Fracture resistance of fiber-reinforced vs. non-fiber-reinforced composite molar crowns.
This study compared fracture resistance of fiber-reinforced and non-fiber-reinforced composite molar crowns under simulated oral stress conditions. Three groups of fiber-reinforced composite crowns were constructed using one polyethylene fiber (belleGlass/Connect) and two glass fiber reinforcement systems (Sculpture/FiberKor, Targis/Vectris). The non-fiber-reinforced crowns based on the facing material alone: Sculpture, Targis or belleGlass. Additionally, crowns were made of the non-reinforced composite Artglass. Each group consisted of eight crowns. All crowns were luted to human molars and exposed to thermal cycling and mechanical loading (6000 x 5 degrees C/55 degrees C; 1.2 x 10(6x)50 N; 1.66 Hz). The fracture resistance was measured using a Zwick universal testing machine.


RESULTS
The non-reinforced Artglass crowns demonstrated the highest fracture resistance, significantly higher than the resistance shown with belleGlass, belleGlass/Connect or Targis. Artglass showed an extremely wide distribution of values, however. No statistically significant differences were found between the reinforced and non-reinforced composite crowns of Vectris/Targis, FiberKor/Sculpture or Connect/belleGlass although the reinforced crowns showed a tendency towards higher values. The fracture resistance values scattered markedly more for the reinforced crowns, and their lowest fracture values also reached the level of the lowest non-reinforced crowns. The small distribution of fracture values for the non-reinforced crowns indicates that they will be less susceptible for manufacturing faults and more reliable under clinical conditions.


CONCLUSIONS
RESULTS of this study suggest that single molar composite crowns (tested in this study) do not benefit from fiber-reinforcement.
Behr
M
M
Department of Prosthodontics, University of Regensburg, 93042 Regensburg, Germany. michael.behr@klinik.uni-regensburg.de
Rosentritt
M
M
Latzel
D
D
Handel
G
G
D000704:Analysis of Variance; D002484:Cementation; D003188:Composite Resins / Q000737:chemistry*; D003442:Crowns; D003764:Dental Materials / Q000737:chemistry*; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D005898:Glass / Q000737:chemistry*; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008963:Molar; D020959:Polyethylene / Q000737:chemistry*; D012823:Silicate Cement / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties; D013816:Thermodynamics
D003188:Composite Resins; D003764:Dental Materials; C113550:FiberKor, sculpture; D005899:Glass Ionomer Cements; D008689:Methacrylates; C110370:belleGlass; C111282:dental polyglass; C009753:fiberglass; D012823:Silicate Cement; D020959:Polyethylene