RESIDUAL MONOMER ADDITIVE RELEASE AND VARIABILITY IN CYTOTOXICITY OF LIGHT-CURING GLASS-IONOMER CEMENTS AND COMPOMERS

In previous studies, light-cured glass-ionomer cements have been shown to evoke cytotoxic reactions. It was the purpose of this investigatio n (a) to determine the nature of the ingredients released into an aque ous medium from 2 light-cured glass-ionomer cements (GICs) and 3 compo mers; (b) to evaluate the cytotoxicity of these extracts; and (c) to c orrelate the extent of the cytotoxic effects with eluted substances. S pecimens of 2 light-cured GICs and 3 compomers were prepared and extra cted in distilled water or cell culture medium for 24 hrs (surface-liq uid ratio 42.4 mm(2)/mL). The aqueous eluates were analyzed by gas chr omatography/mass spectrometry (GC/MS). The relative amounts of the com ponents released from various products were compared by means of an in ternal caffeine standard [%CF]. For evaluation of cytotoxic effects, p ermanent 3T3 fibroblasts were incubated with medium extracts for 24 hr s. In addition, the ED,, concentration of the photoinitiator diphenyli odoniumchloride (DPICl) was determined. In all extracts, several water -elutable organic substances were found: (Co)monomers (especially HEMA and ethylene glycol compounds), additives (e.g., camphorquinone and d iphenyliodoniumchloride), and decomposition products. The extracts of 3 products inhibited cell growth only moderately, whereas the light-cu red GIC Vitrebond and the compomer Dyract Cem revealed severe cytotoxi c effects. Vitrebond liberated the initiator DPICl, whereas Dyract Cem segregated a relatively high quantity [2966 %CF] of the comonomer TEG DMA in comparison with the other products. The present data show that TEGDMA and DPICl may be regarded as the prime causes for cytotoxic rea ctions evoked by the investigated light-cured glass-ionomer cements or compomers. Therefore, leaching of these substances should be minimize d or prevented.