This branch of surgery has to do with the plastic restoration of the oral orifice. Operations of this kind are required to enlarge a contracted mouth, termed microstoma, whether the same be due to congenital origin or to cicatricial contraction after operative interference about this origin. Stomatoplasty may also be needed to rebuild an abnormally enlarged mouth, termed macrostoma, which has already been described on page 149. THE CORRECTION OF MACROSTOMA The operative methods to correct the latter need little mention, since there is usually sufficient tissue present from which the orifice can be properly formed. The simplest method is to excise the borders of the enlarged mouth or buccal clefts, whether unilateral or bilateral, and to bring the raw edges together by suture. These sutures should be made nearly through the muscular walls of the cheek and at sufficient distance from the edges of the wounds to avoid tearing through. When the cleft is of sufficient length to warrant tension sutures, they may be employed, alternating with superficial sutures to neatly coapt the skin surfaces. The mucous membrane should also be sutured with fine silk to insure a perfect closure of the parts, and to avoid, as far as possible, intra-oral infection. When possible the vermilion borders of the lips should be neatly brought out to the angles of the mouth, where they should be sutured one to the other somewhat diagonally. This will tend to give the angles a normal appearance and shape. =Dieffenbach-Von Langenbeck Method.=—It is not unusual after the extirpation of a malignant growth that a greater part of the prolabium has been sacrificed in either of the lips. In this event the vermilion border must be carefully and neatly trimmed away from the healthy lip, leaving a median attachment (see Fig. 251). The two strips of prolabium will be found to stretch easily. They are utilized to line the entire denuded raw surface and are held in position by a number of fine silk sutures, as shown in Fig. 252. [Illustration: FIG. 251. FIG. 252. DIEFFENBACH-VON LANGENBECK METHOD.] Accessory mobilizing incisions, as shown in the above figures, may be necessary to contract the oral orifice sufficiently to permit of such a prolabial grafting, especially where a greater part of the vermilion border has been destroyed. These extra incisions are not necessary when only a small part of the latter is lost; a partial unilateral dissection in that case would suffice to restore the part. This prolabial lining of the mouth gives it a puckered and contracted appearance for a time only, because the parts soon stretch, while oral gymnastics will help much in restoring its size and usefulness. The objection to the above method is the danger of partial or total gangrene of that part of the prolabium which has been dissected up and stitched to line the mouth as a result of lack of nutrition or to the bruising or rough handling of the delicate strips during the operation.