Effect of encapsulation on the fluoride release from conventional glass ionomers

Objectives: The aim of the present study is to investigate the effect of the type of encapsulation and the batch on the fluoride release of conventionally setting glass ionomer cements Ketac-Fil and Fuji Cap II. Methods: Three capsule types were selected: the capsules of Ketac-Fil and Fuji Cap II, and standard capsules. Six individual series of five cylindrical specimens were made from fresh mixes and leached at 37°C with 25 ml distilled water up to 56 days. A second series of five specimens per formulation in original capsules was made from fresh mixes of another batch. The fluoride concentration was determined by means of a fluoride-ion selective electrode. Results: The fluoride release profiles of a given glass ionomer formulation generally run parallel regardless of the type of encapsulation. When the amounts of fluoride released within the specific formulation were compared as a function of the capsule type, statistically significant differences were only found for Ketac-Fil. Comparing the amounts of fluoride released by different batches of a given glass ionomer formulation, statistically significant differences were only found for Fuji Cap II. Significance: The type of encapsulation may affect the fluoride release of a given glass ionomer formulation quantitatively, but not qualitatively. Apparently, different batches of the same formulation may result in different amounts of fluoride released.