Effect of occlusal anatomy of CAD/CAM feldspathic posterior crowns in the stress concentration and fracture load

Objectives: This study evaluated the effect of restoration occlusal design on the maximum fracture load and stress distribution of a feldspathic ceramic crown. Materials and Methods: Twenty dentin analogues were used to simulate a full-crown preparation. Next, 20 feldspathic crowns were milled according to the occlusal design parameter available in the CAD database (Young or Adult). The crowns were cemented with dual cure resin-cement and loaded until fracture at 1 mm/min cross-head speed. Data were analyzed by using one-way ANOVA and Tukey tests (p < 0.05). The same geometry and experimental setup was modeled and exported to the computer aided engineering software and tensile stress concentration was calculated using the finite element method with 300 N occlusal load simulation. Results: The occlusal anatomy significantly influenced the load-to-fracture (p < 0.05). Adult design showed higher mean values (1149 +/- 201 N) than Young design (454 +/- 77 N). The maximum principal stress criteria showed similar stress pattern for both designs, however, the highest stress concentration was calculated for Young design (91 MPa) in the occlusal surface. Conclusions: An anatomy design with reduced cusp angulation and less evident occlusal sulcus can reduce the stress concentration and increase the fracture load for feldspathic CAD/CAM posterior crowns.

Automated summary

The study found that occlusal anatomy significantly influenced the load-to-fracture of the crown, with the adult design showing higher mean values and the young design showing lower values. The maximum principal stress criteria showed similar stress patterns for both designs, but the young design had the highest stress concentration on the occlusal surface.