Dental cosmos . scraper, shaped as shown in Fig. 4, is suited to the proper formationof the groove and the scraping of the plaster investment. Prior to the formation of the groove and the scraping just men-tioned there should be clearly in the mind of the manipulator theconviction that it pays to patiently wait for the hardening of theplaster investment before beginning to cut and scrape, because theparting edge of the groove at its gum-border should be as narrow asthe strength of the plaster will permit. It pays also to consider the character of the gum-outline, and soset the model in the fla
Dental cosmos . scraper, shaped as shown in Fig. 4, is suited to the proper formationof the groove and the scraping of the plaster investment. Prior to the formation of the groove and the scraping just men-tioned there should be clearly in the mind of the manipulator theconviction that it pays to patiently wait for the hardening of theplaster investment before beginning to cut and scrape, because theparting edge of the groove at its gum-border should be as narrow asthe strength of the plaster will permit. It pays also to consider the character of the gum-outline, and soset the model in the flask and trim the investment that the surface FLASKING DENTURES FOR VULCANIZATION. 529 of the teeth-half shall slope up relatively to the gum-border, in orderthat the pressure of finally closing the flask shall not under anycircumstances jeopardize the thin porcelain blocks. An excellent Fig. method for making close joints is to grind the section sides to fitsquarely in front and bevel slightly half-way to the front from be-hind until they are nearly in the exact relations de-sired. Then while still in the wax, press the edge of aknife-blade into the joint to* separate the sections evenlya. very little distance. A thin diamond disk rapidlyrevolved in the dental engine hand-piece may then besteadily passed dry through the joint and simultane-ously cut both section sides true and parallel, so that asquare tight joint along the gum faces of the sectionswill be insured. In fact, a large diamond disk jointerwill be found to be of great value in the laboratory. At this point it may be well to say that in waxing upporcelain sections the gum-edges should be slightlybeveled, and the wax overlap the bevel but a very little,so that the contraction of the vulcanite in cooling shallnot pull the section inward with a force that evensteel could hardly resist if provision were not made fo
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Keywords: ., bookauthor, bookcentury1800, bookdecade1880, booksubjectdentistry
