Does layering minimize shrinkage stresses in composite restorations?

J Dent Res. 2003 Dec;82(12):967-71. doi: 10.1177/154405910308201206.

Abstract

Polymerization shrinkage of resin composites may impair restoration longevity. It is hypothesized that layering, rather than bulk, techniques result in less stress in the tooth-restoration complex. The aim of this study was to compare shrinkage stresses for different restorative techniques used for cusp-replacing restorations with direct resin composite. In a 3-D FE model, the dynamic process of shrinkage during polymerization was simulated. Time-dependent parameters (shrinkage, apparent viscosity, Young's modulus, Poisson ratio, and resulting creep), which change during the polymerization process, were implemented. Six different restorative procedures were simulated: a chemically cured bulk technique, a light-cured bulk technique, and 4 light-cured layering techniques. When polymerization shrinkage is considered, a chemically cured composite shows the least resulting stress. The differences seen among various layering build-up techniques were smaller than expected. The results indicate that the stress-bearing locations are the interface and the cervical part of the remaining cusp.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chemical Phenomena
  • Chemistry, Physical
  • Composite Resins / chemistry*
  • Computer Simulation
  • Dental Cavity Preparation
  • Dental Enamel / physiology
  • Dental Restoration, Permanent / methods*
  • Elasticity
  • Finite Element Analysis
  • Humans
  • Materials Testing
  • Models, Biological
  • Polymers / chemistry
  • Stress, Mechanical
  • Surface Properties
  • Tooth Cervix / physiology
  • Viscosity

Substances

  • Composite Resins
  • Polymers