Abstract
This study compared the surface roughness, contact angle, surface energy, residual monomers, degree of conversion, and flexural strength of 3D-printed dental resin under various washing conditions. The specimens were printed with a digital light processing (DLP) printer and were divided into four groups: the group dipped in IPA for 5 s (IPA-D), the group washed in IPA for 1 min (IPA-1), the group washed in IPA for 10 min (IPA-10), and the group washed with TPM for 10 min (TPM-10). Following, the groups were redivided into two groups: a cured group and an uncured group. All experimental data were statistically analyzed using one-way analysis of variance and Tukey’s test. In all groups, the surface roughness showed a value of 1.2–1.8 μm, with no significant difference (p > 0.05). Contact angle showed a significant difference between the three groups using IPA and the TPM group, whereby the TPM-washed specimen showed a low contact angle (p < 0.05). The degree of conversion (DOC) increased in the following order: IPA-D group, IPA-1 group, IPA-10 group, and TPM-10 group, exhibiting a significant difference between all groups (p < 0.05). Flexural strength was measured at 110–130 MPa in all groups, with no significant difference between groups (p > 0.05). The washing time and washing solution type of the 3D printing material had no significant effect on surface roughness and flexural strength.
Highlights
3D printing is being widely used in the dental field [1,2]
For the IPA-D group, which had a relatively short washing time, it could be observed that suspensions remained on the surface of the specimen, and groups A and B, which had a relatively long washing time of 10 min, contained relatively few foreign substances (Figure 1)
In the case of surface energy, the TPM for 10 min (TPM-10) group (125.8 ± 0.13 mN/m) had the highest energy compared with the IPA-D group (100.4 ± 2.31 mN/m), the IPA for 1 min (IPA-1) group (104.0 ± 1.48 mN/m), and the IPA for 10 min (IPA-10) group (104.8 ± 0.07 mN/m), and the difference was determined to be statistically significant (p < 0.05) (Figure 5)
Summary
The development of various materials based on polymers has made it possible to replace existing dental restorations and devices [1,3]. As the use of 3D-printed dental restorations based on the digital method is increasing, the research and products are under development [4]. When 3D printing is applied to dentistry, it is crucial for dental clinicians to make accurate and precise printouts, and as of the various research on this topic is performed and related results have been published [5,6]. The suitable materials for printing need to be selected and developed. Once the printer and material have been selected, the thing to consider is the method of printing. Studies and trial and errors about this topic have been published, such as the thickness of the printing layer, the speed of printing, and the position and number of supporters for the stacked layer [7]
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