Comparison of Stress Distribution in Fixed Partial Dentures With an Endocrown Abutment Made of Two Ceramic Materials and Different Residual Tooth Structures, Using Finite Element Analysis.

Statement of Problem: The use of endocrowns as retainers for fixed partial dentures (FPD) may be considered questionable. Purpose: This study aimed to compare stress distribution in FPD with an endocrown abutment made of two ceramic materials and different residual tooth structures. Materials and Methods: Models with a missing mandibular right first premolar and an endodontically treated second premolar with two different residual tooth wall height (RWH) of 4.5 and 3 mm were designed in CAD software. These models received two types of FPD made of lithium disilicate and zirconia ceramics and were subjected to occlusal and buccal force conditions. Finally, the von Mises stress distribution was assessed using ANSYS software. Results: Comparison of stress distribution revealed that the model with 4.5 mm of RWH experienced a lower maximum von Mises stress than the model with 3 mm of RWH. Irrespective of load points, under both occlusal and buccal forces, the connector region is the area of greatest stress concentration. The results indicated that in all scenarios, the maximum von Mises stress in zirconia FPD was more than in lithium disilicate FPDs. Conclusion: Increasing the extent of tooth preparation and structural damage will lead to higher von Mises stress. The highest maximum von Mises stresses were generated in the zirconia models and buccal load conditions. Both materials and designs were acceptable and could be used as FPDs with an endocrown as a retainer. Clinical Implications: The use of endocrowns as retainers for FPD can be considered as an alternative in certain cases, offering a balance between conservation of tooth structure and mechanical stability.