Marginal adaptation and fracture resistance of adhesively luted glass fibre-composite reinforced molar crowns with different inner crown surfaces.
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.
Behr
M
M
Department of Prosthodontics, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93042, Regensburg, Germany. michael.behr@klinik.uni-regensberg.de
Rosentritt
M
M
Sikora
M I
MI
Karl
P
P
Handel
G
G
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
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