title: An in vitro study of coronal leakage after intraradicular preparation of cast-dowel space.
abstract: BACKGROUND
  Coronal leakage can produce contamination of periapical tissues, resulting in endodontic failure.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to evaluate the ability of 2 sealers to prevent coronal leakage in canals filled with gutta-percha and prepared for cast dowels but without coronal sealing.
  
  
  METHODS
  The crowns of 60 extracted single-rooted teeth were amputated. The root canals were prepared corono-apically and filled with gutta-percha cones and 1 of 2 different endodontic sealers: a resin-based sealer (AH Plus) and a calcium hydroxide-based sealer (Sealapex). Specimens were then stored in water for 7 days to allow the sealers to set. The specimens were prepared in 1 of 2 ways: no preparation for cast dowel or preparation of cast-dowel space (n=15). External surfaces of the roots were sealed with cyanoacrylate cement. The teeth were thermal cycled at 5 degrees and 55 degrees C in water baths (dwell time=30 seconds) for 500 cycles. Specimens were then submerged in 2% methylene blue colorant for 24 hours. Microleakage was measured according to the percentage of area stained with the colorant. Effects of each factor (cast-dowel preparation and type of sealant) on microleakage were analyzed by the Student t test (alpha=.05).
  
  
  RESULTS
  The AH Plus and Sealapex sealers with cast-dowel preparation resulted in significantly (P<.001) more leakage compared to sealers with no dowel preparation.
  
  
  CONCLUSIONS
  Cast dowel-space preparation had a negative influence on the sealing ability of the remnant root-canal filling material.
authors.affiliation: Department of Endodontics, School of Dentistry, University Federal de Pelotas, Rio Grande do Sul, Brazil.
authors.forename: A F
authors.initials: AF
authors.lastname: Pappen
authors.forename: M
authors.initials: M
authors.lastname: Bravo
authors.forename: S
authors.initials: S
authors.lastname: Gonzalez-Lopez
authors.forename: M P
authors.initials: MP
authors.lastname: Gonzalez-Rodriguez
mesh_terms: D002126:Calcium Hydroxide; D003763:Dental Leakage / Q000209:etiology / Q000517:prevention & control*; D004853:Epoxy Resins; D006801:Humans; D011176:Post and Core Technique / Q000009:adverse effects*; D012044:Regression Analysis; D012387:Root Canal Filling Materials; D018915:Root Canal Preparation / Q000009:adverse effects*; D012459:Salicylates
chemical_list: D004853:Epoxy Resins; D012387:Root Canal Filling Materials; D012459:Salicylates; C534916:epoxy resin-based root canal sealer; C055601:Sealapex; D002126:Calcium Hydroxide