title: 2-Hydroxyisocaproic acid is bactericidal in human dental root canals ex vivo.
abstract: OBJECTIVE
  To compare the activity of 2-hydroxyisocaproic acid (HICA), calcium hydroxide (Ca(OH)2) and chlorhexidine digluconate (CHG) against Enterococcus faecalis T-75359 (root canal isolate) in the root canals of extracted human teeth.
  
  
  METHODS
  Bacterial suspensions (108cfu mL-1) were incubated in root canals with 0.9 mm diameter root blocks (n = 73) for 21 days. Bacterial penetration into dentine was analysed by the Brown and Brenn method (n = 5). Canals (n = 17/group) were medicated with 40% of HICA paste, 40% of Ca(OH)2paste, 2% of CHG solution or 0.9% of saline solution for 7 days. Samples taken from the inner (first 0.1 mm) and deeper (second 0.1 mm) dentine, and residual roots were cultured in broth for 24 h. Bacterial growth was detected by spectrophotometry (optical density, OD) and confirmed by culture on agar. The OD data were analysed with Kruskal-Wallis and Friedman with Wilcoxon signed-rank test between and within groups, respectively, and agar culture data with Pearson chi-square with Mann-Whitney and Cochran with McNemar tests, respectively (P < 0.05).
  
  
  RESULTS
  Bacterial invasion into dentine tubules was confirmed. In deeper dentine, HICA inhibited >90% of bacterial growth in comparison with saline. No bacterial growth was observed in 82-100% of inner and deeper dentine samples. CHG prevented the growth in 88%, Ca(OH)2in 59-76% and saline in 65-71%, respectively. HICA was significantly more active than Ca(OH)2(P = 0.008) in the residual roots. The viability testing on agar showed essentially the same result.
  
  
  CONCLUSIONS
  HICA paste exerted superior activity against E. faecalis and could have potential for root canal medication.
authors.affiliation: Institute of Dentistry, University of Oulu, Oulu, Finland.|Department of Bacteriology and Immunology, Haartman Institute, Helsinki University Hospital, University of Helsinki, Helsinki, Finland.|Medical Research Center Oulu, Oulu University Hospital, University of Oulu, Oulu, Finland.|Department of Oral and Maxillofacial Diseases, Helsinki University Hospital, University of Helsinki, Helsinki, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Sakko
authors.affiliation: Institute of Dentistry, University of Oulu, Oulu, Finland.|Medical Research Center Oulu, Oulu University Hospital, University of Oulu, Oulu, Finland.|Department of Oral and Maxillofacial Diseases, Helsinki University Hospital, University of Helsinki, Helsinki, Finland.
authors.forename: L
authors.initials: L
authors.lastname: Tjäderhane
authors.affiliation: Department of Oral and Maxillofacial Diseases, Helsinki University Hospital, University of Helsinki, Helsinki, Finland.|Division of Periodontology, Department of Dental Medicine, Karolinska Institute, Huddinge, Sweden.
authors.forename: T
authors.initials: T
authors.lastname: Sorsa
authors.affiliation: Extracta Ltd, Vantaa, Finland.
authors.forename: P
authors.initials: P
authors.lastname: Hietala
authors.affiliation: Manchester Academic Health Science Centre, Institute of Inflammation and Repair, The University of Manchester, Manchester, UK.|University Hospital of South Manchester, Manchester, UK.
authors.forename: R
authors.initials: R
authors.lastname: Rautemaa
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001431:Bacteriological Techniques; D002126:Calcium Hydroxide / Q000494:pharmacology; D002208:Caproates / Q000494:pharmacology*; D002710:Chlorhexidine / Q000031:analogs & derivatives / Q000494:pharmacology; D003786:Dental Pulp Cavity / Q000382:microbiology*; D013293:Enterococcus faecalis / Q000187:drug effects / Q000254:growth & development / Q000472:pathogenicity; D006801:Humans; D066298:In Vitro Techniques; D013053:Spectrophotometry; D018709:Statistics, Nonparametric; D014092:Tooth Root / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents; D002208:Caproates; C019419:alpha-hydroxyisocaproic acid; C010882:chlorhexidine gluconate; D002126:Calcium Hydroxide; D002710:Chlorhexidine
keywords: 
  Enterococcus faecalis
  ; calcium hydroxide; chlorhexidine; human teeth; interappointment medication; root canal medicament