Magnesium oxide nanoparticles-modified 3D-printed denture tooth resin: Interfacial antibiofilm activity against Streptococcus mutans biofilms and material performance in vitro

Stereolithography (SLA) printable denture-tooth resin was modified with magnesium oxide nanoparticles (nMgO) to suppress Streptococcus mutans ( S. mutans ) biofilms while maintaining key material properties. nMgO was characterized prior to incorporation: ζ-potential ≈ +15 mV, cubic phase (XRD), reactive oxygen species generation (EPR), and near-spherical to polyhedral particles of ∼50–100 nm (TEM). Liquid resin containing 0–5 wt% nMgO was printed and post-cured under a standardized protocol. Antibiofilm activity was evaluated after a 24 h S. mutans challenge using viable biofilm counts and live/dead imaging. At 5 wt% nMgO, viable counts decreased by ∼89 % (p < 0.001); microscopy indicated increased bacterial death. Degree of conversion (FTIR), wettability, wear, compressive strength, and microhardness showed no significant differences from the unfilled control (p > 0.05). Flexural properties and water sorption and solubility remained within ISO 10477 limits, and cell-extract tests with human gingival fibroblasts met ISO 10993–5 non-cytotoxicity. These results indicate that embedding nMgO confers antibiofilm activity while retaining properties and standards compliance for denture-tooth materials, with potential utility at plaque-prone tooth–prosthesis interfaces.