Purpose: This study was conducted to determine the effect of various impression techniques on the displacement of flabby tissues overlying the edentulous maxillary ridge. In this study Ten completely edentulous maxillary arches patients with anterior flabby ridges participated in this study. For each patient five secondary impressions were recorded and divided into five groups according to impression technique used. Group I: comprised impressions following the mucocompressive technique. While, in Groups II, III, IV and V had used different mucostatic impression techniques. Soft tissue displacements in X, Y, Z axes and total 3-D in relation to a fixed reference point were recorded for each impression using modified Measurescope. The data were collected and statistically analyzed. The results obtained showed that there were significant differences in soft tissue displacement of all tested groups in both three coordinates (X, Y and Z) and total 3-D. Also; the results showed significant difference in soft tissue displacement of tissues recorded by the four mucostatic impression technique groups compared to mucocompressive impression technique. A significant difference was found between one step mucostatic impression technique group, and two step mucostatic impression techniques.
Conclusions: Based on the results of this study, soft tissue displacement of maxillary flabby ridge during impression procedure occurred along X, Y and Z directions for all tested impression techniques. The mucostatic impression techniques generated less soft tissue displacement than the mucocompressive technique. Two-step mucostatic impression techniques produced less soft tissue displacement compared to the one step mucostatic impression technique.