Effect of fluoride amalgams on artificial recurrent enamel and root caries

The present study examined the effect of F-containing amalgams on recurrent caries in vitro. Four amalgams were tested: A - Conventional amalgam; B - Amalgam A with 1% SnF2; C - Non-gamma-2 amalgam; D - Amalgam C with 1% SnF2. Twenty fillings from each amalgam were placed at the cementoenamel junction in sound extracted human teeth. The teeth were covered with varnish except for a 2-mm-wide zone around the fillings and immersed in separate vials containing dialyzed 15% gelatin gel, pH 4.2, for 17 days. Longitudinal sections through the created enamel and root lesions were examined using polarized light microscopy with distilled water as imbibition medium. Lesion depth was measured adjacent to the fillings and at the midpoint of the lesions. In the amalgam D group, 14 enamel lesions and 15 root lesions showed no demineralization in the area closest to the fillings, and mean lesion depth was significantly smaller than adjacent to the F-free amalgams in enamel as well as in root surfaces. In the root lesions, protection was most evident in amalgam D. At the midpoint of the lesions, depths were not statistically different between groups A-D. This study suggests that fluoride amalgams have anticaries properties sufficient to inhibit recurrent caries.