IADR Abstract Archives
Step-Growth Dental Resins with Improved Performance From Ester-Free Thiol-Ene Formulations
Objectives: The objective of this work was to evaluate the performance of new thiol-ene mixtures and their cured compositions that contain no interchain ester linkages as dental resin materials.
Methods: Ester-free multifunctional thiols such as tetra(2-mercaptoethylene)-silane (SiTSH) and 1,2,3-tris(3-mercaptopropylene)-1,3,5-triazyne-2,4,6-trion (TTTSH) were synthesized, oligomerized with divinyl sulfone, and used in thiol-ene reactions with 1,3,5-triallyl-1,3,5-triazyne-2,4,6-trion.
The formulations were cured at ambient conditions by 400-500 nm light (50mW/cm2) using bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide-BPO, 1wt% and the resulting network materials were evaluated for properties relevant to dental materials.
Conversion (near-IR, n=5,), shrinkage stress (Tensometer, unfilled resin, n=3), glass transition temperatures-Tg (DMA, tensile mode, measured at tan δmax, n=3, unfilled bars, f=1Hz, temp. ramp 3°C/min), flexural strength and extension at break (MTS, n=6, unfilled bars, crosshead speed 0.2mm/min), water sorption/solubility tests (n=5, unfilled discs, stored 37°C, 7d) were performed and compared to those of BisGMA/TEGDMA methacrylate control.
Results: The results (Table 1) show that all the thiol-ene photopolymers here are glassy materials with Tgs ranging between 70 and 90°C. Generally, they reach higher functional group conversions than the BisGMA/TEGDMA resin control. The experimental flexural strengths are less than that of the control but the greater extensions at break suggest improved toughness. These materials contain no ester linkages and their water uptake is generally lower compared with the dimethacrylate control, which together indicates greater potential network stability.
Conclusions: Based on the results tabulated it can be concluded that ester-free thiol-ene formulations yield glassy, tough and water resistant materials whose properties can be tuned to exceed those of commercial dental resins.
Methods: Ester-free multifunctional thiols such as tetra(2-mercaptoethylene)-silane (SiTSH) and 1,2,3-tris(3-mercaptopropylene)-1,3,5-triazyne-2,4,6-trion (TTTSH) were synthesized, oligomerized with divinyl sulfone, and used in thiol-ene reactions with 1,3,5-triallyl-1,3,5-triazyne-2,4,6-trion.
The formulations were cured at ambient conditions by 400-500 nm light (50mW/cm2) using bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide-BPO, 1wt% and the resulting network materials were evaluated for properties relevant to dental materials.
Conversion (near-IR, n=5,), shrinkage stress (Tensometer, unfilled resin, n=3), glass transition temperatures-Tg (DMA, tensile mode, measured at tan δmax, n=3, unfilled bars, f=1Hz, temp. ramp 3°C/min), flexural strength and extension at break (MTS, n=6, unfilled bars, crosshead speed 0.2mm/min), water sorption/solubility tests (n=5, unfilled discs, stored 37°C, 7d) were performed and compared to those of BisGMA/TEGDMA methacrylate control.
Results: The results (Table 1) show that all the thiol-ene photopolymers here are glassy materials with Tgs ranging between 70 and 90°C. Generally, they reach higher functional group conversions than the BisGMA/TEGDMA resin control. The experimental flexural strengths are less than that of the control but the greater extensions at break suggest improved toughness. These materials contain no ester linkages and their water uptake is generally lower compared with the dimethacrylate control, which together indicates greater potential network stability.
Conclusions: Based on the results tabulated it can be concluded that ester-free thiol-ene formulations yield glassy, tough and water resistant materials whose properties can be tuned to exceed those of commercial dental resins.