title: Evaluation of the Effect of Enterococcus faecalis Biofilm on the 2% Chlorhexidine Substantivity: An In Vitro Study.
abstract: BACKGROUND
  The aim of this study was to correlate the bacterial viability and the presence of 2% chlorhexidine (CHX) solution on dentin by means of confocal laser scanning microscopy and high-performance liquid chromatography for 48 hours, 7 days, and 30 days.
  
  
  METHODS
  One hundred twenty-three extracted human teeth were used. Samples were divided into 4 groups according to the solution (CHX or saline) and the presence of Enterococus faecalis biofilm. Samples were kept in contact with 5 mL of the solution for 5 minutes. Each group was divided into 3 subgroups according to the evaluation period (n = 10). Statistical analysis was performed by using the Kruskal-Wallis test, the Mann-Whitney U test (P < .05), and the Spearman rank correlation coefficient (P < .01).
  
  
  RESULTS
  There was a negative correlation between the percentage of live cells and the amount of remaining CHX (P = .000). CHX significantly reduced the percentage of viable cells compared with saline after 48 hours (P = .007). Differences were maintained in the 7-day evaluation period (P = .001). After 30 days, the CHX group presented an increase of viable cells, thereby becoming similar to saline (P = .623). Simultaneously, the remaining CHX was significantly reduced in the 30-day specimens (P = .000).
  
  
  CONCLUSIONS
  The results of this study indicate that 2% CHX solution was detected for 48 hours and 7 days with a low percentage of viable cells. The presence of microorganisms on human dentin did not affect 2% CHX maintenance.
authors.affiliation: Department of Conservative Dentistry, School of Dentistry, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul, Brazil. Electronic address: daibottcher@hotmail.com.
authors.forename: Daiana Elisabeth
authors.initials: DE
authors.lastname: Böttcher
authors.affiliation: Biotechnology and Biochemical Engineering Laboratory (BiotecLab), School of Food Engineering, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Nicole T
authors.initials: NT
authors.lastname: Sehnem
authors.affiliation: Department of Conservative Dentistry, School of Dentistry, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Francisco
authors.initials: F
authors.lastname: Montagner
authors.affiliation: Social and Preventive Dentistry Department, School of Dentistry, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Clarissa Cavalcanti
authors.initials: CC
authors.lastname: Fatturi Parolo
authors.affiliation: Department of Conservative Dentistry, School of Dentistry, Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Fabiana Soares
authors.initials: FS
authors.lastname: Grecca
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D002710:Chlorhexidine / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D003786:Dental Pulp Cavity / Q000187:drug effects / Q000382:microbiology / Q000473:pathology / Q000503:physiopathology; D003804:Dentin / Q000187:drug effects / Q000382:microbiology / Q000473:pathology / Q000503:physiopathology; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D016908:Gram-Positive Bacterial Infections / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D018613:Microscopy, Confocal; D011671:Pulpitis / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D011897:Random Allocation; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D002710:Chlorhexidine
keywords: Chlorhexidine; Enterococcus faecalis; substantivity