title: Influence of crown ferrule heights and dowel material selection on the mechanical behavior of root-filled teeth: a finite element analysis.
abstract: OBJECTIVE
  This study used the 3D finite element (FE) method to evaluate the mechanical behavior of a maxillary central incisor with three types of dowels with variable heights of the remaining crown structure, namely 0, 1, and 2 mm.
  
  
  METHODS
  Based on computed microtomography, nine models of a maxillary central incisor restored with complete ceramic crowns were obtained, with three ferrule heights (0, 1, and 2 mm) and three types of dowels (glass fiber = GFD; nickel-chromium = NiCr; gold alloy = Au), as follows: GFD0--restored with GFD with absence (0 mm) of ferrule; GFD1--similar, with 1 mm ferrule; GFD2--glass fiber with 2 mm ferrule; NiCr0--restored with NiCr alloy dowel with absence (0 mm) of ferrule; NiCr1--similar, with 1 mm ferrule; NiCr2--similar, with 2 mm ferrule; Au0--restored with Au alloy dowel with absence (0 mm) of ferrule; Au1--similar, with 1 mm ferrule; Au2--similar, with 2 mm ferrule. A 180 N distributed load was applied to the lingual aspect of the tooth, at 45° to the tooth long axis. The surface of the periodontal ligament was fixed in the three axes (x = y = z = 0). The maximum principal stress (σ(max)), minimum principal stress (σ(min)), equivalent von Mises (σ(vM)) stress, and shear stress (σ(shear)) were calculated for the remaining crown dentin, root dentin, and dowels using the FE software.
  
  
  RESULTS
  The σ(max) (MPa) in the crown dentin were: GFD0 = 117; NiCr0 = 30; Au0 = 64; GFD1 = 113; NiCr1 = 102; Au1 = 84; GFD2 = 102; NiCr2 = 260; Au2 = 266. The σ(max) (MPa) in the root dentin were: GFD0 = 159; NiCr0 = 151; Au0 = 158; GFD1 = 92; NiCr1 = 60; Au1 = 67; GFD2 = 97; NiCr2 = 87; Au2 = 109.
  
  
  CONCLUSIONS
  The maximum stress was found for the NiCr dowel, followed by the Au dowel and GFD; teeth without ferrule are more susceptible to the occurrence of fractures in the apical root third.
authors.affiliation: Centro de Pesquisas Odontológicas, São Leopoldo Mandic, Brazil.
authors.forename: Mauricio U
authors.initials: MU
authors.lastname: Watanabe
authors.forename: Rodolfo Bruniera
authors.initials: RB
authors.lastname: Anchieta
authors.forename: Eduardo Passos
authors.initials: EP
authors.lastname: Rocha
authors.forename: Sidney
authors.initials: S
authors.lastname: Kina
authors.forename: Erika Oliveira de
authors.initials: EO
authors.lastname: Almeida
authors.forename: Amilcar Chagas
authors.initials: AC
authors.lastname: Freitas
authors.forename: Roberta Tarkany
authors.initials: RT
authors.lastname: Basting
mesh_terms: D002516:Ceramics / Q000737:chemistry; D002858:Chromium Alloys / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D003198:Computer Simulation; D003442:Crowns; D003743:Dental Enamel / Q000502:physiology; D003764:Dental Materials / Q000737:chemistry*; D017267:Dental Prosthesis Design; D003786:Dental Pulp Cavity / Q000502:physiology; D003799:Dental Stress Analysis; D003804:Dentin / Q000502:physiology; D055119:Elastic Modulus; D020342:Finite Element Analysis; D005898:Glass / Q000737:chemistry; D006047:Gold Alloys / Q000737:chemistry; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007180:Incisor; D008422:Materials Testing; D008954:Models, Biological; D010513:Periodontal Ligament / Q000502:physiology; D011176:Post and Core Technique / Q000295:instrumentation*; D013314:Stress, Mechanical; D019227:Tooth Apex / Q000502:physiology; D019228:Tooth Crown / Q000502:physiology; D019231:Tooth Preparation, Prosthodontic / Q000145:classification*; D014092:Tooth Root / Q000502:physiology; D019553:Tooth, Nonvital / Q000503:physiopathology
chemical_list: D002858:Chromium Alloys; D003188:Composite Resins; D003764:Dental Materials; D006047:Gold Alloys; C009753:fiberglass