Chemically enhanced denture acrylics

Despite the inherent material and processing advantages of acrylic resin polymers (ARPs), ARP dental restorations routinely fail due to mechanical fracture, discoloration or infection. To improve their clinical performance, a unique chemically modified ARP was developed that provides improved mechanical properties and a modified surface to which inorganic films can be deposited. Encapsulating the chemically strengthened ARPs with thin, impermeable inorganic polymer films can provide several unique advantages, including: increased resistance to discoloration and infection, improved abrasion resistance and enhanced intraoral ARP adhesion. The chemically enhanced ARPs were prepared by adding variable concentrations (0-40 wt%) of a silanol coupling agent, trimethoxysilylpropylmethacrylate [TMSPMA, (H₃CO)₃Si(CH₂)₃OOC(CH₃ )=CH₂] to a commercial acrylic resin monomer solution [Lucitone 199] prior to polymerization. The polymers were processed according to manufacturers´ specifications, trimmed, and polished (9 μm). Four point bend tests (500 kg, 2 mm/min., Model 1125 Instron) were performed on wet, polished samples (30×10×4 mm). According to the results, the addition of 20 wt.% TMSPMA improved the fracture and yield strengths of the ARP by 50% (84, 43 MPa). The simultaneous ductility (ε_f-2.65%, 125%) and elastic modulus (E-4.0 GPa, 73%) improvements correlate to a tremendous improvement in the fracture toughness of the chemically modified ARPs