. The science and practice of dental surgery. d. For this purpose, as also for the greaterpart of the fitting, Booth Pearsalls rotaryburnishers are very useful; failing these, aperfectly smooth instrument must be employed. 416 so that the foil may not be cut or torn at themargin. The metal plate carrying the model and foilmatrix is now transferred to the swaging press,and any warp or sjiringiness removed by press-ing \\ell \\ith the water-bag plunger. The matrix, which should now fit perfectly,must at this stage be removed from the order to prevent distortion, it should firstbe filled
. The science and practice of dental surgery. d. For this purpose, as also for the greaterpart of the fitting, Booth Pearsalls rotaryburnishers are very useful; failing these, aperfectly smooth instrument must be employed. 416 so that the foil may not be cut or torn at themargin. The metal plate carrying the model and foilmatrix is now transferred to the swaging press,and any warp or sjiringiness removed by press-ing \\ell \\ith the water-bag plunger. The matrix, which should now fit perfectly,must at this stage be removed from the order to prevent distortion, it should firstbe filled with some substance that ^^ill sufficientlysupport it, and that can be easily and com-pletely removed after the matrix is , gutta-percha, or camphor may be usedfor this jnirpose. Of the various kinds of gutta-percha the most suitable is the pink base-plate ; it should be packed into the matrixcomparatively cold, so that it will not adheretoo firmly to the platinum. After the invest-ment has set it can readily be removed if it is. (A) Aslis Inlay Press. (B) The bed-plate, to which is fixed the cement model. (C) The water-bag plimger for fitting thin foil. (D and E) Iron plunger and hard rubber block forheavy swaging. warmed on the top surface; if the mould itselfis heated, there is danger of the gutta-perchasticking to the platinum foil and pulling itaway from the investment. If wax is usedit should be that supplied for casting andguaranteed to leave no fixed residue on most convenient substance of all is small pieces are packed into the mould, theycan readily be made to cohere into a solid masswhich acts as a very satisfactory support tothe foil; after investment the camphor caneasily be removed with a blast of hot air, as itvolatilizes at a low temperature without meltingto a liquid and so rumiing into the pores of theinvestment, as wax does. Various substances are used for investing thematrix, such as asbestos powder, alone or mixedwith pl
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectdentistry, bookyear19
