title: Stress distribution in root filled teeth restored with various post and core techniques: effect of post length and crown height.
abstract: OBJECTIVE
  To investigate interfacial stress distribution in restored root filled teeth with various post lengths and crown heights.
  
  
  METHODS
  Three-dimensional mathematical models of a root filled mandibular premolar tooth were constructed. Parts of the tooth structures were replaced with ceramic crowns having three crown heights incorporating, either a cast post and core or a resin post and cores with fibre post or metallic post with four post lengths. Finite element linear analysis was performed to calculate equivalent and shear stress distribution at the interfaces between the teeth and post and cores under mesiodistal symmetrical boundary conditions and an oblique static load of 400 N.
  
  
  RESULTS
  For the resin post and core with fibre and metallic posts, shear stress at the interface was greater in the cervical area than the post area, depending on the crown height. The resin post and core with metallic post had lower shear stress at the interface of cervical area than that of the fibre post model; however, the metallic post models produced a high concentration of shear stress at the interface between the post and resin composite. On the other hand, for the cast post and core, the shear stress at the interface was mainly produced in the post end area, which increased with decrease of post length.
  
  
  CONCLUSIONS
  For the resin post and core, bonding integrity to the cervical area would play a critical role in the survival of the restored tooth, whereas for the cast post and core, the bond of the post would be essential.
authors.affiliation: Cariology and Operative Dentistry, Oral Restitution Department, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kainose
authors.affiliation: Cariology and Operative Dentistry, Oral Restitution Department, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Nakajima
authors.affiliation: Division of Conservative Dentistry, King's College London Dental Institute at Guy's, King's and St Thomas' Hospitals, King's College London, London, UK.
authors.forename: R
authors.initials: R
authors.lastname: Foxton
authors.affiliation: Removable Partial Prosthodontics Department, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Wakabayashi
authors.affiliation: Cariology and Operative Dentistry, Oral Restitution Department, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.|Global Center of Excellence (GCOE) Program, International Research Center for Molecular Science in Tooth and Bone Diseases, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Tagami
mesh_terms: D001641:Bicuspid; D003188:Composite Resins / Q000737:chemistry; D019245:Compressive Strength; D003442:Crowns; D003764:Dental Materials / Q000737:chemistry*; D003786:Dental Pulp Cavity / Q000503:physiopathology*; D003799:Dental Stress Analysis; D020342:Finite Element Analysis; D006801:Humans; D008422:Materials Testing; D011176:Post and Core Technique; D018915:Root Canal Preparation / Q000379:methods; D013314:Stress, Mechanical; D013499:Surface Properties; D019228:Tooth Crown; D014082:Tooth Fractures / Q000503:physiopathology*; D014092:Tooth Root / Q000503:physiopathology; D019553:Tooth, Nonvital
chemical_list: D003188:Composite Resins; D003764:Dental Materials
keywords: adhesive; debonding; finite element analysis; fracture; root; stress