title: Cervical microleakage in Class II open-sandwich restorations: an in vitro study.
abstract: BACKGROUND
  The open-sandwich technique was proposed to solve the problem of cervical micro-leakage of deep Class II composite restorations by making use of the self-adhesive nature of the glass-ionomers. Recent advances in the properties of this family of materials may continue to make the technique relevant today.
  
  
  OBJECTIVE
  The aim of this in vitro study was to determine the effect of thermocycling, cervical position and the use of different materials on the cervical microleakage of Class II open-sandwich restorations.
  
  
  METHODS
  Two hundred standardised Class II cavities with the cervical margins placed in either enamel (100) or dentine (100) were prepared in 100 extracted human molars. Ketac Molar, set with ultrasound (US), Ketac Molar, Ketac Nano and Vitremer were used in equal groups to restore the cervical boxes, while Filtek Z250 was used to complete the restorations and also provided a control group in which the sandwich technique was not used. One half of each group was subjected to thermocycling. Microleakage was assessed by measuring the distance of penetration of basic fuchsin dye along the cervical step.
  
  
  RESULTS
  The open-sandwich technique significantly (p<0.001) reduced the microleakage otherwise seen in Filtek Z250 when margins were placed in dentine and thermocycled.
  
  
  CONCLUSIONS
  The use of an ultrasonically cured glass-ionomer in the open-sandwich resulted in the least microleakage (after thermocycling) when the cervical margins of Class II restorations were placed in dentine.
authors.affiliation: Department of Periodontics and Oral Medicine, University of Pretoria, Faculty of Health Sciences, School of Dentistry. Jeanine.fourie@up.ac.za
authors.forename: J
authors.initials: J
authors.lastname: Fourie
authors.forename: C F
authors.initials: CF
authors.lastname: Smit
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D004396:Coloring Agents; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003737:Dental Cavity Preparation / Q000145:classification; D003743:Dental Enamel / Q000473:pathology; D003763:Dental Leakage / Q000145:classification*; D003764:Dental Materials / Q000737:chemistry*; D003793:Dental Restoration, Permanent / Q000145:classification* / Q000379:methods; D003804:Dentin / Q000473:pathology; D017220:Dentin-Bonding Agents / Q000737:chemistry; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D053761:Nanocomposites / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry; D012394:Rosaniline Dyes; D013696:Temperature; D013997:Time Factors; D019237:Tooth Cervix / Q000473:pathology*; D014465:Ultrasonics
chemical_list: D004396:Coloring Agents; D003188:Composite Resins; D003764:Dental Materials; D017220:Dentin-Bonding Agents; C444701:Filtek Z250; D005899:Glass Ionomer Cements; C510940:Ketac Dentin Conditioner; D019279:Resin Cements; D012394:Rosaniline Dyes; C084018:Scotchbond Multi-Purpose; C084550:Vitremer; C110712:ketac-molar; C025485:basic fuchsin