title: In vitro comparison of microleakage of posterior resin composites with and without liner using two-step etch-and-rinse and self-etch dentin adhesive systems.
abstract: OBJECTIVE
  Composite restorations frequently have gingival margins apical to the cemento-enamel junction (CEJ). Microleakage at the cementodentinal margins is one of the most important causes of failure in these restorations. The current study evaluated microleakage at the occlusal and gingival margins of Class II packable composite restorations using resin-modified glass ionomer and flowable composite as liners, using the two-step etch-and-rinse and self-etch dentin-bonding systems.
  
  
  METHODS
  This in vitro study was carried out on 48 intact human premolars. Class II preparations were made with the gingival margins placed 1.0 mm apical to the CEJ. The teeth were randomly assigned to six groups of 16 boxes and restored using the following techniques: Group 1: Single Bond (3M ESPE) + Filtek P60 (3M ESPE); Group 2: Clearfil SE Bond (Kuraray) + Filtek P60; Group 3: Single Bond + Filtek Flow (3M ESPE) + Filtek P60; Group 4: Clearfil SE Bond + Filtek Flow + Filtek P60. Group 5: Single Bond + Fuji II LC (GC) + Filtek P60; Group 6: Clearfil SE Bond + Fuji II LC + Filtek P60. The restorations were thermocycled for 1000 cycles at 5{degree sign}C and 55°C, soaked in 2% methylene blue for 48 hours, then sectioned mesiodistally and viewed under a stereomicroscope for leakage at the gingival margin. The data were statistically analyzed using the Kruskal-Wallis, two-way ANOVA and Mann-Whitney U-tests.
  
  
  RESULTS
  The resin-modified glass-ionomer liner demonstrated significantly less leakage than flowable composite (p<0.05). There was no difference between restorations with flowable resin composite liners and those without the liner; in addition, no significant difference was observed between the two kinds of adhesive systems.
  
  
  CONCLUSIONS
  The current study supports the use of resin-modified glass ionomer as a liner in closed-sandwich technique to decrease microleakage of Class II packable composite restorations, applying either the two-step etch-and-rinse or the self-etch dentin adhesive system.
authors.affiliation: Dental Research Center, Operative Dentistry, Hamadan, Iran. sh_kasraie@yahoo.com
authors.forename: Shahin
authors.initials: S
authors.lastname: Kasraei
authors.forename: Mohadese
authors.initials: M
authors.lastname: Azarsina
authors.forename: Somayeh
authors.initials: S
authors.lastname: Majidi
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods*; D001641:Bicuspid / Q000648:ultrastructure; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D004396:Coloring Agents; D003188:Composite Resins / Q000737:chemistry*; D003736:Dental Cavity Lining; D003737:Dental Cavity Preparation / Q000145:classification; D003738:Dental Cements / Q000737:chemistry*; D003743:Dental Enamel / Q000648:ultrastructure; D003763:Dental Leakage / Q000145:classification*; D003764:Dental Materials / Q000737:chemistry*; D003793:Dental Restoration, Permanent / Q000145:classification; D017220:Dentin-Bonding Agents / Q000737:chemistry*; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D008751:Methylene Blue; D019279:Resin Cements / Q000737:chemistry; D012117:Resins, Synthetic / Q000737:chemistry; D013696:Temperature; D013997:Time Factors; D019237:Tooth Cervix / Q000648:ultrastructure
chemical_list: C438313:Clearfil SE Bond; D004396:Coloring Agents; D003188:Composite Resins; D003738:Dental Cements; D003764:Dental Materials; D017220:Dentin-Bonding Agents; C467913:Filtek Flow; C438835:Filtek P60 Composite Resin; C079765:Fuji II LC cement; D005899:Glass Ionomer Cements; D019279:Resin Cements; D012117:Resins, Synthetic; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate; D008751:Methylene Blue