Fatigue resistance and structural characteristics of fiber posts: three-point bending test and SEM evaluation.
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.
Grandini
Simone
S
Department of Restorative Dentistry and Dental Materials, University of Siena, Piazza Attias 19, Livorno 57120, Italy.
Goracci
Cecilia
C
Monticelli
Francesca
F
Tay
Franklin R
FR
Ferrari
Marco
M
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
D003188:Composite Resins; D003764:Dental Materials; C009753:fiberglass; D012822:Silicon Dioxide