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Mucogingival Surgery

Dentistry 664

Module G: Free Gingival Grafts

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Mucogingival Surgery Procedures

• Free gingival graft• Pedicle graft• Connective tissue graft• Coronally positioned flap• Frenectomy

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Free Gingival Grafts:

Gingival soft tissue grafts that are completely detached from one site

and transferred to a remote site

As previously noted, free gingival grafts are disconnected from their blood supply when they are harvested from the donor site. For the first three days after transplantation, their survival is totally dependent on the seepage of nutrients from a carefully prepared graft bed. This suggests that free gingival grafts are ill-suited for root-coverage procedures, because denuded root surfaces are avascular and have no potential to provide nutrients to a free soft tissue graft. In fact, the free gingival graft procedure has been modified for covering roots. This module will explain how this works.

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Root Coverage with Free Gingival Grafts

Example 1: The patient pictured above has severe gingival recession over the prominent root of a mandibular right canine. The patient is enrolled in a study of the efficacy of free gingival grafts for root coverage. In this photo, a reference stent and a compass are being used to obtain accurate gingival recession measurements. Note that this relatively broad area of recession is bordered mesially, distally and apically by intact soft tissue that could potentially be used as a large graft bed.

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A common feature of root coverage graft procedures of all types is that the existing marginal tissue must be removed before a soft tissue graft can be placed. Note that the marginal tissue has been removed and the adjacent interdental areas have been de-epithelialized to expose bleeding connective tissue.

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The graft bed has been dramatically extended in the mesial, distal and apical directions by split thickness dissection. The bed surface is connective tissue or periosteum. Notice that the area of the graft bed is considerably larger than the denuded root surface area. This provides a large area for nutrient exchange to allow the center portion of the soft tissue graft to survive over an avascular surface.

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This figure illustrates a cross sectional view of palatal mucosa. As shown above, there are relatively few capillary channels in a thin graft, more in a graft of intermediate thickness and even more in a thick graft. These capillary channels provide a means for nutrients to move from one part of a soft tissue graft to another. For example, these channels allow nutrients to move from the peripheral areas of a graft to its center. This is crucial for the survival of a free graft over an avascular root.

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A thick free soft tissue graft has been harvested from the posterior palate and carefully sutured over the graft bed. Notice that the graft is placed slightly coronal to the CEJ of the canine. Meticulous suturing maximizes adaptation of the graft to the bed and enhances the passage of nutrients from bed to graft. Capillary channels within the thick graft provide a means for nutrients to reach the portion of the graft that overlies the root surface.

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At the post-operative appointment ten days later, there has been some loss of tissue at the gingival margin, but substantially all of the graft survived. The beefy red appearance is typical of the early post-operative course of this type of graft.

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After 17 days, there is evidence of minor shrinkage of the graft. The red pinpoints throughout the graft are accessory salivary glands that are normally found in palatal mucosa. Note that a substantial amount of root surface has been covered.

Although not shown in this series, root surface conditioning with citric acid or tetracycline is frequently carried out in conjunction with root coverage grafts. Animal studies suggest that this treatment exposes collagen fibrils and removes the “smear layer” on the root surface. It also detoxifies the root surface. Human studies are relatively few and are less supportive of the benefits of root conditioning. Many periodontists condition the roots anyway, since this treatment has little or no potential to do any harm.

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After six months, maturation of the graft has resulted in an increase in its tensile strength. Epithelium appears more keratinized than before. The graft blends in relatively well with the adjacent tissue, but would never be mistaken for anything other than a graft. The thickness of the graft and pronounced keratinization contribute the graft’s relatively pale appearance.

It is important to note that the graft attached to the root surface during healing. This attachment and resultant shallow probing depth are compatible with gingival health. A graft that merely covered the root without attaching to it would be considered unsuccessful.

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Example 2: This patient has gingival recession and root exposure in the central incisor areas. There has never been a wide zone of attached gingiva over the lower central incisors and there is very little attached gingiva in evidence at this appointment. The patient has a recent history of orthodontic treatment to alleviate mandibular crowding. Facial movement of the incisors was accompanied by thinning of the bone and soft tissue covering the facial surface of the root. Over a period of nine months, the gingival margin receded. Note the inflamed appearance of the marginal tissue. Fortunately, there is much less root surface to cover in this patient than in the previous example. The narrow and somewhat shallow configuration of the recession enhances the success of root coverage by free soft tissue grafting.

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The graft bed was prepared by split thickness dissection of the mucosa mesial, distal, apical and coronal to the recession defects. De-epithelialization of the facial aspect of the interdental papillae is particularly important for graft survival.

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A thick rectangular graft was obtained from the posterior palate, trimmed to fit the bed and sutured to stabilize the graft so that contact with the graft bed was maximized. As in the previous example, the graft was positioned slightly coronal to the CEJ of the central incisors.

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At the ten day post-operative appointment, there has been some retraction of the marginal tissue, but overall graft survival is excellent. It is essential that the patient avoid traumatizing the graft during the first week or two of healing.

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After suture removal, the bulkiness of the soft tissue graft is evident. At this early post-operative stage, the site exhibits unambiguous signs of inflammation.

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After eight weeks of healing, inflammation has resolved and the site looks healthy. Almost all of the denuded root surfaces were covered in this procedure. The probing depths facial to the lower central incisors are shallow and there is firm attachment of the soft tissue graft to the root. The palatal donor site (not shown) healed by second intention.

The next two modules will present alternative techniques for root coverage. They will use a different approach to providing nutrients to the soft tissue graft.