Effect of simulated resin-bonded fixed partial denture clinical conditions on resin cement mechanical properties.

The purpose of this study was to determine changes in flexural properties of resin cement under simulated resin-bonded fixed partial denture (RBFPD) clinical conditions using aqueous ageing and cyclic loading. Panavia F flexural modulus and strength were measured by static loading to failure after 48-h and 60-day aqueous ageing at 37 degrees C with and without simulated cyclic occlusal loading. Panavia F sorption and solubility were also measured. Scanning electron microscopy (SEM) was used to characterize the morphology of the fractured surfaces. A two-factor anova (P </= 0.05) indicated that cyclic loading produced a significant increase in the flexural modulus with no significant effect on the flexural strength. Conversely, aqueous ageing time produced a significant decrease in flexural strength with no effect on the flexural modulus. The SEM fracture analysis indicated that resin matrix fracture occurred in static-aqueous specimens; while in the aqueous-cycled specimens, resin matrix fracture occurred in addition to an increasing proportion of filler/resin interface fracture. Collectively, these outcomes suggest that initial degradation under simulated resin cement clinical function may be related to breakdown of the filler/resin interface bond, which could contribute to in vivo RBFPD resin cement cohesive failure.