Finite Elements Analysis of Tooth—A Comparative Analysis of Multiple Failure Criteria

Abstract

Herein Finite elements analysis (FEA) study assesses the adequacy and accuracy of five failure criteria (Von Mises (VM), Tresca, maximum principal (S1), minimum principal (S3), and Hydrostatic pressure) for the study of tooth as a structure (made of enamel, dentin, and cement), along with its stress absorption–dissipation ability. Eighty-one 3D models of the second lower premolar (with intact and 1–8 mm reduced periodontium) were subjected to five orthodontic forces (intrusion, extrusion, tipping, rotation, and translation) of 0.5 N (approx. 50 gf) (in a total of 405 FEA simulations). Only the Tresca and VM criteria showed biomechanically correct stress display during the 0–8 mm periodontal breakdown simulation, while the other three showed various unusual biomechanical stress display. All five failure criteria displayed comparable quantitative stress results (with Tresca and VM producing the highest of all), showing the rotational and translational movements to produce the highest amount of stress, while intrusion and extrusion, the lowest. The tooth structure absorbed and dissipated most of the stress produced by the orthodontic loads (from a total of 0.5 N/50 gf only 0.125 N/12.5 gf reached PDL and 0.01 N/1 gf the pulp and NVB). The Tresca criterion seems to be more accurate than Von Mises for the study of tooth as structure.

Development of patient-specific finite element model for study of composite dental implants

“…Fourthly, the von-Mises stress is failure criteria used for mainly ductile materials and maximum principal stress is often used to study failure of hard tissues. However, as per our review of literature, several studies have used von-Mises stress values to understand the failure of composite materials [46] and also hard tissues such as the tooth [47]. As the focus of this work is on evaluation the use of composite materials for development of highly stable dental implants based on the realistic patient specific geometries and through comparison of the results with traditional implants, we have used von-Mises stress to understand possible failure.…”

Investigating the Ability of the Tooth and Surrounding Support Tissues to Absorb and Dissipate Orthodontic Loads during Periodontal Breakdown—Finite Elements Analysis

“…It must be emphasized that, from a biomechanical point-of-view, linear elasticity and isotropy assumptions are correctly employed only if the applied forces are up to 1 N, and the non-homogeneity of materials is considered and addressed using the Tresca criterion. There is no available data on the above issues for higher applied forces in dental tissues and no studies, except for our previous studies [2,3,5,6,9,10,16,48], acknowledged and addressed these issues.…”

“…In dental field, the numerical studies' results are regarded with care since they often contradicted clinical knowledge and displayed various results from one report to another . This issue was not addressed, except for our previous research [5,6,9,10,16,48].…”

“…FEA accuracy depends on the selection of proper failure criteria which are suitable for the analyzed material, anatomically correct models, and proper boundary conditions. Our previous studies [5,6,9,10,16,48] reported that since dental tissues are ductile-like materials (with a certain brittle flow mode) only a failure criterion specially designed for ductile materials is suitable (i.e., Von Mises overall stress and Tresca shear stress). Moreover, for validation, the quantitative results must be correlated with MHP, while qualitative results with acknowledged clinical data.…”

“…Moreover, for validation, the quantitative results must be correlated with MHP, while qualitative results with acknowledged clinical data. Despite many FEA studies 49,50] investigating PDL and bone-implant interface, none approached these vital issues, thereby supplying questionable and contradictory results [5,6,9,10,16,48]. Only one older numerical FEA study [30] was found to make a limited distinction between brittleness and ductileness for the root canal filling, but without further development.…”