title: Fatigue resistance and structural characteristics of fiber posts: three-point bending test and SEM evaluation.
abstract: OBJECTIVE
  The aim of the present study was to assess the fatigue resistance of different types of fiber posts, and to observe their ultrastructure through scanning electron microscopy (SEM) before and after undergoing the fatigue test.
  
  
  METHODS
  Eight types of fiber posts were selected for this study. Easypost (Group 1), Para Post Fiber White (Group 2), FibreKor (Group 3), Ghimas White (Group 4), DT Light-Post radiopaque (Group 5), FRC Postec (Group 6), Luscent Anchors (Group 7), Snowpost (Group 8). Ten out of fifteen posts in each group were used for the fatigue test, and the other five were processed for SEM. A three-point bending machine, loading at an angle of 90 degrees and a frequency of 3 Hz was employed for fatigue testing. The test was carried out until two million cycles were completed or until fracturing of the post. SEM evaluation was performed using a three-step scale method to assess the fiber/resin ratio and fiber dimension.
  
  
  RESULTS
  The fatigue test showed statistically significant differences among the different posts. Groups 5 and 6 performed better than all the other groups, withstanding practically all the stipulated number of load cycles. All the other posts fractured before the end of the test. SEM observations of the surface integrity of the fiber posts showed that Groups 4-6 obtained better scores for both longitudinal sections and cross-sections.
  
  
  CONCLUSIONS
  There was a large variation in the response of different kinds of fiber posts a fatigue resistance test. The absence of correlation between results of fatigue testing and parameters of structural integrity suggests that the latter mostly reflect random variations in the fiber post manufacturing process.
authors.affiliation: Department of Restorative Dentistry and Dental Materials, University of Siena, Piazza Attias 19, Livorno 57120, Italy.
authors.forename: Simone
authors.initials: S
authors.lastname: Grandini
authors.forename: Cecilia
authors.initials: C
authors.lastname: Goracci
authors.forename: Francesca
authors.initials: F
authors.lastname: Monticelli
authors.forename: Franklin R
authors.initials: FR
authors.lastname: Tay
authors.forename: Marco
authors.initials: M
authors.lastname: Ferrari
mesh_terms: D003188:Composite Resins / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D019232:Dental Restoration Failure; D005898:Glass / Q000737:chemistry; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D018583:Pliability; D011176:Post and Core Technique / Q000295:instrumentation*; D012822:Silicon Dioxide / Q000737:chemistry; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D003188:Composite Resins; D003764:Dental Materials; C009753:fiberglass; D012822:Silicon Dioxide