4-N,N-dimethyl amino benzoic acid ethylester (DMABEE), a leachable lipophilic component of dental fillings, has been shown to interact with membrane lipids.   Objectives: To investigate the effect of DMABEE on cellular viability.   Methods: Human monoblastoid U937 cells were grown for 24 hrs at 5x10⁵ cells/ml in RPMI medium +10% FBS with DMABEE (10, 20, 40, 80, 120, 160, and 200 µM) or without DMABEE (control). At the culture end-point apoptotic and necrotic cells were detected by labeling with Annexin V-FITC and propidium iodide (NeXins Research, Holland). At least 2,500 cells per sample were then examined on a Coulter Epics XL flow cytometer. Experiments were run three times in duplicate.  Results: The tested concentrations of DMABEE induced significantly higher proportions of apoptosis and necrosis when compared to the control with only one exception: apoptosis at 10 µM (independent-samples t test, p < 0.05).  

	CONTROL				DMABEE
		10 µM	20 µM	40 µM	80 µM	120 µM	160 µM	200 µM
Apoptosis %	3,2 ± 0,4	3,5 ± 0,3	4,8 ± 0,8	4,1 ± 0,6	8,1 ± 0,7	16,6 ± 2,4	35 ± 2,1	37,3 ± 2,4
Necrosis %	1,5 ± 0,2	2,2 ± 0,5	2,1 ± 0,3	2,2 ± 0,5	9,6 ± 1,9	30,5 ± 2,7	50,3 ± 2,8	57 ± 2,3

Conclusions: Our data indicate that DMABEE activates death-signaling pathways in a concentration-dependent fashion. 

This study was supported by the Faculty of Dentistry, University of Bergen, Norway.

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