The effect of different reinforcements on the fracture toughness of materials for interim restorations.
BACKGROUND
Fracture of an interim fixed partial denture (FPD) may jeopardize the success of the interim prosthodontic treatment phase and cause patient discomfort.


OBJECTIVE
The purpose of this study was to compare the fracture toughness of a polymethyl methacrylate (PMMA) resin and a bis-acryl composite (BAC) resin reinforced with stainless steel wire, glass fiber, and polyethylene fiber.


METHODS
Four groups (n=13) of each of the 2 materials were prepared for the single-edge notch 3-point-bending test. Three groups had the different reinforcements, and the group without reinforcement served as the control. Using a universal testing machine, peak load to fracture was recorded and fracture toughness (K(IC)) was calculated in MNm(-1.5). Median K(IC) values were compared by means of nonparametric ANOVA (Kruskal-Wallis test, alpha=.05).


RESULTS
For the controls, the fracture toughness for PMMA resin (K(IC)=27.9) was significantly lower (P<.01) than for BAC resin (K(IC)=31.2). Glass fibers and stainless steel wire reinforcements produced significantly higher fracture toughness for both PMMA (K(IC)=34.4, P<.01, and K(IC)=39.0, P<.001, respectively) and BAC resin (K(IC)=42.3, P<.001, and K(IC)=44.0, P<.001, respectively), but the polyethylene fibers did not (K(IC)=25.8, P>.10, for PMMA resin and K(IC)=33.1, P>.10, for BAC resin). There was no significant difference between the fracture toughness of the wire and glass fiber reinforcements for both interim materials (P>.10 in both instances).


CONCLUSIONS
Of the 3 reinforcement methods evaluated, wire and glass fiber reinforced the PMMA and BAC resin materials best.
Department of Restorative Dentistry, University of the Western Cape, Tygerberg, Republic of South Africa. ggeerts@uwc.ac.za
Greta A V M
GA
Geerts
Jan-Hendrik
JH
Overturf
Theuns G
TG
Oberholzer
D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D019232:Dental Restoration Failure; D003830:Denture, Partial, Fixed; D003833:Denture, Partial, Temporary; D005898:Glass / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D018583:Pliability; D011095:Polyethylenes / Q000737:chemistry; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D013193:Stainless Steel / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties
D003188:Composite Resins; D003764:Dental Materials; D011095:Polyethylenes; C009753:fiberglass; D013193:Stainless Steel; D019904:Polymethyl Methacrylate