title: Effect of bonding application time on the microleakage of Class V sandwich restorations.
abstract: BACKGROUND
  The aim of this study was to assess the effect of bonding application time on the microleakage of Class V sandwich restorations.
  
  
  METHODS
  Eighty non-carious third molars were randomly divided into 16 groups. Two Class V cavities were prepared on the buccal and lingual surfaces of teeth. Three groups were restored with Fuji II GIC and treated with a total-etch bonding system (Stea/SDI) immediately after insertion, at 7 minutes and 15 minutes after mixing the glass ionomer cements (GICs). Another three groups were restored with Riva Self Cure GIC and treated with the total-etch system identically. The other six groups were subjected to self-etching bonding (Frog/SDI) after GIC placement in an identical procedure. The remaining groups were made using light cure GICs (Fuji II or Riva Light Cure) in conjunction with the total-etch or self-etching systems. Cavities were then restored with composite (Valux plus, 3M/ESPE). Samples were subsequently immersed in 2% methylene blue solution for 48 hours and observed under a stereomicroscope after sectioning. Four-scale grading was used to assess microleakage in occlusal and gingival walls. Data were analysed using Kruskal-Wallis and Mann-Whitney tests.
  
  
  RESULTS
  The self-etching bonding system exhibited more microleakage in occlusal margins regardless of time. Over time, microleakage significantly decreased in gingival margins in all self-cure groups except for Riva Self Cure treated with the total-etch system (p < 0.05).
  
  
  CONCLUSIONS
  Bonding application time had no effect on the microleakage of occlusal margins. However, maturation of GICs induced a decreased microleakage in gingival margins.
authors.affiliation: Iran Center for Dental Research and Department of Restorative Dentistry, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: A
authors.initials: A
authors.lastname: Ghasemi
authors.forename: H
authors.initials: H
authors.lastname: Torabzadeh
authors.forename: M
authors.initials: M
authors.lastname: Mahdian
authors.forename: M
authors.initials: M
authors.lastname: Afkar
authors.forename: A
authors.initials: A
authors.lastname: Fazeli
authors.forename: A
authors.initials: A
authors.lastname: Akbarzadeh Baghban
mesh_terms: D045662:Dental Etching / Q000379:methods*; D003763:Dental Leakage; D003793:Dental Restoration, Permanent / Q000379:methods*; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D005899:Glass Ionomer Cements / Q000737:chemistry*; D008751:Methylene Blue; D008853:Microscopy; D008964:Molar, Third; D018709:Statistics, Nonparametric; D013997:Time Factors
chemical_list: D017220:Dentin-Bonding Agents; D005899:Glass Ionomer Cements; D008751:Methylene Blue