title: The flexural properties of endodontic post materials.
abstract: OBJECTIVE
  To measure the flexural strengths and moduli of endodontic post materials and to assess the effect on the calculated flexural properties of varying the diameter/length (D/L) ratio of three-point bend test samples.
  
  
  METHODS
  Three-point bend testing of samples of 2mm diameter metal and fiber-reinforced composite (FRC) rods was carried out and the mechanical properties calculated at support widths of 16 mm, 32 mm and 64 mm. Weibull analysis was performed on the strength data.
  
  
  RESULTS
  The flexural strengths of all the FRC post materials exceeded the yield strengths of the gold and stainless steel samples; the flexural strengths of two FRC materials were comparable with the yield strength of titanium. Stainless steel recorded the highest flexural modulus while the titanium and the two carbon fiber materials exhibited similar values just exceeding that of gold. The remaining glass fiber materials were of lower modulus within the range of 41-57 GPa. Weibull modulus values for the FRC materials ranged from 16.77 to 30.09. Decreasing the L/D ratio produced a marked decrease in flexural modulus for all materials.
  
  
  CONCLUSIONS
  The flexural strengths of FRC endodontic post materials as new generally exceed the yield strengths of metals from which endodontic posts are made. The high Weibull modulus values suggest good clinical reliability of FRC posts. The flexural modulus values of the tested posts were from 2-6 times (FRC) to 4-10 times (metal) that of dentin. Valid measurement of flexural properties of endodontic post materials requires that test samples have appropriate L/D ratios.
authors.affiliation: University of Birmingham, School of Dentistry, Birmingham, West Midlands B4 6NN, UK. d.a.stewardson@bham.ac.uk
authors.forename: Dominic A
authors.initials: DA
authors.lastname: Stewardson
authors.forename: Adrian C
authors.initials: AC
authors.lastname: Shortall
authors.forename: Peter M
authors.initials: PM
authors.lastname: Marquis
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Lumley
mesh_terms: D002244:Carbon; D000077482:Carbon Fiber; D003188:Composite Resins; D003722:Dental Alloys; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis; D055119:Elastic Modulus; D004708:Endodontics / Q000295:instrumentation; D005898:Glass; D006047:Gold Alloys; D008422:Materials Testing; D018583:Pliability; D011176:Post and Core Technique; D013193:Stainless Steel; D016019:Survival Analysis; D014025:Titanium
chemical_list: D000077482:Carbon Fiber; D003188:Composite Resins; D003722:Dental Alloys; D006047:Gold Alloys; C009753:fiberglass; D013193:Stainless Steel; D002244:Carbon; D014025:Titanium