting technology was applied to produce a three-dimensional dentin-pulp complex with patient-specific shapes by inducing localized differentiation of human dental pulp stem cells within a single structure. A fibrin-based bio-ink was designed for bioprinting with the human dental pulp stem cells. The effects of fibrinogen concentration within the bio-ink were investigated in terms of printability, human dental pulp stem cell compatibility, and differentiation. The results show that micro-patterns with human dental pulp stem cells could be achieved with more than 88% viability. Its odontogenic differentiation was also regulated according to the fibrinogen concentration. Based on these results, a dentin-pulp complex having patient-specific shape was produced by co-printing the human dental pulp stem cell-laden bio-inks with polycaprolactone, which is a bio-thermoplastic used for producing the overall shape. After culturing with differentiation medium for 15 days, localized differentiation of human dental pulp stem cells in the outer region of the three-dimensional cellular construct was successfully achieved with localized mineralization. This result demonstrates the possibility to produce patient-specific composite tissues for tooth tissue engineering using three-dimensional bioprinting technology

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Department of Biomedical Engineeringclos

Thermo-mechanical properties of ABS parts fabricated by fused deposition modeling and vapor smoothing

FDM is one of the popular 3D printing technologies due to an inexpensive extrusion machine and multi-material printing. However, FDM could only use thermoplastics such as ABS and PLA and has a problem related to the post-processing. In this study, we measured the mechanical property of ABS parts fabricated by FDM and the vapor smoothing technique which is one of the post-processing methods. Using dynamic mechanical analysis (DMA) and dilatometer, we observed temperature-dependent storage modulus and CTE for specimens varying with amount of acetone in the vapor smoothing process. In result, we could not observe the effect of the amount of acetone in the given range but differentiate one without the vapor smoothing process and the others with the vapor smoothing process in terms of the storage modulus and CTE. Moreover, we could perform finite element analysis using the measured mechanical properties and make a design guideline for an ABS product. We could conclude that the vapor smoothing process weakens thermal stability of ABS 3D printed parts