Abstract
The formation of the oxygen inhibition layer is examined on some commercial methacrylate resin based composite restorative materials: nano-filled Filtek Ultimate Universal Restorative and Filtek Supreme XT Universal Restorative and for comparison the microfilled Filtek Z250 Universal Restorative. Each material type is analyzed using scanning electron microscopy for microstructure and energy-dispersive X-ray spectroscopy for the chemical composition. Two polymerization lamps were used for various exposure times. It results an excellent chemical stability for Filtek Ultimate, while the percent of oxygen is increasing with the photo-polymerization time for the other two composites. From element mapping, the filler particles were identified and their volume percents and cluster particle size distributions were calculated. No correlation of these parameters with oxygen inhibition layer was found. Keywords: oxygen inhibition layer, chemical composition, dental restorative composites