Antibacterial properties of and element release from some dental amalgams

Nine commercial dental amalgams were tested for antibacterial properties in vitro. A bactericidal test on salivary bacteria, a growth inhibition test on Streptococcus mutans OMZ 176, and a time-dependent bactericidal test on Strep. mutans were used. All amalgams displayed some antibacterial properties. Dispersalloy and Revalloy were strongly antibacterial in all tests; ANA 2000 and Sybraloy killed Strep. mutans but were less potent in the salivary test and in the growth inhibition experiments. The copper amalgams, Neo-Silbrin and Cupromuc, were the most active in the salivary test but less inhibitory in the growth curve experiments. Spheraloy, Indiloy, and Amalcap showed intermediate activity in the salivary bactericidal test but were relatively weak in the growth inhibition studies. Analysis of Hg, Ag, and Cu in media from the growth inhibition studies showed release of Hg from the copper amalgams and, particularly, from Revalloy; Indiloy gave off Ag, whereas Neo-Silbrin, Cupromuc, Sybraloy, and ANA 2000 released more Cu than the other brands.