Environmental Ageing and its Effect on Compressive Properties of Dental Composite

Abstract

Dental composite materials (CM) are widely used in dentistry for restorations. The aim of this study was to determine how compressive properties of commercially available dental CM change in simulated intraoral conditions. The investigated material was 3M ESPE Filtek™ Ultimate A2 Enamel Shade that is widely used in dental clinic and preclinical studies for anterior and posterior restorations. First, the compressive properties of dental composite were determined in uncondensed state. The compressive modulus, strength and maximal deformation were evaluated from the stressstrain curves obtained for the prismatic CM specimens. The specimens were immersed in distilled water (pH = 6), water and vinegar solution (pH = 4), and alkaline mineral water (pH = 8) at 50 C until equilibrium moisture content. Then, the mechanical testing in compression was repeated. It was experimentally confirmed that the storage in simulated intraoral conditions caused a significant reduction of compressive properties of the dental CM, which can negatively influence the lifespan of the restoration. The strength and compressive modulus of the moistened samples were reduced by 27% and 25%, accordingly, but the maximal deformation was increased by 0.4% in comparison with the unconditioned samples. The CM stored in solution with pH = 8 had the highest elastic modulus and strength and the lowest maximal deformation in comparison with the CM stored in more acidic solutions (pH is 4 and 6), indicating to lower inner degradation phenomena of the dental CM.