. The Dental cosmos. —Black. Showing segment of the margin of an amalgam filling in steel tube. (Enlarged 54 diam.)a. Amalgam, b, Steel tube. (This amalgam shows no movement.) Fig. —Black. Showing filling in steel tube. (Enlarged 54 diam.) a, Amalgam, b, Steel tube. The scaleis also attached. Such shrinkage is common with annealed amalgam composed ofsilver and tin, varying from 50 to G5 per cent, of silver. Adding gold, platinum, orcopper gives but little change in the results. This point of balance has been found erly concluded, the only scientific methodas low as 72J silver by Dr. Black.
. The Dental cosmos. —Black. Showing segment of the margin of an amalgam filling in steel tube. (Enlarged 54 diam.)a. Amalgam, b, Steel tube. (This amalgam shows no movement.) Fig. —Black. Showing filling in steel tube. (Enlarged 54 diam.) a, Amalgam, b, Steel tube. The scaleis also attached. Such shrinkage is common with annealed amalgam composed ofsilver and tin, varying from 50 to G5 per cent, of silver. Adding gold, platinum, orcopper gives but little change in the results. This point of balance has been found erly concluded, the only scientific methodas low as 72J silver by Dr. Black. It of arriving at correct proportions con-may readily be seen that any set formula sists in working out the balance in the 184 THE DENTAL COSMOS. manner indicated above, and securing aseparate formula for each lot of metalsprocured from the market. Even a silvershortage of one-half of 1 per cent, willallow shrinkage sufficient to destroy theutility of a filling, regardless of the de-gree of skill used in placing the fillingin the tooth. To be inaccurate the 1/10,000 of aninch in the movement of a filling mayruin the filling. If the balance pointis missed by one-half of 1 per
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectdentist, bookyear1912
