A new screening test for toxicity testing of dental materials

Objectives: The development of a micro plate assay for cytotoxicity testing of dental materials based on a bioassay using brine shrimp larvae (artemia salina) as sensitive organisms. Methods: Brine shrimp larvae are commonly used for cytotoxicity assays in pharmacology. These larvae are sensitive to toxic substances. The ratio between dead larvae (no motility) and living larvae (high motility) in comparison to a control without any toxic substances is used to estimate the toxicity of the test solutions. The test materials (Arabesk®, Solitaire®, Pertac® II, Tetric®, Herculite® and the compomer materials Dyract®, Hytac®, Compoglass®) were polymerized and consecutively milled. After incubation of 1 g in 4 ml distilled water at 37°C for 48 h, the solid materials were separated by centrifugation. The solutions were equibrilated with NaCl to a salt content of 25 g/l. Aliquots of 200 μl were distributed in eight micro wells and 50 μl of a artemia salina containing (n=8–14) solution were added to each well. As controls eight wells with 250 μl salt solution containing a comparable number of brine shrimp were used. At baseline, after 2, 5, 24 and 48 h, the dead shrimp were counted using a stereo microscope. Finally all shrimps were sacrificed using Na-acid (5%) and counted to get the number of shrimps per well. Results: All compomers and Solitaire caused 100% brine shrimp lethality after 24 h and showed significantly (p<0.01, signed rank test) higher toxicities than the remaining composites. With the exception of Pertac II, all composites showed significantly higher toxic values than the control. Pertac II did not show any differences from the controls used. Conclusions: This new technique has some advantages for toxicity testing of restorative materials, because it can quickly be carried out at low costs. The disadvantage is the high quantity of material used and the low sensitivity.