Evaluation of the stress pattern in the resin-based composite restoration of an endodontically treated premolar tooth : a finite element analysis study

This study aimed to assess the stress values in an endodontically treated maxillary premolar restored with a direct placement of adhesive composite restoration. An ortho-grade root-treatment was performed on a single-rooted maxillary premolar. Three types of cavities were prepared as follow: (1) O: Occlusal access cavity (one surface), (2): MO: access cavity with mesial extension equal to one third of bucco-palatal cusp width and 1 mm above the cementoenamel junction (two surfaces), (3) MOD: access cavity with mesial and distal extensions equal to one third of buccopalatal cusp width and 1 mm above the cementoenamel junction (three surfaces). After each restorative procedure, the restored-tooth complex was scanned using a micro-computed tomography scanner. A three-dimensional (3D) structure for each individual layer, including the enamel, dentine, composite restoration, and the gutta-percha of the restored tooth complex, was generated with interactive medical image processing software, whereas the biomechanical behavior and stress pattern distribution were evaluated using a finite element analysis software programme. The results revealed that the MO-restored tooth complex showed lower stress values than the onesurface (O) and three-surface (MOD) restored cavities. The generated stress values in the twosurface (MO) restored cavity in the present study were less than that of the one-surface (O) or three-surface (MOD) restored cavities. It can be concluded that, by increasing the C-factor, higher stress values are more likely to occur in the restored tooth. Greater stress values were observed in endodontically treated tooth with MOD restoration, which might have negative consequences on the fracture strength of the whole structure