Exploring the role of electrospun zirconia nanofibers in 3D-printed self-healing denture base resin composites

OBJECTIVE: This study investigated the synergistic effects of electrospun silanized zirconia nanofibers and polyurea-formaldehyde (PUF) microcapsules on the mechanical properties and self-healing efficiency of 3D-printed denture base resin composites. METHODS: Electrospun zirconia nanofibers (Zr) were surface-modified using 1 % MPS and characterized using FTIR and SEM. PUF microcapsules (TEGDMA as core) were synthesized via an oil-in-water emulsion and characterized for composition and surface morphology. The control group consisted of unmodified resin with 0 wt% fillers. Experimental groups included 1 wt% and 3 wt% silanized zirconia nanofibers, 25 wt% PUF microcapsules, and their combinations (1 % Zr + 25 % PUF and 3 % Zr + 25 % PUF) incorporated into the resin matrix. Degree of conversion was evaluated using FTIR; surface hardness was measured using a microhardness tester; and flexural strength, flexural modulus, fracture toughness, and self-healing efficiency were assessed using a universal testing machine. RESULTS: The control group exhibited the highest degree of conversion, which progressively decreased with the addition of zirconia nanofibers, PUF microcapsules, and their combinations. Zirconia nanofibers alone significantly improved flexural strength, surface hardness, and fracture toughness. However, combined incorporation of zirconia nanofibers and PUF microcapsules reduced flexural strength and hardness while significantly enhancing fracture toughness (p ≤ 0.05). Self-healing efficiency was highest in the 25 wt% PUF group but was significantly reduced in the combined groups (p ≤ 0.05). SIGNIFICANCE: The combined approach enhanced fracture toughness but compromised flexural strength and healing efficiency, indicating a trade-off between mechanical reinforcement and self-healing performance, highlighting the need for optimized filler concentrations.