The effect of using different impression techniques and materials on vertical tissue displacement in free end extension ridges. (Dental survey and clinical study)

Various impression techniques used in the construction of free- end extension partial denture are based on theories relative to the compressibility and behaviour of the soft tissue during impression making and during function, the aim of the study was to measure vertical tissue displacement during impression making for free- and extension using different impression technique and materials. Material and methods: the study consisted of two parts (question are and clinical) the questionnaire was circulated among (90) dentists at different working places, to see which impression technique they use in free- and extension. In the clinical part (24) mandibular distal extension impression were made using three impression techniques and materials (special tray with alginate, special tray with polyether and double tray with zinc- oxide eugenol impression paste). The amount of vertical tissue displacement was measured on stone cast using (dial indicator dimension). Results: The results of the survey showed that (44%) of the dentist tend to use special tray with alginate, and (38.1%) of prosthodontist use double tray impression, the clinical part showed that there was significant difference between the impression techniques. Conclusions: The most popular impression technique used is special tray with alginate, which showed more tissue displacement in the clinical part of the study, while the double tray impression technique showed the least