"Instructions for Making Instruments from PianoWire for the Removal of the Contents of Pulp-Canals. -The very best quality of piano-wire, of No. 20 or No. 22 standard wire or plate gauge, should be used.

"It should be cut into lengths of three inches, and should then be filed down to the required size and taper. The wire should commence to taper at one and one-half inches from the point, while the last half inch should be of nearly uniform size.

"Three sizes of these instruments are all that are needed, and they should measure, at the smallest diameter, 0.007, 0.010, and 0.013 of an inch, respectively, before the hook is made; with the hook they should measure o.010, 0.014, and 0.017 of an inch.

"When the wire is reduced to the required size, the hook is to be formed by placing the wire on an anvil, or other smooth hard surface, and holding the smooth edge of a thin knife blade upon it, near the end of the wire, when the wire is to be drawn up sharply and tightly, making a hook with a somewhat acute angle. The hook can then be honed down to the desired length.

"The instruments should then be fastened in small handles, which can be procured of dealers in watchmakers' supplies for twenty-five cents a dozen, or they can be easily made from any soft or hard wood.

"Piano-wire should never be heated, and should be filed lengthwise."

"Method of Rendering Swiss Broaches of Spring Temper. To draw Swiss broaches to a spring temper they should be placed on a steel, iron, or brass plate, one-eighth of an inch in thickness and three inches square. This should be held by pliers or forceps over the flame of a spirit lamp, and be kept continually moving over it, so as to keep the plate as uniformly heated as possible. The broaches should be watched very carefully, and when they become of a dark-blue color they should be dropped in cold water."

"Method of Rendering Swiss Broaches Completely Soft. -A piece of tin may be cut and bent so as to make a rough

box, two and one-half inches long by one inch square. This should be filled half full of slaked lime, and the broaches-one, two, or three dozen--placed in the middle of the lime, and the box then filled over them. This should then be heated to a red heat, either with the blowpipe or in a stove fire, and then allowed to gradually cool. They can then be polished by holding them flat on a hard smooth surface and rubbing them lengthwise with oo emery paper.

"Broaches rendered soft in this manner are very tough and can hardly be broken, and are safer for use in places difficult of access than those of spring temper.

"They should be fastened in small handles, or used in the universal broach holder."*

INSTRUMENTS.

The number and variety of dental instruments now manufactured is so great that it would be impossible to describe or name them in this work, and a description of important classes only will be attempted.

Excavators are made in great variety of form, the principal of which are hatchets, hoes and spoons.

We have the following in various sizes:

The right-angle hatchet (Fig. 4), the obtuse-angle hatchet (Fig. 5), the acute-angle hatchet (Fig. 6), hoes of the various

"Management of Pulpless Teeth." Chicago, 1887.

sizes (Fig. 7), spoons (Fig. 8). Fig. 9 shows a style of excavator in which the cutting edge is brought on a line with the handle, thus working with much greater ease and steadiness than the ordinary style.

FIG. 6.

FIG. 7.

FIG. 8.

All these instruments are also made with two angles in the shank. (Fig. 10.) They are also made in pairs, curved to cut right and left.

FIG. 9.

FIG. 10.

Chisels of various sizes and forms are useful in breaking down the edges of cavities, dressing down the exposed edges of enamel and removing decayed dentine.

A class of these instruments, known as Head's Excavators

-shown in Fig. 11-gives a variety of forms which enables the operator to cut in every direction.

0

FIG. II.

Another class are known as hard bits, the cutting edges of which are right angles, and the temper very hard. They are very effective in dressing away enamel, as they cut smoothly and evenly without chipping. They are shown in Fig. 12.

FIG. 12.

FIG. 13.

FIG. 14.

Each has eight cutting edges, and each edge will cut in two directions.

Two forms of drills are illustrated: the flat, square-pointed and the spear-pointed.

The flat, square-pointed are especially useful for drilling retaining pits (Fig. 13). The spear-pointed (Fig. 14) are

adapted for drilling enamel and dentine, to reach the pulp chamber, and for other purposes.

These are made in various sizes-some quite small, and with long, spring-tempered shanks, which allow them to be used in canals inaccessible to straight instruments that are not flexible. Burs are made in great variety of forms and sizes, as shown in Fig. 15. They are known as round, wheel, cone, inverted cone, bud, fissure and oval. These are made both for use as hand instruments and for the engine.

FIG. 15.

Instruments for Pulp Canals.-These consist of broaches, drills, reamers and pluggers. Broaches for removal of the

FIG. 16.

FIG. 17.

pulp are of various forms, as the barbed broach (Fig. 16), the fine, spring-tempered hook broach (Fig. 17).