Factors Affecting Mammalian Cytotoxicity of 3D-printed Antifungal Denture Base Resins

Objectives: DABCO compounds, which have strong antifungal activity, can be incorporated into denture base resins as a potential treatment for Candida-associated denture stomatitis. With the increasing use of 3D printing in dentistry, we recently showed that 3D-printed denture disks prepared according to manufacturer’s recommendations had equivalent antifungal activity to heat-cured standard disks, but also significant cytotoxicity against mammalian oral cells. Objective: To determine the factor(s) contributing to mammalian cell cytotoxicity of 3D-printed denture disks.
Methods: Denture base disks were 3D-printed with Dentca Denture Base II (DENTCA) on Freeform PRO2 printer with a short UV cure. The disks were washed with isopropanol (manufacturer recommendation), ethyl acetate, or acetone, and some exposed to additional UV with intensity, including 30, 70, 120, 150, 200, and 250 mW/cm²for 10 or 20 minutes on each side (total 20 or 40 min), and finally polished with 600 grit SiC abrasive paper. Cytotoxicity against periodontal ligament cells (PDL) and gingival fibroblasts (GF) was tested using a Calcein-based cytotoxicity assay. Ultimately, antimicrobial monomers (5% C2DC12DMA, 5%C2DC16DMA) were formulated into disks and activity against C. albicans was confirmed using the XTT biofilm assay.
Results: 3D-printed denture base disks washed in isopropanol, but not ethyl acetate and acetone, had significant cytotoxicity against PDL and GF (p<0.0001). Additional UV exposure to isopropanol-treated disks could not reverse the cytotoxic effect. Likewise, additional UV exposure to ethyl acetate- or acetone-washed disks had no effect on mammalian cell survival (>80%). DABCO-infused disks washed with ethyl acetate or acetone had antifungal activity similar to isopropanol-washed disks (p<0.0001).
Conclusions: The solvent for washing 3D-printed denture base resin impacts mammalian cell cytotoxicity. Because acetone can promote cracking in denture base resin, ethyl acetate should be the solvent of choice to wash 3D-printed antifungal denture base resins to be evaluated for efficacy against Candida-associated denture stomatitis.