Scientific Reports (May 2022)

Cytotoxicity of polymers intended for the extrusion-based additive manufacturing of surgical guides

  • Felix Burkhardt,
  • Benedikt C. Spies,
  • Christian Wesemann,
  • Carl G. Schirmeister,
  • Erik H. Licht,
  • Florian Beuer,
  • Thorsten Steinberg,
  • Stefano Pieralli

DOI
https://doi.org/10.1038/s41598-022-11426-y
Journal volume & issue
Vol. 12, no. 1
pp. 1 – 11

Abstract

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Abstract Extrusion-based printing enables simplified and economic manufacturing of surgical guides for oral implant placement. Therefore, the cytotoxicity of a biocopolyester (BE) and a polypropylene (PP), intended for the fused filament fabrication of surgical guides was evaluated. For comparison, a medically certified resin based on methacrylic esters (ME) was printed by stereolithography (n = 18 each group). Human gingival keratinocytes (HGK) were exposed to eluates of the tested materials and an impedance measurement and a tetrazolium assay (MTT) were performed. Modulations in gene expression were analyzed by quantitative PCR. One-way ANOVA with post-hoc Tukey tests were applied. None of the materials exceeded the threshold for cytotoxicity (< 70% viability in MTT) according to ISO 10993-5:2009. The impedance-based cell indices for PP and BE, reflecting cell proliferation, showed little deviations from the control, while ME caused a reduction of up to 45% after 72 h. PCR analysis after 72 h revealed only marginal modulations caused by BE while PP induced a down-regulation of genes encoding for inflammation and apoptosis (p < 0.05). In contrast, the 72 h ME eluate caused an up-regulation of these genes (p < 0.01). All evaluated materials can be considered biocompatible in vitro for short-term application. However, long-term contact to ME might induce (pro-)apoptotic/(pro-)inflammatory responses in HGK.