Schleier P E, Gardner F M, Nelson S K, Pashley D H
School of Dentistry, The Medical College of Georgia, Augusta, GA 30912-1260, USA.
J Prosthet Dent. 2001 Sep;86(3):244-50. doi: 10.1067/mpr.2001.117758.
It has been stated that reversible hydrocolloid impression material must be poured immediately to remain accurate. This may not be true with modern formulations of reversible hydrocolloid. The accuracy of the impression, if kept at 100% humidity for varying periods, may not be affected as critically as has been suspected.
The purpose of this study was to evaluate the effect of storage time in a 100% humidity environment on the accuracy of gypsum casts poured from a newer formulation of reversible hydrocolloid impressions.
With the use of a stainless steel master model, 5 standardized reversible hydrocolloid impressions were made for each time interval tested (n = 5). Impressions were made with the use of both Cartiloid blue syringe and Slate tray reversible hydrocolloid material (both manufactured by Van R) to simulate a common clinical protocol. Six groups, representing times at 0, 30, 60, 120, 180, and 210 minutes, were evaluated for a total of 30 specimens. Gypsum casts were measured with a traveling microscope, and dimensional changes were compared between groups with ANOVA and Tukey intervals (alpha=.05).
Measurements made up to and including the 60-minute storage time showed clinically acceptable distortion levels. These measurements were similar to the metal model and the gypsum casts poured at time 0 minutes. The only statistically significant difference between the gypsum cast and the metal master model was the distance between abutments at storage time 180 minutes (master model = 30.04 mm [SD 0.001]; gypsum casts = 29.944 mm [SD 0.076]). This difference was -91 microm (P=.002). In general, the gypsum abutments became wider and shorter with time. There was no significant difference between any gypsum abutment in regard to width or height when compared with the metal master model for all the storage times tested. However, as time increased, measurement became harder to accomplish, leading to a larger standard deviation and less reliable results. The distance between abutments remained relatively constant for storage times up to and including 60 minutes. For times longer than 60 minutes, the distance between abutments was reduced and more difficult to read. The distance between abutments at the 3-hour storage time was significantly different than the metal standard and time 0 gypsum casts.
If a discrepancy of 78 microm (twice the 39 microm single margin opening) is clinically acceptable, then the results of this study show that this type of reversible hydrocolloid can be stored in 100% humidity for at least 60 minutes.
据说可逆性水胶体印模材料必须立即灌注才能保持精确性。对于现代配方的可逆性水胶体而言，情况可能并非如此。如果在100%湿度下保存不同时长，印模的精确性可能不会像人们怀疑的那样受到严重影响。
本研究的目的是评估在100%湿度环境下的储存时间对由新型可逆性水胶体印模灌注的石膏模型精确性的影响。
使用不锈钢主模型，针对每个测试的时间间隔制作5个标准化的可逆性水胶体印模（n = 5）。使用Cartiloid蓝色注射器和板岩托盘可逆性水胶体材料（均由Van R制造）制作印模，以模拟常见的临床操作流程。评估了6组，分别代表0、30、60、120、180和210分钟的时间点，共计30个标本。用移动式显微镜测量石膏模型，并通过方差分析和Tukey区间比较各组之间的尺寸变化（α = 0.05）。
在长达60分钟的储存时间内进行的测量显示出临床上可接受的变形水平。这些测量结果与金属模型以及在0分钟时灌注的石膏模型相似。石膏模型与金属主模型之间唯一具有统计学意义的差异是在180分钟储存时间时基牙之间的距离（主模型 = 30.04毫米[标准差0.001]；石膏模型 = 29.944毫米[标准差0.076]）。此差异为 -91微米（P = 0.002）。一般来说，随着时间推移，石膏基牙会变宽变短。在所有测试的储存时间内，与金属主模型相比，任何石膏基牙在宽度或高度方面均无显著差异。然而，随着时间增加，测量变得更加困难，导致标准差增大且结果可靠性降低。在长达60分钟（包括60分钟）的储存时间内，基牙之间的距离保持相对恒定。对于超过60分钟的时间，基牙之间的距离减小且更难读取。3小时储存时间时基牙之间的距离与金属标准以及0分钟时的石膏模型有显著差异。
如果临床上可接受78微米的差异（单边缘开口39微米的两倍），那么本研究结果表明这种类型的可逆性水胶体可以在100%湿度下储存至少60分钟。
