Dimensional Stability of Orthodontic Alginates

Introduction:This study aims to discover which brand among four commonly marketed alginates is the most stable and the best,to send to OrthoCad for the most accurate digital models. Materials and Methods: Kromopan 100, Alginmax 120, Jeltrate, and Identic were used. Five specimens per type of alginate were prepared for each time period of one hour, 24 hours, 48 hours, 72 hours, 100 hours and 120 hours. The mixed materials were introduced into a ring block and pressed by a plate, put into a water bath to simulate the impressions in the mouth and then removed from the mold and stored for various time periods in a zip lock bag at room temperature. After storage, the samples were then taken out of the storage bag and measured using a traveling microscope. Linear dimensional change (%) was calculated and analysis of variance (ANOVA) and Fisher's PLSD test were used to analyze the data. Results: Kromopan 100 showed the most accuracy of the materials with the most shrinkage at 96 hours (0.25%). Alginmax 120 showed shrinkage at all time points and it was similar to Kromopan 100 in that it showed the most contraction at 96 hours (1.69%). Jeltrate showed a mean of 0.36% expansion at one hour and contraction at all other storage times, with the most at 120 hours (1.83%). Identic exhibited shrinkage at all time points, varying from 0.92% at one hour to 2.81% at 120 hours. Conclusions: Examination of the four alginates under similar conditions recommended by OrthoCad revealed Kromopan 100 as the most dimensionally stable and Identic as the least accurate, with Alginmax 120 and Jeltrate falling in the middle. In general, when fabricating casts after 24 hours, one can expect shrinkage of the material anywhere from less than 0.25% to nearly 3%, depending on the material.