The Influence of the Internal Design and Layer Thickness on the Accuracy of 3D-Printed Dental Models

This study investigated the effect of the internal design and layer thickness on 3D-printed dental models. The internal designs were classified based on the presence or absence of the palatal surface (Opened or Closed palate) and the outer wall thickness (1 mm, 3 mm, and Full). They were named as follows: O1, O3, OF, C1, C3, and CF. Based on the internal design and layer thickness (50 and 100 µm), a total of 12 experimental groups were created (n = 120). The control group was fabricated using dental stone (n = 10). The measurement sites were defined as follows: the mesiodistal width (MD) and occlusocervical height (OC) of the crown and the intercanine width (ICW) and intermolar width (IMW). Statistical significance was tested using a two-way ANOVA, one-way ANOVA, and independent sample <i>t</i>-test (α = 0.05). In comparisons with and without palatal surfaces, O3 and C3 showed a similar accuracy (<i>p</i> > 0.05) in the MD and OC, but C3 showed better (<i>p</i> < 0.05) or similar values (<i>p</i> > 0.05) than O3 in the ICW and IMW. Meanwhile, there was no significant difference between OF and CF in all measurement sites (<i>p</i> > 0.05). In comparisons of the outer wall thickness, CF showed a higher accuracy than C1 at all measurement sites (<i>p</i> < 0.05), whereas no statistical significance was observed between CF and C3 except for the ICW (<i>p</i> > 0.05). OF and CF did not show statistical significance according to the layer thickness at all measurement sites (<i>p</i> > 0.05). In all measurement sites except OC, the experimental group showed a superior (<i>p</i> < 0.05) or similar accuracy than the control group (<i>p</i> > 0.05). Within the limitations of this study, a 3 mm outer wall, including the palatal surface, and a 50 µm layer thickness is recommended as the optimal 3D printing condition for dental model fabrication.