title: Evaluation of time required for recontamination of coronally sealed canals medicated with calcium hydroxide and chlorhexidine.
abstract: OBJECTIVE
  To determine in vitro the time required for recontamination of coronally sealed canals medicated with either calcium hydroxide (CaOH2), 2% chlorhexidine gel (CG) or with a combination of both.
  
  
  METHODS
  Eighty intact, caries-free, premolar teeth with straight roots and mature apices were selected for the study. After biomechanical preparation of 75 teeth, they were randomly divided into nine groups according to the intracanal medicament and the coronal seal with 'Intermediate Restorative Material' (IRM) as follows: (i) 10 teeth medicated with CG, coronally unsealed; (ii) 10 teeth medicated with CaOH2, coronally unsealed; (iii) 10 teeth medicated with CaOH2 + CG, coronally unsealed; (iv) 10 teeth medicated with CG + coronal seal; (v) 10 teeth medicated with CaOH2 + coronal seal; (vi) 10 teeth medicated with CG + CaOH2 + coronal seal; (vii) 10 teeth without intracanal medicament and coronally sealed; (viii) 5 teeth without intracanal medicament and coronally unsealed, used as the positive control group (PC); (ix) 5 teeth with intact crowns used as the negative control group (NC). Glass flasks were filled with Brain Heart Infusion broth (BHI), so that only the root apex was in contact with the broth, while the crown was immersed in human saliva + BHI (3:1). The flasks were then incubated at 37 degrees C in an atmosphere of 10% CO2, and microbial growth was checked daily.
  
  
  RESULTS
  All specimens of the PC showed contamination within 1 day of incubation, while the NC showed no evidence of broth turbidity. Recontamination was detected after an average time of 3.7 days in the unsealed canals medicated with CG, 1.8 days in the group medicated with CaOH2 and 2.6 days in the group medicated with CaOH2 + CG. When the crowns were sealed with IRM, recontamination was detected within 13.5 days in the canals medicated with CG, after 17.2 days in the group medicated with CaOH2 and after 11.9 days in the group medicated with CG + CaOH2. The group with no medication, but sealed with IRM, showed recontamination after 8.7 days. There were statistically significant differences between the teeth with or without coronal seal (P<0.05).
  
  
  CONCLUSIONS
  The coronal seal delayed but did not prevent leakage of microorganisms. There was no difference between the various medicaments.
authors.affiliation: Department of Restorative Dentistry, Endodontic Unit, Dental School of Piracicaba, State University of Campinas, Piracicaba, SP, Brazil. bpgomes@fop.unicamp.br
authors.forename: B P F A
authors.initials: BP
authors.lastname: Gomes
authors.forename: E
authors.initials: E
authors.lastname: Sato
authors.forename: C C R
authors.initials: CC
authors.lastname: Ferraz
authors.forename: F B
authors.initials: FB
authors.lastname: Teixeira
authors.forename: A A
authors.initials: AA
authors.lastname: Zaia
authors.forename: F J
authors.initials: FJ
authors.lastname: Souza-Filho
mesh_terms: D000891:Anti-Infective Agents, Local / Q000627:therapeutic use*; D002126:Calcium Hydroxide / Q000627:therapeutic use*; D002710:Chlorhexidine / Q000627:therapeutic use*; D003763:Dental Leakage / Q000382:microbiology; D003786:Dental Pulp Cavity / Q000382:microbiology*; D006801:Humans; D008768:Methylmethacrylates / Q000627:therapeutic use; D012388:Root Canal Irrigants / Q000627:therapeutic use*; D012389:Root Canal Obturation; D018915:Root Canal Preparation; D018709:Statistics, Nonparametric; D013997:Time Factors; D015035:Zinc Oxide-Eugenol Cement / Q000627:therapeutic use
chemical_list: D000891:Anti-Infective Agents, Local; D008768:Methylmethacrylates; D012388:Root Canal Irrigants; D015035:Zinc Oxide-Eugenol Cement; C031667:IRM cement; D002126:Calcium Hydroxide; D002710:Chlorhexidine