title: The effect of an additional flowable compomer layer on microleakage of Class V compomer restorations.
abstract: BACKGROUND
  Polymerisation shrinkage and the associated stress on composite resins and surrounding structures have been regarded as a major cause of leakage and clinical failures in modern polymer restorations. The purpose of this study was to investigate the effect of an additional flowable compomer layer on the microleakage of Class V dental cavities, which were further filled with a compomer.
  
  
  METHODS
  Cavities (32) were prepared in human premolars, conditioned with a non-rinsing agent (Prime & Bond NRC) and treated with the bonding agent (Prime & Bond NT). Sixteen of these cavities were then lined with a layer of flowable compomer (Dyract Flow, approximately 0.5 mm) and further filled with Dyract AP. The other 16 cavities were filled without the flowable compomer. The specimens were thermo-cycled in a 0.5% basic fuchsin solution, sectioned and evaluated for dye penetration using a scoring system of 0 to 4.
  
  
  RESULTS
  Lower microleakage values were found at the enamel as well as at the dentine sides when a layer of Dyract Flow was used as a liner. Furthermore, significantly (p < 0.05) lower microleakage was found in enamel than in dentine for both layered and unlayered restorations.
  
  
  CONCLUSIONS
  It can be concluded that a layer of flowable compomer (i.e. Dyract Flow) in a cavity under a compomer may be recommended to improve the marginal seal of a restoration.
authors.affiliation: Oral and Dental Research Institute, School for Oral Health Sciences, University of Stellenbosch, Tygerberg, South Africa. tgo@sun.ac.za
authors.forename: Theunis G
authors.initials: TG
authors.lastname: Oberholzer
authors.forename: Sias R
authors.initials: SR
authors.lastname: Grobler
authors.forename: Roelof J
authors.initials: RJ
authors.lastname: Rossouw
authors.forename: Theuns J
authors.initials: TJ
authors.lastname: Kotze
mesh_terms: D001641:Bicuspid; D020770:Compomers; D003736:Dental Cavity Lining; D003737:Dental Cavity Preparation / Q000379:methods; D003763:Dental Leakage / Q000517:prevention & control*; D018772:Dental Marginal Adaptation; D003793:Dental Restoration, Permanent / Q000379:methods*; D006801:Humans; D011109:Polymethacrylic Acids
chemical_list: D020770:Compomers; C477384:Dyract Flow Compomer; D011109:Polymethacrylic Acids; C425843:Prime and Bond NT