title: Stress and strain distribution in demineralized enamel: A micro-CT based finite element study.
abstract: Physiological oral mechanical forces may play a role on the progression of enamel carious lesions to cavitation. Thus, the aim of this study was to describe, by 3D finite element analysis, stress, and strain patterns in sound and carious enamel after a simulated occlusal load. Micro-CT based models were created and meshed with tetrahedral elements (based on an extracted third molar), namely: a sound (ST) and a carious tooth (CT). For the CT, enamel material properties were assigned according to the micro-CT gray values. Below the threshold corresponding to the enamel lesion (2.5 g/cm(3) ) lower and isotropic elastic modulus was assigned (E = 18 GPa against E1  = 80 GPa, E2  = E3  = 20 GPa for sound enamel). Both models were imported into a FE solver where boundary conditions were assigned and a pressure load (500 MPa) was applied at the occlusal surface. A linear static analysis was performed, considering anisotropy in sound enamel. ST showed a more efficient transfer of maximum principal stress from enamel to the dentin layer, while for the CT, enamel layer was subjected to higher and concentrated loads. Maximum principal strain distributions were seen at the carious enamel surface, especially at the central fossa, correlating to the enamel cavity seen at the original micro-CT model. It is possible to conclude that demineralized enamel compromises appropriate stress transfer from enamel to dentin, contributing to the odds of fracture and cavitation. Enamel fracture over a dentin lesion may happen as one of the normal pathways to caries progression and may act as a confounding factor during clinical diagnostic decisions.
authors.affiliation: Faculdade de Odontologia, Departamento de Odontopediatria e Ortodontia, Universidade Federal do Rio de Janeiro, Rio De Janeiro, RJ, Brazil.
authors.forename: Aline Almeida
authors.initials: AA
authors.lastname: Neves
authors.affiliation: Departamento de Formação Específica em Odontologia, Universidade Federal Fluminense, Nova Friburgo, RJ, Brazil.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Coutinho
authors.affiliation: Departamento de Física Aplicada e Termodinâmica, Instituto de Física Armando Dias Tavares, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
authors.forename: Haimon Diniz Lopes
authors.initials: HD
authors.lastname: Alves
authors.affiliation: Departamento de Engenharia Mecânica e Energia, Instituto Politécnico, Universidade do Estado do Rio De Janeiro, Nova Friburgo, RJ, Brazil.
authors.forename: Joaquim Teixeira
authors.initials: JT
authors.lastname: de Assis
mesh_terms: D003731:Dental Caries / Q000473:pathology*; D003743:Dental Enamel / Q000737:chemistry*; D004602:Elements; D006801:Humans; D055595:Mechanical Phenomena; D008963:Molar / Q000737:chemistry*; D055114:X-Ray Microtomography
chemical_list: D004602:Elements
keywords: demineralized enamel; dental caries; finite element analysis; micro-CT