title: Effect of the crown, post, and remaining coronal dentin on the biomechanical behavior of endodontically treated maxillary central incisors.
abstract: BACKGROUND
  It is unclear how the amount of remaining coronal dentin and the type of post and core rehabilitation affect the strain, stress distribution, and fracture resistance of endodontically treated teeth.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate the effects of the type of post, type of crown, and the amount of remaining coronal dentin on the biomechanical behavior of endodontically treated teeth.
  
  
  METHODS
  The investigation was conducted by using 3-dimensional finite element analysis and laboratory tests. Three-dimensional models of a maxillary central incisor were generated: without remaining coronal dentin, with 1.0 mm of remaining coronal dentin, with 2.0 mm of remaining coronal dentin, and restored with a glass-fiber post or a cast post and core in combination with a metal crown or an alumina-reinforced ceramic crown. The results were evaluated by using the von Mises criterion and Maximum Principal Stress. One hundred twenty bovine incisors were selected and divided into 12 treatment groups (n=10). Specimens were loaded at a 135-degree angle to perform strain measurements and were then loaded until fracture. The strain and fracture resistance results were analyzed with 3-way analysis of variance and the Tukey honestly significant difference test (α=.05).
  
  
  RESULTS
  The alumina-reinforced ceramic crowns and metal crowns associated with a glass-fiber post showed a homogeneous stress distribution within the root. The cast post and core concentrated higher stresses at the post-dentin interface. Significant differences were found among the mean fracture resistance values for all groups (P<.05). The presence of 2.0 mm of coronal remnants resulted in lower strains and higher fracture resistance for both the metal and ceramic crowns. Roots restored with glass-fiber posts exhibited more favorable fractures.
  
  
  CONCLUSIONS
  The presence of 2 mm of remaining coronal dentin improved the mechanical behavior of the endodontically treated maxillary incisors. Teeth restored with glass-fiber posts and composite resin cores showed a homogeneous stress distribution within the root dentin.
authors.affiliation: Graduate student, Biomechanics Group, Department of Operative Dentistry and Dental Materials, School of Dentistry, Federal University of Uberlândia, Uberlândia, Minas Gerais, Brazil.
authors.forename: Crisnicaw
authors.initials: C
authors.lastname: Veríssimo
authors.affiliation: Professor, Biomechanics Group, Health Technical School, ESTES/UFU - Federal University of Uberlândia, Uberlândia, Minas Gerais, Brazil.
authors.forename: Paulo Cézar
authors.initials: PC
authors.lastname: Simamoto Júnior
authors.affiliation: Professor, Biomechanics Group, Department of Operative Dentistry and Dental Materials, School of Dentistry, Federal University of Uberlândia, Uberlândia, Minas Gerais, Brazil.
authors.forename: Carlos José
authors.initials: CJ
authors.lastname: Soares
authors.affiliation: Mechanical Engineer, Researcher, Renato Archer Information Technology Center, Ministry of Science and Technology, Campinas, São Paulo, Brazil.
authors.forename: Pedro Yoshito
authors.initials: PY
authors.lastname: Noritomi
authors.affiliation: Professor, Biomechanics Group, Department of Operative Dentistry and Dental Materials, School of Dentistry, Federal University of Uberlândia, Uberlândia, Minas Gerais, Brazil. Electronic address: paulocesarfs@foufu.ufu.br.
authors.forename: Paulo César Freitas
authors.initials: PC
authors.lastname: Santos-Filho
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry; D000818:Animals; D001696:Biomechanical Phenomena; D002417:Cattle; D002516:Ceramics / Q000737:chemistry; D003198:Computer Simulation; D017076:Computer-Aided Design; D003442:Crowns / Q000145:classification*; D003722:Dental Alloys / Q000737:chemistry; D017267:Dental Prosthesis Design; D003786:Dental Pulp Cavity / Q000503:physiopathology; D003804:Dentin / Q000473:pathology*; D055119:Elastic Modulus; D020342:Finite Element Analysis; D005898:Glass / Q000737:chemistry; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D007180:Incisor / Q000473:pathology / Q000503:physiopathology*; D008953:Models, Anatomic; D008954:Models, Biological; D011176:Post and Core Technique / Q000295:instrumentation*; D013314:Stress, Mechanical; D014082:Tooth Fractures / Q000503:physiopathology; D014092:Tooth Root / Q000503:physiopathology; D019553:Tooth, Nonvital / Q000503:physiopathology / Q000534:rehabilitation*
chemical_list: D003722:Dental Alloys; C009753:fiberglass; D000537:Aluminum Oxide