title: Influence of surface area and geometry of specimens on bond strength in a microtensile test: an analysis by the three-dimensional finite element method.
abstract: OBJECTIVE
  This study employed three-dimensional (3D) finite element analysis to investigate the stress distribution patterns in a microtensile test with the goal of evaluating the effects of the bond surface area and geometry on bond strength.
  
  
  METHODS
  Finite element models of six specimens were generated: three stick models and three hourglass models. All models simulated the bond strength between dentin and ceramic. The mechanical properties of the materials-the modulus of elasticity and Poisson's coefficient-were defined according to a literature review. The base of each specimen was considered inserted (constrained area) and possessed nodes with displacements restricted in all directions. A traction load, which was calculated to generate a uniformly distributed stress of 20 N/mm(2) at the bond interface, was applied to the top of the specimen. The distribution pattern of the generated stress was qualitatively and quantitatively measured based on color scales ranging from blue to red, according to the von Mises equivalent stress.
  
  
  RESULTS
  Specimens with similar shapes demonstrated similar stress distributions. Ceramic specimens had a higher stress value (30.35 MPa) compared to specimens consisting of resinous cement (23.59 MPa) and dentin (19.77 MPa). At the bond interface, the specimens with square sections demonstrated stress values ranging from 22.00 to 24.20 MPa. For the circular section, the stress values ranged from 23.40 to 27.00 MPa.
  
  
  CONCLUSIONS
  The maximum stress values determined for the circular and square sections were similar among specimens with the same interface area. At the bond interface, the highest stress values were observed in hourglass-shaped specimens.
authors.affiliation: Department of Dentistry, UNIMONTES, Minas Gerais, Brazil. ferreira_rc@hotmail.com
authors.forename: Raquel C
authors.initials: RC
authors.lastname: Ferreira
authors.forename: Juliana
authors.initials: J
authors.lastname: Caldas
authors.forename: Gustavo A
authors.initials: GA
authors.lastname: Paula
authors.forename: Rodrigo C
authors.initials: RC
authors.lastname: Albuquerque
authors.forename: Carla M
authors.initials: CM
authors.lastname: Almeida
authors.forename: Walison Arthuso
authors.initials: WA
authors.lastname: Vasconcellos
authors.forename: Rodrigo Barreto
authors.initials: RB
authors.lastname: Caldas
mesh_terms: D001840:Dental Bonding; D003776:Dental Porcelain / Q000737:chemistry*; D003799:Dental Stress Analysis; D003804:Dentin / Q000648:ultrastructure*; D017220:Dentin-Bonding Agents / Q000737:chemistry; D055119:Elastic Modulus; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D019279:Resin Cements / Q000737:chemistry; D013499:Surface Properties; D013718:Tensile Strength
chemical_list: D017220:Dentin-Bonding Agents; D019279:Resin Cements; D003776:Dental Porcelain