Triethylene glycol dimethacrylate

Triethylene glycol dimethacrylate (TEGDMA) is a resin monomer widely used in the composition of dentin bonding agents and composite resins to restore teeth structures impaired by caries and/or fractures. However, resin monomers can be released into the oral environment and can trigger hazardous biological effects on oral tissues. The release of the resin monomers due to degradation and incomplete polymerization can occur hours or days after the treatment. Due to its hydrophilic nature, hydrolysis plays an important role in the degradation processe of TEGDMA. Chemical interactions with oral fluids and mechanical influences may also cause the degradation of resin monomers. Direct contact or diffusion of resin monomers through the dentinal tubules creates ways of interaction between dental pulp tissue and resin monomers. Dentin thickness and the severity of caries lesions are important factors in determining the amount of resin monomers interacting with dental pulp tissue. TEGDMA has been reported to cause cytotoxicity, impaired cellular functions, pulpal inflammatory responses, and changes in the immune system. In addition, TEGDMA may reduce the mineralization capacity of dental pulp cells by decreasing the expression of the mineralization related genes pathways and causing adverse effects.

Biomass dibasic acid-based unsaturated polyester resins:

Dai et al. synthesized a series of biobased unsaturated polyesters (UPRs) derived from 2,5-furandicarboxylic acid (FDCA), itaconic acid (IA), succinic acid (SA), and 1,3-propanediol (PD) by direct polycondensation and cured them with a biobased, non-volatile reactive diluent, guaiacol methacrylate. The results showed that the thermal properties, flexural strength and modulus of the cured UPRs improved considerably after the introduction of FDCA; heat loss of 5 wt% was achieved up to a temperature of 330 C, and flexural strength and modulus reached 122.8 MPa and 3521 MPa, respectively.Rorrer et al. combined muconic acid from biomass with poly(ethylene glycol succinate), poly(propylene glycol butanedioate), poly(succinic acid) butylene glycol) and poly(butylene glycol adipate) into polyesters by polycondensation.Dai et al. introduced a molar ratio of 1.2:1 of itaconic acid (20 g, 154 mmol) and ethylene glycol (7.76 g, 0.125 mol), p-toluenesulfonic acid-hydrate (0.146 g, 0.5 mol% (based on itaconic acid)) as catalyst for prepolymerization, and 4-methoxybenzene (0.146 g, 0.5 mol% (based on itaconic acid)) as a free-radical polymerization blocker 4-methoxyphenol (0.139 g, 0.5 wt% (based on the total amount of itaconic acid and diol)) were added to a four-necked round-bottomed flask fitted with a mechanical stirrer, a thermometer, a reflux condenser and a nitrogen inlet. The mixture was pre-polymerized by reacting at 160C for 2 hours to form oligomers. Then 0.028 g of dibutyltin dilaurate (1 wt% relative to the total weight of the reactants) was added as a polycondensation catalyst. After reacting the oligomer at 160C for 6 hours, the target resin was obtained by cooling to 100C under a vacuum of 0.09-0.095 MPa.