title: Microleakage in endodontically treated teeth: influence of calcium hydroxide dressing following bleaching.
abstract: OBJECTIVE
  The purpose of the present study was to evaluate microleakage of a fourth generation dentine-bonding agent and composite restoration during a walking bleach treatment.
  
  
  METHODS
  Thirty extracted non-carious incisors were selected and conventional root canal treatment was performed. Teeth were randomly divided into 3 groups (n = 10): group A (control), access cavities were restored with a fourth generation dentine-bonding agent, and incrementally restored with composite resin; group B, a paste composed of sodium perborate and hydrogen peroxide was placed into the pulp chamber and sealed with glass ionomer cement for 7 days, teeth were then restored in the same manner as group A; group C, a paste of sodium perborate and hydrogen peroxide was placed in the pulp chamber for 7 days and then after removal of the bleaching mixture, pulp chambers were filled with a calcium hydroxide paste and cavities sealed with glass ionomer for 1 week. The cavities were then restored with bonded restorations as in groups A and B. Teeth were subjected to thermal cycling and immersed in methylene blue for 8 h. Teeth were sectioned from buccal to lingual, through the centre of the restoration, using a diamond disk. Leakage was assessed using a standard scheme, under magnification (x20). Data were submitted to statistical analysis using nonparametric Kruskal-Wallis test.
  
  
  RESULTS
  Groups A and C exhibited similar leakage patterns, and both demonstrated less leakage values than group B (P < 0.05).
  
  
  CONCLUSIONS
  It was concluded that bleaching with sodium perborate and hydrogen peroxide increases microleakage; short-term use of a calcium hydroxide medicament did not increase microleakage.
authors.affiliation: Department of Operative Dentistry, Faculty of Dentistry, Federal University of Pelotas, RS, Brazil. sancha@uol.com.br
authors.forename: F F
authors.initials: FF
authors.lastname: Demarco
authors.forename: J M
authors.initials: JM
authors.lastname: Freitas
authors.forename: M P
authors.initials: MP
authors.lastname: Silva
authors.forename: L M
authors.initials: LM
authors.lastname: Justino
mesh_terms: D001881:Borates / Q000737:chemistry / Q000627:therapeutic use; D002126:Calcium Hydroxide / Q000737:chemistry* / Q000627:therapeutic use; D004396:Coloring Agents; D003188:Composite Resins / Q000737:chemistry; D001840:Dental Bonding; D003763:Dental Leakage / Q000145:classification*; D003786:Dental Pulp Cavity / Q000648:ultrastructure; D003793:Dental Restoration, Permanent; D017220:Dentin-Bonding Agents / Q000737:chemistry / Q000145:classification; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000627:therapeutic use; D007101:Immersion; D008751:Methylene Blue; D016877:Oxidants / Q000737:chemistry / Q000627:therapeutic use; D012387:Root Canal Filling Materials / Q000737:chemistry* / Q000627:therapeutic use; D012390:Root Canal Therapy / Q000379:methods*; D018709:Statistics, Nonparametric; D013816:Thermodynamics; D014073:Tooth Bleaching
chemical_list: D001881:Borates; D004396:Coloring Agents; D003188:Composite Resins; D017220:Dentin-Bonding Agents; D005899:Glass Ionomer Cements; D016877:Oxidants; D012387:Root Canal Filling Materials; D006861:Hydrogen Peroxide; D002126:Calcium Hydroxide; D008751:Methylene Blue; C027707:sodium perborate