Fracture resistance of polyethylene fiber reinforced composite versus glass fiber reinforced composite fixed partial dentures (In vitro)

Over there past few years, the use of fiber reinforced composites has increased in dentistry. The type of fiber used for reinforcement plays an important role in the structural strength of composites. This in vitro study compares the fracture resistance of posterior reinforced composite inlay bridges with two different fiber types.

This experimental, in vitro study was performed on 20 FRC bridges which replaced maxillary second premolars. The abutment teeth were prepared with proximal box design and the samples were divided in to two groups of 10 (n=10). For the first group polyethylene fiber reinforced composites (Fiber span/ NSI/ Australia) were used directly. In second group pre impregnated glass fiber (INTERLIG/ Angelus/ Brazil) were applied the same. After thermo cycling process (5000 cycles, 5°c / 55°c, dwell time 30s, interval 2s) fracture testing was performed in a universal testing machine (Zwick/ Roell/ Germany, 1 mm/ min) applying direct vertical force to the center of the pontic. The One Sample Kolmogorov Smirnov Test showed a normal distribution. Data analysis was done using independent sample T-test.

The mean fracture strength and the standard deviation of the FRC Inlay Bridge was 469± 247 N for polyethylene fiber group and 541± 206 N for glass fiber group. The result of Independent Sample Test was not statistically significant (P= 0.491). The most failure mode observed, was crack and fracture on the surface of FPDs in distal part of the pontics. Frameworks remained with no damage in all samples. There was no stateside difference between two groups of FPDs.

Direct application of each fiber reinforced composite (glass or polyethylene fiber) with the same architecture (Braided) of fibers is comparable in posterior region of maxilla so the structural design of the fiber is more important than the fiber type itself, in fracture resistance of FPDs.