A Practical Model for Cytotoxicity Studies of Dentine Bonding Agents

Objective: The cytotoxicity of Scotchbond 1 (3M) dentine bonding agents was studied on 4 different cell lines namely 1 established 3T3 cell line and 3 human dental cell lines from 3 different donors. The sensitivities of these 4 cell lines was then compared and a practical cell model proposed for cytotoxicity testing of dentine agents. Methods: 40 reaction vials (10 for each cell line) was cleaned and sterilized. 8ul dentine bonding agent was placed onto permeable membranes (0.45um), attached to reaction vials containing medium and light cured for 10 seconds. The vials were inverted and incubated for 24 hours. The medium was transferred into four 96 well plates containing the cultured cell-lines which were allowed to grow to near confluency. Cell viability following exposure to the test samples was then compared to a similar number of controls using the MTT assay. Each experiment was repeated three times (3 replicates) in order to minimize any differences in inter-cell line growth patterns. Results: Scotchbond 1 was cytotoxic to all four cell-lines. 3T3 cells showed a survival rate of about 60% as compared to two of the human dental pulp cells which showed a significantly lower survival rate (p<0.05 Kruskal-Wallis Multiple-Comparison Z-Value Test). The human pulp fibroblasts were more sensitive to cytotoxic challenge in two cell lines with the third cell line showing similar sensitivity to the 3T3 cell line (p<0.05 Kruskal-Wallis Multiple-Comparison Z-Value Test). Conclusion: Scotchbond 1 was found to be cytotoxic to both 3T3 mouse cells and human dental pulp cells. Human dental pulp cells were found to be more sensitive and should be at least one of the cell-lines used in biocompatibility profiling of dentine bonding agents.