Mechanical and Antibacterial Properties of 3D-Printed Composite Reinforced With Niobium Pentoxide

Objectives: To evaluate the mechanical and antibacterial properties of a 3D-printed composite for definitive restorations (3D-C) reinforced with niobium pentoxide microparticles (Nb-µP).
Methods: A 3D-C based on ≈75% urethane dimethacrylate, >10% methacrylated monomers, and ≤15% inorganic filler (PriZma 3D Bio Crows Resin, Makertech, Brazil) was reinforced with Nb-µP at 0 wt.% (control), 0.5 wt.% (Nb0.5%), 1 wt.% (Nb1%), and 2 wt.% (Nb2%). Nb-µP and 3D-C were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Specimens were printed (0° orientation) and cured for 20 minutes (Anycubic3D, Photon Mono X, Shenzhen, China). Mechanical properties were evaluated by flexural strength (FS), flexural modulus (FM) (n = 12), surface roughness (Ra) (before/after polishing), and microhardness (n = 6). Antibacterial activity was assessed via biofilm formation tests against S. mutans (CFU/mL) (n = 5). Data were analyzed using one-way and two-way ANOVA/Tukey’s tests (α = 5%).
Results: EDX identified Nb-µP peaks, and SEM showed spherical microparticles (~1.92 µm) with agglomeration. Control and Nb0.5% exhibited the highest FS (p < 0.05), reaching 102.98 and 108.45 MPa, respectively, with no differences between them (p > 0.05), while Nb1% and Nb2% decreased FS (p < 0.05). Nb0.5% exhibited the highest FM (2.82 GPa), while Nb2% showed the lowest FM (2.51 GPa) (p < 0.05). Nb1% and Nb2% reduced Ra (~23%) before polishing (p < 0.05), and all groups achieved Ra < 0.2 µm after polishing. Nb2% significantly increased microhardness (p < 0.05). All Nb-µP concentrations provided antibacterial activity against S. mutans compared to the control (p < 0.05), with no differences between them (p > 0.05).
Conclusions: Incorporating 0.5 wt.% Nb-µP into a 3D-C maintained the FS and displayed the highest FM, while higher concentrations (1 and 2 wt. %) reduced FS. After polishing, all groups achieved clinically acceptable Ra. Nb2% increased microhardness, and all Nb-µP concentrations showed antibacterial properties.