title: Ex vivo antimicrobial activity of several bleaching agents used during the walking bleach technique.
abstract: OBJECTIVE
  To investigate ex vivo the antimicrobial activity of a paste of sodium perborate associated with various vehicles comparing it with 37% carbamide peroxide and 35% hydrogen peroxide.
  
  
  METHODS
  The antimicrobial activity of these agents was evaluated against three microorganisms: Enterococcus faecalis, Streptococcus mutans and Candida albicans. One millilitre of each tested substance was placed on the bottom of wells of 24-well cell culture plates. Six wells were used for each time period and group. Two millilitres of the microbial suspension was ultrasonically mixed for 10 s with the bleaching pastes and placed in contact with them for 10, 30, 45 s; 1, 3, 5, 10, 20, 30 min; and 1 and 2 h. After each period of time, 1 mL from each well was transferred to tubes containing 2 mL of freshly prepared brain heart infusion agar + neutralizers. Agar plates were inoculated in appropriate gaseous conditions. Data were analysed statistically by the Kruskal-Wallis test with the level of significance set at P < 0.05.
  
  
  RESULTS
  In all groups containing chlorhexidine (groups 3, 5 and 7), the antimicrobial activity of the bleaching paste was significantly increased when compared with groups with other kinds of vehicle (groups 1, 2, 4, 6 and 8). For all tested groups, the most resistant microorganism was E. faecalis.
  
  
  CONCLUSIONS
  Chlorhexidine when used as a vehicle for sodium perborate enhanced its antimicrobial activity.
authors.affiliation: Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil. danifop@hotmail.com
authors.forename: D P
authors.initials: DP
authors.lastname: Oliveira
authors.forename: B P F A
authors.initials: BP
authors.lastname: Gomes
authors.forename: A A
authors.initials: AA
authors.lastname: Zaia
authors.forename: F J
authors.initials: FJ
authors.lastname: Souza-Filho
authors.forename: C C R
authors.initials: CC
authors.lastname: Ferraz
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology*; D000891:Anti-Infective Agents, Local / Q000494:pharmacology; D001881:Borates / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects; D000077463:Carbamide Peroxide; D002710:Chlorhexidine / Q000494:pharmacology; D004338:Drug Combinations; D024881:Drug Resistance, Bacterial; D013293:Enterococcus faecalis / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008422:Materials Testing; D016877:Oxidants / Q000494:pharmacology*; D010545:Peroxides / Q000494:pharmacology*; D014677:Pharmaceutical Vehicles; D013295:Streptococcus mutans / Q000187:drug effects; D013997:Time Factors; D014073:Tooth Bleaching / Q000379:methods*; D014508:Urea / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D000890:Anti-Infective Agents; D000891:Anti-Infective Agents, Local; D001881:Borates; D004338:Drug Combinations; D016877:Oxidants; D010545:Peroxides; D014677:Pharmaceutical Vehicles; D000077463:Carbamide Peroxide; D014508:Urea; D006861:Hydrogen Peroxide; D002710:Chlorhexidine; C027707:sodium perborate