Abstract
The polymerization shrinkage of composite resins may affect negatively the clinical outcome of the restoration. Extensive research has been carried out to develop new formulations of composite resins in order to provide good handling characteristics and some dimensional stability during polymerization. The purpose of this study was to analyze, in vitro, the magnitude of the volumetric polymerization shrinkage of 7 contemporary composite resins (Definite, Suprafill, SureFil, Filtek Z250, Fill Magic, Alert, and Solitaire) to determine whether there are differences among these materials. The tests were conducted with precision of 0.1 mg. The volumetric shrinkage was measured by hydrostatic weighing before and after polymerization and calculated by known mathematical equations. One-way ANOVA (á=0.05) was used to determine statistically significant differences in volumetric shrinkage among the tested composite resins. Suprafill (1.87±0.01) and Definite (1.89±0.01) shrank significantly less than the other composite resins. SureFil (2.01±0.06), Filtek Z250 (1.99±0.03), and Fill Magic (2.02±0.02) presented intermediate levels of polymerization shrinkage. Alert and Solitaire presented the highest degree of polymerization shrinkage. Knowing the polymerization shrinkage rates of the commercially available composite resins, the dentist would be able to choose between using composite resins with lower polymerization shrinkage rates or adopting technical or operational procedures to minimize the adverse effects deriving from resin contraction during light-activation.
Highlights
The formulation of composite resins has been modified during the past years with the purpose of improving their physical, mechanical and handling characteristics
Less hydroxyl groups were present in the composite resin and the material became less susceptible to the absorption of liquids[12]
It can be mentioned the replacement of BISGMA and TEGMA of the organic matrix by an organic silicium compound known as Ormocers[7], which is the acronym of ORganically MOdified CERamic
Summary
The formulation of composite resins has been modified during the past years with the purpose of improving their physical, mechanical and handling characteristics. Among the main factors related to the clinical outcome of composite resin restorations, the quality of the restorative materialtooth interfacial seal and absence of microleakage are definitely considered[1,16] This is largely determined by the degree of polymerization shrinkage of the composite resin and the quality of bonding to tooth structures[20]. Less hydroxyl groups were present in the composite resin and the material became less susceptible to the absorption of liquids[12] Among other modifications, it can be mentioned the replacement of BISGMA and TEGMA of the organic matrix by an organic silicium compound known as Ormocers[7], which is the acronym of ORganically MOdified CERamic
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