The “Washing Line” Suture Technique for Securing the Subepithelial Connective Tissue Graft

The replacement of single or multiple teeth in an aesthetically sensitive zone is a major challenge. Tooth extraction results in both buccal soft and hard tissue remodeling that manifests itself as a reduction in volume morphology, that is, resorption.

Bone resorption at a new extraction socket is continuous, with the greatest amount occurring within the first month. Pietrokovski et al¹  studied 123 human edentulous dry bone specimens, concluding that in the maxilla, bone resorption was centripetal and apical, that is, bone resorption was overwhelmingly from the buccal surface of every socket with significantly reduced resorption from the palatal aspect of the socket. In the mandible, resorption was centrifugal and apical, forming an edentulous crest central to the former tooth sockets. This difference in resorption produced a reverse horizontal overlap of the residual crests, with the edentulous maxilla at the same level or internal to the facing edentulous mandible.²  Over time, the degree of resorption is directly related to a decrease in the aesthetic value achieved with dental implant replacement surgery. Both bone and soft tissue grafting techniques have been developed to address the loss in tissue volume. The subepithelial connective tissue graft (SCTG) is frequently used at periodontal recession sites to increase the volume of soft tissue at a deficient site and also convert “thin” periodontal phenotype A^3,4  into a stable “thick” gingival phenotype B.

Bashutski and Wang⁵  having reiterated the importance of tissue thickness and transferred the concepts to implant treatment planning. Current understanding is geared toward establishing a thick tissue biotype around implants because of its contribution to the aesthetic result of an implant-supported restoration. A thick biotype resists recession,^6,7,8  is able to better conceal titanium,⁹  and helps maintain gingival morphology.¹⁶  Thus, thick biotype is preferred to thin biotype around dental implants. Evans and Chen¹⁷  performed a study on immediate implants, defining biotype by probe transparency. The study found that peri-implant marginal stability was dependant on the baseline tissue thickness: Increasing soft tissue thickness minimizes the potential for peri-implant mucosal recession. Soft-tissue thickness can be increased by the Abrams roll technique and by placement of a SCTG.

Further, inherent thick tissue biotype is important because thick tissues have an increased blood supply that will enhance neo-vascularization of bone grafts, leading to increased rate of healing and graft incorporation. Another advantage of thick tissue is its ability to attain and maintain primary wound closure. Adequacy of soft tissue coverage is one of the main factors in ensuring periodontal regeneration. Flap exposure results in a reduction of the bone regenerated in grafting techniques, primarily as a result of bacterial contamination.¹⁰ 

An intact band of attached keratinized gingival tissue (KGT) is considered critical to the protective function of the mucogingival complex, although there is no agreement as to the minimum requirements.^11,12  The rationale for gingival augmentation around both natural teeth and dental implants includes improved plaque control and improving patient comfort with restorative, prosthetic, or orthodontic procedures and the prevention of gingival recession.¹³  The stability of soft and hard tissues at implant sites have been investigated by Bouri et al.¹⁴  They found that the Mean Gingival Index score, Plaque Index score, and radiographic bone loss were significantly higher for those implants with a narrow zone (<2 mm) of KGT. Further, implants with a narrow zone of KGT were more likely to bleed upon probing. Additionally, they found a significant independent association between the width of keratinized mucosa and radiographic bone loss. They concluded that an increased width of KGT around implants is associated with lower mean alveolar bone loss and improved indices of soft tissue health. This position was most recently reiterated by Kim et al.¹⁵  From the aspect of long-term maintenance and management, as well as aesthetics, the presence of an appropriate amount of keratinized gingiva is required.

Both immediate and delayed implant placement results in a reduction of the inherent width of keratinized gingival tissue (wKGT). The coronally advanced flap (CAF) is one of the options used for primary wound closure at both extraction sites and extraction-immediate dental implant placement sites. However, the CAF moves the mucogingival junction (MGJ) in a coronal direction, resulting in both aesthetic and functional impairment. The placement of the SCTG will both maintain and regenerate the wKGT.

Nonetheless, the placement of harvested connective tissue (CT) at a recipient site can prove difficult. The CT needs to be firmly secured; otherwise, it will be in danger of being fully extruded from the site during the edematous phase of natural healing. Further, if it is mobile, it can be partially extruded from the wound site and suffer “sloughing.” For these reasons, the author has developed a technique for firm fixation of the CT graft under a mucoperiosteal flap while at the same time allowing optimization of its mesiodistal and coronal placement, thus resulting in not only the preservation or reattainment of soft tissue volume but also the retention or improvement of the width of keratinized gingival tissue.

The following case reports detail the surgical procedure of the “washing line” suture technique.

All illustrations are from patients presenting at a private practice dedicated to periodontics, dental implants, and advanced restorative techniques. Where teeth were determined to be beyond further conservative therapy, the patients were offered options of further treatment that included extraction and dental implant replacement therapy. All patients signed informed consent before treatment.

Pre-extraction: One hour prior to surgery, all patients received the same systemic coverage: 2 g amoxicillin (or 600 mg clindamycin when allergic), 400 mg ibuprofen, and 2 mg dexamethasone, as well as a mouthrinse of chlorhexidine gluconate 2% at 20 min prior to surgery.

All surgery was carried out under intravenous sedation (midazolam) and local anesthesia (articaine 4%, Septodont, Saint Maur Des Fosses, France). Mucoperiosteal flaps were either raised after the extractions (Figures 1 through 4) or prior to extraction (Figures 5 and 6). All extractions were facilitated with periotomes to reduce trauma to the socket walls. The sockets were debrided of all inflammatory and granulation tissue, excluding that at the marginal soft tissue: No remaining sulcular epithelium was removed from the soft tissue margin. Other than the presented Figure 3 (“old” edentulous sites of 3 years), all buccal bony walls were thin and often suffered fracture during the implant placement (Figures 2, 4, 5, and 6). Of the latter, the implants were placed immediately (MIS, SEVEN, Tel Aviv, Israel) with displacement of their axis to the palatal wall of the vacant sockets. The primary stability of all inserted implants was high, all implants having an initial seating torque value of 50 Ncm as calibrated on the seating apparatus (Implantmed, W&H Dentalwerk, Buermoos, Germany). Final seating of the implants (torque value in excess of 50 Ncm) was carried out using a handwrench. The vacated sockets were then packed with the xenograft Bio-Oss (Geistlich Pharma, Wohlhusen, Switzerland); particle size 0.25–1.0 mm.

After immediate implant placement and alveolar socket in-fill, or where substantial buccal resorption had occurred, all buccal dehiscences and depressions were further augmented with Bio-Oss (See Figures 1c, 2e, 3e, 4d, 5e, and 6g). The Bio-Oss granules were then covered with its dedicated resorbable membrane Bio-Gide (See Figures 1d, 2f, 3f, 4e, 5f, and 6h)

“The palate is the most common site for the harvesting of autogenous connective tissue. The technique involves an initial vertical incision 90 degrees to the palatal bone in the zone mesial to the second molar tooth, parallel to the arch of the teeth at the donor site just shy of the bone. The blade is removed and reinserted, angled 135 to 180 degrees to undermine the palatal tissues at a depth of 1 mm toward the midline. A micro-periosteal elevator is used to tease a full-thickness flap away from the bone, thus allowing easier manipulation of the palatal tissue. The desired width of connective tissue is then cut away.”¹⁶  In general, the subepithelial connective tissue was harvested from either the right or left hard palatal vault, mesial to the first premolar and anterior to the second molar region (Figure 5g). At the recipient site, the suture material (5.0 Prolene, Johnson & Johnson, New Jersey, USA) was initially placed through the still fixed mucosa and then passed through the donor connective tissue and along its length to penetrate its farthest extremity (Figures 1e, 3g, 4f, 5h, and 6i). The suture needle was then passed under the second fixed mucosal site through to the outer surface. The suture was then reentered into the mucosa and passed through the SCTG once again and through to the start position, where it again penetrated the SCTG. The needle was then finally placed through the fixed mucosa to emerge adjacent to the original penetration, where it was tied off. The fixation of the harvested connective tissue to the recipient site must allow the maintenance of actual volume of the donor tissues; the washing line is placed under the donor tissue, thus maintaining its volume and hindering unwanted compression. The SCTG is now moved along the suture washing line with ease, optimizing its position. To complete the centralizing of the SCTG, the coronal side of the graft was securely sutured under the sulcular margin of the palatal mucosa with interrupted sutures (5.0 Prolene). A variation of this standard suture technique can be used, as shown in Figure 2g and 2k, whereby the suturing is continuous into the coronal portion of the SCTG and the palatal mucosa.

The buccal flaps were all replaced coronally with minimal tension, being secured interdentally and crestally with 5.0 Prolene (Figures 1f, 2h, 3h, 4g, 5i, and 6j). Relieving incisions were secured with 6.0 Prolene interrupted sutures placed apico-coronally (Figures 1f, 2h, 3h, 4gG, 5i, and 6j). To facilitate wound healing, the donor sites were covered with Eugenol-free Coe-Pack for 3 days (GC-Fuji, Leuven, Belgium).

Wound healing was always uneventful. Sutures on the palatal donor site were removed at 14 days. The sutures at the relieving incisions and that of the washing line were removed at 28 days. Five months were allowed for the implants to integrate before they were uncovered (Figures 2i, 3i, 3j, 4h, and 5j) with a modified Abrams roll technique to help thicken the labial soft tissue.¹⁷  The implants were all restored at 6 months following surgery (Figures 4i, 5k, and 6k). Results of the presented cases show that not only is the tissue volume enhanced (or sustained) but that there is a visible maintenance in the position of the mucogingival junction (Figures 2j, 3k, 4j, 5k, and 6l). Figure 1 is an extreme presentation of hyperdontia in a male Caucasian of 76 years of age: Figure 1a shows the initial presentation and the lack of normal marginal tissues associated with a mesiodens and the impacted, malformed right central incisor. Figure 1g shows the creation of an acceptable volume and width of keratinized gingival tissue at the crown on the implant and a simulated central papilla.

The vascularization of a connective tissue graft originates from the periodontal plexus, the supraperiosteal plexus and the overlying flap.¹⁸  “Graft survival being heavily dependent on the maintenance of blood supply and early revascularization. Preparation of the recipient site is to maximize blood supply for blood clot formation and organization to prevent graft necrosis while minimizing mobility to prevent tearing of the delicate blood vessels that will invade the graft and cause neovascularization.”¹⁹  The inability to achieve neovascularization is the causative factor for graft sloughing and the failure or diminishment in attainment of optimal results. Therefore, immobilization of the CT graft and primary closure of the wound are prerequisites for optimization of the results. Though discussed, there is a paucity in descriptive information as to the fixation methods for the CT graft in the dental literature, especially in relation to dental implant surgery and large open surgical sites. The purpose of this paper is to rectify that lack of descriptive documentation.

The author performs the washing line suture technique as routine for the firm fixation of the subepithelial connective tissue graft. All grafts heal uneventfully and integrate completely by primary wound healing. The advantage of the method is the certainty that the graft will remain in its secured position with no wandering and danger of exfoliation from the wound site. The tension-free coronally advanced flap^20,21  provides a primary seal for the wounds resulting from immediate implant placement and bone augmentation and the increased volume associated with the placement of the SCTG and the bone augmentation. This is the reason for uneventful bone and soft tissue graft healing, which will then result in nondisplacement of the mucogingival junction. Unfortunately, the volume increase in tissues below the CAF may well result in their physical displacement: The washing line has addressed this problem. The results of all the presented cases display a visual optimization of volume maintenance facilitating aesthetic implant-supported restorations in some trying circumstances.

Where aesthetics are of prime concern to the patient and the surgeon, the role of periodontal plastic surgery techniques has now been amplified. The subepithelial connective tissue graft is still considered the gold standard for maintaining the position of the mucogingival junction and thickening the buccal soft tissue, resulting in the local conversion of thin marginal gingiva into thick marginal tissue. However, the loss or dislodgement of the SCTG must remain a consideration. The author has addressed the problems associated with the securing of the SCTG by providing a predictable suture technique that is within the capabilities of the experienced periodontist/implantologist: the washing line suture technique.

Abbreviations

CAF

coronally advanced flap

CT

connective tissue

KGT

keratinized gingival tissue

SCTG

subepithelial connective tissue graft

wKGT

width of keratinized gingival tissue