Page 390 - IJB-10-3

International Journal of Bioprinting Optimizing 3D-printed mouthguards

Figure 2. Cross-section schematics of double-layer additively manufactured MG samples in the anterior area (A) and posterior area (B); side views of
double-layer additively manufactured MG samples (C, D, E, F). Double-layer additively manufactured MG samples were split from single-layer additively
manufactured MG samples.

2.2. Shock absorption test (LMA-A-1kN; Kyowa Electronic Instruments Co., Tokyo,
According to Fukusawa et al.’s research, a shock absorption Japan) with a capacity of 1 kilo Newton (kN), arranged in
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test was conducted using a 32.6 g metal ball with a 20 mm a triangle under a 10 mm thick stainless-steel platform.
diameter, dropped from a height of about 615 mm onto a The sample was centered on this platform. During the
steel platform. A load cell sensor system was positioned at test, loads were recorded at a 50 kHz sampling rate using
the bottom of the impact load machine. In this research, data analysis software (EDX-100A and DCS-100A, Kyowa
physical experiments were performed in a simulated Electronic Instruments, Inc.). The total impact load was
oral environment to be consistent with future clinical the sum of the three load cell readings, with the maximum
evaluations. Samples were placed in a thermostat set at load defined as the maximal impact force (MIF). The
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37°C and 100% relative humidity for 24 h before testing. A arrival time to MIF was denoted as MIF-t. Each sample
custom-made chamber maintained the sample temperature was tested five times (Figure 3). 26
and humidity during the shock absorption test.
2.3. Fatigue test
A previous study showed that the fracture load of The fatigue test was designed on the basis of Sugimoto
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human teeth falls within the range of 689–1093 N. In the et al.’s research. A concavity was ground at the center
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same mechanical situation, to verify the protective effect of of gravity on the maxillary stone model plane. An iron
MG, the impact force without a sample in this experiment ball was placed in this concavity on the maxillary stone
was controlled within this range. Impact loads were model, which was worn with a MG and meshed with the
measured using three dynamic compression load cells mandibular stone model. Loading forces were examined

Volume 10 Issue 3 (2024) 382 doi: 10.36922/ijb.2469