Cytotoxicity of current adhesive systems: in vitro testing on cell cultures of primary murine macrophages

The aim of this study was to evaluate, in vitro, the potential cytotoxicity of dentinal adhesives on alveolar macrophages of Wistar rats, after diffusion through dentin.

The cytotoxicity of adhesives [single bond plus (SB), clearfil SE bond (CF) and Xeno V (XE)] applied to the occlusal surface of human dentin disks adapted to a dentin barrier test device were analyzed. The sets placed on a monolayer of cells were incubated for 24, 48 and 72h. Culture medium and Escherichia coli lipopolysaccharides (LPS) were used as negative and positive controls, respectively. Cellular cytotoxicity was evaluated by observing the cell survival rate (MTT assay) and nitric oxide production (NO). The data were analyzed by one-way factorial ANOVA and Tukey's and Tamhane's paired comparisons T2 (α=0.05).

All the adhesive systems reduced the percentage of live cells by over 50%, compared with the control group. Within the same period of time, there was a statistically significant difference between the adhesives and LPS compared with the negative control group. SB presented a statistically significant difference between 24h and 72h, and XE between 48h and 72h. The quantity of NO produced in 24h did not differ statistically between the NC and adhesive groups. After 48h there was a significant difference between SB/CF and XE/NC. At 72h only CF showed a significant difference from each of the other groups. LPS differed statistically from all the other groups at all the evaluation times.

Components of the adhesives tested may permeate the dentin in sufficient concentrations to cause death and damage to cell metabolism in the alveolar macrophages of rats, which indicates potential cytotoxicity to pulpal cells.