Effect of polyethylene and glass fibers on fracture resistance of large MOD composite restorations.

Background: Fracture resistance of maxillary premolars with deep MOD cavities restored using resin composite, fibers (Ribbond and Angelus), and cuspal coverage with composite is of importance.

Materials and methods: This experimental study divided 55 sound maxillary premolars into five groups. Group 1: intact teeth. MOD cavities with an occlusal depth of 5 mm, an axial depth of 1.5 mm, and a buccolingual width of 3 mm were prepared in the remaining teeth, Group 2: teeth restored with composite by incremental technique (Bisco Aelite Posterior), Group 3: Ribbond fiber, Group 4: Angelus fiber, and Group 5: 2-mm cuspal reduction and coverage with composite. They were subjected to a fracture strength test after 1000 thermocycles and 100,000 chewing cycles. Data were analyzed using analysis of variance, Tukey, and Chi-square tests. A significance level of P < 0.05 was considered.

Results: The fracture strength of the control group, cuspal coverage, and Ribbond fiber were significantly higher than the composite group (P = 0.01, P = 0.02, and P = 0.001, respectively). The Angelus fiber also showed marginally higher fracture strength compared to the composite (P = 0.098). The Ribbond fiber exhibited a significantly more favorable failure pattern similar to intact teeth. The difference in failure patterns between the cuspal coverage and Ribbond (P = 0.009) and between the cuspal coverage and control (P = 0.034) was statistically significant.

Conclusion: The use of Ribbond fiber, Angelus fiber, and cuspal coverage significantly increased the fracture strength of composite restorations compared to conventional composite in deep MOD of maxillary premolars. In addition, the Ribbond fiber resulted in a more favorable failure pattern, similar to that of intact teeth.