Once the dentist has done an oral cancer exam and checked for good health of the oral mucosa, then the patient is ready for an impression (or mold) in order to construct a complete denture. To make this impression, the dentist first prepares a tray to hold the impression material. This tray can be made in a lab from a preliminary impression or a stock tray can be modified to fit the mouth. The borders of the tray must be properly molded so that they do not protrude too high up into the cheek. If it did, then the resulting denture would constantly rub causing a sore spot. There are a number of impression materials available. The one I prefer to use is a vinyl polysiloxane. It has a rubbery consistency when set and is so accurate that I also use it for precision crown and bridge procedures. It also has a pleasant taste which can be a big factor when one has a mass of goo in their mouth. The material is mixed and placed in the mouth and allowed to set. A special plaster is poured into the resulting mold and a perfect reproduction of the patient’s gums can be produced.