Impact Of Time And Temperature On The Dimensional Stability Of Alginate Impressions: A Comparative In Vitro Analysis

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Objective: This in vitro study aimed to evaluate the dimensional stability and shrinkage behavior of three commercially available alginate dental impression materials (Velplast, Marieflex, and Zelgan) under varying pouring times and storage temperatures. Materials and Methods: A total of 90 impressions were made using Velplast, Marieflex, and Zelgan. Impressions were divided into three groups based on pouring times: immediate, 20 minutes, and 40 minutes. Additionally, impressions were stored at three different temperatures: 25°C, 30°C, and 40°C. Dimensional changes and shrinkage were measured using a traveling microscope, and statistical analysis was performed using p-values to assess significance. Results: The study found that increased delay in pouring and elevated storage temperatures led to significant dimensional changes in all materials. Velplast exhibited minimal shrinkage at 25°C (0.10%) but showed the highest shrinkage at 40°C (-0.30%). Marieflex and Zelgan similarly demonstrated lower shrinkage at 25°C, but their shrinkage increased to -0.25% and -0.28%, respectively, at 40°C. Immediate pouring resulted in the highest dimensional stability, with accuracy rates of 99.5%, 99.7%, and 99.3% for Velplast, Marieflex, and Zelgan, respectively. Delayed pouring led to greater dimensional distortion, particularly at 40 minutes. Conclusion: The dimensional stability of alginate impression materials is significantly influenced by both pouring time and storage temperature. Immediate pouring is recommended to maintain accuracy, and elevated temperatures should be avoided to minimize shrinkage. Marieflex showed the highest stability across all conditions, making it a suitable option for clinical cases requiring delayed pouring.