title: An evaluation of the stresses generated in a bonded orthodontic attachment by three different load cases using the Finite Element Method of stress analysis.
abstract: The objective of the investigation was to develop a clinically valid three-dimensional computer model of the orthodontic bracket-cement-tooth continuum, and determine the magnitude and distribution of stresses generated by three different load cases. A three-dimensional finite element model of the bracket-cement-tooth system was constructed consisting of 15,324 nodes and 2,971 finite elements. The stresses induced in the bracket-tooth interface by a masticatory load, a peel force and a twisting couple were recorded. The maximum principal stresses resulting from occlusal and 'twisting' forces are distributed toward the lute periphery. Peel forces, applied to the bracket tie wing, are concentrated beneath the bracket stem. Twisting forces result in the highest enamel stresses. The quality of orthodontic attachment can be explained by the magnitude and distribution of major principal stresses within the cement and impregnated bracket base. Shear and shear/peel forces are most likely to induce crack propagation within the adhesive layer. However, when a twisting action is used to remove orthodontic brackets, enamel failure is most likely. A clearer insight into the complexity of the bracket-cement-tooth system has been provided by numerical and finite element investigations. Further investigations, evaluating the influence of bracket base designs and orthodontic cement physical and geometric properties are indicated. Refereed Scientific Paper
authors.affiliation: Department of Dental Health and Development, University of Wales College Of Medicine, Dental School, Heath Park, Cardiff CF4 4XY, UK.
authors.forename: J
authors.initials: J
authors.lastname: Knox
authors.forename: M L
authors.initials: ML
authors.lastname: Jones
authors.forename: P
authors.initials: P
authors.lastname: Hubsch
authors.forename: J
authors.initials: J
authors.lastname: Middleton
authors.forename: B
authors.initials: B
authors.lastname: Kralj
mesh_terms: D019245:Compressive Strength; D003198:Computer Simulation; D001840:Dental Bonding; D003738:Dental Cements; D017005:Dental Debonding / Q000379:methods; D003743:Dental Enamel; D003799:Dental Stress Analysis / Q000379:methods*; D004548:Elasticity; D019544:Equipment Failure Analysis; D020342:Finite Element Analysis; D006801:Humans; D008409:Mastication; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D013193:Stainless Steel; D013718:Tensile Strength; D019415:Torque
chemical_list: D003738:Dental Cements; D013193:Stainless Steel