title: Biological and antibacterial properties of a new silver fiber post: In vitro evaluation.
abstract: BACKGROUND
  The incorporation of nano silver particles (AgNPs) to improve antibacterial properties of dental materials has become increasingly common. The aim of the present study was to compare the antibacterial activity and cytotoxicity effects of different fiber posts: glass fiber post, quartz fiber post, nano fiber post and silver fiber post.
  
  
  METHODS
  The antibacterial activity againstS. mutans,S. salivariusandS. sanguiswas evaluated by using the agar disc diffusion test (ADT). Four wells of 3x2 mm (one for each material) were made with a punch by removing the agar and filled with the materials to be evaluated. The size of the inhibition zone was calculated. An extract was made eluting the posts in cell culture medium using the surface area-to-volume ratio of approximately 1.25cm²/ml between the surface of the samples and the volume of medium. Cell cultures were then exposed to 100 μL of the extracts medium. After 24 h, cell viability was determined using the MTT assay.
  
  
  RESULTS
  Silver fiber post was the only material showing a fair antibacterial effect against all the three streptococcal strains. The level of cytotoxicity of all the fiber posts tested was higher than 90% and therefore they were considered not cytotoxic.
  
  
  CONCLUSIONS
  The new silver fiber post reported a fair antibacterial activity. On the other hand all the fiber posts tested (including the post with incorporated AgNPs) proved to be biocompatible, suggesting that their application does not represent a threat to human health.Key words:Antibacterial activity, agar disc diffusion test, biocompatibility, fiber post, MTT test.
authors.affiliation: MD, DDS, Department of Clinical-Surgical, Diagnostic and Pediatric Sciences, Section of Dentistry, University of Pavia, Pavia, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Poggio
authors.affiliation: DMD, Department of Clinical-Surgical, Diagnostic and Pediatric Sciences, Section of Dentistry, University of Pavia, Pavia, Italy.
authors.forename: Federico
authors.initials: F
authors.lastname: Trovati
authors.affiliation: DMD, Department of Clinical-Surgical, Diagnostic and Pediatric Sciences, Section of Dentistry, University of Pavia, Pavia, Italy.
authors.forename: Matteo
authors.initials: M
authors.lastname: Ceci
authors.affiliation: DMD, PhD , Department of Clinical-Surgical, Diagnostic and Pediatric Sciences, Section of Dentistry, University of Pavia, Pavia, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Chiesa
authors.affiliation: DMD, PhD , Department of Clinical-Surgical, Diagnostic and Pediatric Sciences, Section of Dentistry, University of Pavia, Pavia, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Colombo
authors.affiliation: MD, DDS, Department of Molecular Medicine, Unit of Biochemistry, University of Pavia, Pavia, Italy.
authors.forename: Giampiero
authors.initials: G
authors.lastname: Pietrocola