Cytotoxicity of Nano/Non-nano dental bonding agents to CHO-K1 cells

Methods: Cytotoxicity was evaluated by colony forming capacity after exposure to DBAs. Briefly, Chinese hamster ovary (CHO-K1) cells were exposed to serial diluents (0.00025%-0.05%, v/v) of five DBAs (VOCO Solobond,VOCO Futurabond NR,3M Singlebond 2,Dentsply Prime & Bond NT,Dentsply Xeno III) or solvent control for 24h and then changed with fresh medium for 7-10 days of culture. Finally viable cell colonies were stained with Giemsa and counted. Changes in cell cycle progression of CHO-K1 cells after exposure to diluents of five DBAs were evaluated by propidium iodide staining and flow cytometric analysis. The percentage of cells residing in sub-G0/G1, G0/G1, S- and G2/M phases were counted.

Results: All DBAs exhibited a dose-dependent cytotoxicity to CHO-K1 cells especially at concentrations of 0.005-0.025%. Sequentially, the potency of cytotoxicity was Dentsply Prime & Bond NT >3M Singlebond 2 > Dentsply Xeno III > VOCO Solobond M > VOCO Futurabond NR. At concentration of 0.025% (v/v), VOCO Solobond M, 3M Singlebond 2 and Dentsply Prime & Bond NT induced marked apoptosis of CHO-K1 cells as analyzed by flow cytometry. These DBAs also induced differential cell cycle arrest of CHO-K1 cells in G0/G1 and G2/M phases.

Conclusions: (1) Five DBAs showed differential cytotoxicity to CHO-K1 cells. (2) Cytotoxicity of DBAs can be due to inducing the apoptosis and differential arresting of cell cycles in G0/G1, S- and G2/M phases by components in DBAs. (3) Absence or presence of nano-fillers is not the major toxic factor for these DBAs