Effect of Washing Condition on the Fracture Strength, and the Degree of Conversion of 3D Printing Resin

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.