Austrian Pat. No. 53,763 describes a dental mold formed of a main part and an insert. The main part forms most of the U-shaped recess that holds the material that receives the impression and the insert has a portion shaped like the palate and which can be fitted into a cutout in the main part. Such a mold, typically referred to as a spoon, is extremely uncomfortable for the patient whose tongue is given no room when it is used. In addition such a mold is usable only to take an upper-mandible impression.
The impression material, which typically is a gypsum-type material that becomes extremely rigid, hardens in the patient's mouth and is left on the jaw while the mold is separated from it. Then the impression must be broken apart to get it out. Once removed, the parts are reassembled into the desired negative mold and the bridge, plate, or other dental device can be made using it.
Modern-day elastic impression materials are normally held in a one-piece spoon and are removed with this spoon from the patient's mouth once the material has cured enough to hold shape. The spoon is left on the cured negative impression which is filled with the hard plaster or the like used to make the positive impression. Separation of this positive impression from the material in the mold is problematic in that this positive impression frequently breaks during separation.