title: Marginal adaptation and fracture resistance of adhesively luted glass fibre-composite reinforced molar crowns with different inner crown surfaces.
abstract: OBJECTIVE
  This study compared the influence of different inner crown surfaces on the fracture resistance and marginal adaptation of adhesively fixed glass fibre-reinforced molar crowns.
  
  
  METHODS
  Vectris/Targis crowns were constructed with an inner framework of glass fibres (directly on the tooth) or an inner veneering composite layer between the fibre-framework and the tooth-substance. Both groups were sandblasted inside using Al(2)O(3); 50 microm grain size (200 kPa, 20 s) and silane coated. A control group had the inner fibre framework, but was neither sandblasted nor silane coated. The crowns were adhesively cemented on extracted human teeth, and thermally cycled and mechanically loaded (TCML: 6000 x 5 degrees C/55 degrees C; 1.2 x 10(6) x 50 N, 1.66 Hz). The marginal adaptation before and after TCML was evaluated and the fracture resistance was investigated using a Zwick universal testing machine.
  
  
  RESULTS
  After TCML the proportion of 'perfect margin' of the control group decreased significantly at the interface crown/cement. For the variations with an inner fibre framework or inner composite layer the marginal adaptation or fracture resistance did not decrease significantly after ageing. The fracture resistance values were control: 1509N+/-486; inner fibre framework: 1896N+/-342; inner composite layer: 1754N+/-340.
  
  
  CONCLUSIONS
  In the case of the investigated fibre framework and veneering composite, the inner surface of glass fibre-reinforced molar crowns can be covered with a composite layer or with a glass fibre framework. Both methods achieve comparable high fracture strengths and reliable marginal adaptation.
authors.affiliation: Department of Prosthodontics, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93042, Regensburg, Germany. michael.behr@klinik.uni-regensberg.de
authors.forename: M
authors.initials: M
authors.lastname: Behr
authors.forename: M
authors.initials: M
authors.lastname: Rosentritt
authors.forename: M I
authors.initials: MI
authors.lastname: Sikora
authors.forename: P
authors.initials: P
authors.lastname: Karl
authors.forename: G
authors.initials: G
authors.lastname: Handel
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry; D002484:Cementation; D003188:Composite Resins / Q000737:chemistry*; D003442:Crowns; D001840:Dental Bonding; D045662:Dental Etching; D003764:Dental Materials / Q000737:chemistry*; D017267:Dental Prosthesis Design; D003801:Dental Veneers; D017220:Dentin-Bonding Agents / Q000737:chemistry; D005898:Glass / Q000737:chemistry*; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D019279:Resin Cements / Q000737:chemistry*; D012823:Silicate Cement / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D017220:Dentin-Bonding Agents; D005899:Glass Ionomer Cements; D019279:Resin Cements; C078484:Syntac dentine adhesive; C111282:dental polyglass; C009753:fiberglass; D012823:Silicate Cement; C103502:Variolink; D000537:Aluminum Oxide