Abstract—Fluoride availability from two glass‐ionomer luting agents, Ketac‐Cement and Aqua‐Cement, was monitored after a l‐h treatment in distilled water at pH 7. The recorded results were then compared to the ones obtained from those same cements, after l h, in saliva, in water pretreated with saliva (pH 7 and 4.5), and in albumen and phosphate buffer solutions (pH 7). The Mann‐Whitney two‐sample rank test was utilized in order to identify the differences. The presence of proteins and phosphate reduced fluoride availability. A reduction in the pH from 7 to 4.5 resulted in an increased rate of fluoride release, in water, from glass‐ionomers pretreated with saliva. The present study indicates that fluoride availability from glass‐ionomers, in vivo, is pH controlled. The rate controlling factors appear to be phosp