A practical treatise on mechanical dentistry . ss impression of themouth in wax. There are points,not readily accessible to the fingers,where the wax departs from the ex-ternal and posterior borders of thejaw, and is not, therefore, susceptible of easy correction; besides,when reached and the remedy applied, there is no certain assur-ance that in pressing the wax in at one point we are not displacingit at another. The same uncertainty, to a less degree, in regard toresults also attaches to the use of the modeling composition. Forthis reason, we almost invariably use plaster, and we have suffi-
A practical treatise on mechanical dentistry . ss impression of themouth in wax. There are points,not readily accessible to the fingers,where the wax departs from the ex-ternal and posterior borders of thejaw, and is not, therefore, susceptible of easy correction; besides,when reached and the remedy applied, there is no certain assur-ance that in pressing the wax in at one point we are not displacingit at another. The same uncertainty, to a less degree, in regard toresults also attaches to the use of the modeling composition. Forthis reason, we almost invariably use plaster, and we have suffi-cient reason to believe that the results are more uniformly suc-cessful. Manner of Obtaining an Impression of the Lower Jaw in Wax,for Entire Dentures.—The method pursued in securing an im-pression of the lower jaw; in wax for an entire denture differs inno essential respect from that described when taking an impres-sion for lower partial pieces, the form of cup being represented inFig. 52. When the parts are imbedded in the wax, the latter. I38 MECHANICAL DENTISTRY. should be pressed in around the inner border of the holder, butmore especially near the posterior part of the ridge on each sidewhere the latter overhang and approximate each other, formingcorresponding excavations underneath. After adjusting the waxto the ridge along the border of the cup, the latter should againbe pressed directly down upon the jaw before removing it, tocorrect any partial deformity that may have occurred during theprevious manipulations. Modeling composition, of late years, has largely supersededthe use of wax for impressions. It is compounded of gumdammar, stearin, French chalk, carmin, for coloring, and someperfume. The consistence of the mass depends upon the relativequantity of stearin and chalk introduced, the grades as manufac-tured being designated as soft, medium, and hard. This material takes a sharper impression of the parts than wax,and its elastic property makes it more suitable wh
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectdentist, bookyear1903
