Cytotoxicity test in vitro is widely used in evaluating the biocompatibility of dental restorative materials.The three basic types of cytotoxicity test listed in ISO 7405 and ISO 10993 have demonstrated a poor correlation with the results in vivo,which mainly was resulted from the absence of dentin barrier between the tested materials and target cells.Although dentin barrier has been used in some in vitro cytotoxicity test,it is impossible to extend the use of dentin barrier in standard cytotoxicity test because the difficulty in obtaining it and great variance in permeability of dentin discs.