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Visible light-cured composite resins: polymerization contraction, contraction pattern and hygroscopic expansion
Scandinavian Journal of Dental Research
|August 1, 1982
Summary
Polymerization contraction in dental fillings varied, with some materials closing marginal gaps due to water absorption. Contraction increased with depth, differing between light-cured and chemically-cured resins.
Area of Science:
- Dental Materials Science
- Polymer Chemistry
- Biomaterials Engineering
Background:
- Dental restorative materials undergo polymerization, leading to volumetric changes.
- Understanding polymerization contraction and hygroscopic expansion is crucial for marginal integrity and restoration longevity.
- Previous studies have investigated these phenomena, but depth-dependent contraction patterns require further elucidation.
Purpose of the Study:
- To quantify the wall-to-wall polymerization contraction and hygroscopic expansion of four dental composite resins (Durafill, Heliosit, Silux, Visio-Dispers).
- To assess the ability of these materials to close marginal gaps in dentin cavities.
- To investigate the influence of depth on polymerization contraction and compare light-cured resins with a chemically-cured material.
Main Methods:
- Extracted human teeth were prepared with dentin cavities.
- Four light-cured composite resins and one chemically-cured control material were placed in the cavities.
- Linear polymerization shrinkage and marginal gap formation were measured.
- Measurements were taken at various depths below the filling surface.
Main Results:
- Linear shrinkage ranged from 0.24% to 0.63%.
- Only two materials effectively closed marginal gaps, attributed to water absorption (hygroscopic expansion).
- Marginal gaps were generally widest apically.
- Wall-to-wall polymerization contraction significantly increased from 100 to 800 microns below the surface.
- The contraction pattern of light-cured resins differed notably from the chemically-cured material.
Conclusions:
- Dental composite resin properties, including polymerization contraction and hygroscopic expansion, significantly impact marginal seal.
- Depth-dependent polymerization contraction is a critical factor influencing restoration integrity.
- Material selection and understanding their behavior at different depths are essential for successful dental restorations.