Experimental secondary caries around amalgam, composite and glass ionomer cement fillings in human teeth

It was the aim of this in vitro study to examine secondary caries occurring in enamel and dentin adjacent to different filling materials and after different filling methods. The materials used were: amalgam, composite and glass ionomer cement. The highest rate of secondary caries was found on the crown surface as well as root surface of teeth which were conventionally treated with amalgam and composite materials. The preliminary treatment with a copal-ether varnish (Copalite) was of insignificant value. Fluoridation of the cavity walls with a fluoride solution (Elmex-Fluid) resulted a significant cariostatic effect with amalgam- or composite fillings in enamel and in root surfaces. Zones of inhibition of demineralization could be found. The addition of 5% NaF to composite material also produced an inhibition of demineralization, manifesting itself in a reduction of the secondary caries rate and increased percentage of tight margins of the fillings. Although glass ionomer cement has adherent properties to enamel and dentin, a larger percentage of filling-margins, especially of those applied to dentin, were found to be untight. Nevertheless, the demineralizations were not very pronounced and significant zones of inhibition of demineralization were found in the cavity walls and tooth surfaces adjacent to the fillings. The amounts of fluoride released by silicate cement, glass ionomer cement and composites containing 5% NaF were compared. The glass ionomer cement showed higher values than the composite and silicate materials. After 10 days of storage in water, the dosis of fluoride released--by all materials--was 7-20 times less than on the first day.