Monolithic versus Pressed/Layered CAD/CAM zirconia crowns: Effect of Cement Material on the Fracture Strength

The purpose of this study was to evaluate the influence of different types of cements on fracture resistance of full zirconia and zirconia-based ceramic single crowns. Maxillary premolar crowns in 2 mm thickness were fabricated on metal dies in 3 groups: Group MO: 24 monolithic zirconia crowns; Group ZL: 24 zirconia frameworks veneered with feldspathic by the layering technique; Group ZP: 24 zirconia frameworks veneered by the heat-pressed technique. Then groups seperated in two subgroups and half of them were cemented with glass-ionomer cement and the other half were cemented adhesive resin cement. All specimens were stored in distilled water at 37 ºC for 24 hours and then underwent thermal cycling. Single load to fracture test was performed in universal testing machine until failure. The mean fracture values were compared by an one-way ANOVA and a multiple comparison post-hoc Tukey HSD test (p<0.05). Scanning electron microscope was used to evaluate cracks and/or bulk fracture. Results: Group MO cemented with adesive cement showed the highest mean fracture strength ( 2,703.07± 308,98 N).There was no significant difference in the mean fracture resistance of Group ZP and ZL. Monolithic zirconia full crowns had the highest fracture strength values and these single crown restorations did not effected by cementation.