A practical treatise on the technics and principles of dental orthopedia and prosthetic correction of cleft palate . s which are in the flask while drying theinvestments for pouring subsequent castings. Thedanger point of heat may be determined by placinga small fragment of the metal on the heater besidethe flask. This, when it starts to melt will be awarning to reduce the heat. When the metal cast B is secured, the originalplaster model C (Figs. 31 and 38), next to be du-plicated, is fitted to the metal casts in the samemanner as described for B. As it is necessary topress this plaster model
A practical treatise on the technics and principles of dental orthopedia and prosthetic correction of cleft palate . s which are in the flask while drying theinvestments for pouring subsequent castings. Thedanger point of heat may be determined by placinga small fragment of the metal on the heater besidethe flask. This, when it starts to melt will be awarning to reduce the heat. When the metal cast B is secured, the originalplaster model C (Figs. 31 and 38), next to be du-plicated, is fitted to the metal casts in the samemanner as described for B. As it is necessary topress this plaster model C firmly to place—aftersufficient investment material has been placed in position to fill the interspacesoccupied by the obturator-model—numerous gates should be cut extending to thetop edge of the cast for the free overflow of investment. See Fig. 38. In the fittingof the plaster model C, the seating g, Figs. 29 and 37, of the metal cast A, shouldbe corrected and polished, though not to change the sharply outlined edge of theobturator, where there should be perfect coaptation of the casts. After thoroughly. CHAPTER VI. TECHNICS OF THE METAL CASTS AND OBTURATOR 469 preparing the surfaces of the model C for separating, as described with B, and withthe metal casts A and B in the flask secured with the nasal cover, place only therequired amount of investment in the mold to fully fill the interspaces; thenpress the plaster model C firmly to place, holding it in position until the invest-ment is partially hard. It will be seen that if this cast does not go fully to place,the only harm it does is to thicken the palatal and veil portion of the obturatorbeyond that which was designed to be the proper dimensions when the obturator-model was prepared. If this thickened condition is more than a slight scraping ofthe plaster surfaces will correct, all the casts should be removed from the flask, andcleaned and freed from every possible obstruction that may have prevented themfrom being
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Keywords: ., bookcentury1900, bookdecade1920, bookidpracticaltre, bookyear1921
