title: The antimicrobial activity of gray-colored mineral trioxide aggregate (GMTA) and white-colored MTA (WMTA) under aerobic and anaerobic conditions.
abstract: OBJECTIVE
  The objective of this study was to test the hypothesis that the antimicrobial activity of gray-colored MTA (GMTA) and white-colored MTA (WMTA) is related to the induction of reactive oxygen species (ROS).
  
  
  METHODS
  In vitro antimicrobial activity of MTA was carried out using E. coli mutant (AB2463-RecA13), triple mutant (BW535), and wild type (AB1157). The diffusion method on Müller-Hinton agar (MHA) was used. A base layer was made using MHA agar and 4 wells were made by removing agar at equidistant points. MTA was placed into the wells immediately after manipulation. The plates were incubated at 37 degrees C for 48 hours under aerobic and anaerobic conditions. Afterward the zones of inhibition were measured. Also the damage caused to the plasmid DNA in the presence of the cement was evaluated through 0.8% agarose gel electrophoresis.
  
  
  RESULTS
  It was possible to observe a zone of inhibition under aerobic conditions promoted by both cements on both of the mutant E. coli but not in the wild-type E. coli. On the other hand, both cements were not able to induce any bacterial inhibition under anaerobic conditions, suggesting that the inhibitory action is a result of ROS production. Both cements promoted damage in the DNA plasmid when compared with distilled water (control).
  
  
  CONCLUSIONS
  We concluded that MTA under aerobic conditions provoked antimicrobial activity by induction of ROS. Furthermore, the antimicrobial activity occurred by damage caused directly to the bacterial DNA.
authors.affiliation: Department of Endodontics, Federal Fluminense University, Niterói, RJ, Brazil.
authors.forename: Caroline Sousa
authors.initials: CS
authors.lastname: Ribeiro
authors.forename: Miriam F Zaccaro
authors.initials: MF
authors.lastname: Scelza
authors.forename: Raphael
authors.initials: R
authors.lastname: Hirata Júnior
authors.forename: Lidia Maria
authors.initials: LM
authors.lastname: Buarque de Oliveira
mesh_terms: D000890:Anti-Infective Agents; D015169:Colony Count, Microbial; D003116:Color; D004269:DNA, Bacterial / Q000032:analysis; D003738:Dental Cements / Q000737:chemistry / Q000494:pharmacology*; D003785:Dental Pulp Capping; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D005971:Glutamates / Q000737:chemistry / Q000494:pharmacology*; D006147:Guanine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D008826:Microbial Sensitivity Tests / Q000379:methods*; D009154:Mutation; D010100:Oxygen / Q000378:metabolism; D000068437:Pemetrexed; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012387:Root Canal Filling Materials / Q000737:chemistry / Q000494:pharmacology; D013045:Species Specificity; D018709:Statistics, Nonparametric
chemical_list: D000890:Anti-Infective Agents; D004269:DNA, Bacterial; D003738:Dental Cements; D005971:Glutamates; D017382:Reactive Oxygen Species; D012387:Root Canal Filling Materials; D000068437:Pemetrexed; D006147:Guanine; D010100:Oxygen