Influence of pH and time on organic substance release from a model dental composite: a fluorescence spectrophotometry and gas chromatography/mass spectrometry analysis

In this study we assessed the influence of pH and time on the degradation and elution of organic substances from the composite resin material, Z-100. To accomplish this, fluorescence spectrophotometry was evaluated as an appropriate technique for the identification of six organic substances (methacrylic acid, methyl methacrylate, hydroquinone, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate and 4,4'-isopropylidenediphenol) that were eluted from resin composite material stored for 24 h or 6 months at pH 4.0, 6.0 or 8.0. In addition, complementary analyses (solid-phase microextraction/gas chromatography/mass spectrometry) were carried out to identify and quantify the substances. The main substances leached from the resin composite were methacrylic acid, triethylene glycol dimethacrylate and hydroquinone. It was concluded that fluorescence spectrophotometry seems to be a suitable, non-destructive technique for the qualitative analysis of eluted organic components. Critical combinations of time and pH allowed the elution of several organic substances, predominantly methacrylic acid, triethylene glycol dimethacrylate and hydroquinone, from the model resin composite, Z-100.