Free Gingival Grafts
by Dinh X. Bui, D.D.S., M.S.

Free Gingival Grafts
By Dinh X. Bui, D.D.S., M.S.

In the past, mucogingival surgery are periodontal surgical procedures used mainly to achieve a functionally adequate zone of keratinized attached gingiva. The five conditions of which gingival surgery was employed are: shallow vestibule, pocket beyond the mucogingival line, inadequate amount of attached gingiva, frenum pull, and localized recession. Today, with the advance of technology in oral hygiene, the shallow vestibule is no longer a problem as in the past, since shallow vestibule prevent the effective used of the tooth brush (in the past, tooth brush was large and the bristle was hard, which could traumatized the soft tissue. The brush had to be used angle upward toward teeth). For the case of pocket beyond mucogingival surgery, reposition flap is now used with expectation of better result. Localized recesson now is treated with pedicle or connective tissue graft, which produced more acceptable tissue color match. Thus today the mucogingival surgery is used to correct defects in morphology, position, and/or amount of gingiva. Free gingival graft was the method of choice to increase the amount of attached gingiva. It is also used in conjunctin of frenotomy to provide a deeper vestibule and prevent the reattached of the frenum.

Increase the amount of attached gingiva has been a major issue in the past. Friedman in 1962 stressed that keratinized attached gingiva is capable of withstand the stresses of mastication, tooth brushing, trauma from the foreign objects, subgingval restoration preparation, inflammation, and frenum pull. In 1979, Goldman and Cohen outlined the “tissue barrier” concept, demonstrated that the keratinized attached mucosa is consisted of a band of dense collagenous connective tissue and can retard or obstruct the spread of inflammation better than the loose connective tissue fiber arrangement of alveolar mucosa. This zone of keratinized attached gingiva can be augmented to improve the inflammation problem in the area of recession. This viewpoint is supported by Lindhe et al. (1973), Baker and Seymour (1976), Rubin (1979), and Lindhe and Nyman (1980). Ericsson and Lindhe in 1984 states that it is necessary to increase this zone of healthy tissue if it is subjected to the trauma of prosthetic treatment. This concept also is applied to the case of orthodontic restoration as investigated by Maynard and Oschenbein in 1975. Baker and Seymour in 1976 investigated the cases of rapidly progressing recession and also stressed the importance of keratinized attached gingiva as part of the healthy periodontal complex. But how much is the level of adequae attached gingiva? Bowers described the distribution of attached gingiva and found that in the maxillary, the amount of attached gingiva is smallest at the cuspids and bicuspids, and increased anteriorly and posteriorly in the buccal, whereas the palate is all attached gingiva. In the mandibular, the amount of attached gingiva increase anteroposteriorly, with the anterior incisors posess the least amount of attached gingiva. Waerhaug noted that the cuspids and the bicuspids which possesses the least attached keratinized tissue are the least involved periodontally, whereas the incidence of the disease is greatest on the lingual and palatal surfaces where the amount of keratinized tissue is the greatest. Lindhe and Nyman in 1980 examined the alterations of the gingival margin position on the buccal surfaces of human teeth professionally maintained for 10 or 11 years following periodontal surgery. He found that regardless of the amount of attached gingiva, changes observed in the gingival margin position on the buccal surfaces were similar. Dorfman et. al. (1980) also showed that site with or without attached gingiva maintain attachment over a long period of time. Hangorsky and Bissada in 1980 also demonstrated that the absence of keratinized gingiva does not jeopardize the gingival health. Wennstrom in her five year longitudinal study on 26 buccal sites surgically deprived of all gingival tissue has demonstrated the lack of association between the width of the attached gingiva and development of soft tissue recession (1987). Thus there is a controversial issue which concerns the importance of keratinized attached gingiva. No minimal width of attached gingiva has been established as the standard necessary for gingival health. Persons who practiced excellent oral hygiene may maintain healthy areas with almost no attached gingiva. However, in those individual whose oral hygiene practices are less than optimal can be helped with a wider band of keratinized gingiva and vestibular depth, which provides room for placement of toothbrush and facilitate oral hygiene effort. Moreover, teeth with subgingival restoration, teeth that served as abutment for fixed or removable partial dentures, or those teeth that are in position which subjected themselves to higher stress and insult can be better protected from inflammation with a wider band of attached gingiva. Minimal attached gingiva with good vestibular depth may not require mucogingival surgery, but the same minimal amount of attached keratinized gingiva with no vestibular depth will usually benefit from mucogingival correction. Carranza described three situations which may result in a reduced or absent of attached gingival: a) the base of the periodontal pocket being apical or close to the mucogingival line, b) the frenal and muscle that encroach on periodontal pockets and pull them away from the tooth surface, and c) recession causing denudation of root surfaces. Lang and Loe in 1972 shows that in people with good oral hygiene, 1mm or less of keratinized tissue is adequate. Their work in 1975 along with Karring also depicted that it is a connective tissue possesses the genetic code that instructed the epithelium to keratinize. Tissue maintains specificity. These concepts serve as the bases for today mucogingival surgery. Functional adaptation, as believed in the past that gingival tissue become keratinized where it is required and needed, does not exist because the local environment (plaque and inflammation) prevents the genetic expression. Today, the indication for gingival graft concerning the attached gingiva issue should be based on the presence of progressive gingival recession and inflammation. Another word, if recession continues to progress after a period of a few months with good plaque control, the graft can then be placed. This is especially true in the case of the recession reduced the vestibular depth and thus prevent the correct angulation of toothbrush head into the dentogingival junction.

Originally, bone denudation procedures were the popular choices to regenerate attached gingiva. Fox introduced the push back procedure where he demonstrated the concept of functional adaptation ( the tissue is genetically programmed to produce keratinized attached gingiva where it is required functionally). Full thickness flap was raised, the giniva was relocated apically, and bone left denuded. Peridontal dressing then was packed to protect the wound. Upon regeneration, the keratinized attached gingiva was reestablished by functional adaptation. However, the crestal bone loss was observed due to bone exposed. Healing was slow and painful with tissue migrated up the denuded bone surface. The procedure could only performed in the anterior area, where tissue can be relocated apically. Later, modification of the technique was employed by Schluger to perform in the area of posterior mandible. He termed this operation the pouch technique. Instead of relocating the gingival margin of the flap apically, he pack the dressing between the bone and the flap. Again healing was slow and painful, coupled with alveolar bone loss. Histological studies by Wilderman, Wentz, and Orban showed that tissue will heal but bone will disappear. Bone denudation technique results in healing with anatomical defbrmity. The thinner the bone, upon denuded, the more bone loss resulted. Bone thus needed to be protected. In addressing this issue, Goldman and Stewart developed the technique of periosteal retention. Split thickness flap was raised, leaving periosteum layer to protected the bone. This area will granulated in following a healing process. Harry Staflileno and Orban showed this flap operation heals better than the bone denudation procedure. However, Costich and Ramjford showed that the difference between bone denudation and the periosteal retention technique is mainly quantitative rather than qualitative. If bone is thin, the bone will necrose in both case of denudation and periosteal retention. Carranza, Glickman, and Donfefdnian pointed out that the mucogingival level is initially relocated apically but then will move coronally in the case of periosteal retention. However, in the case of bone denudation, the scar tissue occur at the most apical area and prevent the coronal movement of the new mucogingival level. As the result, scorring of the bone was used to produce a scar to prevent this coronal migration of the level of keratinized attached gingiva. Thus the situation required the “scarring” effect of the bone denudation procedure to prevent the coronal migration, and the “protection” effect of periosteal retention procedure to prevent the alveolar bone loss and provided better healing. Robinson addressed this issue by introducing the periosteal fenestration technique. In this procedure, split thickness flap was initially to protect the bone. However, at the level of where “new” mucogingival line is anticipated, the window through the bone of 5mm in width was produced. The effect of this window or “fenestration” is similar to that of the bone denudation procedure, which ultimately produced a scar to producea stable mucogingival line. Split thickness flap was raised to prevent the bone loss with the protection of the periosteum. Finally, Oschenbein introduced the double flap, of which he combined both the split thickness flap and the periosteal flap to produce the similar result. The split thickness flap was raised, reflected, followed by the raising of the periosteal flap (connective tissue and the periosteum). The bone reduced, periosteal flap readapted, and then the split thickness flap is then suture apically to the original level. Thus again the protection of the bone was established by the split thickness flap and the scar tissue (bone reduction) was established to prevent the coronal migration of the new mucogingival line. (The concept of bone protection with tissue coverage is also addressed in the Edlan-Mejchar techquique of deepening the vestibule, with the flip flop of the raised split thickness flap and the periosteal flap to produce a deepen vestibule). Current studies today have shown that all these procedures are no longer valid. Functional adaptation does not exist as the local environmental factors such as plaque and functional trauma can prevent the genetic expression which produced keratinized gingiva from occuring. Dale L. Wood, Phillip Hoag, 0. Walter Donnenfeld, and Leon Rosenfeld in 1972 revealed the loss of crestal radicular bone after both the full thickness and the partial thickness flap. The mean bone loss for the full thickness flap was .62mm, which was statistically significant (p>.0 1). The mean bone loss for the partial thickness flap was .98mm, which was also significant. Comparing the two result, the partial thickness flap actually produced more bone loss than the full thickness flap. The partial thickness flap resulted in a thin layer of connective tissue which provided significant osteoclastic activity. The compromise blood supply in the partial thickness flap also produced the necrosis of the flap margin and lead to the resorption of the bone underneath. Partial thickness flap is not recommended in areas of thin connective tissue. The introduction of the free gingival graft puts an end to all of the bone denudation, periosteal retention, periosteal fenestration, and double flap procedure.

Free gingival graft is the most versatile, most widely used, and most predictable pure mucogingival procedure today. Its application involved its use to increase the band of attached gingiva and to cover the exposed root. The advantage is that it can be done to a single or a oroup of teeth with a very high predictability of success. There is more source of donor tissue and can be done prophylactically if the recession or the inflammation is anticipated due to the area traumatized. Other advantage involved root coverage for functional esthetics and to prevent the progression of recession. The weakness of the procedure is that there are two surgical sites: the donor and the recipient site. Other weakness are the color mismatch between tissues and the unknown nature of its attachment to the root. Finally, the lack of predictability in attempting root coverage and the compromise blood supply to the graft must be mentioned.

The classic technique includes 5 phases: pocket elimination, recipient site preparation, graft harvesting from the donor site, transferring and immobilization of the graft, and donor site protection. Pocket elimination is performed via gingivectomy. Next the firm connective tissue bed is prepared with periosteum leaving intact at the recipient site. Next, a piece of keratinized oral mucosa of approximately the size of recipient site is obtained from the donor site and transfer to the recipient site, making sure of cleaning away excess clot prior to placement of the graft on the periosteal bed. A thick clot interferes with vascularization of the graft and serves as an excellent medium for bacteria and increase the risk of infection. The graft must be immobilized with the suture at the lateral borders to the periosteum. Movement will interfere with healing. Finally, the donor site is protected with periodontal pack for one week and repeat if necessary. A modified Hawley retainer is also useful to cover the pack on the palate and over the edentulous ridges.

Cohen described the current technique of the free gingival graft which involved preparation for the recipient site, the harvesting of the graft from the donor site, the placement of the graft and suture. If root coverage desired, epithelial denudation of marginal and papillary tissue is necessary. If not then only the submarginal incision is used. The initial incision is placed just at or below the mucogingival junction with blad parallel to the bone. The mucosal tissue is reflected, leaving the periosteal bed Next the periosteal bed is prepared such that the bed is overextended 6 to 8mm (exept where anatomically impossible such as mental nerve, external oblique ridge, and zygomatic arch) occlusoapical direction to compensate for primary and secondary shrinkage of the graft during healing. LaGrange curved scissors are recommended for the mandibular bicuspi area to prevent damage to mental nerve. The mucosal flap can be optionally suture apically for hemostasis. Next the donor site is prepared. The tin foil was used as the template for the size of the graft harvested. Thin, or intermediate-thickness grail (.5-.75mm) are ideal for increasing the zone of keratinized attached gingiva and undergo minimal primary contraction because of the amount of elastic fibers (Orban, 1966). The secondary shrinkage is the 25 to 450 0 contraction which is the result of cicatrization, which binds the graft to the underlying bed. This shrinkage is compensate in the periosteal bed preparation to extend 6-8mm in an occlusoapical direction. For the case of root coverage and ridge augmentation, the ideal thickness of the graft is 1.25 to 2mm. This is to have minimal secondary contraction but possess greater primary contraction when compared to the thinner graft. The area of choice for the donor site is the gingival zone distal to the anterior rugae on the posterior portion of the palate because this zone has the least amount of submucosa and widest gingival zone. After the tin foil template is placed and the donor site was outlined with the scalpel blade, the incision begun along the occlusal aspect of the palate and blade held parallel to the tissue. This is to ensure the even thickness of the graft obtained. Access incision can be used to achieved the designed graft thickness. Graft separated mesiodistally. The freed graft is placed in the moistened gauze and the donor site is suture to obtain hemostatis. The graft then is trimmed of all the fat and glandular tissue. Failure to do so will result in the flap that is totally movable when probed. The fat and glandular tissue inhibit the graft take by reducing plasmatic diffusion. The final shaping is done with scissors, outside the mouth, and on the wet gauze. The graft then placed over the prepared periosteal bed and suture. Horizontal stretching suture should be used to overcome the effects of primary contraction. This stretching suture allows the blood vessels within the graft to open, and permit diffusion of fluid.

Four variations to the classic technique has been employed. They are the accordion technique, the strip technique, the connective tissue technique, and the combination technique. The accordion technique involves the use of the alternate incisions on the opposite sides of the graft to attain graft expansion (Rateitschak 1985). The strip technique consists of obtaining two or three strips of tissue about 1 mm wide and long enough to cover the entire length of the recipient site (Han, Carranza Jr., and Takei, 1993). These strips are place at the base and the center of the recipient site, secure by sutures, and wrapped around the tooth. This variant is to alleviate large donor site and facilitate healing in the donor site. However, greater shrinkage is expected in the graft. The connective tissue technique involves the use of connective tissue only as the graft material, since connective tissue carries the genetic message for the overlying epithelium to become keratinize. This technique was originally described by Edel in 1974. Its advantage involves the ability to cover the donor site with epithelium and healing by first intention is attained. Finally, the combination technique consists of using the connective tissue graft at the apical or deeper portion of the recipient site and the epithelial grail on the superficial portion of the recipient site.

The healing of the graft depends on the survival of connective tissue. Sloughing of the epithelium is expected, but the fibrous organization of the interface between the grail and the recipient bed occurs within 2 to several days. The graft is nourished by the process of diffusion of fluid from the host bed, adjacent gingiva, and the alveolar mucosa. On the first day, the connective tissue becomes edematous and disorganized and undergoes degeneration and lysis of some of its elements. On the second or third day, the graft revascularized with the proliferation of the capillaries from the recipient bed (Jansen, Ruben, and Kramer, 1969). This new network of capillaries anastomose with the preexisting vessels. The central section of the surface is the last to vascularize, but this is complete by the tenth day. Gargiulo and Arrocha in 1967 evaluated the healing process of free gingival grail by means of gingival biopsies in eight patients. The critical healing period is the first 48 hours, of which there was no vascularization of the grafts. The grafts initially was nourished by the blood supply from the recipient bed via plasmatic circulation (red blood cell, leukocytes, plasma cells). The exudate formed fibrin net at the interface and establish the early attachment (2-3 days). Between four and seven days, a firm adhesion of the grail to the bed was observed. At the fourteenth days, there was a complete junctional embodiment of graft to the recipient site. The color of the graft changing from grayish white the first two days to pink color. The texture changing from glossy, shiny to a thin, gray, veil like surface that develops normal features as the epithelium matures. The swelling of the graft due to the plasmatic circulation also is reduced as new vessels proliferated and supply the nourishment. As seen microscopically, the healing of the graft of intermediate thickness (.75mm) is complete by 10 ‘2 weeks, and that of the thicker graft (1.75mm) may required 16 weeks or longer (Gordon, Sullivan, and Atkins, 1968).

Functional integration of the graft occurs by the 17th day, but the graft will be
morphologically distinguishable from the surrounding tissue for months. Graft may heal with bulbous appearance and as the result may interfere with the oral hygiene effort. In this case, flap can be raised and the flap is thin from the underside. Several biometric studies have analyzed the width of the attached gingiva after placement of the free gingival graft. Ater 24 weeks, the grafts placed on denuded bone shrink 2500, whereas graft placed on the periosteum shrink 50%. The greatest amount of shrinkage occurs within the first 6 weeks.

Caffesse in 1979 evaluate the healing of free gingival grafts with and without periosteum of 40 grafts on 5 adult Rhesus monkey, with the evaluating period from lhr to 72 days. He found that there is an initial delay in healing for the case of graft placed on bone. However, by day of 28, the rate of healing is similar regarding both techniques. They concluded that the maintenance of the periosteum on the recipient site does not affects the success of the free gingival graft. Grail on bone produces superficial bone remodeling and elastic fibers may persist when grafts are placed on the periosteum.
Jacques Matter in his five year follow up study of ten patients, with isolated narrow recessions less than 3mm in width, have shown that coverage of the recession is not always complete nor always predictable. However, one can always expect some coverage of the denuded root. Preston D. Miller described the factors that associate with incomplete coverage as the improper classification of the marginal tissue recession according to Sullivan and Atkin classification (shallow narrow, shallow wide, deep narrow, deep wide) or the Miller classifcation (1- recession does not extend to the mucogingival junction and there is no loss of bone or soft tissue in the interdental area; II-recession extends to or beyond the mucogingival junction, but there still is no loss of bone or soft tissue in the interdental area; III- recession extends to or beyond the mucogingival junction and there is bone /soft tissue loss interdentally or malpositioning of tooth; IV-recession extends to or beyond mucogingival junction with severe bone loss and soft tissue loss interdentally and/or sever tooth malposition). The class I and II represent good to excellent prognosis for the outcome of root coverage, whereas partial coverage for class III is expected, and poor prognosis for class IV. Another factor he addresses is the inadequate root planing. Root planing is to remove all the local irritants and also flattening the root in the area of CEJ so the margin of the graft can be butted against the CEJ. This also minimized the mesiodistal dimension of the root. Miller also addresses the need of treat the planed root with Citric acid to expose the dentinal tubules or formation of cemental pins, removal of the smear layer, accelerated reattachment, inhibition of epithelial migration, and formation of the connective tissue attachment. Complete root coverage have been obtain up to 880o with the use of Citric acid (Miller, 1985) as compared to the 44 00 obtained in the case without the use of citric acid (Holbrook and Oschenbein, 1983). It is important to complete acid conditioning before preparing the recipient site since citric acid causes coagulation of blood and thus limits the blood flow to the graft. Another issue Miller addresses is the failure to proper preparation of the recipient site. Horizontal incision should be made at the CEJ. If placed below the CEJ, complete coverage will not be expected. If placed above, the portion of the graft onthe enamel will not be in intimate contact and will slough. A butt joint margin should be used in the papilla rather than the beveled margin. The butt joint margin provides a clearly demarcated margin for graft placement, also provide enhanced circulation into the graft. The vertical incision also should be made at the line angles of the adjacent teeth too provide a complete interdental papilla for suturing. It is probably best to treat all recession as though they are wide. The apical extension of the recipient site should be about 3mm apical to the recession to increase the ratio of vascular to avascular surface. Do not use the periosteal separation to produce the apical scar as it may compromise the blood supply to the apical aspect of the graft. The size of interdental papilla should be adequate to allow suturing. The undersurface of the graft should be flat and smooth with the graft have the same type of butt joint margins as those created in the papillae. This is to allow direct contact of graft margin to the margin of the recipient site and allow enhanced circulation to the graft. The size of the graft should be larger mesiodistally. It is better to have too much length than too little. Grafting for root coverage should be thicker than grafting for gaining attached gingiva. The thick graft usually retain the intact capillary system. Graft also must be protected from dehydration by immediately placing it on a moderately bleeding recipient bed. Graft must be adapt to root and periosteal bed to assure intimate contact for plasmatic circulation. This can be obtained via the use of two apical suture into the periosteum at the angle distally and also placement of periodontal dressing. Graft must remain in intimate contact with the root when the lip is manipulated or stretched. Excess or prolonged pressure in adaptation of suture graft also may compromise the necessary blood flow to the graft. Other factors included reduction of inflammation prior to grafting is recommended, trauma to the graft during handling and placement should be minimized, and finally, smoking in excess of 10 cigarettes a day should be refrain from smoking during the initial healing phase of 2 weeks. Surprisingly, light or occasional smoker responded as favorably as nonsmoker. Heavy smokers who refrained achieve the level of root coverage comparable to that of the nonsmokers.

Burton Langer and Laureen Langer describes’ the uses subepithelial connective tissue graft as a donor source for root coverage. The successful resulted has been attribute to the double blood supply at the recipient site from the underlying connective tissue and the overlying recipient flap. Follow up in 4 years have shown no recurrence of recession. Donor site is a closed wound which produces less postoperative discomfort. Tissue color match is better than in the case of free gingival graft. The increase in root coverage has varied from 2 to 6 mm.

Perhaps the use of free gingival graft today is limited with the introduction of connective tissue graft and also the resorbable membrane to treat recession defect. However, it can still be employed in the case of combination of frenulotomy and deepen of vestibule in the pre-prosthetic cases. Free gingival graft also indicated where other surgical techniques cannot predictably be used to attain an adequate zone of attached gingiva. Most importantly, the wound healing model of the free gingival graft and that of the connective tissue graft are very similar since they are both soft tissue healing. Nevertheless, the free gingival graft procedure is an important adjunct to the periodontal therapy. Optimal success is dependent upon the proper case selection and adherence to the basic principal of grafting. Each case should be individualized and carefully plan out the technique to achieve optimal result.

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Reference

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6. Wilderman, M., Wentz, F. Repair of a Dentogingival defect with a pedicle flap, Journal of Periodontology 36: 218, 1965.

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9. Lindhe, Nyman. Alterations of the position of the marginal soft tissue following the periodontal surgery. Journal of Clinical Periodontology 7: 525, 1980.

10. Janson WA, Ruben MP, Kramer GM, Development of the blood supply to split thickness free gingival autografts. Journal of Periodontology 40:707, 1969.

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12. Matter, J, Cimasoni G. Creeping attachment after free gingival grafts. Journal of Peridontology 47:574, 1976.

13. Miller PD. Jr. A classification of marginal tissue recession. International Journal of Periodont Restorative Dentistry 5:9, 1985.

14. Miller PD. Root coverage with the free gingival graft. Factors associates with incomplete coverage. Journal of Periodontology 58: 674, 1987.

15. Miller PD. Root coverage using a free soft tissue autograft following citric acid application. Part I. Technique. mt j Periodont Restor Dent 2:65, 1982.

16. Miller, PD. Root coverage using a free soft tissue autograft following citric acid application. Part Ill. A successful and predictable procedure in the areas of deep wide recession. mt J Periodont Restor Dent 5:15, 1985.

17. Ramljjord, Costich, Healing after exposure of periosteum on the alveolar process. I. Periodontology 39: 199, 1968.

18. Karring, Ostegaard, Loe H. Conservation of tissue specificity after heterotopic transplantation of gingiva and alveolar mucosa. J Periodontal Research 6:282, 1971.

19. Sullivan, H.C., Atkins, J.H. The role of free gingival grafts in the periodontal therapy. Dental clinics of North America, p.1133, Jan 1969.

20. Langer, B. , Langer, L. Subepithelial Connective tissue graft technique for root coverage. Journal of Periodontology, 56:715, 1985.