title: Flexural modulus, flexural strength, and stiffness of fiber-reinforced posts.
abstract: BACKGROUND
  The radiopacity degree of posts is not enough for adequate visualization during radiographic analyses. Glass fiber post with stainless steel reinforcement has been fabricated in an attempt to overcome this limitation.
  
  
  OBJECTIVE
  This study was designed to determine the influence of this metal reinforcement on the post mechanical properties.
  
  
  METHODS
  This study evaluated flexural modulus (E), flexural strength (sigma), and stiffness (S) of five different fiber post systems (n = 5): RfX (Reforpost Glass Fiber RX; Angelus, Londrina, PR, Brazil); RG (Reforpost Glass Fiber, Angelus); RC (Reforpost Carbon Fiber, Angelus); FP (Fibrekor Post; Jeneric Pentron Inc., Wallingford, CT, USA); and CP (C-Post; Bisco Dental Products, Schaumburg, IL, USA), testing the hypothesis that the insertion of a metal reinforcement (RfX) jeopardizes the mechanical properties of a glass fiber post. Posts were loaded in three-point bending using a testing machine with a crosshead speed of 0.5 mm/min.
  
  
  RESULTS
  The results were statistically analyzed using one-way ANOVA and Tukey's multiple range tests (a = 0.05). Mean and standard deviation values of E (GPa), s (MPa), and S (N/mm) were as follows: RfX: 10.8 +/- 1.6, 598.0 +/- 52.0, 132.0 +/- 21.9; RG: 10.6 +/- 1.0, 562.0 +/- 24.9, 137.8 +/- 5.5; RC: 15.9 +/- 2.4, 680.5 +/- 34.8, 190.9 +/- 12.9; FP: 10.9 +/- 1.4, 586.8 +/- 21.9, 122.4 +/- 17.3; CP: 6.3 +/- 1.7, 678.1 +/- 54.2, 246.0 +/- 41.7. Carbon fiber posts showed the highest mean s values (P < 0.05). In addition, RC showed the highest mean E value and CP showed the highest mean S value (P < 0.05).
  
  
  CONCLUSIONS
  The hypothesis was rejected since the metal reinforcement in the glass fiber post (RfX) does not decrease the mechanical property values. Posts reinforced with carbon fibers have a higher flexural strength than glass fiber posts, although all posts showed similar mechanical property values with dentin.
authors.affiliation: Department of Operative Dentistry and Dental Materials, School of Dentistry, Federal University of Uberlândia, Uberlândia, MG, Brazil.
authors.forename: Veridiana R
authors.initials: VR
authors.lastname: Novais
authors.forename: Paulo S
authors.initials: PS
authors.lastname: Quagliatto
authors.forename: Alvaro Della
authors.initials: AD
authors.lastname: Bona
authors.forename: Lourenco
authors.initials: L
authors.lastname: Correr-Sobrinho
authors.forename: Carlos J
authors.initials: CJ
authors.lastname: Soares
mesh_terms: D000704:Analysis of Variance; D002244:Carbon; D000077482:Carbon Fiber; D003722:Dental Alloys; D003764:Dental Materials; D003799:Dental Stress Analysis; D055119:Elastic Modulus; D004548:Elasticity; D005898:Glass; D008422:Materials Testing; D018583:Pliability; D011176:Post and Core Technique / Q000295:instrumentation*; D012390:Root Canal Therapy / Q000295:instrumentation*; D013193:Stainless Steel; D018709:Statistics, Nonparametric; D013314:Stress, Mechanical
chemical_list: D000077482:Carbon Fiber; D003722:Dental Alloys; D003764:Dental Materials; C009753:fiberglass; D013193:Stainless Steel; D002244:Carbon