A master impression is fabricated for the purpose of creating a master model or cast that a laboratory can use to fabricate accurate dental restorations. It’s important that the master impression be high-quality and meet the functional, biological, and aesthetic needs of the patient. Errors in the master impression could result in a dental laboratory being unable to create the appropriate restorations. The impression should be as crisply detailed as possible and without contamination. To create a master impression, a patient is typically anesthetized before the procedure. An appropriately-sized tray is chosen and filled with low-viscosity mixed impression material. Then, the tray is seated into the patient’s mouth and the material is allowed to set into a semi-solid substance. The completed master impression should reproduce the occlusal surfaces of all teeth, the mucobuccal fold, and the palate. It should not have any air bubbles, voids, or pulls.