The Use of the FEM to Identify the Optimal Groove Dimensions Ensuring the Least Stressed Connection between a Zirconia Coping and Veneering Ceramic.

To examine the influence of coping notches with varying groove widths and depths on the quality of the connection with ceramic. Ten rectangular sintered zirconia (3Y-TZP) samples were etched with a neodymium-yag laser Nd:YAG. Then, a profilometer was used to test the depths and spacing of the grooves. A notch profile was used to design the shapes and spacing of the grooves based on a finite element method (FEM) simulating zirconia. The following situations were simulated: an increase in groove width from 100% to 180% and depth from 40% and 80%; and a 40% depth and width. An increase of 10% in the baseline width caused an insignificant reduction of the strain in the connection. A further increase in this dimension led to a 50% increase in strain with a 40% increase in width. An increase in the groove depth by 40% reduced the strain level by 13%, while an increase in the groove depth by 80% reduced the strain level by 22%. Simultaneous deepening and widening of the groove by 40% had no significant impact on the strain level. Maintaining the width of the groove bottom while increasing the depth offers fewer advantages than deepening and narrowing the groove bottom.