This article provides an overview of the best-documented surgical techniques for recession coverage and draws conclusions for the clinician. Use of a connective tissue graft with either coronally advanced flap (CAF) or tunnel is the most predictable technique for the treatment of single and multiple gingival recessions. Long-term results exist only for CAF with/without connective tissue graft providing evidence for long-term stability with only minor relapses. Soft tissue replacement materials and biologics may represent a valuable modality to additionally improve the clinical outcomes obtained with CAF alone or, in certain clinical situations, to serve as an alternative to autogenous tissue.
Key points
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The coronally advanced flap and tunnel are the most predictable techniques for the treatment of single and multiple gingival recessions.
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So far, long-term results for the coronally advanced flap with or without a connective tissue graft provide evidence for long-term stability with minor relapses.
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Biooogics and soft tissue replacement materials may additionally improve the clinical outcomes or may be used as an alternative to autogenous grafts.
Introduction
Gingival recession (GR) is a frequent clinical feature affecting most of the adult population with an incidence of about 54% in young adults (26–35 years) and about 100% in middle-elderly adults (36–45 years). GR is defined as the apical displacement of the gingival margin while exposing a portion of the root surface. Various predisposing and/or causative factors may induce the appearance of GR, such as traumatic tooth brushing, plaque-induced inflammation, periodontitis , or viruses, inadequate dental procedures invading the biologic width, inadequate tooth alignment or other anatomic or periodontal features, presence of muscle insertions close to the gingival margin, lack of an adequate band of keratinized/attached gingiva, reduced buccal-lingual thickness of the alveolar bone plate, orthodontic tooth movement, or oral jewelry. , The presence of GR is regularly linked to aesthetic impairment, tooth hypersensitivity, and root caries, and may hinder an optimal self-performed oral hygiene leading to plaque accumulation and further tissue loss. ,
Successful treatment of GR aims at restoring the lost periodontal tissues by achieving complete root coverage with optimal tissue integration, scar-free tissue blending, and physiologic clinical probing pocket depths. Thus, periodontal plastic surgical procedures with clinically predictable results for root coverage are indicated. At the beginning of the twentieth century, the use of pedicle gingival grafts or free gingival grafts (FGG) were first described by Younger (1902), Harlan (1906), and Rosenthal (1981) for the surgical treatment of GR. Later, further surgical approaches, such as coronally advanced flaps (CAFs), coronally advanced tunnel flaps, laterally repositioned flaps alone or combined with FGG, or subepithelial connective tissue grafts (CTG) were presented as successful surgical techniques to improve recession depth, clinical attachment level, and width of keratinized tissue.
Although the choice for the optimal surgical technique is still debatable, it is unequivocal that the additional use of a CTG represents the gold standard by providing the highest probability for complete root coverage with the greatest aesthetic results. The combination with other biomaterials of various origins, such as acellular dermal matrix (ADM), xenogenic collagen matrices (XCM), enamel matrix derivatives (EMD), hyaluronic acid (HA), or platelet-rich fibrin (PRF), has also been investigated in this context.
This narrative review provides an overview on the clinical outcomes and stability in time of the best-documented surgical techniques and biomaterials used for coverage of single and multiple GRs.
Biologic background
The healing process after soft tissue grafting has been extensively described in various animal and human histologic studies. The healing and revascularization of an FGG was described in a histologic study in monkeys. Three healing phases were recognized. First, an initial phase (0–3 days), where the graft was separated by the periosteum by a thin fibrin layer, accompanied by degeneration of the epithelium and desquamation of the outer layers. The following 4 to 11 days a revascularization phase was observed, characterized by minimal resorption of the alveolar bone, fibroblast proliferation in the graft-periosteum region, vascularization and capillary ingrowth at the base of the graft, and formation of an epithelial layer from the adjacent tissues over the graft. Thereafter, in the third phase, the maturation phase (11–42 days), the epithelium layer thickens and by the 28th day is keratinized. Meanwhile, the connective tissue increases in its density and gets poorer in vascular vessels. Similar histologic descriptions were reported by other authors, , , emphasizing additionally that grafts placed onto the periosteum seem to have a better initial adaptation and graft nourishment as opposed to those placed directly onto the bone. Additionally, the latter ones seem to be characterized by wider degenerative changes and delayed epithelialization. Nonetheless, by the 28th healing day, in both situations (graft placed directly onto the bone, or onto the periosteum) the tissue seems to be keratinized. , ,
Soft tissue maturation after grafting, irrespective of the graft type (CTG or FGG) is accompanied by a significant tissue shrinkage, between 25% and 45%. , , It was also described that thicker grafts provide less shrinkage but a more delayed revascularization. , ,
In a series of histologic animal studies, it was determined that the specificity of the epithelium (clinical and structural features) is genetically determined rather than the result of functional adaptation. Additionally, it has been shown that even after complete excision of the keratinized tissue at teeth, a new band of attached gingiva will be formed. Further histologic evidence exists related to the key role of the gingival connective tissue in genetically determining the specificity of the epithelia. It has been additionally shown in animal and human studies, that the granulation tissue that proliferates from the periodontal ligament and the supra-alveolar connective tissue leads to formation of a keratinized tissue, whereas that originating from the alveolar mucosa leads to a nonkeratinized mucosa. ,
Another biologically and clinically relevant aspect when using CTGs for keratinization purposes, is the depth of the donor tissue layer: possible differences between superficial and deep connective tissue layers seem to exist. Evaluations using histology, immunofluorescence, and gel electrophoresis provided evidence that CTGs from deep layers lead to a tissue containing keratinized and nonkeratinized characteristics. However, grafts originating from superficial layers (epithelial CTGs) always provide histologic and biochemical features of a keratinized mucosa. Based on these findings and further human evidence, the authors concluded that deep palatal CTGs may have a poorer potential to induce keratinization as opposed to connective tissues situated in immediate epithelial vicinity.
Taken together, the results of the previously mentioned studies indicate that keratinization is induced from granulation tissue originating from periodontal ligament or from connective tissue initially covered by keratinized epithelium; consecutively, this indicates for the use of a palatal CTG in clinical situations with GR and/or with lack of keratinized tissue.
Surgical therapy for single recessions
The ultimate goal of surgical root coverage procedures is the complete root coverage with optimal color and texture blending of the covering tissue. , Numerous root coverage procedures including pedicle flaps, FGGs, laterally positioned flaps, double pedicle flaps, and various forms of CAFs or tunnels have been described. ,
One of the most reliable and best investigated surgical approaches for single recessions is the CAF. , With CAF, the soft tissue apical to the recession is coronally advanced to accomplish root coverage, as follows. Mesially and distally to the recession, two beveled horizontal incisions (about 3 mm) are made; these are located at a distance from the tip of the anatomic papillae that equals the recession depth plus 1 mm. From the horizontal incisions, two beveled vertical incisions are performed into the alveolar mucosa resulting in a trapezoidal flap with two surgical papillae. This is elevated as a split flap in the papilla region, followed by a full-thickness elevation of the tissue apical to the recession until the mucogingival junction and 3 mm of the apical bone is exposed; thereafter, a second split-flap is raised apically until tension-free, passive coronal flap advancement so that it is possible to completely cover the recession coronally to the cementoenamel junction (CEJ). For this, all muscle insertions attached to the flap are cut. Next, the vestibular sites of the anatomic papillae are de-epithelialized coronally to the initial horizontal incisions to obtain a connective tissue bed where the surgical papillae will be sutured. Finally, the flap is sutured with single interrupted sutures, oriented from the flap to the adjacent soft tissue in apicocoronal direction. At the apical end of the vertical incisions, the flap is fixed with two periosteal sutures, so as to minimize any coronal flap movements. The surgical papillae are adapted to the anatomic papillae by means of sling sutures allowing a tight and precise flap adaptation to the crown of the tooth.
In CAF and most of the previously mentioned surgical procedures, a split flap approach is adopted, which sometimes, specifically in clinical situations with a thin gingiva, may be difficult to perform risking flap perforation and possible graft necrosis. To minimize these risks, the modified coronally advanced tunnel (MCAT), a modification of the tunnel procedure, and the laterally closed tunnel (LCT) with either CTG with or without biologics, such as EMD or HA, or soft tissue replacement materials have been described. , , , ,
In MCAT, a mucoperiosteal flap is prepared by means of tunneling instruments while maintaining the interdental papillae intact. The mucoperiosteal tunnel is then extended apically and laterally into a partial thickness flap while all attaching muscles and inserting collagen fibers are sectioned and released from the inner aspect of the tunnel flap. The interdental papillae are gently undermined with specially designed tunneling knives paying special attention not to rupture or perforate the flap and/or the papillae. Subsequently, the prepared tunnel flap is passively advanced coronally. In cases with thin phenotype a CTG is indicated. The CTG is harvested from the palate and then pulled in the tunnel using single or mattress sutures. The graft is fixed at the inner aspect of the tunnel flap mesially and distally, and tightly adapted at the CEJ by a sling suture. Finally, the tunnel flap is moved coronally using sling sutures to completely cover the graft and the recession, thus creating an excellent environment for wound healing.
In cases with deep isolated anterior mandibular GRs LCT may be indicated. Similar to MCAT, in LCT, a mucoperiosteal pouch is prepared using tunneling instruments and mobilized extensively mesially, distally, and apically beyond the mucogingival junction to attain passive lateral displacement of the pouch margins and cover completely/the greatest part of the exposed root. To achieve tension-free mobilization, all muscle insertions and fibers must be released from the inner aspect of the pouch. Interdental papillae are carefully undermined with tunneling knives and microsurgical blades taking special care not to disrupt them ( Fig. 1 A–D ). Thereafter, a CTG harvested from the palate is pulled and fixed at the inner aspect of the pouch using single or mattress sutures. Subsequently, the CTG is tightly adapted at the CEJ level by means of a sling suture ( Fig. 1 E, F). Then the pouch margins are carefully pulled together over the graft and sutured with single interrupted sutures allowing a tension-free coverage and enabling an excellent healing ( Fig. 1 G, H).
Surgical therapy for multiple adjacent gingival recessions
Surgical treatment of multiple adjacent gingival recessions (MAGR) represents a challenging clinical situation. Treatment of MAGR supposes the coverage of multiple adjacent recessions of various depths and widths, with frequently different tooth positions, shallow vestibulum, and large avascular surfaces to be covered.
Three major surgical techniques have been shown to be successful for treating MAGR : (1) CAF with two vertical incisions mesially and distally, (2) the modified version of CAF without releasing incisions, and (3) the MCAT. Irrespective of the used technique, it seems that for all types of recessions (Miller I-IV, respectively, RT1, 2, 3) the addition of a CTG provides the best aesthetic results and is the most predictable method for achieving complete root coverage. ,
Similarly as in CAF for single GRs, CAF applied in MAGR defects starts with a horizontal incision in the papilla area continuous with intrasulcular incisions that extend to one tooth more mesially and distally from the recessions creating several surgical papillae. Thereafter, a split-full-split thickness envelope flap is prepared in the entire recession area and all inserting muscle fibers are released to achieve passive mobilization over the exposed root surfaces. Additionally, a CTG may be sutured with resorbable sutures to the papillae and periosteum over the exposed root surfaces and at the level of the CEJ. Finally, the flap is tightly adapted over the CTG and the exposed root surfaces with sling sutures. After previous de-epithelization of the anatomic papillae, the newly formed surgical papillae are sutured at the tip of the anatomic papillae.
Another technique with promising results that has been intensively tested in the last decade is MCAT. , After intrasulcular incisions, a mucoperiosteal flap is raised using tunneling knives beyond the mucogingival junction and further extended as split flap apically and laterally. All inserting muscle and collagen fibers are released from the inner aspect of the tunnel flap to achieve passive (tension-free) complete coronal displacement over the exposed root surfaces. The interdental papillae are also carefully undermined to allow a CTG or a soft tissue replacement material to be pulled in the tunnel and fixed with mattress and sling sutures at the inner aspect of the tunnel and at the CEJ. Finally, the tunnel is coronally advanced to completely cover the graft/membrane and fixed with sling sutures to the teeth ( Figs. 2 and 3 ).
Several short- and long-term studies pointed out that the additional use of a CTG to CAF is more effective and predictable in achieving complete root coverage compared with CAF alone in single and multiple recessions. , , , Moreover, it seems that the addition of CTG provided not only long-term stability but also greater increase in keratinized tissue.
Soft tissue biomaterials and substitutes
The adjunctive use of a CTG in surgical GR coverage has been repeatedly proven to show the best results in terms of complete root coverage, recession reduction, and increase in tissue thickness and attached/keratinized gingiva. , Nonetheless, in cases where a longer CTG is needed, graft prelevation becomes sometimes difficult, especially in cases with a thin palatal tissue, which in turn may increase patient morbidity and the risk for postsurgical complications. Most of the complications associated with soft tissue grafting are related to the donor site. Harvesting of a free epithelial CTG may result in more severe complications, such as excessive hemorrhage, postoperative bone exposure, painful open palatal wound, and chewing discomfort compared with harvesting of a subepithelial CTG. It has been reported that mucogingival surgery including harvesting of epithelial CTGs was associated with 3.5 times more pain compared with osseous surgery and six times more pain compared with recession coverage.
Because the infection rate following soft tissue grafting is low, the routine administration of systemic antibiotics in conjunction with these procedures is not mandatory and lacks scientific support. However, in cases of severe postoperative infection, extending beyond the surgical area, the administration of systemic antibiotics may be considered.
Another aspect that needs to be kept in mind when autogenous soft tissue grafts are used is the possibility of sensory changes that can occur after graft harvesting from the palate. Although the data are limited, the patients need to be informed on the possibility to have a transient or persistent numbness on the palatal surface following graft harvesting. ,
Soft Tissue Replacement Materials
To overcome the drawbacks related to autogenous graft harvesting, alternative biomaterials, such as EMD, soft tissue replacement material, PRF, or HA, have been investigated. ,
Xenogeneic and allogenic membranes as a substitute for CTG have been intensively tested in the past decade. Several clinical studies provided promising clinical results for root coverage when CTG substitutes, such as ADM, , EMD, , PRF, , or XCM, , , , have been used for the coverage of Miller class I, II, or III (RT1 and 2) GRs. Several studies have evaluated the effectiveness of various CTG substitutes associated to CAF for the treatment of RT1 (Miller class I and II) recession defects. Based on results from 27 studies, the evaluated CTG substitutes (ADM, PRF, EMD, XCM) showed superior results compared with CAF alone. The network analyses indicated the treatment ranking of these substitutes, pointing to ADM as providing the best results, followed by PRF, EMD, and XCM. However, when comparing CTG with ADM or XCM, another recent meta-analysis obtained comparable results in terms of relative root coverage (see Fig. 3 ).
Enamel Matrix Derivative
Results from histologic animal and human studies have provided evidence that EMD induces periodontal regeneration (ie, formation of new cementum, new periodontal ligament, and bone) in the surgical treatment of GRs. Several authors have reported improved results for root coverage in Miller class I and II recessions where EMD and CAF were used as compared with CAF alone. , , A recent meta-analysis reported statistically significant better results for recession reduction and clinical attachment level (CAL) gain when EMD was associated to CAF or CAF + CTG. In a recent clinical study evaluating the clinical results after 3 years, CTG + EMD provided significantly better outcomes for the percentage of mean root coverage (90.69% ± 10.10% for CTG + EMD, 79.25% ± 19.55% for CTG) and for residual recession depth (0.39 ± 0.19 mm for CTG + EMD, 0.92 ± 0.43 mm for CTG) compared with those treated with CTG alone. Corroborating data were reported by Spahr and coworkers pointing to better recession coverage and less recession recurrence after 2 years for the EMD group. Promising results were also reported when EMD was associated to CTG using MCAT for the treatment of single mandibular Miller class I and II recessions or for maxillary MAGR. However, the single use of EMD adjunctive to CAF seems to provide inferior clinical and aesthetic results as compared with CTG + tunnel technique 5 years after surgery, pointing to the fact that CTG remains the gold standard for achieving optimal recession coverage.
Platelet-Rich Fibrin
In the past years, PRF has been increasingly used for the surgical treatment of GRs. , Biologically, the concept is based on the slow and gradual release of growth factors from the fibrin-dense membrane obtained after blood centrifugation. Studies evaluating PRF adjunctive to CAF as opposed to CAF alone showed significantly better outcomes for root coverage and CAL gain favoring PRF. , This was also obtained in a recent meta-analysis, which pointed to statistically significant better outcomes for the relative recession coverage and CAL gain in cases where PRF was used. When PRF was combined with CAF + CTG, statistically significantly better relative root coverage and CAL gain was obtained compared with CAF + CTG alone. However, when CAF + PRF was compared with CTG, significantly better outcomes (root coverage, CAL gain, gain in keratinized gingiva) were obtained favoring the CTG group. ,
Hyaluronic Acid
HA is a natural carbohydrate component of the extracellular matrix found in skin, joints, eyes, and periodontium and has hygroscopic, viscoelastic, anti-inflammatory, and antiedematous properties. It also supports clot formation, angiogenesis, osteogenesis and cell adhesion, migration, and differentiation. , , A recent histologic study in dogs has shown that the additional use of HA to CAF provides statistically significant better results for CAL, bone formation, formation of cementum, and connective tissue attachment compared with CAF alone. Other reports confirm that adjunctive use of HA to CAF increases the probability of complete root coverage compared with CAF alone in Miller class I recessions. Promising results were also obtained in single and multiple GRs treated with MCAT or the LCT and HA. , Nonetheless, further randomized clinical studies are needed to determine the adjunctive benefit of HA in the surgical treatment of GRs.
Summary
Taken together, the use of a CTG with either CAF or tunnel seems to be the most predictable techniques for the treatment of single and multiple GRs. So far, long-term results (ie, 5-year follow-up or more) exist only for CAF with/without CTG providing evidence for long-term stability with only minor relapses. Soft tissue replacement materials and biologics may represent a valuable modality to additionally improve the clinical outcomes obtained with CAF alone or, in certain clinical situations, to serve as alternative to autogenous tissue.
Clinics care points
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Soft tissue healing after connective tissue graft or free gingival graft is characterised by a significant tissue shrinkage.
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The coronaly advanced flap is one of the best investigated surgical techniques for gingival recession coverage.
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The modified coronally advances tunnel (MCAT) has been develod in order to minimize the risks for flap perforation.
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The routine administration of antibiotics after surgical recession coverage procwdures lacks evidence and is not recommended.
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Alternative to autogenous grafts, biological materials such as an enamel matrix derivative, plasma rich fibrin, hyaluronic acid or sof tissue xenogeneic or allogenic replacement membranes have been investigated.
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