Factors responsible for pulp cell cytotoxicity induced by resin-modified glass ionomer cements

Resin-modified glass ionomer cements (RM-GICs) are the last generation of G ICs commonly used in restorative dentistry. They contain various resins tha t improve their mechanical properties. These modifications, however, may al so affect their biocompatibility, We compared the cytotoxicity of seven bio materials (five RM-GICs, one metal-reinforced GIC (M-GIC), and a zinc-oxyph osphate cement) using an assay of pulp cell viability in vitro (MTT assay). The most toxic materials appeared to be the M-GIC Hi-Dense and the RM-GIC Vitremer, The less toxic ones appeared to be the RM-GICs Compoglass and Pho tac-Fil, Attempts made to identify the factors responsible for their cytoto xicity indicated that in vitro cytotoxicity did not seem to be caused by an y change in pH of the biomaterial eluates. Adsorption of biomaterial eluate s on dentin powder significantly reduced the cytotoxicity of all biomateria ls. The concentration of F-, Sr2+, and Al3+ (major ionic elements present i n GICs) in the eluate of six glass ionomer containing biomaterials was too low to be cytotoxic, However, Cu2+ and Ag+ (present in alloys of M-GIC) wer e present in toxic concentrations in Hi-Dense eluates, Unpolymerized monome rs leached from resins were identified by Fourier transform IR spectroscopy in biomaterial eluates, The monomers hydroxyethyl methacrylate (HEMA), tri ethylene glycol dimethacrylate (TEGDMA), and poly(acrylic) acid were identi fied in eluates of Vitremer, Compoglass, and Hi-Dense, respectively, After ethanol elution of HEMA and TEGDMA from Vitremer and Compoglass, respective ly, the cytotoxicity of these two RM-GICs was drastically reduced. Our resu lts suggest that the principal compounds responsible for cytotoxicity are u npolymerized resin monomers in the two RM-GICs and Cu2+ and Ag+ in the M-GI C, (C) 1999 John Wiley & Sons, Inc.