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International Journal of Bioprinting Optimizing 3D-printed mouthguards

correction was used to analyze the number of MG samples The lowest MIF among the double-layer additively
destroyed during the mid-fatigue test. One-way ANOVA manufactured samples was observed for D-A70 at 328.2
tested the retention force and RMS at each stage. Tukey ± 7.3 N, with values increasing sequentially on both sides
test was performed if there was a statistical significance for of the Shore A hardness scale. All additively manufactured
each ANOVA test. The Friedman test and Dunn’s pairwise materials (except D-A95) absorbed more impact force than
test analyzed the retention force at various stages, while the conventional materials ERK and MG21 (Figure 6).
paired t-test compared RMS differences at each fatigue test
stage. The significance was set at P < 0.05. All statistical Each single-layer additively manufactured sample was
analyses were conducted using SPSS software (version statistically significant compared to its corresponding
25.0, IBM Corp.). double-layer additively manufactured sample of the same
hardness of soft layer that was superior to the double-layer
3. Results sample in shock absorption (all pairs; P < 0.001).
3.1. MIF and MIF-t during shock absorption test
The MIF of the free-falling steel ball without a sample was Figure 7 illustrated the approximation function of the
709.0 ± 16.7 N. The MIF of conventional materials, ERK and material for additively manufactured D-A and A samples
MG21, were 386.5 ± 5.5 N and 393.9 ± 6.9 N, respectively. in a variety of layer designs. A linear approximation
The MIF for single-layer additively manufactured samples function was found in single-layer designed samples
2
increased progressively from 245.8 ± 3.2 N to 318.5 ± (R = 0.9749), but a quartic approximation function was
10.8 N with increasing Shore A hardness of materials. found in double-layer designed samples (R = 0.9928), with
2

Figure 6. Maximal impact force (MIF) of various material samples in shock absorption test. Abbreviations: A, single-layer Agilus or/and Vero composites
MG samples; D-A, double-layer MG samples without layer D-ABS, inlayer Agilus, or/and Vero composites; ERK, Erkoflex.

Volume 10 Issue 3 (2024) 385 doi: 10.36922/ijb.2469