To evaluate the effectiveness of a fibre-reinforced composite to increase the fatigue resistance and fracture strength of extensively restored premolars, including restoration of a missing cusp.
Method:
Sixteen extracted inferior premolars received standard, extensive MOD Class-II cavities with removal of the lingual cusp. After 24h of water storage at 37°C, the teeth were directly restored, using either the fibre-reinforced composite EverX Posterior (GC) as base, along with the micro-hybrid composite G-aenial (GC) as outside composite (experimental group), or using G-aenial (GC) only (control) (n=8 per group). The restored teeth were subjected to 1,200,000 axial compressive load cycles using a chewing simulator (Willytec). All specimens that survived fatigue loading were fractured using a universal loading device (MicroTester, Instron). The mode of fracture was analysed using scanning electron microscopy (SEM). The data were submitted to Student T-test with 5% as level of significance.
Result:
All specimens survived the mechanical fatigue simulation. No statistical difference in fracture resistance was recorded between the ‘EverX Posterior + G-aenial’ (1329.23±85.43 MPa) and the ‘G-aenial only’ (1222.01±251.89 MPa) restorative protocol. SEM revealed, respectively, two and one non-repairable failure(s) for the ‘EverX Posterior + G-aenial’ and the ‘G-aenial only’ restorative protocol, all due to root fracture. All other specimens revealed a mixed fracture pattern, including cohesive failure within the composite and tooth, as well as adhesive failure at the adhesive-composite interface.
Conclusion:
The fatigue resistance and fracture strength of extensively restored premolars with a missing cusp were not increased using the fibre-reinforced composite employed.