A Novel Dental Polymer with a Flipped External Ester Group Design that Resists Degradation via Polymer Backbone Preservation

Current dental sealants with methacrylate-based chemistry are prone to hydrolytic degradation. A conventional ethylene glycol dimethacrylate (EGDMA) was compared to a novel methacrylate monomer with a flipped external ester group (ethylene glycol ethyl methacrylate, EGEMA) that was designed to resist polymer degradation effects. Fourier transform infrared spectroscopy and water contact angle measurements confirmed a comparable degree of initial conversion and surface wettability for EGDMA and EGEMA. EGDMA disks initially performed better than EGEMA disks, as suggested by their higher surface hardness and 1.5 times higher diametral tensile strength (DTS). After 15 weeks of hydrolytic and accelerated aging, EGDMA and EGEMA DTS were reduced by 88 and 44%, respectively. This accelerated aging model resulted in 3.3 times higher water sorption for EDGMA disks than for EGEMA disks. EGDMA had an increase in grain boundary defects and visible erosion sites with accelerated aging, while for EGEMA, the changes were not significant.