title: Elastic modulus of posts and the risk of root fracture.
abstract: The definition of an optimal elastic modulus for a post is controversial. This work hypothesized that the influence of the posts' elastic modulus on dentin stress concentration is dependent on the load direction. The objective was to evaluate, using finite element analysis, the maximum principal stress (sigma(max)) on the root, using posts with different elastic modulus submitted to different loading directions. Nine 3D models were built, representing the dentin root, gutta-percha, a conical post and the cortical bone. The softwares used were: MSC.PATRAN2005r2 (preprocessing) and MSC.Marc2005r2 (processing). Load of 100 N was applied, varying the directions (0 degrees, 45 degrees and 90 degrees) in relation to the post's long axis. The magnitude and direction of the sigma(max) were recorded. At the 45 degrees and 90 degrees loading, the highest values of sigma(max) were recorded for the lowest modulus posts, on the cervical region, with a direction that suggests debonding of the post. For the 0 degrees loading, the highest values of sigma(max) were recorded for higher modulus posts, on the apical region, and the circumferential direction suggests vertical root fracture. The hypothesis was accepted: the effect of the elastic modulus on the magnitude and direction of the sigma(max) generated on the root was dependent on the loading direction.
authors.affiliation: Department of Dental Materials, School of Dentistry, University of São Paulo, São Paulo, Brazil. jo@usp.br
authors.forename: Josete B C
authors.initials: JB
authors.lastname: Meira
authors.forename: Camila O M
authors.initials: CO
authors.lastname: Espósito
authors.forename: Mayra F Z
authors.initials: MF
authors.lastname: Quitero
authors.forename: Isis A V P
authors.initials: IA
authors.lastname: Poiate
authors.forename: Carmem Silvia C
authors.initials: CS
authors.lastname: Pfeifer
authors.forename: Carina B
authors.initials: CB
authors.lastname: Tanaka
authors.forename: Rafael Y
authors.initials: RY
authors.lastname: Ballester
mesh_terms: D000539:Alveolar Process / Q000503:physiopathology; D003198:Computer Simulation; D017005:Dental Debonding; D003786:Dental Pulp Cavity / Q000503:physiopathology*; D003804:Dentin / Q000503:physiopathology; D055119:Elastic Modulus; D020342:Finite Element Analysis; D006171:Gutta-Percha / Q000737:chemistry; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D007180:Incisor / Q000503:physiopathology; D008422:Materials Testing; D008954:Models, Biological; D011176:Post and Core Technique / Q000295:instrumentation*; D012387:Root Canal Filling Materials / Q000737:chemistry; D013314:Stress, Mechanical; D019227:Tooth Apex / Q000503:physiopathology; D019237:Tooth Cervix / Q000503:physiopathology; D014082:Tooth Fractures / Q000209:etiology* / Q000503:physiopathology; D014092:Tooth Root / Q000293:injuries* / Q000503:physiopathology; D020390:Tooth Socket / Q000503:physiopathology
chemical_list: D012387:Root Canal Filling Materials; D006171:Gutta-Percha