Resin based materials cured by blue light are used for the majority of dental restorations in the Nordic countries. There is little knowledge of the potential biological effects of the photosensitisation induced by resin based dental materials at the cellular level. Mouse fibroblasts (L-929) were exposed to a commercial bonding material in combination with blue light and the viability and cell death mechanisms were studied. The irradiation device was a polymerisation lamp emitting a spectrum in the range of 350-550 nm, with total irradiance of 1200 W/m² and emission peak at 490 nm. After various periods of incubation the cells were stained with Hoechst (33342) and propidium iodide to score the necrotic and apoptotic fractions, respectively. The viability was confirmed with MTT assay. Preliminary results showed a reduced viability of the cells after exposure to the bonding material alone and also in combination with light after 24 hours incubation. The main death mechanism was necrosis. In addition, a larger fraction of abnormal cells and a smaller fraction of cells in mitosis were found after exposure to the bonding material. A comparison between cells exposed to light without bonding material present and cells without any exposure showed no difference in viability, however, the light treated cells had a higher fraction of abnormal cells and a lower fraction of cells in mitosis. We conclude that the bonding material studied induced cytotoxic effects, both alone and in combination with visible light.


Cytotoxic effects of visible light-cured dental materials.
Roll EB, Dahl JE, Morisbak E, Becher R, Christensen T.
9th Congress of the European Society for Photobiology 2001, Abstr. 515.