title: Magnitude and distribution of stresses in composite resin and sound dentine interface with mechanical retentions.
abstract: BACKGROUND
  Adhesive systems are constantly subjected to mechanical and chemical stresses that negatively impact the integrity and durability of the dentine-adhesive interface. Despite the lack of evidence to support or reject the clinical indication for mechanical retention, the potential further contribution of these preparations to the behavior of the composite resin-sound dentine bond has been rarely addressed. The authors evaluated by finite element analysis the effect of mechanical retention on the magnitude and distribution of stresses in a composite resin-sound dentin bonding interface when subjected to tensile and shear forces.
  
  
  METHODS
  A three-dimensional model was created based on three cylindrical volumes representing the sound dentin, adhesive system, and composite resin. From this main model, two models were designed to simulate dentine bonding: 1) a model with no mechanical retention, which considered flat adhesion; and 2) a model with retention, which considered four hemispherical holes on the dentine surface. Both groups were subjected to linear static analysis under tensile and shear loading of 200N.
  
  
  RESULTS
  At the model with retentions' bonding interface under tensile and shear loading, a concentration of Von Mises equivalent stress was observed within the retentions, with a reduction of those stresses on the bonding boundary surface.
  
  
  CONCLUSIONS
  Additional mechanical retention increases the tensile strength of the sound dentin-composite resin bonding interface, promoting a decrease in the magnitude of the stresses and their redistribution under tensile and shear loading. Key words:Adhesion, composite resins, dentine, finite element analysis.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, Universidad Finis Terrae, Av. Pedro de Valdivia 1509, 7501015 Santiago, Chile ; PhD, Student of Doctoral Program in Medical Sciences, Medicine School, Manuel Montt 112, 4781176 Universidad de La Frontera, Temuco, Chile.
authors.forename: Gisaku
authors.initials: G
authors.lastname: Kuramochi
authors.affiliation: CIMOFIR, Research Centre, Dental School, Universidad de La Frontera, Manuel Montt 112, 4781176 Temuco, Chile ; Dental Materials and Prosthodontics Department, Ribeirão Preto Dental School, University of São Paulo, Av. do Café w/n, 14040904 Ribeirão Preto, SP, Brazil.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Borie
authors.affiliation: Dental Materials and Prosthodontics Department, Ribeirão Preto Dental School, University of São Paulo, Av. do Café w/n, 14040904 Ribeirão Preto, SP, Brazil.
authors.forename: Iara-Augusta
authors.initials: IA
authors.lastname: Orsi
authors.affiliation: Department of Basic Sciences, Faculty of Medicine, Universidad de La Frontera, Av. Francisco Salazar 01145, 4811230 Temuco, Chile.
authors.forename: Mariano
authors.initials: M
authors.lastname: Del Sol