Effect of Fiber Reinforcement on Fracture Resistance and Fracture Toughness for Long Span Provisional Restorations

Aim of the work: This study was aimed to determine the effect of fiber reinforcement on the fracture load and toughness of long span provisional restorations.
Materials and method: Two types of commercially available provisional materials were selected Protemp™4 and Structur3. Two mechanical tests were performed to evaluate the fracture load and fracture toughness for each material. Twenty samples of four units, fixed partial dentures were fabricated to evaluate the fracture loading of both materials. The samples of each group were further subdivided into two equal subgroups (10 samples each). The first subgroup served as control, without fiber reinforcement while, the second subgroup included the addition of ultrahigh modulus polyethylene fibers (UHMPE) which is delivered pre-impregnated by the manufacturer. An electronic scale were used to pre-weight the fibers, then cut to a predetermined length (2.0mm) before incorporation in the resin mix to represent 3% weight of the control sample. For fracture toughness test, twenty rectangular samples (2.5X5X25 mm) from each material were fabricated. Ten samples for each subgroup were used with and without addition of the fibers. The samples were soaked before testing in artificial saliva for 14 days and then were thermocycled for 2500 cycles between 5oC and 55oC.
Conclusions: Structur3 provisional material showed higher fracture load and fracture toughness mean values than Protemp™ 4.
Fiber impregnation into provisional restorations enhanced the fracture load significantly but did not show the same improvement with the fracture toughness.