As reported at the ICAAC (Interscience Conference on Antimicrobial Agents and Chemotherapy), amalgam fillings tend to fend off bacteria significantly better than composite (tooth coloured) fillings, although both seem to be significantly behind the antibacterial properties of titanium (implants), gold (crowns), and good-ol enamel (teeth).
Here's a snippet from the article:
The debate about mercury in amalgam dental fillings not withstanding, amalgam is superior to composite material in reducing adherence of caries-causing Streptococcus mutans, researcher(s) said here.
The least bacterial adherence was seen for titanium, gold and natural enamel followed by amalgam, according to a German study of 73 samples presented in a poster session at the Interscience Conference on Antimicrobial Agents and Chemotherapy.
You can read the entire article from www.medpagetoday.com here: Amalgam Dental Fillings Fend Off Bacteria Better than Composite
Hans Skariah, B.Sc., DMD
Promenade Court Dental Health Group
2233 Hurontario St., Mississauga, ON, Canada (in the Dome Building)