Evaluation of the Fracture Resistance of Nanohybrid Composite Resin Resto rations in Complex Cavities Reinforced with Glass or Polyethylene Fibers

The aim of this study was to evaluate the efficacy of Interlig (INT) glass fiber and Ribbond (RIB) polyethylene in the fracture resistance of complex mesio-occluso-distal (MOD) class II restorations with nanohybrid composite resin (Z350XT).Forty sound human maxillary premolars were selected and prepared with dimensions of 2.5mm3.0mmbucco-lingual and cervico-occlusal, respectively, using a #1014 diamond bur.After the adhesive protocol, the teeth were divided into 4 groups (n=10): CON-conventional restoration (Z350XT); RES-high-viscosity, high-fill flowable resin; INTglass fiber laminate; RIB-polyethylene laminate.Following the different restorative protocols, fracture resistance tests were performed using a mechanical testing machine and fracture patterns were examined under a stereomicroscope.Fracture resistance data were analyzed using one-way ANOVA followed by Tukey's test (P < 0.05).INT and RIB showed higher fracture resistance values (P < 0.05), but were similar to each other (P > 0.05).There was no difference in fracture resistance between CON and RES (P > 0.05).Adhesive type fractures were the most frequent, and the unfavorable fracture pattern was higher in INT and RIB.Aesthetic restorations reinforced with glass or polyethylene fibers are more resistant to fracture, although they exhibit an unfavorable fracture profile.