Effect of fiber position and orientation on fracture load of fiber-reinforced composite

Objectives. The aim of this study was to determine the effect of fiber position and orientation on the initial and final fracture loads of fiber-reinforced composite (FRC). Methods. Test specimens made of two indirect particulate composites (BelleGlass HP, Kerr, Orange, CA) or (Targis, Ivoclar Vivadent, Amherst, NY) were reinforced with ultra high molecular weight polyethylene (UHMWPE) fiber ribbon (Connect, Kerr, Orange, CA), woven E-glass fibers (Vectris Frame, Ivoclar Vivadent, Amherst, NY) or unidirectional R-glass fibers (Vectris Pontic, Ivoclar Vivadent, Amherst, NY). Fibers were placed with different positions, orientations or geometry into the rhombic test specimens (2 x 2 x 25 MM). Control specimens did not contain fiber reinforcement. The test specimens (n = 6) were stored in distilled water for 1 week at 37 degreesC before testing in a three-point loading test to determine the initial and final fracture load values. Results. Initial failure Loads varied from 22.6 to 172.1 N. The lowest value resulted from one UHMWPE reinforcement fiber located in diagonal, orientation and the highest from two unidirectional glass fiber reinforcements, one located on the tension side and the second on the compression side. Significance. Position and fiber orientation influenced the load to initial and final failure, and specimen deflection. Tension side reinforcement was most effective in increasing the load to initial and final fracture. (C) 2004 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.