Abstract:

Objective

To investigate the effect of indenter with different diameters on the fracture resistance and mode of the posterior e.max crowns.

Methods

Twenty e.max crowns were divided equally into two groups （A and B）， and then were subjected to compressive load using two indenters with different diameters of 4 mm and 10 mm respectively. The failure load value（N） and the fracture mode of the crowns were recorded， and faliure modes of the failured crowns were examined using a stereomicroscope.

Results

Statistical analysis showed a lower mean fracture load of group A crowns than that of group B crowns （P=0.012）. Both cone-shaped cracks and the radical cracks initiated from adhesive interface were observed in group A crowns， while group B crowns fractured throughout mesio-distally accompanied by tooth fracture.

Conclusions

The diameter of the spherical indenter has an obvious influence on fracture resistance and fracture mode of the all-ceramic crowns. The crowns loaded with large diameter spherical indenter exhibit higher fracture resistance values than those loaded with small one. When loaded by a small diameter indenter， the all-ceramic crowns exhibited similar failure mode as usually seen in clinical.

Key words: Dental porcelain, Dental restoration, Failure analysis, Fracture mode