Two-dimensional FEA of dowels of different compositions and external surface configurations.
OBJECTIVE
The degree of stress generated in the endodontically treated and restored tooth can be influenced by the composition and configuration of the dowels used for the restoration. Using two-dimensional (2D) finite element analysis (FEA), this study tested the hypothesis that the characterization of the stress distribution can be influenced by which evaluation method is employed: protrusion loading and 4-point flexural strength test or varying the type of material (carbon and glass fiber) or the external configuration of the dowel (smooth and serrated).


METHODS
For simulation of the protrusion load test, models were generated with Mechanical-AutoCAD V6 software from an image of an anatomical plate, one maxillary central incisor, and two dowels and exported to Ansys 9.0. The bone region model was fixed, and a tangential load of 1 N with a 135 degrees inclination to the tooth longitudinal axis was applied at the level of the palatal surface of the crown. In the simulation of a 4-point flexural strength test, a 1 N perpendicular load was applied in two points to the dowel. The dental materials and structures were considered elastic, isotropic, homogeneous, and linear, with the exception of the dowel, which was assumed to exhibit orthotropic behavior. Mechanical properties were defined based on a review of the literature, and the model was meshed with an eight node tetrahedral element.


RESULTS
The stress results from both tests were analyzed according to von Mises criteria and principal stresses (Sx). Data from the 4-point flexural strength test simulation showed that, for the serrated dowels, a higher stress concentration was found; however, no difference in the occlusal load for material or dowel configuration was found.


CONCLUSIONS
These results suggest that although the external configuration of the dowel influences direct loading, when the dowel is integrated to the tooth and setting material, the influence on biomechanical behavior disappears.
Soares
Carlos José
CJ
Biomechanical Group, Dentistry and Dental Materials, School of Dentistry, Federal University of Uberlandia, Uberlandia, Minas Gerais, Brazil. carlosjsoares@umuarama.ufu.br
Castro
Carolina Guimaraes
CG
Santos Filho
Paulo César Freitas
PC
Soares
Paulo Vinícius
PV
Magalhaes
Denildo
D
Martins
Luis Roberto Marcondes
LR
D002244:Carbon; D000077482:Carbon Fiber; D003188:Composite Resins; D017076:Computer-Aided Design; D003776:Dental Porcelain; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis / Q000379:methods*; D004548:Elasticity; D020342:Finite Element Analysis; D005898:Glass; D006801:Humans; D007180:Incisor / Q000502:physiology; D008437:Maxilla; D018583:Pliability; D011176:Post and Core Technique; D033081:Shear Strength; D013314:Stress, Mechanical; D013499:Surface Properties
D000077482:Carbon Fiber; D003188:Composite Resins; C009753:fiberglass; D003776:Dental Porcelain; D002244:Carbon