Effect of 3 medicaments on the dimensional accuracy and surface detail reproduction of polyvinyl siloxane impressions

Objective: The purpose of this study was to determine the effect of retract ion cord medicaments (aluminum chloride, ferric sulfate, and ferric subsulf ate/ferric sulfate) on the dimensional accuracy and surface detail reproduc tion of polyvinyl siloxane impressions. Method and materials: Polyvinyl sil oxane impressions were made of standardized metal dies (American Dental Ass ociation [ADA] specification No. 19) treated with 1 of the 3 retraction cor d medicaments. Dimensional accuracy was evaluated by comparing the average length of a line in the impressions to the standard die. Surface detail rep roduction was evaluated by viewing the impressions under low-angle illumina tion at x 10 magnification. Reproduction was considered satisfactory if 2 o f 3 horizontal lines were reproduced continuously. The dies were also evalu ated under the microscope before the impression was made. Results: The medi caments did not significantly effect the dimensional accuracy; mean shrinka ge was within ADA guidelines in the treatment groups. All of the medicament s had an adverse effect on surface detail reproduction. These effects were statistically significant compared to the untreated control. Conclusion: Al though the changes in dimensional accuracy were within ADA guidelines, the surface detail reproduction was modified such that the impression would be considered clinically unacceptable. For optimal results, care must taken to remove all traces of these retraction cord medicaments prior to recording of a polyvinyl siloxane impression.