Shaping the Base of the Master Cast

Boxing wax is used to encircle the land area, to form a mold for the impression base, and to fix the unset model impression in a horizontal position until fully set. The wax should extend 10 mm above the highest point of the impression.

Dental stone is vacuum-mixed to minimize bubbles and to ensure maximum model strength. The mix is vibrated into the boxed and beaded impression and filled to the top of the boxing wax.

The impression is allowed to set for at least 1 hour. If boxing wax was used, it is removed. If modeling compound was used, it is removed. The set cast is placed in hot water for at least three minutes, which will soften the compound as well as disintegrate the 50/50 plaster/pumice mix if it was used. The impression is the gently and carefully removed from the master cast.

Trimming the Maxillary Master Cast

A final trimming of the master cast must be with care to avoid marring any surface of the model other than the land area. Models can be trimmed by rotary bur or by hand. A wax instrument can be used to carefully remove any remaining impression material.