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International Journal of Bioprinting 3D-printing silicone patient-specific soft-tissue expander

dose, and geometric design are particularly important. weight, high viscosity, high hydrophilicity, and rapid fluidity,
Biocompatible silicone 3D-printing technology offers for use as the material for swellable tablets. Carbopol
8
remarkable flexibility and elasticity, enabling bending 940 has passed the in vitro cytotoxicity test for biological
and compression without breakage, and exhibiting good compatibility according to ISO 10993-5 (2009).
9
resistance to elevated temperatures and the complex oral To evaluate the swollen characteristics of solid
chemical environment. Silicone 3D printing represents Carbopol 940 in a liquid environment, powdered Carbopol
4–7
a novel approach to developing soft-tissue expanders that 940 NF was first compressed in a slot mold of 8 mm in
rapidly form patient-specific complex geometric shapes length, 4 mm in width, and 1 mm in height (Figure 2a).
and intricate structural details. Approximately, 50 mg of Carbopol 940 NF powder was
This study developed a patient-specific self-inflated filled into the tablet mold and subsequently compressed
gingival tissue expander for large individual mandibular using an oil press machine (SSP-10A, Shimadzu, Japan)
bone defects to improve the precision and predictability at a pressure of 100 kN for 20 min to form a slot-shaped
of the expansion. A biocompatible polymer material was swellable tablet (Figure 2b). The tablet was crosslinked
formed into a solid swellable tablet through compression with calcium lactate aqueous solution, resulting in an
molding and placed into a 3D-printed silicone membrane outer layer membrane that constrained the tablet into a
with surface pores to create a novel soft-tissue expander. fixed shape. The expansion tablet was placed into an oven
The expander was expected to completely conform to at 60°C for 12 h for complete drying and shaping.
the shape requirements within 6 weeks. Simultaneously, Phosphate-buffered saline (PBS) is commonly used
clinical patients with large mandibular bone defects in cell culture, biochemical experiments, and cellular and
affecting at least two teeth on the left or right sides were tissue analyses to simulate the physiological environment
included in this study to validate the design, manufacture, inside living organisms. The PBS solution used in this
and feasibility of the new soft-tissue expander.
experiment was prepared by mixing 0.27 g potassium
2. Methods dihydrogen phosphate (KH PO ), 1.42 g disodium
2
4
hydrogen phosphate (Na HPO ), 8 g sodium chloride
2
4
2.1. Fabrication of swellable tablets and volume (NaCl), and 0.2 g potassium chloride (KCl) uniformly in
expansion test 800 mL deionized water. The solution was adjusted to pH
This study utilized the Carbopol 940 polymer (Carbopol 940 7.4 and topped up to 1 L with deionized water, constituting
NF, Lubrizol, United States of America [USA]), a crosslinked the tablet-soaking solution. The experimental environment
polyacrylic acid polymer characterized by its high molecular was set at 37°C. All tablets were soaked in the PBS solution,

Figure 2. Preparation of swellable tablets: (a) a slot mold with 8 mm length, 4 mm width, and 1 mm height; (b) compression procedure using an oil press
machine to form slot-shaped swellable tablets.

Volume 10 Issue 4 (2024) 567 doi: 10.36922/ijb.2918