Impact of Storage Environment and Temperature on Dimensional Stability of Alginate Impression

BACKGROUND Alginate impression materials have been extensively used in dentistry. After making an impression, the final alginate structure is very sensitive to condition which can change the amount of trapped water in fibrillar structure; thus, the dimensional stability of alginate impression is highly vulnerable to weather and moisture conditions and any change in it will lead to distortion of impression. The purpose of this study is to assess the dimensional changes of alginate impression by weight loss method by storing the specimens in 0.02% of NaCl solution and 0.05% K2SO4 solution at room temperature and at 8 +/- 2 degrees C for 24 hours. METHODS The study was done in Department of Prosthodontics, Sharad Pawar Dental College, Sawangi (Meghe), Wardha, India. Alginate impressions were made with ivory tooth mounted in dental stone and the impressions were stored at atmospheric conditions in 0.02% of NaCl solution in zip lock polythene sachets, at atmospheric conditions in 0.05% K2SO4 solution in zip lock polythene sachets, in zip lock polythene sachets at 8 +/- 2 degrees C in 0.02% NaCl solution, in zip lock polythene sachets at 8 +/- 2 degrees C in 0.05% K2SO4 solution. The following materials were used-alginate impression material, cylindrical ring, glass slab, ivory tooth mounted in dental stone, zip lock polythene sachets, refrigerator, 0.02% NaCl and 0.05 % K2SO4 and Blotting paper. RESULTS The 0.02% Sodium chloride solution showed lesser weight loss during storage of irreversible hydrocolloid impression material as compared to potassium sulphate. CONCLUSIONS For maximum dimensional stability, theoretically the cast should be poured immediately. If it is not possible, the impression can be stored in 0.02% NaCl at 8 +/- 2 degrees C solutions preferentially followed by 0.05% of K2SO4 at 8 +/- 2 degrees C solutions, in a sealed polythene sachet for about 24 hours.