The Periodontal Flap

Classification of Flaps

Periodontal flaps can be classified on the basis of the following:

For bone exposure after reflection, the flaps are classified as either full-thickness (mucoperiosteal) or partial-thickness (mucosal) flaps (Figure 57-1).

In a full-thickness flap, all of the soft tissue, including the periosteum, is reflected to expose the underlying bone. This complete exposure of and access to the underlying bone is indicated when resective osseous surgery is contemplated.

The partial-thickness flap includes only the epithelium and a layer of the underlying connective tissue. The bone remains covered by a layer of connective tissue that includes the periosteum. This type of flap is also called the split-thickness flap. The partial-thickness flap is indicated when the flap is to be positioned apically or when the operator does not want to expose bone.

Conflicting data surround the advisability of uncovering the bone when this is not actually needed. When bone is stripped of its periosteum, a loss of marginal bone occurs, and this loss is prevented when the periosteum is left on the bone.⁴ Although this is usually not clinically significant,⁷ the differences may be significant in some cases (Figure 57-2). The partial-thickness flap may be necessary when the crestal bone margin is thin and exposed with an apically placed flap or when dehiscences or fenestrations are present. The periosteum left on the bone may also be used for suturing the flap when it is displaced apically.

For flap placement after surgery, flaps are classified as either (1) nondisplaced flaps, when the flap is returned and sutured in its original position, or (2) displaced flaps, which are placed apically, coronally, or laterally to their original position. Both full-thickness and partial-thickness flaps can also be displaced. However, to do so, the attached gingiva must be totally separated from the underlying bone, thereby enabling the unattached portion of the gingiva to be movable. Palatal flaps cannot be displaced because of the absence of unattached gingiva.

Apically displaced flaps have the important advantage of preserving the outer portion of the pocket wall and transforming it into attached gingiva. Therefore, these flaps accomplish the double objective of eliminating the pocket and increasing the width of the attached gingiva.

For the management of the papilla, flaps can be conventional or papilla preservation flaps. With the conventional flap, the interdental papilla is split beneath the contact point of the two approximating teeth to allow for the reflection of the buccal and lingual flaps. The incision is usually scalloped to maintain gingival morphology and to retain as much papilla as possible. The conventional flap is used (1) when the interdental spaces are too narrow, thereby precluding the possibility of preserving the papilla, and (2) when the flap is to be displaced.

Conventional flaps include the modified Widman flap, the undisplaced flap, the apically displaced flap, and the flap for reconstructive procedures. These techniques are described in detail in Chapter 59.

The papilla preservation flap incorporates the entire papilla in one of the flaps by means of crevicular interdental incisions to sever the connective tissue attachment as well as a horizontal incision at the base of the papilla to leave it connected to one of the flaps.

Flap Design

The design of the flap is dictated by the surgical judgment of the operator, and it may depend on the objectives of the procedure. The necessary degree of access to the underlying bone and root surfaces and the final position of the flap must be considered when designing the flap. The flap design may also be dictated by the aesthetic concerns of the area of surgery. Preservation of good blood supply to the flap is another important consideration.

Two basic flap designs are used. Depending on how the interdental papilla is managed, flaps can either split the papilla (conventional flap) or preserve it (papilla preservation flap).

For the conventional flap procedure, the incisions for the facial and the lingual or palatal flap reach the tip of the interdental papilla or its vicinity, thereby splitting the papilla into a facial half and a lingual or palatal half (Figures 57-3 and 57-4).

The entire surgical procedure should be planned in every detail before the procedure is initiated. This should include the type of flap, the exact location and type of incisions, the management of the underlying bone, and the final closure of the flap and sutures. Although some details may be modified during the actual performance of the procedure, detailed planning allows for a better clinical result.

Incisions

Periodontal flaps involve the use of horizontal (mesial–distal) and vertical (occlusal–apical) incisions.

Horizontal Incisions

Horizontal incisions are directed along the margin of the gingiva in a mesial or distal direction. Two types of horizontal incisions have been recommended: the internal bevel incision,⁶ which starts at a distance from the gingival margin and which is aimed at the bone crest, and the crevicular incision, which starts at the bottom of the pocket and which is directed to the bone margin. In addition, the interdental incision is performed after the flap is elevated to remove the interdental tissue.

The internal bevel incision is basic to most periodontal flap procedures. It is the incision from which the flap is reflected to expose the underlying bone and root. The internal bevel incision accomplishes three important objectives: (1) it removes the pocket lining; (2) it conserves the relatively uninvolved outer surface of the gingiva, which, if apically positioned, becomes attached gingiva; and (3) it produces a sharp, thin flap margin for adaptation to the bone–tooth junction. This incision has also been termed the first incision, because it is the initial incision for the reflection of a periodontal flap; it has also been called the reverse bevel incision, because its bevel is in reverse direction from that of the gingivectomy incision. The no. 15 or 15C surgical blade is used most often to make this incision. That portion of the gingiva left around the tooth contains the epithelium of the pocket lining and the adjacent granulomatous tissue. It is discarded after the crevicular (second) and interdental (third) incisions are performed (Figure 57-5).

The internal bevel incision starts from a designated area on the gingiva, and it is then directed to an area at or near the crest of the bone (Figure 57-6). The starting point on the gingiva is determined by whether the flap is apically displaced or not displaced (Figure 57-7).

The crevicular incision, which is also called the second incision, is made from the base of the pocket to the crest of the bone (Figure 57-8). This incision, together with the initial reverse bevel incision, forms a V-shaped wedge that ends at or near the crest of bone. This wedge of tissue contains most of the inflamed and granulomatous areas that constitute the lateral wall of the pocket as well as the junctional epithelium and the connective tissue fibers that still persist between the bottom of the pocket and the crest of the bone. The incision is carried around the entire tooth. The beak-shaped no. 12D blade is usually used for this incision.

A periosteal elevator is inserted into the initial internal bevel incision, and the flap is separated from the bone. The most apical end of the internal bevel incision is exposed and visible. With this access, the surgeon is able to make the third incision, which is also known as the interdental incision, to separate the collar of gingiva that is left around the tooth. The Orban knife is usually used for this incision. The incision is made not only around the facial and lingual radicular area but also interdentally, where it connects the facial and lingual segments to free the gingiva completely around the tooth (Figure 57-9; see Figure 57-5).

These three incisions allow for the removal of the gingiva around the tooth (i.e., the pocket epithelium and the adjacent granulomatous tissue). A curette or a large scaler (U15/30) can be used for this purpose. After the removal of the large pieces of tissue, the remaining connective tissue in the osseous lesion should be carefully curetted and removed so that the entire root and the bone surface adjacent to the teeth can be observed.

Flaps can be reflected with the use of only the horizontal incision if sufficient access can be obtained in this way and if apical, lateral, or coronal displacement of the flap is not anticipated. If vertical incisions are not made, the flap is called an envelope flap.

Vertical Incisions

Vertical or oblique releasing incisions can be used on one or both ends of the horizontal incision, depending on the design and purpose of the flap. Vertical incisions at both ends are necessary if the flap is to be apically displaced. Vertical incisions must extend beyond the mucogingival line to reach the alveolar mucosa; this allows for the release of the flap to be displaced (see Chapter 59).

In general, vertical incisions in the lingual and palatal areas are avoided. Facial vertical incisions should not be made in the center of an interdental papilla or over the radicular surface of a tooth. Incisions should be made at the line angles of a tooth either to include the papilla in the flap or to avoid it completely (Figure 57-10). The vertical incision should also be designed to avoid short flaps (mesiodistal) with long, apically directed incisions, because this could jeopardize the blood supply to the flap.

Several investigators proposed the interdental denudation procedure, which consists of horizontal, internal bevel, nonscalloped incisions to remove the gingival papillae and to denude the interdental space.^1,2,11,12 This technique completely eliminates the inflamed interdental tissue. Healing is by secondary intention and results in excellent gingival contour. It is contraindicated when bone grafts are used and the graft material placed interdentally will not be covered. It is also contraindicated in aesthetic areas such as the maxillary anterior segment, because the papilla will be lost.

Elevation of the Flap

When a full-thickness flap is desired, reflection of the flap is accomplished via blunt dissection. A periosteal elevator is used to separate the mucoperiosteum from the bone by moving it mesially, distally, and apically until the desired reflection is accomplished (Figure 57-11).

Sharp dissection is necessary to reflect a partial-thickness flap. A surgical scalpel (no. 15) is used (Figure 57-12).

A combination of full-thickness and partial-thickness flaps may be indicated to obtain the advantages of both. The flap is started as a full-thickness procedure, and then a partial-thickness flap is made at the apical portion. In this way, the coronal portion of the bone—which may be subject to osseous remodeling—is exposed, whereas the remaining bone is protected by the periosteum. After the flap is reflected, the osseous shape and contour is examined, and the necessary osseous correction is accomplished. The root surface is than carefully root planed, and the flap is replaced and ready to be sutured.

Suturing Techniques

After all of the necessary procedures are completed, the area is reexamined and cleansed, and the flap is placed in the desired position. The flap should remain in this position without tension. It is convenient to keep the flap in place with light pressure via the use of a piece of gauze to allow the blood clot to form.

The purpose of suturing is to maintain the flap in the desired position until healing has progressed to the point at which sutures are no longer needed.

There are many types of sutures, suture needles, and materials.^5,10 Suture materials may be either nonresorbable or resorbable, and they may be further categorized as braided or monofilament (Box 57-1). The resorbable sutures have gained popularity because they enhance patient comfort and eliminate suture removal appointments.

The monofilament type of suture alleviates the “wicking effect” of braided sutures that may allow bacteria from the oral cavity to be drawn through the suture to the deeper areas of the wound.

The braided silk suture was the most common nonresorbable suture used in the past because of its ease of use and low cost. The expanded polytetrafluoroethylene, synthetic, monofilament suture is an excellent nonresorbable suture that is widely used today.

The most common resorbable sutures used today are the plain and chromic gut sutures. Both are monofilaments, and both are processed from purified collagen of either sheep or cattle intestines. The chromic suture is a plain gut suture that has been processed with chromic salts to make it resistant to enzymatic resorption, thereby increasing the resorption time. The synthetic resorbable sutures are also often used.

Technique

The needle is held with the needle holder, and it should enter the tissues at right angles and be no less than 2 mm to 3 mm from the incision. The needle is then carried through the tissue, where it follows the needle's curvature. The knot should not be placed over the incision.

The periodontal flap is closed either with independent sutures or with continuous, independent sling sutures. The latter method eliminates the pulling of the buccal and lingual or palatal flaps together and instead uses the teeth as an anchor for the flaps. The flaps are less likely to buckle, and the forces on the flaps are better distributed.

Sutures of any type that are placed in the interdental papillae should enter and exit the tissue at a point located below the imaginary line that forms the base of the triangle of the interdental papilla (Figure 57-13). The location of sutures for the closure of a palatal flap depends on the extent of flap elevation that has been performed. The flap is divided into four quadrants as depicted in Figure 57-14.

If the elevation of the flap is slight or moderate, the sutures can be placed in the quadrant closest to the teeth. If the flap elevation is substantial, the sutures should be placed in the central quadrants of the palate.

The clinician may or may not use periodontal dressings. When the flaps are not apically displaced, it is not necessary to use dressings other than those needed for patient comfort.

Ligation

Interdental Ligation.

Two types of interdental ligation can be used: the direct loop suture (Figure 57-15) and the figure-eight suture (Figure 57-16). With the figure-eight suture, thread is placed between the two flaps. This suture is used when the flaps are not in close apposition as a result of apical flap position or nonscalloped incisions. This is simpler to perform than the direct ligation. The direct suture allows for a better closure of the interdental papilla. It should be performed when bone grafts are used or when close apposition of the scalloped incision is required.

Sling Ligation

The sling ligation can be used for a flap on one surface of a tooth that involves two interdental spaces (Figure 57-17).

Types of Sutures

Horizontal Mattress Suture.

The horizontal mattress suture is often used for interproximal areas of diastemata or for wide interdental spaces to adapt the interproximal papilla properly against the bone. Two sutures are often necessary. The horizontal mattress suture can be incorporated with the continuous, independent sling sutures as shown in Figure 57-18.

The penetration of the needle is performed in such a way that the mesial and distal edges of the papilla lie snugly against the bone. The needle enters the outer surface of the gingiva and crosses the undersurface of the gingiva horizontally. The mattress sutures should not be close together at the midpoint of the base of the papilla. The needle reappears on the outer surface at the other base of the papilla and continues around the tooth with the sling sutures.

Continuous, Independent Sling Suture.

A sling suture is used when both a facial flap and a lingual flap are used and when they involve many teeth. The continuous, independent sling suture is initiated on the facial papilla closest to the midline, because this is the easiest place to position the final knot (Figure 57-19). A continuous sling suture is laced for each papilla on the facial surface. When the last tooth is reached, the suture is anchored around it to prevent any pulling of the facial sutures when the lingual flap is sutured around the teeth in a similar manner. The suture is again anchored around the last tooth before the final knot is tied.

This type of suture does not pull on the lingual flap when this flap is sutured. The facial and lingual flaps are completely independent of each other as a result of the anchoring around both the initial tooth and the final tooth. The flaps are tied to the teeth and not to each other because of the sling sutures.

Continuous, independent sling suturing is especially appropriate for the maxillary arch. This is true because the palatal gingiva is attached and fibrous, whereas the facial tissue is thinner and mobile.

Anchor Suture.

The closing of a flap mesial or distal to a tooth, as in the mesial or distal wedge procedures, is best accomplished by the anchor suture. This suture closes the facial and lingual flaps and adapts them tightly against the tooth. The needle is placed at the line–angle area of the facial or lingual flap adjacent to the tooth, anchored around the tooth, passed beneath the opposite flap, and tied. The anchor suture can be repeated for each area that requires it (Figure 57-20).

Closed-Anchor Suture.

Another technique to close a flap that is located in an edentulous area mesial or distal to a tooth consists of tying a direct suture that closes the proximal flap, carrying one of the threads around the tooth to anchor the tissue against the tooth, and then tying the two threads (Figure 57-21).

Periosteal Suture.

The periosteal suture is used to hold the apically displaced partial-thickness flaps on the periosteum. There are two types of periosteal sutures: the holding suture and the closing suture. The holding suture is a horizontal mattress suture that is placed at the base of the displaced flap to secure it into the new position. Closing sutures are used to secure the flap edges to the periosteum. Both types of periosteal sutures are shown in Figure 57-22.

Conclusion

Periodontal flap surgery is the most widely used surgical procedure to reduce the pocket depth. Periodontal flaps are designed to preserve gingival integrity and to gain access to root surfaces for residual calculus removal and to thoroughly remove granulation tissue so that bone defects can be visualized and treated. Gentle and efficient procedures result in optimum healing and minimal postoperative pain. When flaps need to be repositioned apically or, less often, coronally, then the flaps must sit passively at the appropriate level before suturing. To ensure this, buccal and lingual flaps need to be elevated beyond the mucogingival junction so that the elasticity of the mucosa allows for flap mobility. Sometimes it may be necessary to extend the flap elevation apically with a split incision approach to minimize the effect of the less elastic periosteum. Vertical incisions can aid in flap positioning by allowing the clinician to suture the flap at a different level to the adjacent untreated gingiva.

Palatal flaps are less mobile as a result of the absence of oral mucosa, so the apical position of the flap depends on how much marginal gingival tissue is discarded with the use of a reverse bevel incision. The more apical positioning desired, the more extensive is the reverse bevel cut. Palatal flaps are more difficult to position coronally than buccal or lingual flaps. Thus, if it is required to position flaps coronally or even at their original levels, then a sulcular incision is used. During osseous periodontal surgery, flaps are apically positioned to minimize postoperative pocket depth. During regenerative periodontal surgery, soft-tissue coverage of bony defects, graft materials, membranes, and biologic agents is important, so sulcular incisions and tight suturing techniques are crucial.