Effect of two types of composite fibers on fracture resistance of endodontically treated maxillary premolars: an in vitro study.

AIM The aim of the present study was to evaluate the effect of the use of composite fibers (glass fiber and polyethylene fiber) at the gingival third of mesio-occlusodistal (MOD) cavities on the fracture resistance of endodontically treated premolars. MATERIALS AND METHODS A total of 45 extracted premolars underwent endodontic treatment. MOD cavities, 2.5 ± 0.2 mm thick at the buccal and lingual heights of contour, were prepared, with the gingival cavosurface margin 1.5 mm coronal to the cementoenamel junction. Then the teeth were randomly divided into three groups. In group 1, the cavities were restored with Z250 composite resin without the use of any fibers. In groups 2 and 3, the teeth were restored in the same manner as that in group 1 after placement of glass fiber and polyethylene fiber at the gingival third of the cavities, respectively. Subsequent to thermocycling, fracture resistance of the specimens was measured in Newton (N). STATISTICAL ANALYSIS Data were analyzed with one-way ANOVA and a post hoc Tukey test at a significance level of p < 0.05. RESULTS There were significant differences in the means of fracture resistance values between the three groups (p = 0.001). Statistically significant differences were observed in the fracture resistance between group 2 and groups 1 and 3 (p < 0.05). However, the differences between groups 1 and 3 were not significant (p = 0.25). CONCLUSION The type of fiber influenced the fracture resistance of endodontically treated human premolars. CLINICAL SIGNIFICANCE Using glass and/or polyethylene fibers in the gingival third of composite restorations leads to different results in fracture resistance of endodontically treated maxillary premolars.