Kinetics of fluorine in deciduous enamel after application of fluoride-containing varnish (Duraphat)

The fluorine concentration in tooth enamel was determined in vivo after one single application of Duraphat fluoride varnish from 24 hours up to six months after treatment. A micro-acid-drop technique was used in 68 clinically intact deciduous upper central incisors in 34 pre-school children 4-5 years of age to determined the fluoride concentration in the enamel. The experimental data from the biopsy procedures were analysed by means of analysis of variance. The application of fluoride varnish results in an increase in fluoride in surface as well as subsurface enamel 24 hours after treatment. Thereafter a releasing process of fluorine from the enamel seems to start. Therefore the results indicate that there might be a caries inhibiting effect of fluoride varnish in primary enamel based more upon the kinetics of fluorine rather than a permanent uptake.