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Published on: April 29, 2014
Comparison of the three-dimensional correctness of impression techniques: a randomized controlled trial
Ralph Gunnar Luthardt1, Michael H Walter, Sebastian Quaas
1Ulm University, Department of Prosthetic Dentistry, Ulm, Germany. Ralph.Luthardt@computerzaehne.de
Objective:
In vitro studies showed superior impression correctness for one-stage impressions. However, clinical data, especially clinical trials, are lacking in this matter. The aim of the study was to investigate the three-dimensional correctness of impressions for final restorations applying three different impression techniques.
Method And Materials:
Three impressions each were made from 48 patients with different techniques using metal stock trays. In a randomized order, one-stage putty-wash, two-stage putty-wash, and monophase impressions (respectively, Dimension Penta H and Garant L, Dimension Penta H Quick and Garant L Quick, Impregum Penta; 3M ESPE) were made with either polyvinyl siloxane or polyether materials. The double-cord technique was applied at all abutment teeth. Factors potentially influencing the correctness of the impressions were recorded. The precision of the impressions was three-dimensionally analyzed using the resulting gypsum models. Discrepancies between the impressions were calculated using the one-stage putty-wash impression as reference.
Results:
Discrepancies between the one-stage putty-wash impressions and the monophase impressions are significantly lower compared with two-stage putty-wash impressions. The depth of the most subgingival portion of the preparation margin significantly influences the discrepancies between the impression techniques.
Conclusion:
In light of the major influence of clinical parameters on impression correctness, one-stage procedures should be favored. These findings support the results of in vitro investigations.