title: Bonding of low-shrinking composites in high C-factor cavities.
abstract: OBJECTIVE
  Polymerization shrinkage causes stress at the tooth-restoration interface. The magnitude of the stress depends upon several factors, such as the configuration factor (C-factor) of the cavity, the polymerization-conversion rate and filling technique. The aim of this study was to investigate the effect of curing time and filling method when high C-factor cavities were filled with low-shrinking composites.
  
  
  METHODS
  Three low-shrinking (Filtek Silorane, 3M ESPE: FS; N'Durance, Septodont: N'D; Kalore, GC: Ka) and one conventional composite (Z100, 3M ESPE) were bonded into standardized occlusal Class-I cavities using either a two-step self-etch adhesive (Silorane System Adhesive, 3M ESPE: SSA) or a one-step self-etch adhesive (G-Bond, GC: GB). Five experimental groups were formed according to the employed adhesive/composite combination (SSA/FS, SSA/Z100, GB/N'D, GB/Ka, GB/Z100), and further divided into three subgroups conforming to curing time and filling technique (20 s/bulk; 80 s/bulk; 80 s/layered). For each subgroup, non-trimmed 1 mm×1 mm sticks were prepared from five teeth to measure the micro-tensile bond strength (μTBS) to cavity-bottom dentine.
  
  
  RESULTS
  The two-step self-etch adhesive SSA generated higher bond strengths than the one-step self-etch adhesive GB, irrespective of the filling method. When GB was used, bulk filling with a low-shrinking composite revealed the highest bond strengths. For all composites, the layering method provided the highest bond strengths.
  
  
  CONCLUSIONS
  The two-step self-etch adhesive Silorane System Adhesive (3M ESPE) performed better than the one-step self-etch adhesive G-Bond (GC), regardless of the composite used. When the latter all-in-one adhesive was used, effects of shrinkage stress became more apparent.
authors.affiliation: KU Leuven-BIOMAT, Department of Oral Health Sciences, KU Leuven (University of Leuven), Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Van Ende
authors.forename: A
authors.initials: A
authors.lastname: Mine
authors.forename: J
authors.initials: J
authors.lastname: De Munck
authors.forename: A
authors.initials: A
authors.lastname: Poitevin
authors.forename: B
authors.initials: B
authors.lastname: Van Meerbeek
mesh_terms: D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003737:Dental Cavity Preparation / Q000145:classification*; D003764:Dental Materials / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D003804:Dentin / Q000648:ultrastructure; D017220:Dentin-Bonding Agents / Q000737:chemistry; D006801:Humans; D055115:Light-Curing of Dental Adhesives / Q000379:methods; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D058105:Polymerization; D012822:Silicon Dioxide / Q000737:chemistry; D062047:Silorane Resins; D012833:Siloxanes / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013718:Tensile Strength; D013997:Time Factors; D014867:Water / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D017220:Dentin-Bonding Agents; C498353:G-Bond; D008689:Methacrylates; C551012:N'Durance composite resin; D062047:Silorane Resins; D012833:Siloxanes; C083568:Z100 composite resin; C555513:silorane composite resin; D014867:Water; D012822:Silicon Dioxide; D015040:Zirconium