In this study, cell reaction after exposure to several dental cements was determined using a dentin barrier test device. The reaction of mouse fibroblasts grown on the "pulpal" side of a bovine dentin disk was determined after exposure to dental cements applied on the "cavity" side of the disk. For pretreatment, dentin disks (500-micrometer-thick) were etched on one side and either sterilized by autoclaving or disinfected with ethanol. It was found for both pretreatment groups that zinc phosphate cement was less toxic than the conventional glass ionomer cements. A light-cured glass ionomer cement and zinc oxide-eugenol were the most toxic materials tested. Disinfecting the dentin slices instead of autoclaving reduced the toxicity of the phosphate cement and the glass ionomer cements tendentiously. Because the strong cytotoxic reaction evoked by zinc oxide-eugenol and by the glass ionomer cements is in contrast to in vivo findings, further improvements of the dentin barrier test device will be necessary.