Overcoming the Viscosity-Strength Trade-Off in 3D-Printable Dental Resins by Hydrogen Bond Engineering.

Abstract

Objective: To overcome the trade-off between the low viscosity required for printability and the high mechanical strength required for functionality in dental resins for vat photopolymerization 3D printing by developing a hydrogen-bond engineering strategy.

Methods: Three dental oligomers (Bis-GMA, UDMA, and Bis-EMA) were blended with four diluents differing in hydrogen-bonding ability. Fourier transform infrared (FTIR) spectroscopy, rheometry, three-point bending tests and 3D printing performance tests were carried out to evaluate hydrogen bond formation, viscosity, mechanical properties, printability and accuracy.

Results: FTIR and rheological tests confirmed strong hydrogen bonding between MAA and matrix oligomers. The optimized formulation, n(MAA): n(UDMA) = 2:1, achieved flexural strengths of 228 MPa (mold-filled) and 178 MPa (3D-printed) and elastic modulus of 5.3 GPa and 4.0 GPa, respectively, whereas the viscosity was only 307 mPa·s-a dramatic improvement over that of neat UDMA (viscosity 9689 mPa·s, mold-filled mechanical strength 174 MPa and 3.8 GPa). The hydrogen-bonding diluents also demonstrated significant advantages in composite resin formulations.

Conclusions: Hydrogen bond engineering decouples viscosity from mechanical strength, enabling the fabrication of low-viscosity, high-strength dental resins for 3D printing. This scalable platform overcomes the longstanding viscosity-strength trade-off, offering promising potential for dentistry and other fields of photocurable additive manufacturing.