Page 276 - IJB-10-5

International Journal of Bioprinting A TPMS framework for complete dentures

The comparison between the actual and theoretical presence of pores. These characteristic round defects
porosity and height was conducted by measuring the size are attributed to gases trapped within the powder
and weight of each sample, and the results are summarized during the melting process, with no visible cracks
in Table 6. The results indicate that under the same printing detected. The microstructure of the etched sample
process conditions, the actual height of the test sample is (Figure 12F) exhibits a typical basketweave pattern,
lower than the theoretical height, and this discrepancy permeated by the acicular α-phase. In summary, the
can be attributed to the loss of some height during sample exhibits good manufacturing quality, with no
sample detachment from the substrate. Additionally, the cracks or significant defects that would compromise its
actual relative density of all samples is higher than the mechanical properties.
theoretical relative density due to the thermal gradient
between the layers during the SLM preparation process, 3.3. Mechanical properties
thereby inducing powder adherence to the surface of 3.3.1. Compressive characteristics
the sample. This observation is further supported by Three sets of experimental data were acquired, and
Figure 12, which is in line with pertinent literature the average values were computed to generate a fitted
findings. Among the samples, the actual relative density stress–strain curve (Figure 13B). Based on the curve, the
45
of A-II is closest to the theoretical relative density, with a elastic modulus and yield strength of the samples were
difference of only 2.24%. The relative density error of B-I determined and summarized in Table 7. From the FE
is the largest, with a difference of 9.51%. results, it is observed that the mechanical properties of
SEM was used to characterize the surface morphology the porous samples obtained through experimentation
and local features of the samples. Figure 12A, B, and C are lower than the simulated values. This difference
displays the top, middle, and bottom portions of the may arise due to various factors, such as the uneven
sample, respectively. It can be observed that a multitude distribution of powder particle size, powder oxidation,
of spherical particles adhere to the surface, including and residual stress during the manufacturing process, as
incomplete metal and welding particles (Figure 12D). well as the geometric discrepancies between the modeled
In addition, a small amount of step effect and pores are and manufactured structures. The ratio of experimental
also observed, causing the sample surface to be rough. mechanical property values of porous structures to
Additionally, the sample was bisected and polished FE simulation values reported in the literature ranges
to a mirror finish. The microstructure obtained via from 23.41% to 92.37%. 46,47 The comparative results
SEM is displayed in Figure 12E, revealing a minimal of experimental and FE simulation values presented

Table 6. Comparison between the computer-aided design (CAD) and experimental characteristics of samples

Sample Height (mm) Relative density (%)
CAD Reality Difference CAD Reality Difference
A-II 18 17.32 (±0.52) −0.68 45 47.24 (±0.86) +2.24
A-III 18 17.28 (±0.23) −0.72 45 47.83 (±0.44) +2.83
B-I 18 17.35 (±0.11) −0.65 45 54.51 (±0.35) +9.51
C-II 18 17.25 (±0.59) −0.75 45 53.07 (±0.36) +8.07
C-III 18 17.30 (±0.25) −0.70 45 52.59 (±0.41) +7.59
Sample
Characteristic
A-II A-III B-I C-II C-III
Height (mm)
CAD 18 18 18 18 18
Experimental 17.32 ± 0.52 17.28 ± 0.23 17.35 ± 0.11 17.25 ± 0.59 17.30 ± 0.25
Difference −0.68 −0.72 −0.65 −0.75 -0.70
Relative density (%)
CAD 45 45 45 45 45
Experimental 47.24 ± 0.86 47.83 ± 0.44 54.51 ± 0.35 53.07 ± 0.36 52.59 ± 0.41
Difference +2.24 +2.83 +9.51 +8.07 +7.59

Volume 10 Issue 5 (2024) 268 doi: 10.36922/ijb.3453