Cyclic Fatigue Endurance of Fiber Posts

Objective:

To compare the cyclic fatigue resistance of 5 fiber post systems.

Methods:

The 5 fiber post systems used in this in-vitro study were ICEPost, ParaPost Fiber, FibreKor, Flexi-Post Fiber, and Flexi-Flange Fiber. Extracted human anterior teeth were instrumented and posts were placed according to their manufacturer's instructions. ICEPost, ParaPost Fiber, and FibreKor used a 1.2 mm diameter reamer to prepare the root canal. Flexi-Post Fiber and Flexi-Flange Fiber used a 0.9 mm diameter reamer. Standardized core restorations were placed with the aid of a core form and the post manufacturer's recommended bonding agent. The samples (7 per group) were cured at 37ºC for 24 hours and then subjected to 2 million cycles of a pneumatic force of 110 Newtons delivered at an angle of 30º. Such testing approximates 5-10 years of function under the average masticatory force. Every 500,000 cycles the samples were visually inspected for signs of failure. Inspection was performed with the aid of 2.5x magnification on samples in both the loaded and un-loaded state. The modes of failure inspected for were root fracture, core fracture, loss of core-tooth adhesion without post fracture, and loss of core-tooth adhesion with core fracture. Results were compared using Kruskal-Wallis One Way Analysis of Variance on Ranks.

Results:

The only type of failure that occurred was loss of adhesion between the core and the coronal surface of the tooth without any fracture of the tooth. This occurred once in every group except for ParaPost Fiber in which 3 of the 7 samples lost core/dentin adhesion before 2 million cycles. The difference was not significant (P=0.46).

Conclusions:

Average masticatory forces did not lead to catastrophic failure of the uncrowned fiber post restorations, even the thinner diameter Flexi-Post Fiber and Flexi-Flange Fiber.