Lawson Nathaniel C, Burgess John O, Litaker Mark
School of Dentistry, University of Alabama at Birmingham, Birmingham, AL 35295-0007, USA.
J Esthet Restor Dent. 2008;20(3):186-93. doi: 10.1111/j.1708-8240.2008.00176.x.
PROBLEM/AIMS: Thin sections of impression materials are susceptible to tearing in gingival crevices and interproximal spaces. This study measures the tear strength of six fast and regular set impression materials after different setting times and at different tearing rates.
MATERIALS/METHODS: Tear strength specimens were prepared of four addition silicone materials: Aquasil (Dentsply, Konstanz, Germany), Imprint 3 (3M ESPE, Seefeld, Germany), Stand Out (Kerr, Orange, CA, USA), Virtual (Ivoclar Vivadent, Schaan, Liechtenstein); one polyether material: Impregum (3M ESPE); and a new hybrid material: Senn (GC, Aichi, Japan) using a split mold. Specimens were divided into four groups (N = 5). Groups 1 and 2 were immediately removed from the mold and loaded in tension until failure using an Instron testing device (Instron Corp., Canton, MA, USA). Groups 3 and 4 were tested 24 hours after fabrication. Groups 1 and 3 were tested at 1 mm/minute, and groups 2 and 4 were tested at 500 mm/minute.
A two-factor analysis of variance (ANOVA) and Tukey's test revealed differences among material brands (alpha = 0.05) in all experimental groups. The polyether and hybrid material were in the lowest statistically significant ranking group for all experimental groups. A three-factor ANOVA determined that a 500 mm/minute tearing rate and a 24-hour set time produced higher tear strengths and that fast set materials produced greater tear strength than regular set materials.
Most addition silicone materials provide higher tear strengths than polyether and hybrid materials. Materials display higher tear strengths after longer set times and at faster tearing rates. Impressions should be removed from the mouth with the fastest possible speed.
Addition silicone materials should be used in impressions requiring replication of gingival crevices or interproximal spaces to prevent tearing of thin sheets of material. Impressions should be removed from the mouth and separated from the model with the fastest possible speed.
问题/目的：印模材料的薄片在龈沟和邻间隙中容易撕裂。本研究测量了六种快速凝固和常规凝固印模材料在不同凝固时间和不同撕裂速率下的撕裂强度。
材料/方法：使用分体模具制备了四种加成型硅橡胶材料（Aquasil（德国登士柏，康斯坦茨）、Imprint 3（德国3M ESPE，塞费尔德）、Stand Out（美国克尔，奥兰治）、Virtual（列支敦士登义获嘉伟瓦登特，沙恩））、一种聚醚材料（Impregum（德国3M ESPE））和一种新型混合材料（Senn（日本GC，爱知县））的撕裂强度试样。试样分为四组（N = 5）。第1组和第2组立即从模具中取出，并使用英斯特朗测试装置（美国英斯特朗公司，马萨诸塞州坎顿）进行拉伸加载直至破坏。第3组和第4组在制作后24小时进行测试。第1组和第3组以1毫米/分钟的速度进行测试，第2组和第4组以500毫米/分钟的速度进行测试。
双因素方差分析（ANOVA）和图基检验显示，所有实验组中材料品牌之间存在差异（α = 0.05）。聚醚材料和混合材料在所有实验组中均处于统计学意义最低的等级组。三因素方差分析确定，500毫米/分钟的撕裂速率和24小时的凝固时间产生更高的撕裂强度，且快速凝固材料比常规凝固材料产生更大的撕裂强度。
大多数加成型硅橡胶材料比聚醚材料和混合材料具有更高的撕裂强度。材料在更长的凝固时间和更快的撕裂速率下显示出更高的撕裂强度。印模应尽可能快地从口腔中取出。
在需要复制龈沟或邻间隙的印模中应使用加成型硅橡胶材料，以防止材料薄片撕裂。印模应尽可能快地从口腔中取出并与模型分离。
