title: Three-dimensional FEA of effects of two dowel-and-core approaches and effects of canal flaring on stress distribution in endodontically treated teeth.
abstract: OBJECTIVE
  The aim of this 3D finite element analysis (FEA) was to assess stress distribution and levels in endodontically treated teeth restored with two dowel-and-core systems with differing root canal configurations.
  
  
  METHODS
  Four 3D finite element models of a laser-digitalized maxillary central incisor embedded in alveolar bone were created. Internal morphology data and mechanical properties of the materials were obtained from the literature. Models included a (1) sound tooth (control) versus an endodontically treated maxillary central incisor with a crown ferrule preparation with two restorative approaches of a ceramic crown over a (2) gold alloy dowel-and-core or (3) glass-fiber dowels with composite cores (4) the latter with a flared root canal. A 100 N static load was applied in the center of the palatal surface at a 45° angle, and the stress distribution pattern was analyzed using ANSYS(®) software.
  
  
  RESULTS
  In Model 1 (control), maximum stresses occurred at the coronal third of the buccal (2.32 × 10(7) Pa) and palatal aspects of dentin. The stress peak value of the model (2.45 × 10(7) Pa) occurred on the palatal aspect of the enamel at the level of the cementoenamel junction. With the insertion of dowels with thin cement layers (Models 2 and 3), stress concentrations in radicular dentin decreased, while they increased in the dowel/cement/dentin interface. These models exhibited the greatest stress peak values in the incisal margin of the gold alloy core (18.9 × 10(7) Pa) and in the cement layer (4.7 × 10(7) Pa). In Model 4, stress peak value was observed in the porcelain crown (4.62 × 10(7) Pa), and there was no stress concentration inside the cement layer.
  
  
  CONCLUSIONS
  Within the limits of this study, the results suggest that the use of dowels and cements with mechanical properties similar to those of dentin, and an increased cement layer thickness, results in mechanical behavior similar to the physiological behavior of a sound tooth.
authors.affiliation: Department of Prosthodontics, Postgraduate Program in Dentistry, Faculty of Dentistry, Lutheran University of Brazil, Canoas, Brazil. lmezzomo@hotmail.com
authors.forename: Luis André
authors.initials: LA
authors.lastname: Mezzomo
authors.forename: Leandro
authors.initials: L
authors.lastname: Corso
authors.forename: Rogério José
authors.initials: RJ
authors.lastname: Marczak
authors.forename: Elken Gomes
authors.initials: EG
authors.lastname: Rivaldo
mesh_terms: D003188:Composite Resins; D003442:Crowns; D003776:Dental Porcelain; D003799:Dental Stress Analysis / Q000379:methods; D055119:Elastic Modulus; D020342:Finite Element Analysis; D005898:Glass; D006047:Gold Alloys; D006801:Humans; D007180:Incisor; D008437:Maxilla; D008954:Models, Biological; D011176:Post and Core Technique; D018915:Root Canal Preparation / Q000379:methods*; D033081:Shear Strength; D013718:Tensile Strength; D019231:Tooth Preparation, Prosthodontic; D019553:Tooth, Nonvital
chemical_list: D003188:Composite Resins; D006047:Gold Alloys; C009753:fiberglass; D003776:Dental Porcelain