Work of fracture of a composite resin: Fracture-toughening mechanisms

The aim of this work was to investigate those mechanical parameters able to describe the fracture behavior of dental composite resins. A commercially available fine‐particle micro‐hybrid resin composite was used. Classical parameters as Young's modulus, strength distribution, and critical stres...

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Bibliographic Details
Published in:Journal of Biomedical Materials Research Part B 2009-06, Vol.89A (3), p.751-758
Main Authors: Baudin, Carmen, Osorio, Raquel, Toledano, Manuel, de Aza, Salvador
Format: Article
Language:English
Subjects:
composite resin
Composite Resins - chemistry
Elastic Modulus
Materials Testing
Microscopy, Electron, Scanning
strength
Tensile Strength
toughening
work of fracture
Young's modulus
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Summary:The aim of this work was to investigate those mechanical parameters able to describe the fracture behavior of dental composite resins. A commercially available fine‐particle micro‐hybrid resin composite was used. Classical parameters as Young's modulus, strength distribution, and critical stress intensity factor were considered. Strength values were determined using the diametrical compression of discs test and for the critical stress intensity factor both unstable and controlled fracture tests were used. Controlled fracture tests allowed determining the work of fracture. Microstructure was studied by optical and field emission scanning electron microscopy. The obtained properties have been Young's modulus, 17.7 ± 0.6 GPa; Weibull modulus, m = 14 (upper and lower limits for 90% confidence: 17 and 10); characteristic strength 51 MPa (upper and lower limits for 90% confidence: 53 and 49 MPa); critical stress intensity factor in mode I, KIC = 1.3 ± 0.1 and work of fracture, γwof = 8–9 J/m2. Pores and bubbles formed during the packing of the composite were identified as critical defects in the tested specimens. Crack deflection and branching have been identified as toughening mechanisms. Classical mechanical parameters (Young's modulus, hardness…) are not able to efficiently predict the major clinical failure mode of composite resins by fatigue. Work of fracture analysis, which is dependant on microstructural parameters such as particle size and shape, have to be included when testing mechanical properties of dental composite resins in future research studies. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
ISSN:1549-3296
1552-4965
1552-4981
DOI:10.1002/jbm.a.32016