Abstract
By means of a finite element method (FEM), the present study evaluated the effect of fiber post (FP) placement on the stress distribution occurring in endodontically treated upper first premolars (UFPs) with mesial–occlusal–distal (MOD) nanohybrid composite restorations under subcritical static load. FEM models were created to simulate four different clinical situations involving endodontically treated UFPs with MOD cavities restored with one of the following: composite resin; composite and one FP in the palatal root; composite and one FP in the buccal root; or composite and two FPs. As control, the model of an intact UFP was included. A simulated load of 150 N was applied. Stress distribution was observed on each model surface, on the mid buccal–palatal plane, and on two horizontal planes (at cervical and root-furcation levels); the maximum Von Mises stress values were calculated. All analyses were replicated three times, using the mechanical parameters from three different nanohybrid resin composite restorative materials. In the presence of FPs, the maximum stress values recorded on dentin (in cervical and root-furcation areas) appeared slightly reduced, compared to the endodontically treated tooth restored with no post; in the same areas, the overall Von Mises maps revealed more favorable stress distributions. FPs in maxillary premolars with MOD cavities can lead to a positive redistribution of potentially dangerous stress concentrations away from the cervical and the root-furcation dentin.
Highlights
Treated teeth (ETT) are structurally different from non-restored vital teeth
The use of metal posts appeared associated to high fracture indexes, ranging in some studies between 2% and 4% [10], which has been attributed to stress concentration on dentin substrate [11,12]
The maximum Von Mises stresses and the stress distribution maps achieved on the model surfaces and along the buccal–palatal planes are respectively shown in Figures 2 and 3
Summary
Treated teeth (ETT) are structurally different from non-restored vital teeth. The differences include changes in the amount of the tooth structure, in the properties of dentine, and in proprioception. For these reasons, they require specific restorative treatments [1]. The concepts on the basis of endodontically treated tooth restoration have undergone significant changes over the last years, mainly in the direction of a better preservation of tooth structures and tissues [2,3,4]. Non-adhesive posts are not able to homogeneously spread forces along the tooth–post interface area, typically concentrating the stresses in the dentin around the central third of the canal [13]
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