Marginal microleakage in bonded amalgam restorations: a combined in vivo and in vitro study

This study evaluated the marginal microleakage in bonded amalgam restorations in teeth extracted a month after restoration placement.

Nine teeth in a patient scheduled for complete extraction were selected. In each tooth, a buccal prepared cavity was treated with Scotchbond Plus and filled with high copper amalgam. In four teeth, a lingual unlined restoration was also prepared as control. A month later, all the teeth were extracted; seven teeth were immersed for 48 hours in a 0.05% basic fucsine dye solution and then sectioned. Sections were observed with a stereomicroscope at 10X. Results were statistically evaluated using a nonparametric Mann-Whitney test for independent data. The remaining two teeth were sectioned and observed using a scanning electron microscope (SEM).

Stereomicroscopic analysis revealed that 80% of bonded specimens did not exhibit dye infiltration at the enamel margin; the same percentage of bonded specimens showed partial infiltration at the cervical margin. In the unlined control specimens, there was a complete dye infiltration at both margins. SEM analysis revealed a good adaptation between resin and tooth and between resin and amalgam.

Bonded amalgam restorations are effective in reducing marginal microleakage, particularly at the enamel margin.