Fracture resistance of teeth restored with dentin-bonded crowns constructed in a leucite-reinforced ceramic

Laboratory studies and preliminary clinical data have demonstrated satisfactory fracture resistance of all-ceramic crowns placed using a resin-composite luting material and a dentin-bonding system. This study investigates the fracture resistance of crowns constructed in a leucite-reinforced ceramic when placed using a dentin-bonding system and a dual-cure resin composite luting material and compares this with the fracture resistance of feldspathic porcelain crowns.

Standardised preparations were carried out on 10 sound, unrestored, maxillary premolar teeth, the mean bucco-palatal width of which did not vary by more than 2.5%. Ceramic crowns (Fortress; Chameleon Dental, KS, US) were constructed using a standardised technique. Their fitting surface was etched with hydrofluoric acid. The crowns were placed using the dentin-bonding system Mirage ABC and the luting system Mirage FLC (Chameleon Dental, KS, US). The restored teeth were loaded in compression at 1 mm/min through a 4 mm steel bar placed along the midline fissure.

A mean fracture load of 0.88 kN was recorded. Results from previous work indicate a fracture resistance of 0.77 kN for feldspathic porcelain crowns placed using the same luting systems on similarly standardised preparations. Statistical analysis by one-way ANOVA and Tukey's multiple comparison procedure indicated that there was no significant difference in the mean fracture resistance of the teeth restored using the leucite reinforced ceramic and the teeth restored with feldspathic porcelain.

Crowns constructed in a leucite-reinforced ceramic and placed using dentin-bonding and dual-cure resin composite luting materials may provide some increase in fracture resistance, but the results may not be significantly different from the feldspathic porcelain.