Finite element analysis of stresses in endodontically treated, dowel-restored teeth.
BACKGROUND
Endodontically-treated, dowel-restored teeth may experience fracture, but investigations of variables related to fracture are often inconclusive and occasionally contradictory.


OBJECTIVE
The finite element method was used to analyze the stresses in dowel-restored teeth. The variables studied were material, shape, bonding, modulus of elasticity, diameter, and length of the dowel.


METHODS
The model of the dowel-restored tooth involved dentin, ligament, cortical and trabecular bone, gingiva, and gutta-percha. The dowels were made of glass fiber, titanium, or zirconia and modeled as an approximation of the brands ParaPost Fiber White, ParaPost XH, and Cerapost, respectively. The dowel was cemented with zinc-phosphate cement or with bonded or nonbonded resin luting agents, and an approximation of the material properties of these 2 materials were used in the modeling. The restoration included a composite resin core and a gold crown. Other variables included taper versus parallel-sided posts, modulus of elasticity, diameter, and length of post. The model was axisymmetrical in 3 dimensions. A load of 100 N was applied to the crown at an angle of 45 degrees, and tensile, shear, and von Mises stresses were calculated.


RESULTS
The generated stresses decreased with respect to the dowel material in the following order: glass fiber, titanium, and zirconia. Stresses were in general higher with tapered than with parallel-sided dowels. Stresses were reduced by bonding and with an increasing modulus of elasticity, increasing diameter, and increasing length of the dowel.


CONCLUSIONS
Within the limitations of this study, it was found that all investigated dowel-related factors influenced the stress field generated in dowel-restored teeth.
Asmussen
Erik
E
Department of Dental Materials, Faculty of Health Sciences, School of Dentistry, University of Copenhagen, 20 Nørre Alle, DK-2200 Copenhagen N, Denmark. ea@odont.ku.dk
Peutzfeldt
Anne
A
Sahafi
Alireza
A
D000539:Alveolar Process / Q000503:physiopathology; D003188:Composite Resins / Q000737:chemistry; D003738:Dental Cements / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry; D017267:Dental Prosthesis Design; D003804:Dentin / Q000503:physiopathology; D004548:Elasticity; D020342:Finite Element Analysis; D005881:Gingiva / Q000503:physiopathology; D005898:Glass / Q000737:chemistry; D006047:Gold Alloys / Q000737:chemistry; D006171:Gutta-Percha / Q000737:chemistry; D006801:Humans; D021621:Imaging, Three-Dimensional; D010513:Periodontal Ligament / Q000503:physiopathology; D011176:Post and Core Technique; D012390:Root Canal Therapy; D013314:Stress, Mechanical; D013499:Surface Properties; D013718:Tensile Strength; D014025:Titanium / Q000737:chemistry; D019553:Tooth, Nonvital / Q000503:physiopathology; D015036:Zinc Phosphate Cement / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry
D003188:Composite Resins; D003738:Dental Cements; D003764:Dental Materials; D006047:Gold Alloys; C009753:fiberglass; D015036:Zinc Phosphate Cement; D006171:Gutta-Percha; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide