Marginal fit of machine-milled titanium and cast titanium single crowns.

Eighteen type IV dental stone dies were fabricated from a metal master die that replicated a tooth prepared to receive a metal ceramic crown. They were divided into three groups according to the type of crowns to be made: (a) machine-milled, spark-eroded titanium crowns (Procera); (b) cast titanium crowns; and (c) noble alloy crowns (as the control). The control specimens showed the smallest mean marginal openings at 25 microns and were significantly different from both the machine-milled crowns (54 microns) and the cast titanium crowns (60 microns). The two types of titanium crowns were not significantly different from each other.