Different Restorative Procedures Can Influence Stresses in Tooth Tissues: FEA

Objectives: Endodontically treated teeth are more prone to fracture and restoration failure due to great loss of tooth structure. The optimal post-endodontic restoration has been debated in the literature, with the indirect restorations being the more traditional option, nowadays challenged by the direct composite restorations due to advances in adhesive dentistry. The aim of this study was to investigate using finite element analysis (FEA) the influence of different post-endodontic restorative options on the stresses in tooth tissues and restorative materials.
Methods: A 3D tooth model was created in SolidWorks 2014 software (Dassault Systemes SolidWorks Corp, USA), based on computed tomography scans of an extracted maxillary second premolar. A deep and wide mesial-occlusal-distal (MOD) cavity was simulated to test a clinical situation with great loss of tooth tissue. Four different restorative options were tested: 1) MOD direct composite restoration; 2) direct composite restoration with cusp reduction (MODPB); 3) CAD/CAM ceramic endocrown; 4) post, core and CAD/CAM ceramic crown restoration. Occlusal loading (150N) was simulated and von Misses stresses were calculated.
Results: Significantly lower von Mises stresses in tooth tissues were recorded in indirectly restored teeth, while the MODPB cavity design showed lower stresses in the directly restored groups. However, the restorative options that were favorable for dentin seemed to be unfavorable for restoration, since endocrowns demonstrated the highest, while MOD filling the lowest stresses. Maximum stresses were mostly distributed in the loading areas and the cervical portion of the palatal part of the crown.
Conclusions: Within the limitations of this study, restorative materials with a high elastic modulus seem to cause lower stresses in dentin of an endodontically treated structurally weakened tooth. It is important to remember the importance of cusps reduction if direct restorations are placed. Further research could involve the use of different materials and cavity designs.