Improving flexural strength of resin modified glass-ionomer cement by poly(alkenoic acid) modifications

Poly(alkenoic acid)s based on copolymers of acrylic acid and itaconic acid were synthesized and further modified with glutamic acid (Glu) and glycidyl methacrylate (GMA). The resultant polymers were characterized by means of proton nuclear magnetic resonance, gel permeation chromatography, and elemental analysis. Specimens of resin modified glassionomer cement (RMGIC) prepared from the cement-forming reactions between the synthesized polymers and a commercially reactive glass were fabricated and investigated for flexural strength using three-point bending test. The effects of different amounts of Glu and GMA on the flexural strength were evaluated. The results showed significantly improved cement strength due to the incorporation of Glu into the copolymer with an optimal feed of Glu and GMA at 0.1-0.2 and 0.4 per mole of copolymer, respectively. The addition of 2-hydroxyethyl methacrylate (HEMA) to the RMGIC formulations tremendously increased the cement strength. In this study, a formulation containing 20%-wt. of HEMA and 45%-wt. of polymer concentration gave the highest flexural strength with 62.7±3.4 MPa.