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

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.