Fluoride uptake by cavity walls following application of Duraphat around amalgam restorations

This study aimed to assess possible fluoride uptake by cavity walls following a single application of Duraphat around class V or I amalgam restorations which were inserted in seventeen human premolars in vitro and in vivo. Six cavities were lined with one layer of Copalite before insertion of the restorations. After a week in vivo and 12--24 h in vitro, 200--300 micrometers thick longitudinal sections passing through the cavities were prepared. By electron probe microanalysis F concentrations ranging from 2000 to 6000 ppm were measured near the surface of the cavity walls. Copalite seemed to inhibit F uptake. The study indicates that F ions released from the Duraphat varnish have been taken up by the cavity walls. Such uptake may influence development of secondary caries (wall lesions) in connection with amalgam restorations.