Usefulness of the subepithelial connective tissue pedicled palatal flap in alveolar reconstruction: A report of case series.

The purpose of this case series report was to describe the subepithelial connective tissue pedicled palatal flap technique, its indications, and its efficacy in closure of alveolar ridge reconstruction. The present case series consisted of all 11 consecutive subjects who underwent a ridge augmentation with biomaterials or with bone grafts. Furthermore, in other cases were placed immediate or delayed implants. All cases were closed with a subepithelial connective tissue pedicled palatal flap reconstruction in our private dental clinic between 2014 and 2020. The main advantages of this flap are that the donor site remains primarily covered, the soft tissue volume at the recipient site is increased, and there is good integration of the graft because the blood supply of the flap comes directly from the base of the pedicle. All cases exhibited an increase in soft tissue height and width after 6 months and primary closure was successful. This case series suggests that the subepithelial connective tissue pedicled palatal flap may be useful for moderate vertical and horizontal augmentation in the recipient site. Copyright:

INTRODUCTION

Tooth extraction is one of the most widely performed dental procedures. In general, postextraction healing of both the hard and soft tissues proceeds uneventfully. However, the removal of a tooth will generally result in some alveolar bone loss as well as structural and compositional changes in the overlying soft tissue.[1] This is because, after tooth extraction, the natural healing process involves both alveolar bone growth and reabsorption of the alveolar process in the buccolingual and apicocoronal dimensions.[2] A systematic review by Tan et al. of the 20 studies that met their inclusion criteria revealed that after tooth extraction in humans, there is a marked reduction in the hard tissue in the horizontal dimension after 6 months (3.79 ± 0.23 mm reduction). The reduction in the vertical dimension is less marked (1.24 ± 0.11 mm, 0.84 ± 0.62 mm, and 0.80 ± 0.71 mm on the buccal, mesial, and distal sites).[1] These changes mean that the fresh extraction socket in the alveolar ridge is a significant challenge in everyday practice.[2]

To facilitate subsequent treatments and to ensure their good outcomes, it is necessary to maintain the hard and soft tissue envelope and to stabilize the alveolar ridge volume. A number of different procedures that aim to fulfill these objectives have been proposed.[2]

To maintain the objective bone volume, alveolar ridge preservation techniques are performed. These techniques aim to reduce but not eliminate the horizontal and vertical bone reabsorption after tooth extraction.[3] Commonly used for ridge preservation are the same as those used to promote bone regeneration, namely, demineralized freeze-dried bone allograft and deproteinized bovine bone mineral.

Other graft materials include autologous bone or alloplastic materials such as bioactive glass, β-tricalcium phosphate, hydroxyapatite, and calcium sulfate.[45] If we use the autologous bone, an alveolar reconstruction with a palatal core graft can be employed. This immediately regenerates the vertical, horizontal, and combined defects at the alveolar level with minimal morbidity in a time-effective manner.[6]

At present, it is unclear whether the primary wound in alveolar preservation/reconstruction surgery should be closed to cover the membranes and biomaterials. The approaches that have been used to date range from simply placing the graft in the extraction socket to raising and replacing a flap in the original position with or without exposing the membrane to the oral cavity.[4] Yilmaz et al.[7] and Babbush et al.[8] partially closed the primary wound without using a barrier membrane, while Iasella et al.[3] and Carmagnola et al.[9] partially closed the primary wound but covered the exposed socket/graft with a collagen membrane. By contrast, Froum et al.[10] left the membrane barrier exposed and advised their patients to rinse with chlorhexidine for a prolonged period of time.[10] However, the majority of studies report primary closure, either by a coronally advanced flap over the graft/socket alone or covering membrane or by a pedicled split-thickness palatal flap over the graft.[411121314151617]

The subepithelial connective tissue pedicled split palatal flap for soft tissue coverage on extraction sites was first published by Wang in 1993[18] and then by Nemcovsky and Artzi in 1999.[12] This flap consists of a strip of connective tissue that is separated from the palatal vault and then rotated over the defect.[19] The donor site remains primarily covered thanks to the remaining epithelial portion of the palate flap. This flap increases both the height and width of the soft tissue at the recipient site. This approach is advantageous for various reasons.[19] First, there is a direct blood supply from the base of the pedicle, which reduces the risk of necrosis. Second, the esthetics achieved with this flap is good. Third, the procedure is relatively simple, requiring only an accurate fixation on the buccal part of the crest. Fourth, there is little morbidity. Finally, the flap increases the soft tissue at the recipient site both in horizontal and vertical dimensions.[20]

Success with the palatal flap depends on the thickness of the palatal mucosa, which is greatest between the canines and molars. The flap can be done from premolars rotating to anterior zone or from canine rotating to premolar or molar zone, only changes the blood supply that comes from nasopalatine artery first or greater palatine artery in the second variant of the technique. Another important factor is the distance from the gingival margin to the palatine neurovascular bundle which varies from 7 to 17 mm at second premolar sites.[21]

The palatal flap can be also used for indications other than soft tissue coverage at extraction sites. These indications include closure of the alveolus after ridge preservation with biomaterials or after immediate implant placement, correction of local tissue defects or dehiscence, and multilayer closure after alveolar bone grafting.[20]

Purpose

The purpose of this case series report was to describe the subepithelial connective tissue pedicled palatal flap technique, its indications, and its efficacy in closure of ridge reconstruction. The lessons learned in particular from three cases are described.

CASE REPORT

Case description

The present case series consisted of all consecutive patients who underwent a ridge augmentation or immediate implant placement with a subepithelial connective tissue pedicled palatal flap reconstruction in our private dental clinic between 2014 and 2020. All patients signed an informed consent form prior to treatment. This case series consisted of 11 consecutive patients [Table 1]. Six were men and Five women, were women. The mean age was 47.6 (range, 30–67) years. Ten and one patients had anterior and posterior maxillary defects, respectively, and a reconstruction with a connective tissue pedicle rotated flap was planned. Two patients were smokers. All patients were in good general health. The connective tissue pedicle rotated flap was used after ridge preservation in one case, concurrently with a palatal core graft for alveolar reconstruction in five cases [Figures 1-8], for alveolus closure and simultaneous implant placement in two cases [Figures 9-16], to help primary closure in a reconstruction with symphysis onlay bone graft in one case, for alveolus closure in delayed implants reconstructed with autologous bone in one case and as a soft tissue graft for a large gingival buccal defect in one case. All procedures were performed under local anesthesia (2% lidocaine with epinephrine Normon 1:100.000) by two surgeons (JM and SG).

Table 1

Ridge reconstruction and flap characteristics and complications in the case series

Case number	Zone of the graft	Flap thickness (mm)	Flap length (mm)	Flap width (mm)	Technique used for socket reconstruction	Complications
Case 1	Posterior maxilla	3	15	8	Socket preservation with Keraos® and Bio-Gide® membrane	Necrosis in the buccal part of the flap
Case 2	Anterior maxilla	4	15	7	Palatal core graft	Necrosis in the buccal part of the flap
Case 3	Anterior maxilla	3	14	7	Palatal core graft	No complications
Case 4	Anterior maxilla	3	15	7	Palatal core graft	No complications
Case 5	Anterior maxilla	4	20	7	Symphysis bone graft with Geistlich Bio-Oss® and Bio-Gide® membrane	Fistula and infection in the upper zone of the Bio-Oss® graft. No complications in the bone block or in the pedicled flap
Case 6	Anterior maxilla	3	20	8	Palatal core graft	No complications
Case 7	Anterior maxilla	4	20	7	Delayed implant with autogenous bone and a AT collagen membrane	Dehiscence in the epithelial repositioned flap
Case 8	Anterior maxilla	3	15	7	Immediate implant with autogenous bone in the gap	No complications
Case 9	Anterior maxilla	4	16	8	Immediate implant with Geistlich, Bio-Oss® and Bio-Gide® membrane	No complications
Case 10	Anterior maxilla	4	25	8	Esthetic zone with the palatal flap only (no bone graft)	No complications
Case 11	Anterior maxilla	4	24	8	Palatal core graft	No complications

AT – AT is the comercial name of the membrane

Figure 1

Case number 6. The 1.1 teeth have to be extracted. A large defect on the vestibular wall can be observed.

Figure 8

Two years after the surgery. The definitive crown placement.

Figure 9

Case 7 of the table. A horizontal clinical view of the defect. A medium combined defect as rated by Wang in 2002.

Figure 16

Four years after the surgery in Case 7. Some of the height has been lost but the gingival margin of the implant is similar to the gingival margin of the tooth.

View of a palatal core that was 10 mm long and 4 mm wide that was obtained for case 6.

Placing the palatal core in the socket.

A rotated palatal flap that was 3 mm thick, 20 mm long, and 8 mm wide was obtained for Case 6. The palatal flap was used to cover the collagen membrane and the palatal core.

The suture and the exposed connective tissue. The pedicled palatal flap is sutured in the vestibular zone.

At 4 months after pedicled surgery. The exposed connective tissue was completely re-epithelialized. The implant was placed in a correct position.

The healing and the definitive crown placed at 6 months of implant placement.

A vestibular full thickness flap to place a single implant.

The rotated palatal flap obtained in Case 7. The flap was 4 mm thick, 20 mm long, and 8 mm wide.

Two years after the surgery in Case 7. The width obtained is quite similar to the width of the adjacent tooth.

Two years after the surgery in Case 7. Some of the height has been lost but the gingival margin of the implant is similar to the gingival margin of the tooth.

Surgical description

The thickness of the palatal gingiva was determined by probing after administering local anesthetic. Only patients whose gingival thickness was at least 4 mm were considered suitable for the pedicled palatal flap.[22] To raise the palatal flap, a palatal paramarginal or marginal incision is made from the molar region to the defect that is to be covered. At this point, a small distal releasing incision can be made to facilitate the elevation of the full-thickness palatal flap [Figure 17].[23] The length of the incision depends on the size of the defect. A dissection of the full mucoperiosteal palatal flap is done to access the connective tissue donor. Thereafter, a sharp incision of the subepithelial tissue parallel to the first incision is made in the same way that a connective tissue graft is harvested (i.e., seeking to maintain a constant thickness of 2 mm but leaving it attached in the anterior region) [Figure 18]. The subepithelial connective tissue flap is then elevated and rotated to cover the defect. Pedicle base must be wider than the coronal portion thereof. In this way, we ensure the proper vascularization of the flap [Figure 19].[20] The flap is then sutured in the vestibular zone. To fix the connective pedicled palatal flap, a horizontal mattress suture is made to secure it in the labial side [Figure 20]. Finally, the subepithelial connective tissue flap is just completely fixed with suspensory suture points and simple suture points in the vestibular zone [Figure 21].

Figure 17

Case 3 of the table. A small distal full - thickness flap reflected incision can be made to facilitate elevation of the connective tissue flap.

Figure 18

A sharp incision of the subepithelial connective tissue that is parallel to the first incision is made, maintaining a constant thickness of 2 mm but leaving it attached in the anterior region.

Figure 19

The subepithelial connective tissue flap is then elevated and rotated to cover the defect. Special attention is paid to the base of the pedicle to prevent harm to the blood supply vessels.

Figure 20

To fix the connective peddled palatal flap, a horizontal mattress suture is made to secure it in the labial side.

Figure 21

The subepithelial connective tissue flap is just completely fixed with suspensory suture points and simple suture points in the vestibular zone.

If the purpose of the procedure was only to increase buccal gingival thickness, a partial-thickness flap in the vestibular zone was raised, similar to the pocket created for a free connective tissue graft. If an implant was placed simultaneously, or a palatal core graft or a guided bone regeneration procedure was performed, the flap should have full thickness at the alveolar crest.[1920] In the case where block grafting was performed, incisions in the periosteum were made at the base of the buccal flap to facilitate displacement toward the coronal aspect, thus increasing the chance of obtaining a perfect fit and a primary closure without tension.

Since the donor site is situated in an area that is well vascularized by the greater palatine artery, heavy bleeding can occur while elevating the flap. Cauterization may be necessary. Since only a subepithelial connective tissue flap is removed, the palatal wound at the donor site can be totally closed by suturing together the epithelial part of the original full-thickness flap.[20]

All patients were prescribed broad-spectrum antibiotics (amoxicillin with acid clavulamic 500/125 mg 1/8 h 1 week) to prevent infection and ibuprofen 600 mg 1/8 h 3–7 days to reduce edema and inflammation. The patients were advised to rinse with 0.2% chlorhexidine for 1 week and to apply chlorhexidine gel on the wound 3 times a day for 2 weeks.

RESULTS

Immediate postsurgical bleeding in the palate was not common. However, when it did occur, it was easily controlled with additional palatal sutures and compression. There were no cases of late postsurgical bleeding.

The augmented connective tissue showed little shrinkage and was covered by epithelium after approximately 2–3 weeks. Postoperative morbidity was similar to that observed when a free subepithelial connective tissue graft is taken from the palate. The pedicled flap blended with the surrounding tissue. In all cases, a slight difference in color relative to the buccal keratinized mucosa was noted between the reconstruction site and the gingiva of the neighboring proximal teeth. However, esthetically, this was not important and was hardly noticeable when the final restoration was completed.

After 2 weeks, one patient developed signs of infection, while two patients exhibited partial flap necrosis. One patient displayed dehiscence in the epithelial repositioned flap.

DISCUSSION

Small or moderate defects in partial fixed prosthesis implantation therapy can be treated with soft tissue grafts only. However, when implantation therapy of severe defects is planned, surgical approaches that augment both hard and soft tissues are preferred.[6820] Several techniques were proposed to augment the soft tissue, including free grafts,[2425] palatal roll flaps,[26272829] or palatal mucosal flaps.[1113141617] The present case series report describes a surgical technique that can increase the soft tissue before or at the time of ridge preservation or implant placement, namely, the subepithelial connective tissue pedicled palatal flap.

A subepithelial connective tissue pedicled flap between the mucosa and the periosteum has more predictable outcomes than free flaps as it has a much better chance of survival. This is because an important part of the flap blood supply is maintained during and after the procedure.[202829] Such flaps are particularly indicated for grafting over poorly or nonvascularized areas such as a bone graft or a nonresorbable membrane.[20] The good vascularization of the flap may explain why it exhibits minimal contraction.[2029]

With regard to the vascularization of the subepithelial connective tissue pedicled palatal flap, the blood supply of the flap is assumed by the mesial strip after the distal palatal vessels are severed. In this area, there are small arterial branches that accompany the incisive nerve and ensure blood circulation to the anterior palatal mucosa. The blood supply is directed to the base of the pedicle by the palatine artery and the nasopalatine artery.[19]

One important limitation of the pedicled palatal flap relates to the shape of the palatal vault. In shallow palates, the neurovascular bundle is located closer to the gingival margin, which will result in a narrower flap. In addition, if the palatal vault is high and steep, the flap will tend to be thinner.[21] Another important limitation is the thickness of the flap. While the placement of the soft tissue flap over the alveolar ridge results in a vertical rise, the degree of vertical gain is limited by the thickness of the flap.[20] In the second case of the present series, the palatal vault was very narrow, and the flap obtained was quite thin. The shrinkage of the pedicled palatal flap and the free gingival connective tissue graft has been assessed previously. Orsini et al. reported that free gingival connective tissue grafts shrink by 43.25% at 52 weeks. This is higher than the shrinkage reported for free gingival grafts used for gingival augmentation procedures (25% after 4 years of follow-up). Despite this, Orsini et al. found that there was a significant increase in the amount of keratinized tissue in the graft area.[30]

On the other hand, Akcali et al. test whether or not vascularized interpositional pediculated connective tissue grafts are as successful as free subepithelial connective tissue grafts in augmenting volume defects in the anterior maxilla. Twenty subjects with Seibert class 1 ridge defects in the anterior maxilla were randomly, equally assigned to augmentation by vascularized interpositional periosteal-connective tissue graft (test) or free subepithelial connective tissue graft (control). The results were that contour changes in labial distance between baseline and follow-up for the control group were (median, range) 1 mm, 0.37–1.45 (t0–t1); 1.18 mm, 0.39–1.40 (t0–t3); and 0.63 mm, 0.28–1.22 (t0–t6) and for test group 1.21 mm, 0.74–2.47 (t0–t1); 1.26 mm, 0.50–1.71 (t0–t3); and 1.18 mm, 0.16–1.75 (t0–t6). Significantly less shrinkage of the graft was observed in the test group after 6 months (P = 0.03).[31]

Augmentation of single tooth gaps with moderate ridge defects in the anterior maxilla was successfully performed using both techniques. However, after 6 months, sites treated by the pediculated graft were superior in maintaining the initially augmented volume and showed less shrinkage of the graft. This could be attributed to better perfusion of the pediculated graft.[31]

In the present case series, a collagen membrane was used in all cases where regeneration was induced by using a bone block graft or guided bone regeneration with biomaterial [Figure 11]. Like Simion et al. and Buser et al.,[3233] we believe that this approach yields more predictable bone regeneration. The pedicled palatal connective tissue flap will not fail when collagen membranes are used, because although the flap surface that rests on the membrane will not have direct blood supply, it will be amply vascularized by the base and the enveloping buccal and palatal flaps.[29] The rotated connective tissue will also partially protect the membrane if vestibular dehiscence develops between the buccal and palatal flaps during healing. Therefore, the flap reduces the risk of major complications of guided bone regeneration that arise when the collagen membrane is exposed.[29]

Figure 11

The regeneration with AT Collagen membrane and autologous bone obtained from the drilling of the implant.

In cases of immediate implantation, the palatal connective tissue flap ensures safe soft tissue closure without compromising esthetics.[11]

In all of our patients, the exposed connective tissue was re-epithelialized with keratinized tissue. This was observed previously for the pedicled palatal connective tissue flap.[29] In addition, a bridge of keratinized tissue was created over the implant site without jeopardizing the normal anatomical relationship of the buccal area [Figure 13]. This was also observed by Goldstein et al.[17] Such peri-implant keratinized mucosa influences peri-implant health and soft tissue esthetics. In particular, the integration of the flap with the surrounding tissue generates keratinized mucosa at the crest, thus maintaining the mucogingival border in its proper place and yielding good esthetics.[11]

Figure 13

Four weeks after the surgery in Case 7. The cicatrization of the rotated palatal flap can be observed.

Pedicle fixation by suturing the vestibular area [Figure 20], as proposed by Nemcovsky et al. and Goldstein et al., simplifies the technique and reduces the working time.[1314151617]

Bleeding at the donor site may cause problems. This complication was reported with other techniques where subepithelial connective tissue is harvested.[202425] In all of our cases, we used a palatal template to minimize the potential risk of bleeding.[20]

Our experiences with the subepithelial connective tissue pedicled palatal flap showed that it has numerous advantages. First, this surgical technique is suitable for mild to moderate deformities of the alveolar ridge such as one or two missing teeth in the anterior upper maxilla. Second, the procedure is versatile as it can be used in implantology, periodontics, and prosthodontics. Third, height is gained because the flap drapes over the crest. Fourth, the flap receives a direct blood supply from the base of the pedicle. Fifth, the flap is autogenous and thus integrates well with the surrounding keratinized tissue.

Sixth, it allows primary closure in immediate implant and ridge preservation procedures. Seventh, the rotated connective flap will protect the membrane if dehiscence develops in the healing stage. This prevents a major complication that greatly increases the risk of failure.

Thus, the subepithelial connective tissue pedicled palatal flap is an ideal addition to bone regeneration techniques. However, the long-term stability of the regenerated tissue must be demonstrated with longitudinal studies.

As a learning pointer, it is important to note that this technique has to be considered in patients whose gingival thickness has at least 4 mm. Moreover, the connective tissue flap obtained must be a minimum of 2 mm of thickness, not less. Another important question is the base of the pedicle. It must be wider than the coronal portion thereof and the flap should be as flat as possible. In this way, we ensure the proper vascularization of the flap. Respect the fixation of the pedicle, the coronal part has to be sutured as a packet above the vestibular partial-thickness flap with a horizontal mattress suture as a free connective tissue graft.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.