An evaluation, using a three-point bending test, of the fatigue resistance of certain fiber posts

Aim

The aim of the present study was to assess the fatigue resistance of several types of fiber posts by using a 3-point bending test and to observe their ultrastructure through Scanning Electron Microscopy (SEM) before and after undergoing the fatigue test.

Methods

Six types of fiber posts were selected for this study, EasyPost (Group 1), ParaPost Fiber White (Group 2), FibreKor (Group 3), D. T. Light-Post (Group 4), Lucent Anchors (Group 5), and SnowPost (Group 6). Each group contained 15 posts; 5 posts in each group were observed with SEM, the other ten were used for the fatigue test. 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 2 million cycles were completed or until the post fractured. After the fatigue test had been completed, further evaluations were carried out with SEM on the fractured posts and the posts that went to the end of the fatigue cycles.

Results

The fatigue test showed statistically significant differences among the different posts. Group 4 (D.T. Light-Post; RTD, St Egreve, France)) performed better than all the other groups, withstanding the entire load cycles without fractures.

Conclusions

There are great variations in the responses of different kinds of fiber posts to a fatigue resistance test. Structural integrity is already very different even before undergoing the fatigue test, and this proves that many of the performance differences noted are due to the differences in the manufacturing processes of the fiber posts.