Fluoride release and absorption at different pH from glass-ionomer cements

The aim of this study was to evaluate the fluoride release (release-tests) from two glass-ionomer cements (GIC), before and after NaF solution treatment (fluoride treatment) in different pH environments. After 21 days, every second sample was submitted to fluoride treatment to simulate a fluoride recharge. After fluoride treatment every second sample was submitted to a further three days of long release-tests. Sample surfaces were analyzed by SEM before and after the release-tests in all pH solutions studied. The present study showed that GICs released fluoride ions for the duration of the examination period. For both materials the amount of F − released at low pH was considerably greater than at higher pH. The massive superficial breaking up observed by SEM probably promoted the releasing processes. Recharge is possible at different pH levels using NaF solution. Fluoride release may depend on GICs surface degradation caused by pH in the solution. The use of this kind of material may be an important issue in patients with with low pH saliva and with a high risks caries.