Do low-shrink composites reduce polymerization shrinkage effects?

D. Tantbirojn, C. S. Pfeifer, R. R. Braga, A. Versluis

Research output: Contribution to journalArticle

63 Scopus citations

Abstract

Progress in polymer science has led to continuous reduction of polymerization shrinkage, exemplified by a new generation of "low-shrink composites". The common inference that shrinkage stress effects will be reduced in teeth restored with such restoratives with lower shrinkage was tested in extracted human premolars. Mesio-occluso-distal slot-shaped cavities were cut and restored with a conventional (SupremePlus) or low-shrink (RefleXions, Premise, Kalore, and LS) composite (N = 5). We digitized the coronal surfaces before and 10 min after restoration to determine cuspal deflection from the buccal and lingual volume change/area. We also determined the main properties involved (total shrinkage, post-gel shrinkage, degree of conversion, and elastic modulus), as well as microleakage, to verify adequate bonding. It was shown that, due to shrinkage stresses, buccal and lingual surfaces pulled inward after restoration (9-14 microns). Only Kalore and LS resulted in significantly lower tooth deformation (ANOVA/Student-Newman-Keuls post hoc, p = 0.05). The other two low-shrink composites, despite having the lowest and highest total shrinkage values, did not cause significant differences in cuspal deflection. Deflection seemed most related to the combination of post-gel shrinkage and elastic modulus. Therefore, even for significantly lower total shrinkage values, shrinkage stress is not necessarily reduced.

Original languageEnglish (US)
Pages (from-to)596-601
Number of pages6
JournalJournal of dental research
Volume90
Issue number5
DOIs
StatePublished - May 1 2011

Keywords

  • cusp flexure
  • elastic modulus
  • polymerization shrinkage
  • tooth deformation

ASJC Scopus subject areas

  • Dentistry(all)

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