A Novel High-strength GIC System Composed of Poly (Acrylic Acid) With Different Molecular Architectures

Aims: The objective of this study was to synthesize and characterize the poly (acrylic acid) or PAA with different molecular architectures, use these polymers to formulate the cements with glass fillers, and evaluate the mechanical strengths of the formed cements.
Materials and Methods: The novel poly (acrylic acid)s with different molecular architectures were synthesized via ATRP technique. The reaction kinetics was studied. The formed cements were evaluated using compression, diametral compression, and 3-point bending, fracture toughness, knoop hardness, and wear resistance tests. The experimental cement was also evaluated for its in vitro biocompatibility.
Results: The results showed that either hyperbranched or star-hyperbranched polymer synthesis proceeds more slowly at the early stage but accelerates more quickly at the later stage than the star-shaped polymer synthesis. The higher the arm number and initiator concentration, the faster the ATRP reaction. It was also found that the higher the arm number and branching that the polymer had, the lower the viscosity of the polymer aqueous solution and the lower the mechanical strengths of the formed cement exhibited. The mechanical strengths of all three experimental glass-ionomer cements were very similar to each other but much higher than those of Fuji II LC. The aging study showed that all the experimental cements increased their CS continuously during 30 days, unlike Fuji II LC. This novel cement system was proven to be in vitro biocompatible because it showed no any noticeable cytotoxicity to human dental pulp cells and mouse 3T3 mouse fibroblasts.