Finite Element Comparison of Fiber Post Techniques Before Tooth Reconstruction

Objectives: The aim of this study was to determine, by finite element analysis, the most adapted fiber post number and root canal preparation for the clinical reconstruction of a endodontically-treated premolar.
Methods: A premolar requiring a prosthetic crown was scanned before any therapeutics by cone beam computed tomography. Slice images were converted using segmentation in different meshes in function of areas, and several fiber post techniques were evaluated using finite element analysis. Five models were created depending on the root canal preparation and the fiber post technique. In four models, the canal preparation was modelled with a conventional diameter of 2.1 mm. In the fifth model, the canal preparation had a narrower diameter (1.7 mm). Four different techniques were assessed using either one standard fiber post, 14 microfibers, 9 microfibers or 4 microfibers. The diameter of the standard fiber post was 2.0 mm, whereas microfibers had a diameter of 0.3 mm each. The load was applied on the buccal cuspid of the premolar and the root was embedded. Stress distribution and extreme stress value were calculated by linear static finite element analysis using the Abaqus™ software. The post technique to implement clinically was then chosen by comparing stress values between different models and the premolar reconstructed.
Results: The highest stresses were always located on the peripheral parts of the root irrespective of the model studied. The extreme stress value decreased with the augmentation of the number of microfibers and in the narrow canal.
Conclusions: The finite element analysis allowed prosthetic treatment simulation by comparing different solutions before modifying the tooth. Our results indicate that the highest number of fibers should be placed in the canal and might not need root canal enlargement. Further clinical studies are required to confirm these results.