Comparison of three types of fiber-reinforced composite molar crowns on their fracture resistance and marginal adaptation.
Three types of fiber-reinforced composite (FRC) molar crowns were tested on their fracture resistance and marginal adaptation under simulated oral stress conditions. Two glass fiber systems, one processed with a vacuum/pressure system, the other by manual fiber adaptation, and a polyethylene fiber system were evaluated. Every group consisted of 12 crowns. All crowns were luted adhesively on human molars and exposed to thermal cycling and mechanical loading (TCML: 6000 x 5 degrees C/55 degrees C; 1.2 x 10(6) x 50N; 1.66Hz). The marginal adaptation was evaluated through dye-penetration and analyzed semi-quantitatively with a scanning electron microscope. The fracture resistance was measured using a Zwick universal testing machine. The highest fracture resistance was observed on the glass-fiber systems (FibreKor/Sculpture 1875N +/- 596; Vectris/Targis 1726+/-542), though statistically, the polyethylene system (belleGlass/Connect 1388+/-620) was not significantly weaker. All systems exceeded the fracture resistance required to withstand the maximum masticatory forces expected in the molar region. The marginal adaptation generally had a tendency towards larger gaps after TCML. The crown/composite-cement bond deteriorated significantly after TCML with the manual fiber adaptation and the polyethylene fiber system. The cement/tooth bond strength depended on which composite-cement/dentin-adhesive system was used.


CONCLUSIONS
The fracture resistance of molar crowns made of glass-fiber reinforced composite was higher than those of polyethylene fiber-reinforced composite crowns. However, there was no statistically significant difference. The marginal adaptation seems to depend on the fiber systems and composite-cement/dentin adhesive system used.
Behr
M
M
Department of Prosthetic Dentistry, University of Regensburg, 93053, Regensburg, Germany. michael.behr@klinik.uni-regensburg.de
Rosentritt
M
M
Latzel
D
D
Kreisler
T
T
D000704:Analysis of Variance; D001732:Bite Force; D002484:Cementation; D004396:Coloring Agents; D003188:Composite Resins / Q000737:chemistry*; D003442:Crowns; D003738:Dental Cements / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry; D017267:Dental Prosthesis Design; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis / Q000295:instrumentation; D017220:Dentin-Bonding Agents / Q000737:chemistry; D005898:Glass / Q000737:chemistry; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D008963:Molar; D020959:Polyethylene / Q000737:chemistry; D011095:Polyethylenes / Q000737:chemistry; D011312:Pressure; D012823:Silicate Cement / Q000737:chemistry; D013223:Statistics as Topic; D013314:Stress, Mechanical; D013499:Surface Properties; D013816:Thermodynamics
D004396:Coloring Agents; D003188:Composite Resins; D003738:Dental Cements; D003764:Dental Materials; D017220:Dentin-Bonding Agents; C113550:FiberKor, sculpture; D005899:Glass Ionomer Cements; D008689:Methacrylates; D011095:Polyethylenes; C084063:RIBBOND; C110370:belleGlass; C111282:dental polyglass; C009753:fiberglass; D012823:Silicate Cement; D020959:Polyethylene