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Contraction stresses in dental composites adjacent to and at the bonded interface as measured by crack analysis

Paper ID Volume ID Publish Year Pages File Format Full-Text
1825 91 2011 7 PDF Available
Title
Contraction stresses in dental composites adjacent to and at the bonded interface as measured by crack analysis
Abstract

The objective of this study was to calculate stresses produced by polymerization contraction in regions surrounding a dental resin composite restoration. Initial cracks were made with a Vickers indenter at various distances from the edge of a cylindrical hole in a soda-lime glass disk. Indentation crack lengths were measured parallel to tangents to the hole edge. Resin composites (three brands) were placed in the hole and polymerized (two light irradiation protocols) at equal radiation exposures. The crack lengths were re-measured at 2 and 10 min after irradiation. Radial tensile stresses due to polymerization contraction at the location of the cracks (σcrack) were calculated from the incremental crack lengths and the fracture toughness Kc of the glass. Contraction stresses at the composite–glass bonded interface (σinterface) were calculated from σcrack on the basis of the simple mechanics of an internally pressurized thick-walled cylinder. The greater the distance or the shorter the time following polymerization, the smaller was σcrack. Distance, material, irradiation protocol and time significantly affected σcrack. Two-step irradiation resulted in a significant reduction in the magnitude of σinterface for all resin composites. The contraction stress in soda-lime glass propagated indentation cracks at various distances from the cavity, enabling calculation of the contraction stresses.

Keywords
Dental restorative material; Composite; Crack; Fracture toughness; Residual stress analysis
First Page Preview
Contraction stresses in dental composites adjacent to and at the bonded interface as measured by crack analysis
Publisher
Database: Elsevier - ScienceDirect
Journal: Acta Biomaterialia - Volume 7, Issue 1, January 2011, Pages 417–423
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering