An in vitro quantitative antibacterial analysis of amalgam and composite resins

Nurit Beyth, Abraham J. Domb, Ervin I. Weiss*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Objectives: Antibacterial properties of restorative dental materials such as amalgam and composite resins may improve the restorative treatment outcome. This study evaluates the antibacterial properties of three composite resins: Z250, Tetric Ceram, P60 and a dental amalgam in vitro. Methods: Streptococcus mutans and Actinomyces viscosus served as test microorganisms. Three quantitative microtiter spectrophotometric assays were used to evaluate the effect of the restorative materials on: (i) early-stage biofilm using a direct contact test (DCT); (ii) planktonic bacterial growth; (iii) bacterial growth in the materials' elute. For comparison purposes, agar diffusion test (ADT) was also performed. Results: The effect of the composite resins on bacterial growth was minimal and limited to a few days only. One-week-aged composites promoted growth of S. mutans and A. viscosus. The antibacterial properties in direct contact were more potent than in planktonic bacterial growth. Amalgam showed complete inhibition of both bacteria in all phases, and the effect lasted for at least 1 week. The materials' elute had no effect on both bacterial growth with the exception of complete inhibition of S. mutans in amalgam. The later results correlated with the ADT. Conclusions: The present findings demonstrate potent and lasting antibacterial properties of amalgam, which are lacking in composite resins. This may explain the clinical observation of biofilm accumulated more on composites compared to amalgams. It follows that the assessment of antibacterial properties of poorly-soluble materials has to employ more than one assay.

Original languageEnglish
Pages (from-to)201-206
Number of pages6
JournalJournal of Dentistry
Issue number3
StatePublished - Mar 2007
Externally publishedYes


  • Antibacterial activity
  • Composite resins
  • Dental amalgam
  • Direct contact test


Dive into the research topics of 'An in vitro quantitative antibacterial analysis of amalgam and composite resins'. Together they form a unique fingerprint.

Cite this