title: Bacterial microleakage and post space timing for two endodontic sealers: an in vitro study.
abstract: OBJECTIVE
  The effects of immediate versus delayed post space preparation on the apical seal using resin and zinc oxide eugenol (ZOE) sealers were compared by a bacterial leakage model.
  
  
  METHODS
  Eighty-six premolars were randomly assigned to four experimental groups of 20 teeth. Three teeth were assigned to each control group, either positive (filled only with guttapercha) or negative (not obturated but root surfaces completely covered). Obturation was achieved by gutta-percha with resin or gutta-percha with a ZOE sealer and lateral condensation technique. Post space was prepared either immediately or a week later, while the obturated teeth had been stored in 100 percent relative humidity at 37 degrees C. The teeth were inserted into plastic vials and suspended in glass bottles. All teeth were covered with cyanoacrylate and layers of nail varnish but the apical 3 mm and were sterilized using gamma rays. Phenol red lactose broth was inoculated into the vials. Staphylococcus epidermidis was introduced into the root canal access of the teeth. Turbidity of the broth in the vials (discoloration) was evaluated daily for a period of 70 days. The data was analyzed statistically with Pearson Chi Square and two ways with ANOVA at 45 days and 70 days.
  
  
  RESULTS
  When the depth of time was considered, the mean time of leakage showed no differences between immediate and delayed preparation for resin AH26 versus ZOE Dorifil at 45 and 70 days (p = 0.37 and p = 0.217, respectively). In 45 days, considering the number of teeth with leakage, there was a significant difference between immediate preparation and delayed preparation in AH26 sealer groups (p = 0.028). No difference was present between immediate and delayed preparation groups for the ZOE sealer groups (p = 0.14).
  
  
  CONCLUSIONS
  According to the results of this study and despite type of sealer, immediate post space preparation did not achieve better sealing than delayed post space preparation. Resin AH26 showed the least leaking teeth in 45 days, but it made no difference in 70 days.
authors.affiliation: Department of Endodontics, University of Medical Sciences, Hamadan, Iran.
authors.forename: Seyed Mohsen
authors.initials: SM
authors.lastname: Jalalzadeh
authors.forename: Ahmad
authors.initials: A
authors.lastname: Mamavi
authors.forename: Hasan
authors.initials: H
authors.lastname: Abedi
authors.forename: Rasoul Yousefi
authors.initials: RY
authors.lastname: Mashouf
authors.forename: Amin
authors.initials: A
authors.lastname: Modaresi
authors.forename: Virginia
authors.initials: V
authors.lastname: Karapanou
mesh_terms: D001641:Bicuspid / Q000382:microbiology; D001729:Bismuth / Q000627:therapeutic use; D003763:Dental Leakage / Q000382:microbiology*; D003786:Dental Pulp Cavity / Q000382:microbiology; D004853:Epoxy Resins / Q000627:therapeutic use; D006171:Gutta-Percha / Q000627:therapeutic use; D006801:Humans; D006813:Humidity; D008422:Materials Testing; D011176:Post and Core Technique; D019279:Resin Cements / Q000627:therapeutic use; D012387:Root Canal Filling Materials / Q000627:therapeutic use*; D012389:Root Canal Obturation / Q000379:methods; D018915:Root Canal Preparation / Q000379:methods; D012834:Silver / Q000627:therapeutic use; D013212:Staphylococcus epidermidis / Q000254:growth & development*; D013696:Temperature; D013997:Time Factors; D014025:Titanium / Q000627:therapeutic use; D019231:Tooth Preparation, Prosthodontic / Q000379:methods*; D015035:Zinc Oxide-Eugenol Cement / Q000627:therapeutic use
chemical_list: D004853:Epoxy Resins; D019279:Resin Cements; D012387:Root Canal Filling Materials; D015035:Zinc Oxide-Eugenol Cement; D012834:Silver; C028044:epoxy resin AH-26; D006171:Gutta-Percha; D014025:Titanium; D001729:Bismuth