Evaluating the conversion degree of interim restorative materials produced by different 3-dimensional printer...

Three-dimensional (3D) printers are a relatively new technology, but the degree of conversion (DC) of the resin specimens produced by using this method is currently unknown. However, the DC of resin interim restorative materials is critical for their biocompatibility and physical properties.

The purpose of this in vitro study was to evaluate the DC of interim restorative materials produced by using different 3D printer technologies and compare them with conventionally manufactured polymethyl methacrylate.

Stereolithography, digital light processing, and liquid crystal display 3D printers were used as experimental groups, and a conventional (C) method was used as the control. Five different 3D printers (DWS Systems, Formlabs [FL], Asiga, Mega, and Vega) were included. The 3D printed specimens were designed in a rectangular prism geometry (10×4×2.5 mm) by using a computer-aided design software program (Materialise 3-matic) and printed with a layer thickness of 50 µm in the horizontal direction (n=15). Fourier transform infrared spectroscopy (FT-IR) spectra were measured in 3 steps: the liquid state of the resins, after washing with 99% isopropanol, and after final polymerization. For the C method, FT-IR spectra were assessed in 2 steps: immediately after mixing the liquid and powder and after polymerization. Statistical analysis of the data was performed with 1-way ANOVA followed by the post hoc Tukey honestly significant difference (HSD) test (α=.05).

There was no statistically significant difference in DC values between the 3D printed groups (P>.05). There was a statistically significant difference only between FL and the C in terms of DC (P=.042).

Three-dimensionally printed interim resin materials found comparable results with those of the C group. The DC was not affected by different 3D printing technologies.