Finger W
Scand J Dent Res. 1980 Apr;88(2):159-60. doi: 10.1111/j.1600-0722.1980.tb01208.x.
The present investigation has shown that the setting expansion of two dental stones when measured according to the ADA Specification No. 25, was lower than the expansion determined by a dial gauge method. The values from this latter test and the percentage deviation of the diameter of full crown stone dies (produced in individual silicone impressions) from the base diameter of the original preparation were identical. A reduction of the effective expansion to a value of 0.05% or less is desirable and proved possible for the stone materials studied without altering other important properties.
目前的研究表明，根据ADA规范第25号测量的两种牙科石膏的凝固膨胀率低于用百分表法测定的膨胀率。后一种测试的值与全冠石膏代型（在单独的硅橡胶印模中制作）的直径相对于原始预备体基牙直径的百分比偏差是相同的。将有效膨胀率降低到0.05%或更低是可取的，并且对于所研究的石膏材料来说，在不改变其他重要性能的情况下证明是可行的。
