Film thickness of resin cements used with adhesive systems.

The final film thickness of a resin adhesive and a resin cement could be affected by previous polymerization of the adhesive systems on dentin surfaces. The aim of this work was to evaluate changes in the film thickness of dual resin based cements with their adhesives as a function of polymerization of the latter on dentin surfaces. The materials used were: RelyX ARC (R) + Single Bond (SB) and Variolink base (VB) and high (HV) or low (LV) viscosity catalyst + Syntac Classic (S) or Excite DSC (E); 56 human dentin discs and 56 composite resin discs (Z250).

Effect of energy density on color stability in dental resin composites under accelerated aging.

The effects of the energy density that is used for polymerization on properties of dental resin composites are well known. However, few studies relate color stability to this factor. The aim of this study was to assess color changes (deltaE*), in vitro, in terms of accelerated aging under UV exposure of specimens prepared with different energy densities.

Immediate polymerization shrinkage in light cured restorative resins.

The purpose of this study was to evaluate the immediate polymerization shrinkage of restorative resins following activation with different amounts of light energy. The composites used were: Z-100 (3M-ESPE), Z-250 (3M-ESPE), Ariston pHc (Ivoclar-Vivadent), Filtek P-60 (3M-ESPE), SureFil (Dentsply), Tetric Flow (Ivoclar-Vivadent), Silux Plus (3M-ESPE) and F-2000 (3M-ESPE). The percentage shrinkage after an 80-second activation was determined by means of a capillary mercury dilatometer The power of the light beam that reached the unpolymerized material was regulated at 350 mW/cm2 (Group I) or 275 mW/cm2 (Group II) positioning the end of the light source (XL-3000, 3M-ESPE) either in contact with or 5 mm from the dilatometer stopper.