Effects of Cellulose Nanofiber Reinforcement on the Properties of Three-Dimensional-Printed Denture Base Resin: An In Vitro Study

Although the use of three-dimensional-printed (3D-printed) denture base resins is becoming increasingly widespread in digital dentistry, information regarding the reinforcing effects of cellulose nanofibers and their most favorable concentration remains limited. We evaluated the effects of adding cellulose nanofibers (CNFs, 0–2.0 wt%) on the mechanical and physical properties of three-dimensional-printed denture base resins. The addition of cellulose nanofibers improved flexural strength (FS) and Vickers hardness (HV), with more balanced performance observed at low concentrations; no significant differences were observed in flexural modulus. Color stability did not show a linear concentration-dependent trend, and the 1.0 wt% group exhibited the most favorable overall performance. Water sorption slightly increased at higher CNF concentrations. SEM observations revealed relatively uniform CNF dispersion at lower concentrations, whereas agglomeration and void formation occurred at higher concentrations. Appropriate CNF incorporation may be a promising strategy for reinforcing 3D-printed denture base materials.