Lindquist Terry J, Stanford Clark M, Mostafavi Homan, Xie Xian-Jin
Department of Prosthodontics, College of Dentistry, University of Iowa, Iowa City, Iowa 52242, USA.
J Prosthet Dent. 2002 Mar;87(3):319-22. doi: 10.1067/mpr.2002.122015.
Limited abrasion resistance is one of the disadvantages of gypsum materials. One means to improve these properties may be the addition of various polymers to reinforce surface and subsurface wear resistance.
The purpose of this study was to evaluate the abrasion resistance of 3 types of gypsum materials with a novel abrasion wear device.
A standard test specimen (50 x 50 x 8 mm) with repeating 1 mm, 45 degrees -angle vertical ridges was used as the test surface. Three types of gypsum materials were evaluated: a type III stone, a conventional type IV stone, and a resin-impregnated type IV stone. Specimens of each material (n = 30) were poured in a vinyl polysiloxane impression of the standard test specimen with the use of an acrylic resin custom tray. Each gypsum product was mixed according to the manufacturer's instructions, poured, and separated 1 hour later. Specimens were trimmed and allowed to bench set for 24 hours (n = 15) or 7 days (n = 15). Abrasion was evaluated with the use of a reciprocal moving stage positioned below a weighted stylus. The stylus was loaded with 3 different weights (15, 50, and 75 g), and the individual gypsum specimens were moved reciprocally for 10 passes. Before and after each set of passes, the specimen was measured on an analytical balance to determine material loss. Three-way ANOVA and Scheffe's multiple comparisons test were used to analyze the data (P<.05).
Type III gypsum at 24 hours exhibited significantly greater material loss than type IV stones at both 7 days and 24 hours (P<.001). Type III gypsum specimens exhibited significantly greater material loss at 24 hours than at 7 days (P<.001). There was no significant difference in the abrasion resistance of type IV specimens at 24 hours and 7 days.
Within the limitations of this study, no significant differences in abrasion resistance were found between specimens fabricated with resin-impregnated and conventional type IV stones, although the former exhibited the least material loss.
耐磨性有限是石膏材料的缺点之一。改善这些性能的一种方法可能是添加各种聚合物以增强表面和次表面耐磨性。
本研究的目的是使用新型磨损装置评估3种石膏材料的耐磨性。
使用具有重复的1毫米、45度角垂直脊的标准测试样本（50×50×8毫米）作为测试表面。评估了三种类型的石膏材料：III型石膏、传统IV型石膏和树脂浸渍IV型石膏。每种材料的样本（n = 30）使用定制丙烯酸树脂托盘倒入标准测试样本的乙烯基聚硅氧烷印模中。每种石膏产品均按照制造商的说明进行混合、灌注，并在1小时后脱模。样本经过修整，并在台面上放置24小时（n = 15）或7天（n = 15）。使用位于加重触针下方的往复移动平台评估磨损情况。触针加载3种不同重量（15、50和75克），各个石膏样本往复移动10次。在每组移动前后，在分析天平上测量样本以确定材料损失。使用三因素方差分析和谢费多重比较检验分析数据（P<0.05）。
III型石膏在24小时时的材料损失显著大于IV型石膏在7天和24小时时的材料损失（P<0.001）。III型石膏样本在24小时时的材料损失显著大于7天时的材料损失（P<0.001）。IV型样本在24小时和7天时的耐磨性没有显著差异。
在本研究的局限性内，树脂浸渍IV型石膏和传统IV型石膏制作的样本在耐磨性方面没有发现显著差异，尽管前者的材料损失最少。
