Effect of adding impression material to mandibular denture space in Piezography.

The purpose of the study was to examine the effect of adding impression material on denture space using a piezographical record. Subjects were ten voluntary edentulous patients, aged from 61 to 84 years old. A maxillary trial denture with anterior artificial teeth and a mandibular base plate with a keel were inserted into the oral cavity. Three ml of tissue-conditioning materials was injected on the base plate for each trial. Afterwards, the patients were instructed to pronounce various phonemes, so that tongue, cheeks and lips conformed to the denture space. The impression complexes were cut at the level of the estimated occlusal plane. Occlusal analogues were made by duplicating the impression complexes. Measurements were performed for five analogues from the first to fifth additions for each subject. The data were compared using analysis of variance (ANOVA), and a Friedman's test followed by a Bonferroni test for multiple comparisons with a level of significance at 5%. At the molar and premolar positions, the bucco-lingual widths of the occlusal table increased significantly at incremental injection of impression materials from P1 to P4. The midpoints of the analogues were located at a distance of 1.5 mm buccally at the molar position and at a distance of 1.9 mm buccally at the premolar position from the top of the alveolar crest, independent of the addition of impression material. It was concluded that denture space was regulated by volume of material and was located slightly on the buccal side from the crest of the residual alveolar ridge.