One Year Monomer Elution From Composites

Objectives: Resin-based dental materials, intended to replace amalgam, have raised debates concerning their safety and biocompatibility. Together with these concerns regarding potential toxicity comes the growing necessity to bridge the gap between the current alarming literature and the limited clinical observations and to acquire more precise knowledge on the actual quantity of released eluates.
Methods: Eight different materials were tested, i.e. G-aenial anterior, G-aenial posterior (GC Europe), Venus, Venus Pearl, Venus Diamond (Heraeus Kulzer GmbH), Ceram X mono, Dyract (Dentsply DeTrey GmbH) and Filtek Supreme XTE (3M ESPE). Cylindrical specimen disks (n=6) were prepared in molds (6 mm diameter, 2 mm thick). Cured specimens were immersed in three different extraction solutions (1 mL ethanol, water, artificial saliva containing α-amylase) and stored at 37°C. Extraction solutions were renewed every week for one year. Ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was used to quantify the release of monomers from resin-based materials.
Results: Even after 4 weeks, the composites remained to release monomers. The highest concentration of monomers amounted 24, 5 and 34 nmol/mm² after the first week and decreased to 0.44, 0.38 and 0.54 nmol/mm² after 4 weeks, for TEGDMA, UDMA and BisGMA, respectively. As expected, ethanol resulted in higher amounts of eluted monomers. Within this short period, no significant difference was found between monomer elution in water and artificial saliva.
Conclusions: It could be demonstrated that composites continue to release small quantities of monomers over longer periods when a continuous refreshing protocol is followed. After 4 weeks, no difference in release between water and artificial saliva could be observed, but longer periods are necessary to exclude whether biodegradation may take place in artificial saliva due to the enzyme α-amylase.