Dental Impressions

Dental impressions create a negative replica of the teeth and surrounding oral structures, which is used to fabricate study models, custom trays, and dental restorations. Traditional impressions use elastomeric materials such as polyvinyl siloxane (PVS) or polyether loaded into a tray that is placed in the patient's mouth for several minutes until the material sets. The impression tray is selected based on the patient's arch size and the area being recorded. A two-step technique uses a preliminary impression followed by a wash impression for greater detail. Single-step techniques use materials of different viscosities simultaneously. Alginate impressions are used for diagnostic models and are less expensive but less accurate than elastomeric materials. Accurate impressions are critical for well-fitting dental restorations. Factors affecting quality include proper tray selection, material mixing, moisture control, and removal technique. While digital impressions are increasingly common, traditional impressions remain valuable in many clinical situations and continue to produce excellent results when performed correctly.