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