Composite resin vs resin cement for luting of indirect restorations: comparison of solubility and shrinkage behavior.

The aim of this study was to evaluate relationship between shrinkage development and early solubility of two commonly used luting materials, a self-adhesive cement (GCem chemical and light cured) and composite resin (Tetric). Linear displacement, shrinkage forces and leaching of UDMA from specimens immersed in 75% ethanol/25% water were measured. The least amount of linear shrinkage (33.0±2.9 µm) and polymerization force (4.1±0.3 kg) was observed in Tetric. UDMA leaching (% µg/mL) was the following: chemically cured GCem (4.2±0.2)>light cured GCem (1.5±0.1)>Tetric (0.1). Shrinkage development in the early stages of polymerization was much slower in the self-cured specimens in respect to light cured ones. With the chemically cured self-adhesive cement, incomplete materials' setting during the initial stages after polymerization favored monomer leaching from the cements' mass.