Fluoride Release from Fluoride Varnishes is Affected by Incubation Conditions

Objectives: To evaluate the effects of temperature, medium and volume on fluoride release of different fluoride varnishes in vitro.�

Methods: Fluoride release from 5%NaF varnishes [Duraphat-Colgate (FV1), Vanish-3M (FV2), EnamelPro-Premier (FV3)] was determined in three independent experiments (one per varnish). �Each varnish was mixed well, applied to 40 custom-made holders (14-16 mg/holder) and divided into four groups (n=10).� A control group was incubated at 36^oC in 3ml of stirring artificial saliva (AS; ionic strength similar to human saliva). Each of the other groups changed one variable: temperature (to ~25�C), medium (to H₂O) or volume (to 15 ml).� After 1, 4, 8, 24 and 48h, varnish holders were transferred to fresh media. �Fluoride concentration was measured in the liquids from each time period.� Accumulated fluoride released, as a percentage of the theoretical amount present in each sample, was calculated and statistically analyzed using ANOVA models.

Results: The three factors studied significantly affected fluoride release (p<0.05).� Lower temperature was the major factor, decreasing release from all three varnishes.� For FV2, H₂O medium increased the fluoride release dramatically after 24h.�

Conclusion: Results of this investigation strongly suggest that incubation conditions significantly affect the amount of fluoride released from varnishes in vitro.� The magnitude of this effect differed for various types of fluoride varnishes.