Evaluation of retention cavity geometry and ferrule effect in maxillary central incisors restored with anatomically shaped glass fiber post: a finite element analysis.

Objectives: This study evaluated the influence of two novel internal retention cavity designs and the presence of a ferrule on stress distribution in endodontically treated maxillary central incisors restored with anatomically shaped fiber posts using finite element analysis (FEA).

Method and materials: The models were divided into ferrule-present and ferrule-free groups and further subdivided according to cavity configuration: no additional retention, Retention Area 1, and Retention Area 2. A static oblique load of 100 N at 45° was applied to the palatal surface, 2 mm from the incisal edge. All simulations were conducted in ANSYS under standardized boundary conditions, with dentin stresses prioritized as dentin represents the primary load-bearing structure.

Results: The ferrule-free reference model showed the highest dentin stress (187.54 MPa, σ = 7.40 MPa), indicating increased fracture risk. In the absence of a ferrule, Retention Area 1 reduced peak dentin stress substantially (62.74 MPa, σ = 4.12 MPa) and produced the most uniform stress distribution, while Retention Area 2 also lowered stresses compared with the reference (σ = 5.36 MPa). In the ferrule-present groups, stresses were overall lower, confirming the ferrule's protective role; within this group, Retention Area 1 recorded the lowest dentin stress (82.18 MPa).

Conclusion: The ferrule remains biomechanically critical for preserving cervical dentin. However, in cases where a ferrule cannot be achieved, retention-oriented cavity designs demonstrated potential as a clinically viable alternative, though further validation is required.