Mechanical properties and micro-morphology of fiber posts

Objectives. To evaluate flexural properties of different fiber posts systems and to morphologically characterize their micro-structure. Methods. Six types of translucent fiber posts were selected: RelyX Post (3M ESPE), Para-Post Taper Lux (Colthene-Whaledent), GC Fiber Post (GC), LuxaPost (DMG), FRC Postec Plus (Ivoclar-Vivadent), D. T. Light-Post (RTD). For each post system and size, ten specimens were subjected to a three-points bending test. Maximum fracture load, flexural strength and flexural modulus were determined using a universal loading device (5848 MicroTester (R), Instron). Besides, for each system, three intact posts of similar dimensions were processed for scanning electron microscopy to morphologically characterize the micro-structure. The following structural characteristics were analyzed: fibers/matrix ratio, density of fibers, diameter of fibers and distribution of fibers. Data were statistically analyzed with ANOVA. Results. Type and diameter of posts were found to significantly affect the fracture load, flexural strength and flexural modulus (p < 0.05). Regarding maximum fracture load, it was found to increase with post diameter, in each post system (p < 0.001). Regarding flexural strength and flexural modulus, the highest values were recorded for posts with the smallest diameter (p < 0.001). Finally, structural characteristics significantly varied among the post systems tested. However, any correlation has been found between flexural strength and structural characteristics. Significance. Flexural strength appeared not to be correlated to structural characteristics of fiber posts, but it may rather be affected by mechanical properties of the resin matrix and the interfacial adhesion between fibers and resin matrix. (C) 2013 Published by Elsevier Ltd on behalf of Academy of Dental Materials. All rights reserved.