Glossary

A master cast is a cast made to replicate a patient’s entire oral structures, including teeth, gums, upper and lower jaw, and soft tissue structures. Master casts are first created by taking an impression of the patient’s mouth, usually with a flexible putty or liquid that will form around the structures inside the mouth. The putty or liquid is left in the patient’s mouth long enough to harden into a semi-solid, elastic material that will maintain the shape of the patient’s oral cavity once removed. This process usually only takes a few minutes. The impression is then taken to the lab where it is filled with dental stone or plastic. Once this is done, a complete replication of the patient’s entire mouth has been created. Master casts can be used to manufacture a wide variety of dental prostheses, including but not limited to dental implants, bridges, crowns, and partial and complete dentures.

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.