title: Numerical analysis of the biomechanical behaviour of a weakened root after adhesive reconstruction and post-core rehabilitation.
abstract: OBJECTIVE
  The purpose of this study was to perform a finite element analysis to determine whether adhesive reconstruction is able to restore the original biomechanical behaviour of weakened roots, in terms of fracture resistance, when compared with post/crown-restored teeth with intact roots.
  
  
  METHODS
  A three-dimensional model of a maxillary central incisor was created. The model simulated an endodontically treated tooth restored with a glass-fibre post, a composite-resin core and a metal crown (Model 1). Based on Model 1, a new volume was created in the root cervical third that represented the area where the dentine structure was lost, resulting in a structurally damaged root (Model 2). A 100N load was applied to the palatal surface at 130° from the long axis of the tooth. After processing (Ansys(®) 10.0 - Canonsburg, PA, USA), the principal normal stress data were analyzed (S1, tensile; S3, compressive).
  
  
  RESULTS
  The models demonstrated a similar S1 distribution concentrated in the lingual cervical region but different S1 levels (Model 1: 28.7MPa; Model 2: 35.3MPa). The S3 distribution indicated differences in behaviour between the models (Model 1: -18 to -27MPa along the buccal root surface; Model 2: -25 to -32MPa on the post buccal surface and along the buccal root wall).
  
  
  CONCLUSIONS
  Although the stress distribution within the root walls remained below the ultimate stress limit of the root dentine, the adhesive reconstruction of the weakened roots did not recover the load resistance of structurally intact roots.
  
  
  CONCLUSIONS
  The decision of when to prosthetically rehabilitate weakened roots with cervical dentine structural tissue loss is a challenge for clinicians. A 'monoblock' adhesive reconstruction has been proposed for root reinforcement. During treatment planning, the possibility of restoring the mechanical resistance of the root must be evaluated if successful long-term results are to be achieved.
authors.affiliation: PPGMEC, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil. cmamattos@terra.com.br
authors.forename: C M A
authors.initials: CM
authors.lastname: Mattos
authors.forename: E B
authors.initials: EB
authors.lastname: Las Casas
authors.forename: I G R
authors.initials: IG
authors.lastname: Dutra
authors.forename: H A
authors.initials: HA
authors.lastname: Sousa
authors.forename: S M G
authors.initials: SM
authors.lastname: Guerra
mesh_terms: D001696:Biomechanical Phenomena; D002858:Chromium Alloys / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D003198:Computer Simulation; D003442:Crowns; D003764:Dental Materials / Q000737:chemistry; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis; D003804:Dentin / Q000503:physiopathology; D055119:Elastic Modulus; D020342:Finite Element Analysis; D005898:Glass / Q000737:chemistry; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D007180:Incisor / Q000503:physiopathology; D008954:Models, Biological; D009716:Numerical Analysis, Computer-Assisted; D011176:Post and Core Technique; D013314:Stress, Mechanical; D019237:Tooth Cervix / Q000503:physiopathology; D014082:Tooth Fractures / Q000503:physiopathology; D014092:Tooth Root / Q000503:physiopathology*; D019553:Tooth, Nonvital / Q000503:physiopathology / Q000534:rehabilitation*
chemical_list: D002858:Chromium Alloys; D003188:Composite Resins; D003764:Dental Materials; C009753:fiberglass