Digital evaluation of the effect of different impression techniques on mucosal deformation in distal extension ridges: a clinical controlled trial

Aim: The purpose of this study is to compare the effect of different impression techniques for distal extension removable partial dentures in achieving optimal tissue placement.Material & methods: Eight patients were selected from a prosthodontics outpatient clinic with mandibular bilateral distal extension ridges. Four final impressions were made for each patient (single-step full arch impression as reference, intraoral scan, elastomeric 2-step, and altered cast impression). The produced casts were scanned and superimposed for comparison using Geomagic software. The 3D deviations were measured at different anatomical areas. The RMS, AVG., and +AVG. of cast surfaces at each area were calculated. A Kruskal–Wallis test was performed to compare different casts in various areas. Results: Significant differences were found in RMS and -AVG. Overall data in IOS compared to other techniques. For +AVG., the altered cast technique showed significantly higher values at area 1. Conclusion: Intraoral scanning can replace mucostatic impressions in partially edentulous distal extension arches. The new 2-step elastomeric impression technique presents an acceptable alternative to the more complex altered cast impression.