Objectives: We evaluated the dissolution of amalgam in 21 commercially available line cleaners. Methods: The line cleaners evaluated were: SRG Evacuation (A), Patterson Brand (B), Pure Vac (C), Stay Clean (D), ProE-Vac (E), E-Vac (F), BirexSe (G), Biocide (H), Turbo-Vac (I), Green and Clean (J), GC Spray Cide (K), Vacuum Clean (L), Vacusol Ultra (M), Cavicide (N), Clorox (O), Dispatch (P), Vac Attack (Q), Sani-Treet Plus (R), Fresh-Vac (S), Microstat2 (T), DRNA Vac (U) and DI water (Control). Tytin amalgam specimens were prepared according to ADA Specification No.1 and aged for 7 days. One specimen was placed in vials containing each line cleaner (5.5 mL) at the manufacturer's recommended concentration and the pH measured. Sample vials were rolled for 24 hours on a rock'n roller. The line cleaner and the amalgam specimen were removed and the vial rinsed with 2.5 mL of solution containing 5% nitric acid and 0.01% potassium dichromate. The combined line cleaner and rinse were 0.45 µm filtered and analyzed for mercury using modified EPA method 245.1. Results:

Line Cleaner	Control	A	B	C	D	E	F	G	H	I	J
Hg (ng/mm2)	1.36	0.72	0.37	0.12	0.14	0.41	0.51	0.77	ND*	0.31	0.11
pH	4.93	3.27	2.15	1.81	1.86	1.93	1.85	1.98	2.37	2.60	5.63

Line Cleaner	K	L	M	N	O	P	Q	R	S	T	U
Hg (ng/mm2)	0.47	0.26	1.01	0.30	46.42	23.63	29.93	0.23	0.07	3.23	ND*
pH	5.75	6.59	10.54	11.79	10.72	12.35	11.05	4.29	5.93	6.83	9.11

ND^*-Not Detected

Conclusions: Under controlled laboratory conditions, the amalgam in 17 out of 21 line cleaners released less mercury than control. Chlorine-containing line cleaners (e.g. Clorox, Dispatch, Vac Attack) did cause amalgam to release higher amounts of mercury, but when standardized to unit area, it is lower than previously reported (IADR Abstract#943, 2003).