Composite resin reinforced with pre-tensioned glass fibers. Influence of prestressing on flexural properties

• Published in: Dental materials Vol. 26; no. 2; pp. 118 - 125
• Main Authors: Schlichting, Luís Henrique, de Andrada, Mauro Amaral Caldeira, Vieira, Luiz Clóvis Cardoso, de Oliveira Barra, Guilherme Mariz, Magne, Pascal
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.02.2010
• Subjects: Advanced Basic Science; Composite resin; Composite Resins - chemistry; Compressive Strength; Dental Restoration Failure; Dental Stress Analysis; Dentistry; Elastic Modulus; Fiber-reinforced composite; Flexural properties; Flexural strength; Glass; Glass fibers; Initial failure; Materials Testing; Pliability; Prestressed; Prestressing; Pull-out; Stress, Mechanical; Tensile Strength; Initial failure; Prestressed; Flexural strength; Fiber-reinforced composite; Pull-out; Composite resin; Prestressing; Glass fibers; Flexural properties
• ISSN: 0109-5641; 1879-0097
• DOI: 10.1016/j.dental.2009.09.004

Abstract Objectives This investigation evaluated the flexural properties of two composite resins, and the influence of unidirectional glass fiber reinforcements, with and without pre-tensioning. Methods Two composite resins (Q: Quixfil and A: Adoro) were used to fabricate 2 mm × 2 mm × 25 mm beams ( N = 10), reinforced with two fiber bundles along the long axis of the beam and pre-tensioned under a load equivalent to 73.5% of its tensile strength (groups QPF and APF). In two other experimental groups, the bundles were similarly positioned but without pre-tension (groups QF and AF). Two more groups were included without fiber reinforcement (control groups Q and A). After 24 h storage, specimens were subjected to a three-point flexural bending test to establish the flexural module, the deflection at initial failure and the flexural strength. Data were analyzed using a two-way analysis of variance (composite resin system and fiber reinforcement type) and the Tukey HSD post hoc tests ( α = .05). Results The results showed that prestressing increased the flexural module of Adoro specimens ( p < .001) but not Quixfil ( p = .17). Prestressed beams reached greater deflection at initial failure than those conventionally reinforced ( p < .001), namely .85–1.35 mm for Adoro and .66–.90 mm for Quixfil. Prestressing also significantly increased the flexural strength of beams ( p < .001) in both Adoro and Quixfil groups, from 443.46 to 569.15 MPa and from 425.47 to 568.00 MPa, respectively. Significance Pre-tensioning of unidirectional glass fibers increased both deflection until initial failure and flexural strength of Quixfil and Adoro composite resins, however, with limited effects on the flexural modulus.