title: Effect of root canal procedures on endotoxins and endodontic pathogens.
abstract: OBJECTIVE
  The purpose of this study was to determine the amount of endotoxin (lipopolysaccharide) and cultivable bacteria in human necrotic root canals before (S1) and after chemo-mechanical preparation using chlorhexidine (CHX) gel as auxiliary chemical substance (S2), and after 7 days of intracanal dressing (S3) in order to evaluate the anti-endotoxin and antimicrobial effects of endodontic procedures.
  
  
  METHODS
  Twenty-four teeth were selected for the present study. Chemo-mechanical preparation was performed using 2% CHX gel and three different intracanal medicaments [CaOH2 paste; 2% CHX gel; and CaOH2 + 2% CHX gel]. A quantitative chromogenic Limulus amoebocyte lysate assay was used to measure the amount of endotoxin. Aerobic and anaerobic techniques were used to isolate and identify bacteria, and to determine the bacterial reduction by counting colony-forming units (CFU).
  
  
  RESULTS
  Endotoxins and bacteria were present in 100% of the initial samples, with endotoxin concentration ranging from 62.93 to 214.56 UE/ml and CFU ranging from 4 x 10(5) to 2.6 x 10(6). After chemo-mechanical preparation a mean endotoxin reduction of 44.4% was found. Eight (33.3%) root canals were still positive by culture analysis with a mean reduction of bacteria (CFU) of 99.96%. After 7 days of intracanal dressing, endotoxin concentration decreased by only 1.4% compared with S2, and residual bacteria were recovered by culture analysis in 13 cases (54.1%). No significant difference was found among different intracanal medicaments.
  
  
  CONCLUSIONS
  Relatively high values of endotoxin were still present in the root canal after chemo-mechanical preparation although the majority of bacteria were eliminated. No improvement was achieved by 7 days of intracanal dressing.
authors.affiliation: Endodontic Area, Department of Restorative Dentistry, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.
authors.forename: M E
authors.initials: ME
authors.lastname: Vianna
authors.forename: H-P
authors.initials: HP
authors.lastname: Horz
authors.forename: G
authors.initials: G
authors.lastname: Conrads
authors.forename: A A
authors.initials: AA
authors.lastname: Zaia
authors.forename: F J
authors.initials: FJ
authors.lastname: Souza-Filho
authors.forename: B P F A
authors.initials: BP
authors.lastname: Gomes
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000891:Anti-Infective Agents, Local / Q000627:therapeutic use; D001419:Bacteria / Q000145:classification*; D001420:Bacteria, Aerobic / Q000145:classification; D001421:Bacteria, Anaerobic / Q000145:classification; D015373:Bacterial Typing Techniques; D002126:Calcium Hydroxide / Q000627:therapeutic use; D002710:Chlorhexidine / Q000627:therapeutic use; D002863:Chromogenic Compounds; D015169:Colony Count, Microbial; D003786:Dental Pulp Cavity / Q000473:pathology*; D003790:Dental Pulp Necrosis / Q000382:microbiology* / Q000628:therapy; D004731:Endotoxins / Q000032:analysis*; D006090:Gram-Negative Bacteria / Q000145:classification; D006094:Gram-Positive Bacteria / Q000145:classification; D006801:Humans; D008070:Lipopolysaccharides / Q000032:analysis; D008875:Middle Aged; D012388:Root Canal Irrigants / Q000627:therapeutic use; D012390:Root Canal Therapy / Q000379:methods*
chemical_list: D000891:Anti-Infective Agents, Local; D002863:Chromogenic Compounds; D004731:Endotoxins; D008070:Lipopolysaccharides; D012388:Root Canal Irrigants; D002126:Calcium Hydroxide; D002710:Chlorhexidine