Filler-induced cytokine release
is inhibited by methacrylate monomers

Dental composite materials are made up of filler particles (inorganic component), a resin matrix (organic component) and a coupling agent for binding the filler to the matrix. The organic component consists of methacrylate monomers that polymerize upon activation by visible light. The polymerization process is never complete, causing leakage of unreacted monomers during clinical service. Degradation processes may weaken the bond between the fillers and the matrix, leading to release of fillers particles and ions in addition to the organic components. Particulate matter is released to the air in dental clinics during clinical handling, placement and finishing of fillings. Thus, both dental personnel and patients could be exposed to several components including inorganic ions, unpolymerized methacrylate monomers and filler particles.

Objective: Combined exposure to chemicals could result in an altered biological burden compared to that from exposures to single compounds. The aim of the study was to address effects of methacrylates and filler particles separate and in combination, on the secretion of cytokines in THP-1 macrophages, and to elucidate possible mechanisms involved in the response.

Methods: THP-1 differentiated macrophages (20 ng/ml PMA) were used in the current study. Measurement of cytokine release was done by Enzyme-Linked Immunosorbent Assay (ELISA).

Results: Nano-silica (SiO2) particles induced a dose-dependent release of IL-6 and IL-1β in THP-1 macrophage cells. Bis-GMA and TEGDMA did not influence the IL-6 or the IL-1β response alone. However, combined exposure to SiO2 particles and Bis-GMA and TEGDMA reduced the cytokine response induced by the particles. 

Conclusion: In the present study, we show that TEGDMA and BisGMA have an inhibitory effect on particle-induced cytokine release in THP-1 macrophages. The mechanism involved in this response is currently being investigated.

Authors: V Ansteinsson1, JT Samuelsen2, JE Dahl2 and NR Gjerdet3.
Affiliations: 1Department of Clinical Dentistry, University of Bergen, Faculty of Medicine and Dentistry, Bergen, Norway. 2NIOM – Nordic Institute of Dental Materials, Oslo, Norway. 3Department of Clinical Dentiatry, University of Bergen, Bergen, Norway.