title: Marginal quality of flowable 4-mm base vs. conventionally layered resin composite.
abstract: OBJECTIVE
  This study evaluated marginal integrity of bonded posterior resin composite fillings to enamel and dentine with and without 4mm flowable base, before and after thermo-mechanical loading (TML).
  
  
  METHODS
  80 MOD cavities with one proximal box beneath the CEJ were prepared in extracted human third molars. Direct resin composite restorations (SDR with CeramX mono, Tetric EvoCeram, Filtek Supreme XT, and Venus Diamond or the respective resin composites alone) were bonded with system immanent adhesives XP Bond, Xeno V, Syntac, Adper Prompt L-Pop, and iBond self-etch. Before and after thermomechanical loading (100,000×50N, 2500 thermocycles between 5 and 55°C), marginal gaps were analysed using SEM of epoxy resin replicas. Results were analysed with Kruskal-Wallis and Mann-Whitney U-tests (p<0.05). After thermomechanical loading, specimens were cut longitudinally in order to investigate internal dentine adaptation by epoxy replicas under a SEM (200× magnification).
  
  
  RESULTS
  In enamel, high percentages of gap-free margins were initially identified for all adhesives. After TML, etch-and-rinse adhesives performed better than self-etch adhesives (p<0.05). Also in dentine, initially high percentages of gap-free margins were found for all adhesives. After TML, etch-and-rinse adhesives again performed better than self-etch adhesives for both marginal and internal adaptation (p<0.05). The presence of a 4mm layer of SDR had no negative influence on results in any group (p>0.05).
  
  
  CONCLUSIONS
  SDR as 4mm bulk fill dentine replacement showed an good performance with the material combinations under investigation.
authors.affiliation: Department of Operative Dentistry and Endodontics, Dental School, University of Marburg and University Medical Center Giessen and Marburg, Campus Marburg, Georg-Voigt-Strasse 3, 35039 Marburg, Germany.
authors.forename: Matthias J
authors.initials: MJ
authors.lastname: Roggendorf
authors.forename: Norbert
authors.initials: N
authors.lastname: Krämer
authors.forename: Andreas
authors.initials: A
authors.lastname: Appelt
authors.forename: Michael
authors.initials: M
authors.lastname: Naumann
authors.forename: Roland
authors.initials: R
authors.lastname: Frankenberger
mesh_terms: D003188:Composite Resins; D018772:Dental Marginal Adaptation; D003793:Dental Restoration, Permanent / Q000379:methods*; D003799:Dental Stress Analysis; D017220:Dentin-Bonding Agents; D006801:Humans; D055115:Light-Curing of Dental Adhesives; D008964:Molar, Third; D019279:Resin Cements; D018709:Statistics, Nonparametric
chemical_list: D003188:Composite Resins; D017220:Dentin-Bonding Agents; D019279:Resin Cements; C553871:Surefil SDR Flow