Zusammenfassung
Objectives. 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. Material and 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 ...
Zusammenfassung
Objectives. 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. Material and 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 Al2O3; 50 mum 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 degreesC/55 degreesC; 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-reinforced molar crowns can be covered composite, the inner surface of glass fibre with a composite layer or with a glass fibre framework. Both methods achieve comparable high fracture strengths and reliable marginal adaptation. (C) 2003 Elsevier Ltd. All rights reserved.
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