Fatigue crack propagating behaviors of two dental adhesive resins containing filler (PV) and non-filler (SB) were investigated in conjunction with the morphological observation of crack propagation area (CPA) by applying double cantilever beam testing to fatigue test under repeated constant displacement. The major findings were as follows. The fatigue crack propagating behavior was estimated by
Pmax/[
Pmax]
o-
n diagram at the process of fatigue crack propagation, and the diagrams of SB and PV were characerized as follows. In case of SB, the value of
Pmax/[
Pmax]
o began to suddenly decrease when approached the value of about 0.95 regardless of loading levels (κ=0.5, 0.6, 0.7), however, in κ=0.3 and 0.4 the reduction of load was not shown to
n=10
5 cycles. In case of PV, in
Pmax/[
Pmax]
o-
n diagrams for all loading levels (κ=0.7, 0.8, 0.9, 0.95) the load was decreasing slowly. Regarding fatigue CPA, in case of SB, a flat fracture surface was observed and was very different from a rough CPA observed in static test. Adn the area of flat fracture surface was expanded as value of κ became smaller. But, in κ=0.3 and 0.4, the fatigue CPAs were not observed. In case of PV, the fatigue CPA was similar to static CPA and were observed as the very small undulations.
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