Another old method: Take a piece of foil and roll it into a hard ball; then gradually work it into the cavity, being careful to have sufficient around the margin.
Still another suggested method: Roll a piece of foil into a loose ball, place it in the cavity, and pass a wedge-shaped plugger into its center. This has the effect of spreading the tin toward the walls of the cavity, the opening to be filled with folds in a way already described. The wedge is used as often as it can be made to enter, filling each opening with folds; then condense the surface, trim, and burnish.
The English give the Americans the credit of first using cylinders. Anyhow, Dr. Clark, of New Orleans, in 1855, used them made from non-cohesive gold, and also from gold and tin in alternate layers. (See [Fig. 10].)
Cylinders were used which were a little longer than the depth of the cavity, introduced with wedge-shaped pluggers around the walls, each one being closely adapted to the margin; then another row was added, which was forced firmly against the preceding, continuing this process until the cavity was full. The wedge, having a smooth end and sides, is forced into the center so as to drive the tin toward the sides of the cavity, being careful not to split the tooth; the opening is then filled with a cylinder. Now force a smaller-sized wedge into the center of the last cylinder, and into the opening introduce another cylinder, proceeding in this manner until the filling is solid. Then condense the ends of the cylinders, trim, and burnish. For the same operation more recent pluggers are wedge-shaped, with sharp, deep serrations. In these cases the filling is retained by the general form of the cavity and wedging within a certain limit, and not by cohesion of the different parts. For a time tin cylinders were prepared and put on sale at the dental depots.
As far as we are aware, the first tin foil made use of in operative technics was by Dr. F. S. Whitslar, who removed a disk of German silver from an ivory knife-handle in 1845, then used hand pressure to fill the cavity with tin. In the college course of operative technics tin foil can be used, almost to the exclusion of gold foil, to demonstrate the manipulation of both cohesive and non-cohesive gold. Shavings scraped from a bar of tin are also useful in operative technics; they are more cohesive than foil.
Transcriber's Note: Minor typographical errors have been corrected without note. Variant and obsolete spellings, particularly chemical terms, have been retained.