![]() ![]() These two structures can therefore be used as landmarks allowing teeth on complete dentures to be placed in positions similar to those of their natural predecessors ( Fig. The fibrous band running along the residual ridge is the vestige of the palatal gingivae and, like the incisive papilla, remains relatively constant in position during the remodelling of the ridge which follows extraction of the natural teeth. Two small depressions in the mucosal surface, the foveae palatinae, common collecting ducts from minor salivary glands, are often seen in this region and are therefore a useful landmark for this junction. The upper denture is normally extended posteriorly to the vibrating line, which is the junction between the moving tissues of the soft palate and the static tissues anteriorly ( Fig. The surface anatomy of the denture-bearing areas is illustrated in Figs. First, preliminary impressions are taken using stock ‘off the peg’ impression trays and second, the more accurate master impressions are taken using trays which have been ‘tailor-made’ for a particular patient on casts obtained from the preliminary impressions. If maximum accuracy of the casts is to be achieved, a two-stage impression procedure is required. Either plaster of Paris or model stone is then poured into the impression to form the cast, or positive likeness, of the denture-bearing tissues. The impression material, which is held against the tissues and supported by an impression tray, exhibits plastic flow in the initial stages and then subsequently hardens or sets. Before this cast can be made, an impression, or negative likeness, of these tissues is obtained. The information presented here is directly related to the theoretical discussion on stability in Chapter 4.Ī denture is constructed on a cast of the denture-bearing tissues. ![]() This chapter describes the clinical techniques necessary for obtaining accurate preliminary and master impressions. ![]()
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