Leong D, Chai J, Lautenschlager E, Gilbert J
Northwestern University Dental School, Chicago, Illinois.
Int J Prosthodont. 1994 Sep-Oct;7(5):440-7.
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.
从一个复制了准备安装金属烤瓷冠的牙齿的金属母模制作了18个IV型牙科石膏代型。根据要制作的冠的类型将它们分为三组：(a) 机械研磨、电火花加工的钛冠（Procera）；(b) 铸造钛冠；以及(c) 贵金属合金冠（作为对照）。对照样本在25微米处显示出最小的平均边缘开口，并且与机械研磨冠（54微米）和铸造钛冠（60微米）均有显著差异。两种类型的钛冠彼此之间没有显著差异。
