Contraction stress related to degree of conversion and reaction kinetics

R. R. Braga, J. L. Ferracane

Research output: Contribution to journalArticlepeer-review

221 Scopus citations


Polymerization shrinkage of composites bonded to cavity preparations generates stress on the tooth/restoration interface. The purpose of this study was to verify the influence of degree of conversion and speed of polymerization reaction on contraction stress. We prepared experimental composites with different curing rates by varying the concentration of inhibitor (butylated hydroxytoluene). We verified the effect of degree of conversion by submitting one of the composites to different photo-activation times. Contraction stress was monitored for 10 minutes in a tensilometer. Fourier-transformed infrared spectrometry was used for assessment of the degree of conversion. Volumetric shrinkage was determined by means of a mercury dilatometer. Degree of conversion and volumetric shrinkage showed a non-linear relationship with energy density. Degree of conversion showed a pronounced influence on stress. Increased inhibitor concentration reduced curing rate and contraction stress in composites, without compromising the final degree of conversion.

Original languageEnglish (US)
Pages (from-to)114-118
Number of pages5
JournalJournal of dental research
Issue number2
StatePublished - Feb 2002


  • Composites
  • Contraction stress
  • Polymerization
  • Volumetric shrinkage

ASJC Scopus subject areas

  • Dentistry(all)


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