FLUORIDE RELEASE AND UPTAKE BY GLASS-IONOMERS AND RELATED MATERIALS AND ITS CLINICAL EFFECT

The anticariogenic effect of silicate cement is well known and conside red a result of fluoride release. In several studies a similar fluorid e release from conventional glass-ionomer cement (GIC) has been establ ished. Therefore, an anticariogenic effect may be predicted from the G ICs too. In my studies the fluoride release was studied by exposing th e test specimens to a continuous flow of running tap water. At certain time periods the specimens were transferred for 1 week in a small amo unt of deionized water (5 mi). The determination of the fluoride conte nt of the solution showed the fluoride release of the material at that time. There was an initial 'burst' effect of fluoride release and the n the release gradually decreased, settling at a constant level. The l ong-term release from conventional GICs was shown to remain on the sam e level for at least 8 years. The amount of the constant release did n ot differ much between different brands. Resin-modified GICs released fluoride to the same extent and in the similar way as conventional GIC s whereas polyacid-modified composites ('compomers') did not show an i nitial fluoride 'burst' effect. To study the fluoride binding ability of GICs, specimens which had been exposed to running water for differe nt periods of time were treated with a 50 ppm fluoride solution. After this 'recharging' GIC and resin-modified GIC specimens released more than twice the amount of fluoride released before the treatment. The f luoride treatment had no effect on polyacid-modified composites or on fluoride-containing composites or on the amalgams. To get an impressio n of the clinical effect of GICs a questionnaire was handed out to pra ctitioners attending courses in the Nordic countries and in Australia during the period 1991-1992 which resulted in 954 answers. Among other questions, the dentists were asked if they had observed caries and gi ngival inflammation in association with GIC and composite fillings. Ac cording to the opinion of most dentists caries and gingival inflammati on had never or only seldom been observed in association with GIC fill ings whereas most dentists had observed these complications often in c onnection with composite restorations. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.