Types of Mucoperiosteal Flaps
A variety of intraoral tissue flaps can be used. The most common incision is the envelope or sulcular, incision, which produces the envelope flap. In the dentulous patient the incision is made in the gingival sulcus to the crestal bone, through the periosteum, and the full thickness mucoperiosteal flap is apically reflected see (fig. 8-2, A). This usually provides sufficient access to perform the necessary surgery.
If the patient is edentulous, the envelope incision is.made along the scar at the crest of the ridge. No vital structures are found in this area, and the envelope incision can be as long as is required to provide adequate access. The tissue can be reflected buccally or lingually as necessary for the removal of a mandibular torus.
If the envelope incision has a vertical-releasing incision,it is a three-cornered flap, with corners at the posterior end of the envelope incision, at the inferior aspect of the vertical incision, and at the superior aspect of the vertical-releasing incision (Fig. 8-S). This incision provides for greater access with a shorter envelope incision. When greater access is necessary in an apical direction, especially in the posterior aspect of the mouth, this incision is frequently necessary. The vertical component is m0re difficult to close and may cause some mildly prolonged healing, but if care is taken when suturing, the healing period is not noticeably lengthened.
The four cornered flap is an envelope incision with two releasing incisions. Two corners are at the superior aspect of the releasing incision and two corners are at either end of the envelope component of the incision (Fig. 8-6). Although this flap provides substantial access in areas that have limited anteroposterior dimension it is rarely indicated. When releasing incisions are necessary a three cornered flap usually suffices.
An incision that is used occasionally to approach the root apex is a semilunar incision (Fig. 8-7): This incision avoids trauma to the papillae and gingival margin but provides limited access because the entire root of the tooth is not visible. This incision is most useful for periapical surgery of a limited extent. The horizontal component of the semilunar incision should not cross major prominences such as the canine eminence.
Two incisions are useful on the palate The first is the Y incision, which is named for its shape. This incision is useful for surgical access to the bony palate for removal of a maxillary palatal torus. The tissue overlying the torus is usually quite thin and must be reflected carefully. The anrerolateral extensions of the midline incision are anterior to the region of the canine tooth. They are anterior enough in this position that they do not sever major branches of the greater palatine artery therefore bleeding is not usually a problem (Fig. 8-8).
Another flap that is used occasionally on the palate is the pedicle flap. This flap mobilizes from one area and then rotates to fill a soft tissue defect in another area. The pedicled palatal flap is used primarily for closure of oroantral communications (see Chapter 19).