Shrinkage of dental composite in simulated cavity measured with digital image correlation

Jianying Li, Preetanjali Thakur, Alex Fok

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Polymerization shrinkage of dental resin composites can lead to restoration debonding or cracked tooth tissues in composite-restored teeth. In order to understand where and how shrinkage strain and stress develop in such restored teeth, Digital Image Correlation (DIC) was used to provide a comprehensive view of the displacement and strain distributions within model restorations that had undergone polymerization shrinkage. Specimens with model cavities were made of cylindrical glass rods with both diameter and length being 10 mm. The dimensions of the mesial-occlusal-distal (MOD) cavity prepared in each specimen measured 3 mm and 2 mm in width and depth, respectively. After filling the cavity with resin composite, the surface under observation was sprayed with first a thin layer of white paint and then fine black charcoal powder to create high-contrast speckles. Pictures of that surface were then taken before curing and 5 min after. Finally, the two pictures were correlated using DIC software to calculate the displacement and strain distributions. The resin composite shrunk vertically towards the bottom of the cavity, with the top center portion of the restoration having the largest downward displacement. At the same time, it shrunk horizontally towards its vertical midline. Shrinkage of the composite stretched the material in the vicinity of the "tooth-restoration" interface, resulting in cuspal deflections and high tensile strains around the restoration. Material close to the cavity walls or floor had direct strains mostly in the directions perpendicular to the interfaces. Summation of the two direct strain components showed a relatively uniform distribution around the restoration and its magnitude equaled approximately to the volumetric shrinkage strain of the material.

Original languageEnglish (US)
Article numbere51191
JournalJournal of Visualized Experiments
Issue number89
StatePublished - Jul 23 2014


  • Computer-assisted
  • Dental composite restoration
  • Digital image correlation
  • Full-field strain measurement
  • Image processing
  • Interfacial debonding
  • Issue 89
  • Medicine
  • Polymer matrix composites
  • Polymerization shrinkage
  • Testing of materials (composite materials)


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