![]() ![]() Also, failure to precisely follow the instructions for the adhesive regarding setting time can lead to distortion and an ill-fitting crown, bridge, or veneer ( Figure 2). It is extremely important to use the correct adhesive for the specific brand of impression material used. The tray adhesive ensures the retention of the material to the tray, controlling shrinkage. Tray adhesive is critical to accuracy when using vinyl polysiloxane (VPS) impression material. Use of an inadequately sized tray can create exposure of the tray wall through the impression material, which limits the needed material in potentially crucial margin areas and, in the case of double-arch quadrant trays, increases the potential for distortion ( Figure 1). Use of the incorrect tray often produces an impression that failed to capture the contralateral tooth, which leaves the technician “in the dark” regarding the contour and position needed for the crown, bridge, or veneer to match the existing dentition. ![]() Use of a Posterior Quadrant Impression Tray for the Capture of an Incisor Restoration This omission can lead to a misarticulated cast, which results in inaccurate occlusion at delivery. Inadequate Material in the Occlusal Areas Adjacent to the Posterior Crown or Bridge Preparation(s) This article focuses on the most common omissions and mistakes that occur in the impression-taking process and the negative effect(s) each mistake has on the clinical delivery of the prescribed restoration. The technical aspects of impression material use are well documented in the directions for each system manufactured, and the clinician taking the impression needs to follow them carefully. With so much at stake, it is surprising to find that the majority of impressions received in dental laboratories are deficient in some way. ![]() Failure to record the appropriate areas of the oral cavity accurately leads to excessive adjustments, lost chair time and, sometimes, starting over. The most important process is impression taking, which provides the resulting impression and master cast. The successful delivery of dental prosthetics is dependent on many steps in the operatory and the laboratory. Accurate Impressions: A Crucial Link to Prosthodontic Success David Avery, CDT ![]()
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