To compare two conventional types of processing methods for temporary dental crowns and bridges (milling – CAD/CAM and self-curing) to 3D printed parts the elution of residual monomers and the degree of conversion were investigated. The experimental materials used consisted of the base monomers TEGDMA, Bis-GMA and Bis-EMA and 50 wt.% fillers. Additionally, a 3D printing resin without filler addition was tested. For the additive manufacturing of the specimens, the DLP process commonly used in dental technology was used. Specimen were prepared as square samples (14 x 14 x 1.9 mm). The elution of the base monomers into the different media (water, ethanol and ethanol / water (75 / 25 vol. %)) at 37 °C over a period of up to 120 d were investigated by HPLC-DAD as well as the degree of conversion (DC) by FTIR. No monomer elution could be detected in water. Most residual monomers in both other media were released from the self-curing material whereas the 3D printing composite as well as the resin released relatively little. The CAD/CAM blanks released hardly any quantitatively detectable amounts of monomers. It was assumed that higher DC would result in lower monomer elution; this did not correlate for all materials. The 3D printing composite showed similar high DC as the CAD/CAM blanks but higher residual monomer release, likewise the 3D printing resin exhibited similar DC as the self-curing composite but a lower monomer elution. Whereas the 3D printing composite showed a higher DC compared to the self-curing composite and lower monomer elution. This indicates that the monomer elution and/or DC measurement are influenced by another factor e.g. the filler content. In terms of residual monomer elution and DC, the 3D printing composite seems a promising innovative material class for the use as temporary dental crowns and bridges, which is comparable to the CAD/CAM blank.

The enzymatic degradation of the 3D printed composite material in comparison to the CAD/CAM and the self-curing material is currently under investigation. We would like to present the results at the 3rd Symposium - Materials & Additive manufacturing 2022.