Knowing the causes of the most common impression problems is half the battle. Too much moisture on the prep, wicking away the impression material.Removing the heavy-body tray before the material is fully set.Waiting past working time of the light-body material before inserting the heavy-body tray.Inserting a tray of heavy-body material past its working time.Pulls are drag mark distortions caused by: Presence of deep undercuts in the prep or adjacent tooth.Insufficient tissue retraction, particularly where the sulcus is thin and deep.The light-body VPS impression material not setting fully before removal.Tears are breaks in the impression, often caused by: Insufficient proximal reduction or failure to re-contour adjacent tooth anatomy.There’s inadequate sulcular width for light body material to flow.The marginal tissue is not retracted enough to prevent collapse over the sulcus.These errors are caused by insufficient retraction, resulting in the following problems: Thin walls are areas of the impression where there are gaps. Improper retraction (in which the sulcus is not wide enough for light body to flow into it, especially in the line angles).
Improper wetting or intimate contact of prep with light body material.Voids are gaps and spaces left by air pockets in the impression material. The First Step: Understand the Causes of Common Impression Issuesį irst, let’s look at the most common dental impression issues and their causes. This article focuses on a heavy body/light body wash technique in which light-body impression material is applied first, immediately followed by a tray llned with heavy-body material, so that both materials are allowed to polymerize together. And now is the perfect time to think about the materials and techniques you use every day. So we offer seven simple steps you can take to ensure you’re getting accurate, high-quality VPS (Vinyl Polysiloxane) impressions the first time.
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