A urethane-based multimethacrylate mixture and its use in dental composites with combined high-performance properties

Objectives To synthesize and characterize different molar weight urethane multimethacrylates with a single stage (one-pot) procedure. To prepare and characterize the properties of related composites. Methods Two methacrylate precursors were initially synthesized. Then, these precursors and the multimethacrylate system formed by their coupling were characterized by FTIR and ¹H NMR. The final product was used as a matrix (with TEGDMA and SiO₂ silanized microparticles) in the preparation of composites and their physical and mechanical properties were compared to those of a bis-GMA-based resin. Water sorption and solubility measurements of the composites were also performed. Results FTIR and NMR suggested that the proposed synthesis route yields a mixture of mainly urethane-di, -tri, and tetramethacrylates. The composites presented low polymerization shrinkage (e.g. 1.88 ± 0.08% for a resin with 70% of SiO₂) and high flexural strength (e.g. 124.74 ± 9.68 MPa for a resin with 65% of SiO₂) when compared to the bis-GMA based resin and other composites found to date. Water sorption and solubility results show that the composites were deemed compliant with ISO 4049 requirements. Significance The mixture containing different molar weight of urethane multimethacrylates showed to be an excellent substitute for bis-GMA, achieving an equilibrium of properties (unlike reports elsewhere which show the enhancement of some parameters in detriment to others) and composites with low polymerization shrinkage, suitable microhardness and degree of conversion, and up to standard water sorption/solubility and flexural strength.