Elution from light-cured dental composites: comparison of trimethacrylate and dimethacrylate as base monomers

The effect of the number of functional units on a monomer on the elution property of dental composites was first studied. Elution from a composite of a trifunctional methacrylate, 1,1,1-tris[4-(2'-hydroxy-3'-methacryloyloxypropoxy)phenyl]ethane (THMPE), was compared to that of bis-GMA, a typical difunctional base monomer in current dental composites. The degrees of cure and the water solubilities of composites prepared from the two kinds of methacrylates were measured. The concentration of unreacted methacrylates (base monomer and diluent) present in the photo-cured composites as well as the quantity of the methacrylates eluted into water (or 75%, volume fraction, of ethanol in water) from the composites were determined by high-performance liquid chromatography (HPLC). THMPE-based composites showed lesser amounts of residual and eluted methacrylates when compared with bis-GMA composites. This is attributed to the higher degree of functionality and larger molecular size of THMPE compared with those of bis-GMA.