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Crack propagation in the surrounding structure caused by composite polymerization stress: local and material-related effects

Grant number: 09/16267-0
Support Opportunities:Scholarships abroad - Research
Effective date (Start): August 16, 2010
Effective date (End): August 15, 2011
Field of knowledge:Health Sciences - Dentistry - Dental Materials
Principal Investigator:Roberto Ruggiero Braga
Grantee:Roberto Ruggiero Braga
Host Investigator: Michael V. Swain
Host Institution: Faculdade de Odontologia (FO). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Research place: University of Sydney, Australia  


The integrity of the bonded interface is a key feature in the clinical performance of composite restorations. The stress generated due to composite polymerization shrinkage may lead to interfacial gap formation and residual stress build-up on the tooth structure, increasing the risk of failure over time. This research proposal aims at investigating the influence of cavity dimensions and thickness of the surrounding structure on the magnitude of residual stress at the margins of composite restorations. Stress will be quantified based on crack growth observed in indentation cracks produced at the margins of cylindrical restorations using as substrate a ceramic material with elastic modulus and fracture toughness similar to the enamel. A second series of experiments will assess polymerization stress for a series of commercial composites to verify how values correlate with their polymerization shrinkage, measured using the strain gage method, and elastic modulus, determined by nanoindentation. Finally, the same series of materials will be tested for polymerization stress using a mechanical test assembly and the results will be compared to those obtained using the crack propagation method. For each section of this project, data will be statistically analyzed using ANOVA/Tukey test (±=0.05). Also, regression analyses will be performed for the second and third part of the study. (AU)

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Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
BRAGA, ROBERTO R.; YAMAMOTO, TAKATSUGU; TYLER, KENNETH; BOARO, LETICIA C.; FERRACANE, JACK L.; SWAIN, MICHAEL V.. A comparative study between crack analysis and a mechanical test for assessing the polymerization stress of restorative composites. Dental Materials, v. 28, n. 6, p. 632-641, . (09/16267-0)
BRAGA, ROBERTO R.; KOPLIN, CHRISTOF; YAMAMOTO, TAKATSUGU; TYLER, KEN; FERRACANE, JACK L.; SWAIN, MICHAEL V.. Composite polymerization stress as a function of specimen configuration assessed by crack analysis and finite element analysis. Dental Materials, v. 29, n. 10, p. 1026-1033, . (09/16267-0)

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