title: Influence of ferrule, post system, and length on stress distribution of weakened root-filled teeth.
abstract: BACKGROUND
  The aim of this study was to evaluate the influence of a ferrule, post system, and length on the stress distribution of weakened root-filled teeth.
  
  
  METHODS
  The investigation was conducted by using 3-dimensional (3D) finite element analysis. A sound tooth and 8 3D models of a weakened root-filled central incisor were generated using computer-aided design/computer-aided manufacturing software. The models were created without a ferrule and with a 2.0-mm ferrule, restored with a relined glass fiber post or a cast post and core (Cpc), and 12.0- and 7.0-mm post lengths. Each 3D model was imported using ∗.STEP files to the finite element software for mesh generation. The models were subjected to 100-N oblique loading at the palatal surface, and the results were evaluated by von Mises criterion and maximum principal stress distribution.
  
  
  RESULTS
  Finite element analysis showed that the Cpc models showed elevated stress levels in the root canal regardless of the presence of a ferrule. Relined glass fiber post models showed homogeneous stress distribution to the dentin external surface similar to the sound tooth model. Without a ferrule, Cpc with a 7- or 12-mm length promoted high levels of tensile stress inside the root canal.
  
  
  CONCLUSIONS
  Ferrule presence promoted more satisfactory stress distribution to the roots. Post length influenced the stress distribution only for the models restored with a cast post and core. High levels of tensile stress inside the root canals were verified with a cast post and core, which should be avoided to rehabilitate weakened roots, mainly in the absence of a ferrule.
authors.affiliation: Department of Restorative Dentistry and Dental Materials, Dentistry School, Federal University of Uberlandia, Minas Gerais, Brazil. Electronic address: paulocesarfs@foufu.ufu.br.
authors.forename: Paulo César Freitas
authors.initials: PC
authors.lastname: Santos-Filho
authors.affiliation: Department of Restorative Dentistry and Dental Materials, Dentistry School, Federal University of Uberlandia, Minas Gerais, Brazil.
authors.forename: Crisnicaw
authors.initials: C
authors.lastname: Veríssimo
authors.affiliation: Department of Occlusion, Fixed Prosthodontics and Dental Materials, Dentistry School, Federal University of Uberlandia, Minas Gerais, Brazil.
authors.forename: Luís Henrique Araújo
authors.initials: LH
authors.lastname: Raposo
authors.affiliation: Renato Archer Information Technology Center, Ministry of Science and Technology, Campinas, São Paulo, Brazil.
authors.forename: Pedro Yoshito
authors.initials: PY
authors.lastname: Noritomi MecEng
authors.affiliation: Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Piracicaba, São Paulo, Brazil.
authors.forename: Luis Roberto
authors.initials: LR
authors.lastname: Marcondes Martins
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D002858:Chromium Alloys / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D017076:Computer-Aided Design; D003764:Dental Materials / Q000737:chemistry; D003776:Dental Porcelain / Q000737:chemistry; D017267:Dental Prosthesis Design; D003786:Dental Pulp Cavity / Q000473:pathology; D003804:Dentin / Q000473:pathology; D020342:Finite Element Analysis; D005898:Glass / Q000737:chemistry; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008422:Materials Testing; D011176:Post and Core Technique / Q000295:instrumentation; D017680:Potassium Compounds / Q000737:chemistry; D013314:Stress, Mechanical; D019231:Tooth Preparation, Prosthodontic / Q000379:methods*; D019553:Tooth, Nonvital / Q000473:pathology*
chemical_list: D000538:Aluminum Silicates; D002858:Chromium Alloys; D003188:Composite Resins; D003764:Dental Materials; D017680:Potassium Compounds; C009753:fiberglass; D003776:Dental Porcelain; C016447:feldspar
keywords: Cast post and core; flared teeth; glass fiber post; stress distribution