Step 1. The fracture is first reduced. While the apparatus is being fitted, the recurrence of the displacement is prevented by the hands of an assistant, or by lacing the teeth together with stout silk or wire. It is well also to wet the patient’s chin with a sponge and cold water, to prevent the gutta-percha from sticking to his beard while it is soft.

Step 2. A piece of gutta-percha is prepared 2½ inches wide and long enough to reach from one angle of the jaw to the other when passing in front of the chin. This is softened thoroughly by immersion in boiling water, and when quite pliable should be quickly removed from the hot and plunged for a moment into cold water: if a towel be previously laid in the hot basin, the gutta-percha can be lifted on it without stretching. It should be laid on a table, and its surface sponged with cold water to prevent it sticking to the skin, it is then slit from each end into tails 1 inch and 1½ inch wide, leaving 2 inches uncut at the centre. So prepared, the splint is applied to the jaw with the middle pressing against the chin, the narrower ends being carried horizontally backwards to the angles of the jaw; the broader part is next bent up beneath the chin, its ends overlapping the horizontal ones. While the splint is still soft, the surgeon presses it firmly upwards that the gutta-percha may mould itself accurately to the chin. When set, the splint is removed, trimmed, and punched with holes here and there for evaporation. A covering of wash-leather may be added, if desired. When the splint is finished, it is replaced on the chin. If sole leather or pasteboard be used instead of gutta-percha, they must be prepared in the same way, but allowed to remain on the chin twenty-four hours that they may set before the final trimming and adjustment.

Step 3. A bandage, 4 inches wide and 1½ yard long, and slit from each end to about 2 inches from the centre, is then applied to the splint, and a small pad of folded flannel should be placed at the nape of the neck to protect the skin from the crossed bandage. When all is ready, the two upper ends are carried behind the neck, crossed, drawn tight, and tied or pinned on the forehead; the lower ends are carried upwards, taking a turn round the first pair at the temples, and fastened at the vertex (see fig. 23).

Fig. 23.—Outside splint for fracture of the lower jaw.

The ligatures that may have been used on the teeth can now be removed, or if they cause no pain, they may be left for a week or two.

It is a useful precaution to place a piece of soap plaster spread on soft leather, under the chin and along the throat, to protect the skin from the chafing of the splint while it is worn.

Sometimes the jaws close too nearly to allow food to be taken between them. It is then necessary to place a thin wedge of softened gutta-percha, 1½ inch long, ½ inch wide, and about ⅓ inch thick, between the molars on each side. The gutta-percha must not be softened much, or when the bite is taken the teeth will pass through it. These plugs should be omitted unless absolutely required, as the fragments keep a better position without them.

On emergency, when gutta-percha, leather, or pasteboard are not at hand, the jaw may be set, and then kept in position by a four-tail bandage, made from a pocket-handkerchief, until more complicated apparatus can be prepared.

The apparatus must be worn five weeks before it is laid aside and mastication permitted.