Composite resin reinforced with pre-tensioned glass fibers. Influence of prestressing on flexural properties.
OBJECTIVE
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 x 2 mm x 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 24h 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 (alpha = .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.


CONCLUSIONS
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.
Schlichting
Luís Henrique
LH
Department of Operative Dentistry, Federal University of Santa Catarina, Florianópolis, SC, Brazil. schlichting71@gmail.com
de Andrada
Mauro Amaral Caldeira
MA
Vieira
Luiz Clóvis Cardoso
LC
de Oliveira Barra
Guilherme Mariz
GM
Magne
Pascal
P
D003188:Composite Resins / Q000737:chemistry*; D019245:Compressive Strength; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D055119:Elastic Modulus; D005898:Glass; D008422:Materials Testing; D018583:Pliability; D013314:Stress, Mechanical; D013718:Tensile Strength
D003188:Composite Resins; C009753:fiberglass