Hondrum S O
US Army Dental Materials Laboratory, Ft Gordon, GA 30907-5661, USA.
J Prosthet Dent. 2001 Jan;85(1):73-81. doi: 10.1067/mpr.2001.112407.
Storage stability, or shelf life, is a critical property of perishable dental materials.
The purpose of this investigation was to document changes in the properties of nonaqueous elastomeric impression materials over time and on exposure to various environmental conditions.
Materials investigated included a polyether impression material, a polysulfide material (light, regular, and heavy consistencies), and an addition-reaction silicone material (light, regular, heavy, and putty consistencies). Tests included viscosity of individual pastes, elastic recovery, working and setting times, strain in compression, dimensional change, creep compliance, and tear energy. Means and standard deviations were calculated for each test interval. Statistical analysis included 2-way ANOVA (variables: time and storage condition) and comparison to baseline values using 1-way ANOVA (variable: time) and Scheffe's multiple comparison test (P < or = 0.05) within each material, consistency, and test.
Results over 72 months revealed changes in viscosity, working/setting times, elastic recovery, and creep compliance. Separation of components was seen with polysulfide and addition silicone materials. Some batches of polysulfide base paste and polyether reactor paste solidified in the tube.
Most batches of the materials and consistencies tested remained efficacious well past their designated shelf lives under a variety of storage and use conditions. Data for the addition-reaction silicone impression material changed little during the 72-month testing period; thus, the material may be considered relatively storage stable. Creep compliance was the most precise storage-stability indicator. The storage stability of perishable materials should be addressed in American Dental Association Specifications.
储存稳定性，即保质期，是易腐牙科材料的一项关键特性。
本研究的目的是记录非水性弹性印模材料的性能随时间以及在暴露于各种环境条件下的变化。
所研究的材料包括一种聚醚印模材料、一种多硫化物材料（轻质、常规和重质稠度）以及一种加成型硅橡胶材料（轻质、常规、重质和油灰状稠度）。测试包括各糊剂的粘度、弹性回复率、工作时间和凝固时间、压缩应变、尺寸变化、蠕变柔量和撕裂能。计算每个测试间隔的均值和标准差。统计分析包括双向方差分析（变量：时间和储存条件），以及在每种材料、稠度和测试中使用单向方差分析（变量：时间）和谢费多重比较检验（P≤0.05）与基线值进行比较。
72个月的结果显示粘度、工作/凝固时间、弹性回复率和蠕变柔量发生了变化。多硫化物和加成型硅橡胶材料出现了组分分离。一些批次的多硫化物基糊剂和聚醚反应剂糊剂在管中固化。
在各种储存和使用条件下，所测试的大多数材料批次和稠度在超过其指定保质期后仍保持有效。加成型硅橡胶印模材料的数据在72个月的测试期内变化很小；因此，该材料可被认为具有相对较好的储存稳定性。蠕变柔量是最精确的储存稳定性指标。美国牙科协会规范应涉及易腐材料的储存稳定性。
