Manufacturers supply alginate impression materials powder in bulk. Some dental suppliers repackage alginates in plastic container. It is known that storage stability is a critical characteristic for alginates. Objectives: The purpose of this study was to determine storage time effect of repackaging alginates on recovery from deformation. Methods: Two brands of alginates (Tulip® TU, and Aroma Fine DF III® AF) were repackaged into 120 by plastic container. The samples were stored in room condition (temperature 29oC ± 1oC, relative humidity 60% ± 10%) for 1,2,3,4 and 5 weeks. The alginates setting time and recovery from deformation were measured according to the ANSI/ADA specification no 18 (ISO 1563). Results: The results revealed decreasing in setting time during 5 weeks but slight decreasing in recovery from deformation after 3 weeks storage. The ANOVA showed there was not any significant difference of alginates recovery from deformation among the storage times (p>0.05).
Average of setting time and recovery from deformation of repackaging alginates in various storage times
| Storage times | TU | AF | ||
| Setting time (second) | Recovery from deformation (%) | Setting time (second) | Recovery from deformation (%) | |
| Control 1 week 2 weeks 3 weeks 4 weeks 5 weeks | 66.00±2.23 62.80±0.84 59.80±2.28 48.60±0.55 46.60± 0.54 45.60±0.52 | 97.93±0.09 97.95±0.47 97.57±0.72 97.96±0.23 97.73±0.13 97.56±0.19 | 78.80±1.09 76.40±0.55 76.20±4.15 75.20±3.56 73.60±2.07 67.20±0.83 | 98.59±0.26 98.27±0.16 98.60±0.39 98.62±1.09 98.55±0.49 98.29±0.24 |
Conclusion: Storage times of repackaging alginates in plastic container during 5 weeks in room condition were slightly decreasing alginates recovery from deformation although they were not significant. The alginates recovery from deformation remained within the ADA specification limit.