Marginal opening of single and twin platinum foil-bonded aluminous porcelain crowns.

The marginal openings of single and twin foil-bonded aluminous porcelain crowns were compared in crowns fabricated indirectly for extracted teeth and directly on typodont teeth. The crowns were cemented with zinc phosphate, embedded in plastic, and sectioned. Marginal opening was measured directly with a traveling microscope. There was no significant difference between the marginal openings of twin- and single-foil crowns fabricated indirectly for extracted teeth. When the crowns were constructed directly on typodont teeth to eliminate the variables of impression-making and die fabrication, the single-foil crowns possessed a significantly smaller marginal opening than the twin-foil crowns. Both the twin- and single-foil complete porcelain crowns resulted in clinically acceptable margins. The single-foil crowns were easier to make.