A practical treatise on mechanical dentistry . rusion of the gum materialbetween the plaster surfaces, the teeth, whether plate or gum, willbe relatively elongated in proportion to the increased thickness im-parted to the base consequent upon the incomplete closure of theflask, and however accurately or skilfully the porcelain teeth mayhave been originally fitted to the vacuity in front, the artificial willbe found to depart from the natural gum, while the porcelain crowns RUBBER OR VULCANITE BASE. 29I will be displaced and projected below those of the contiguousnatural organs. Such displaceme
A practical treatise on mechanical dentistry . rusion of the gum materialbetween the plaster surfaces, the teeth, whether plate or gum, willbe relatively elongated in proportion to the increased thickness im-parted to the base consequent upon the incomplete closure of theflask, and however accurately or skilfully the porcelain teeth mayhave been originally fitted to the vacuity in front, the artificial willbe found to depart from the natural gum, while the porcelain crowns RUBBER OR VULCANITE BASE. 29I will be displaced and projected below those of the contiguousnatural organs. Such displacement in the cases last referred to,however small in degree, cannot fail either to impair or destroy thevalue, both as respects appearance and utility, of the method of furnishing an exit to redundant material, as usuallypractised, is to form a series of conduits or grooves in the surfaceof the plaster, extending them from the edge of the matrix to therim of the cup. The escape of the gum will be facilitated by cutting Fig. ii<. notches at intervals around the rim of the flask, making the groovesin the plaster continuous with them, the grooves being about Y\ ofan inch apart. To still more effectually prevent the intrusion ofthe vulcanite material between the surfaces of the opposing sectionsof plaster, a circular groove may be cut in the plaster within a lineor two of the margins of the matrix, as is shown in the illustration,Fig. 118, into which narrow channels at short distances are made,leading from the mold; others, again, are made at wider intervals 292 MECHANICAL DENTISTRY. from the circular groove to the outer margins of the flask, termi-nating as before in small notches found in the rim of the cup. Thetwo pieces when closed upon each other form a matrix. Into thegrooved section of the mold, the vulcanizable substance is packedprevious to being indurated. It is at this stage that the materialsemployed to exclude the rubber from between the teeth, and notic
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectdentist, bookyear1903
