Zirconia endocrown with intracanal extension and zirconia posts on maxillary molars: in silico study

Objective: The study aimed to evaluate the stress distribution on tooth and zirconia endocrown restoration with pulp chamber or intracanal extension and zirconia post, performed on maxillary first molars, using finite element analysis. Method and materials: Three 3D endodontically treated maxillary molars were modeled. Cortical bone and cementum were modeled at 2 mm and 200 µm in thickness. Periodontal ligament of 250 µm thickness was constructed. Zirconia endocrown with pulp chamber extension of 2 mm (Model E+PCE), zirconia endocrown with intracanal extension of 4 mm (Model E+ICE), and zirconia post of 4 mm and crown (ZP) were modeled using software. All restoration models were placed on the maxillary molars. Models were subjected to 400 N loading from the three occlusal contact points. Von Mises stress was recorded.
Results: Points where the stress was applied showed high stress compared to other regions of the models. The stress did not occur at the trifurcation in any of the models. For the stresses occurring in the restoration material, these were 14.67 MPa, 57.79 MPa, and 155.56 MPa, in Models E+PCE, E+ICE, and ZP, respectively. At the remaining dentin, these values were 47.04 MPa, 32.85 MPa, and 33.42 MPa in Models E+PCE, E+ICE, and ZP, respectively.
Conclusions: Within the limitations of the study, zirconia endocrowns with intracanal extension exhibit more favorable stress distribution in both restoration material and dentin compared to zirconia posts and pulpal extension endocrowns. These findings suggest that endocrown with intracanal extension may be a better restorative option for reducing stress. (Quintessence Int 2025;56:120–129; doi: 10.3290/j.qi.b5798352) Keywords: endocrown, endodontically treated teeth, maxillary molar, zirconia