0290 Dimensional Stability of Kromopan, an Irreversible Hydrocolloid Impression Material
J. STRAW, F. IUORNO, and S. LINDAUER, Virginia Commonwealth University, Richmond, USA

To achieve dimensional accuracy, it is recommended that impressions made with conventional alginate materials be poured within 24 hours. Kromopan, also an irreversible hydrocolloid, claims to be stable for up to 100 hours, an advantage if impressions are transported before being poured in a laboratory. Objectives: The purpose of this study was to compare the dimensional stability of Kromopan to conventional alginate over time. Methods: A maxillary cast with 14 teeth served as the control. Vertical and horizontal stops were crafted into the cast to ensure standardized impressions. First molars, canines, and one central incisor were replaced with steel rods for measurement accuracy. 70 impressions each were made of the master cast using alginate and Kromopan materials. 10 impressions in each group were poured immediately. The remainder were stored at room temperature, wrapped in moist towels in a plastic bag. 10 in each group were poured after 24, 48, 72, 96, 120, and 144 hours. Deviations in intermolar width, intercanine width, and arch length, compared to the master cast, were evaluated over time and compared between materials using regression analysis and repeated measures ANOVA. Results: Significant increases in distortion as a function of time were recorded for the conventional alginate material (p < 0.001), but not for Kromopan (p > 0.20). Deviations were significantly greater for the alginate (p < 0.05). Conclusions: Kromopan appears to provide significantly better dimensional stability over time than a conventional irreversible hydrocolloid material. (Supported in part by the MCV AD Williams Research Fund)

Seq #44 - Properties of Impression Materials, Orthodontic Materials, Investment Materials, Implants, and Biological Properties
11:00 AM-12:15 PM, Thursday, 13 March 2003 Henry B. Gonzalez Convention Center Exhibit Hall C

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