Cytotoxicity studies of dental restorative materials using human periodontal ligament cells in vitro

A model that simulates conditions of clinical practice in vivo and allows extended exposure of test cells to test substances, was evaluated in vitro by screening the toxicity of seven dental restorative cements. Millipore filter discs, 0.45 micron pore size, or preserved dentine slices were used as diffusion barriers between test cells and test substances. Cytotoxicity was assessed by estimating cell loss from monolayers and by evaluating cytopathic changes in cultured cells. After 24 h exposure to the test materials results were in general agreement with reported observations from similar studies. However, extended exposure to composite resins gave rise to severe cytotoxicity, which has not been reported previously. In addition, monitoring of cultures by inverted microscopy demonstrated attempts at recovery in damaged monolayers with viable cells migrating and proliferating into areas of earlier cell loss. This supports observations in vivo of transient pulpal injury associated with the corresponding materials.