The effect of placement of cervical margins of class II amalgam restorations on plaque accumulation and gingival health.

The effects or restoring early proximal carious lesions were investigated in a series of thirty-six surfaces. In eighteen lesions the cervical margins of the restorations extended subgingivally, and in eighteen the margins were located supragingivally. Three months after restoration, plaque accumulation was not significantly different from pre-restoration levels. The degree of gingival inflammation showed a significant improvement after restoration where cervical margins were finished supragingivally (P less than 0.5). Where margins were finished subgingivally a highly significant deterioration in gingival health occurred (P less than 0.1).