Fracture resistance of complex amalgam restorations with peripheral shelves used as resistance features

This in vitro study compared various peripheral shelves (steps) as resistance features for complex amalgam restorations. Three different sizes of peripheral shelves were evaluated: 1 mm x 1 mm, 2 mm x 2 mm, and 1 mm cervically x 2 mm pulpally. The resistance of these features was compared to a control group that utilized two amalgam pins. The 1 mm x 1 mm shelf provided significantly less resistance than the other groups.