fracture resistance of composite fixed partial dentures reinforced with pre-impregnated and non-impregnated fibers

background and aims. the mechanical properties of fiber-reinforced composite fixed partial dentures (fpds) are affected by fiber impregnation. the aim of this in vitro study was to compare the fracture resistance of composite fixed partial dentures reinforced with pre-impregnated and non-impregnated fibers. materials and methods. groups (n=5) of three-unit fiber-reinforced composite fpds (23 mm in length) from maxillary second premolar to maxillary second molar were fabricated on two abutments with pontic width of 12 mm. one group was fabricated as the control group with composite (gradia) and the other two groups were fabricated with composite (gradia) reinforced with pre-impregnated fiber (fibrex ribbon) and non-impregnated fiber (fiber braid), respectively. the specimens were stored in distilled water for one week at 37°c and then tested in a universal testing machine by means of a three-point bending test. statistical analysis consisted of one-way anova and a post hoc scheffé’s test for the test groups (α=0.05). results. fracture resistance (n) differed significantly between the control group and the other two groups (p<0.001), but there were no statistically significant differences between the pre-impregnated and non-impregnated groups (p=0.565). the degree of deflection measured (mm) did not differ significantly between the three groups (p=0.397), yet the mean deflection measured in pre-impregnated group was twice as that in the other two groups. conclusion. reinforcement of composite with fiber might considerably increase the fracture resistance of fpds; however, the type of the fiber used resulted in no significant difference in fracture resistance of fpd specimens.