. The principles and practice of dental surgery. e of thewax is cut away until it presents the appearance representedin Fig. 2G0. It should be left a little thicker than the artificialteeth will be, allowance having to be made for shrinkage in thebaking, and also for the removal of a small portion in carving,especially at the part corresponding to the position of the inci-sors and cuspids. The plate and wax are now returned to theupper half of the model, and the exposed surfaces of both waxand model are oiled ; then a thick batter of plaster of paris ispoured on in the manner described for mak
. The principles and practice of dental surgery. e of thewax is cut away until it presents the appearance representedin Fig. 2G0. It should be left a little thicker than the artificialteeth will be, allowance having to be made for shrinkage in thebaking, and also for the removal of a small portion in carving,especially at the part corresponding to the position of the inci-sors and cuspids. The plate and wax are now returned to theupper half of the model, and the exposed surfaces of both waxand model are oiled ; then a thick batter of plaster of paris ispoured on in the manner described for making the upper half ofthe antagonizing model: this forms the matrix. As soon as theplaster has hardened sufficiently, the edges are trimmed to thewax, the matrix separated, and the lower part of the antagoniz- I MANNER OF MAKING A MATRIX. 743 ing model applied. Vertical lines are now made across the wax,to indicate the width required for the artificial teeth. See This done, the antagonizing half-model is removed, the Fig. 260. Fig. matrix applied, and the lines in the wax continued across theedge of it, to serve as a guide for marking the width of theteeth preparatory to carving. See Fig. 262. The two parts areagain separated, and the plaster cut away from the surface of thematrix in contact with the wax, forming an open space betweenit and the edge of the wax, equal to about one-tenth or twelfthof the width of the wax. The matrix will now present theappearance, when the twO parts are put together, represented inFig. 262. The object of this space is to provide for the shrink- FiG. 262. Fig. 263.
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