Resin-based dental restorative materials polymerize in situ and are complex mixtures of monomers and filler particles, along with initiators, activators, stabilizers and other additives. However, the polymerization reaction is never complete and several studies have reported unreacted components leaching into the oral cavity. This has been shown to cause allergies and eczema in both patients and dental personnel.
Gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS) are versatile analytical techniques used in a range of scientific disciplines. They are also useful tools towards assessing the biocompatibility of different dental materials and therefore important for improving patient safety. The leaching components, e.g. methacrylate monomers, can be identified and quantified from a solution exposed to resin-based dental materials (i.e. water, ethanol or saliva).
The analysis techniques work by first separating the leaching components in the solution according to size and polarity, either in the gas phase (GC/MS) or liquid phase (LC/MS), before they are injected into the mass spectrometer (MS). In the mass spectrometer, the components of interest are ionized to charged particles and are separated in the gas phase according to their mass to charge (m/z) ratio. This allows for quantification of the individual components. GC/MS and LC/MS are used for analysis of volatile molecules (e.g. HEMA) and non-volatile molecules (e.g. Bis-GMA), respectively. As a result, the whole spectrum of leaching components can be analysed when the two techniques are combined.
Assessing the extent of leaching from different materials is an essential part of NIOM’s activities. In 2016 NIOM will aquire a new high-sensitivity LC/MS to enable quantification when the concentrations of the leaching components are very low.
Recently, the methacrylate-based monomers in dental materials have been shown to affect cells in vitro by reducing cell growth. However, little is known about the mechanism through which this process occurs.
Research projects at NIOM are currently focused on elucidating this mechanism through the use of LC/MS to study interactions between the methacrylate monomers and proteins in cells. This will further provide the possibility of improving the biocompatibility of resin-based dental restorative materials.