Load bearing capacity of fibre-reinforced and particulate filler composite resin combination.

OBJECTIVES: Longevity of particulate filler resin (PFR) is controversial for large restorations with high occlusal-stresses. The aim of this study was to reinforce PFR with fiber reinforced composite (FRC) and to evaluate the effect of thickness of FRC substructure and thickness of overlaying PFR, on the static load-bearing capacity of the material combination.

METHODS: A total of 336 test specimens having a FRC substructure (short random or continuous bidirectional fibre orientation) and layer of restorative PFR were prepared for this study. In Group A, the specimens contained short random oriented fibres (length: 2-3mm) and in Group B, there were continuous bidirectionally oriented fibres. The specimens (n = 12/group) were polymerized with a hand light-curing unit and were either dry-stored or thermocycled before they were statically loaded with a steel ball until fracture, using a universal testing machine.

RESULTS: Increase the volume fraction of the short random FRC versus the fraction of PFR, the load-bearing capacity of the specimen increased (p < 0.001). Short random FRC revealed significantly different behavior than the bidirectionally oriented FRC (p < 0.001). By combining the FRC layer of 0.5mm in thickness with a layer of 2.5mm of PFR gave load values of 1462N and 1196N, which were considerably higher than values for plain PFR of 3mm in thickness (782N and 729N).

CONCLUSION: The results suggest that by adding a FRC substructure under the PFR, the load-bearing capacity of the material combination was increased.