Water sorption and filler characteristics of composites for use in posterior teeth.

The purpose of this investigation was to determine the water sorption and solubility, as well as the filler composition and extent of chemical degradation in water, of eight different posterior composites. With one exception, the materials with the largest quantity of fillers had the least water sorption and solubility after three months in water at 37 degrees C. The emission spectroscopy results showed that silicon was the major element in all the fillers except one, which had both silicon and strontium as major elements. Other components registered in quantities of 5-10 wt-% were barium, aluminum, zinc, and zirconium. The leaching of inorganic ions into water from the fillers varied depending on filler composition and filler treatment.