Modified Roll Envelope Technique Combined With Apically Repositioned Flap (MRARF) for Peri-Implant Soft Tissue Augmentation–A Case Series

Introduction

Dental implants have been used widely to restore dentition defects and are the first choice for some patients to repair missing teeth. In the recent decade, substantial evidence has shown that the quantity and quality of the existing peri-implant soft tissue are essential determinants of the long-term stability of endosseous dental implants, in addition to the pink aesthetics aspects.^1,2 Peri-implant soft tissue phenotype is a new term coined to describe the morphological and dimensional features surrounding a dental implant, encompassing keratinized mucosa width, mucosal thickness, and supracrestal tissue height.^3,4 Peri-implant soft tissues are crucial as a first barrier between the oral environment and the endosseous dental implants.⁵ Therefore, soft tissue management and peri-implant long-term health have become a focus of modern and effective implant dentistry.

For patients with periodontitis, due to the tooth loss sites accompanied by different degrees of bone resorption, bone augmentation surgery is often required before or during implant placement to improve the success rate of dental implants.^6,7 When labial-buccal bone dehiscence and bone fenestration are found during implant placement, guided bone regeneration (GBR) and submerged implant healing should be considered.^8,9 In submerged healing, the mucosal wound is closed after implantation, and the upper soft tissue can increase implant stability and avoid fibrous tissue wrap on the implant surface, which is conducive to the osseointegration of implants.¹⁰

However, horizontal or vertical bony defects and the lack of soft tissue volume or quality following tooth loss have frequently occurred in patients with periodontitis. Furthermore, in patients who underwent GBR simultaneously with implant placement, the wound should be closed without tension due to the implantation of bone graft materials. This may lead to the relocation of the attached gingiva and reduced keratinized tissue width.¹¹ The soft tissue contour is often compromised because coronally repositioned flap techniques create an optimal barrier to bacterial ingrowth during the hard tissue augmentation procedure. Some studies have also reported that the bone remodeling of the implant site can cause a certain degree of vertical and horizontal bone loss even when conducted with GBR, and patients may still have insufficient peri-implant soft tissue phenotypes postoperatively, which appears as a series of esthetic and functional complications.^12,13 Soft tissue treatment can be considered in the second-stage surgery to improve the above situation because, at this time, the implant location and the bone augmentation obtained by GBR are known, and the postoperative effect is easy to predict. Moreover, this could decrease the number of operations conducive to patient acceptance.¹⁴

When the submerged implant has achieved osseointegration during the healing process, it is necessary to perform the second-stage surgery to expose the implants and place healing abutments to promote soft tissue contouring.¹⁴ In the early days, the implant was exposed by circumferential incision, which was applicable for abundant keratinized mucosa.^15,16 The second-stage surgery’s incision type and flap design were gradually modified to improve the peri-implant soft tissue phenotype. Several methods have been described for this task, including apically repositioned flaps, roll flaps, and free gingival grafts. At the same time, drawbacks were reported, such as inadequate peri-implant soft tissue thickness, gingival recession, and soft tissue harvesting from another area.^17–19

In this study, an attempt was made to perform a modified roll envelope technique combined with an apically repositioned flap (MRARF) at the second-stage implant-prosthetic surgery to improve the peri-implant soft tissue phenotypes of patients who underwent dental implantation and GBR treatment simultaneously. A case series is presented to provide a reference for obtaining better peri-implant soft tissue morphology after second-stage surgery.

Clinical presentation

This case series describes 4 patients treated at the Periodontology Department, The Second Affiliated Hospital Zhejiang University School of Medicine. Informed consent was obtained from all patients in accordance with the guidelines as per the Helsinki Declaration of 1975, revised in 2013. The first patient presented with the maxillary left central incisor (#9) deficiency in the aesthetic zone accompanied by grade III° mobility of the upper lateral incisor (#10). The second patient had a #9 deficiency. The third patient presented with tooth loss of the mandibular left second premolar (#20). The fourth patient presented with missing teeth of #19 and #20. All 4 patients had received dental implants and GBR treatment 6 months earlier and were to be taken up for second-stage surgery. The cone-beam computed tomography data showed sufficient and intact labial-buccal bone tissue in the arches. A written informed consent was obtained before each surgical treatment. Information on the patients is shown in Table 1.

Table 1 The details of the patients

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Surgical technique

To obtain a good gingival profile of peri-implant and effectively improve soft tissue deficiency, we proposed a modified buccal pedicled flap technique at second-stage surgery. Ideally, a gingivectomy would have been used to thoroughly expose the implant. However, to reconstruct and augment the peri-implant soft tissue phenotypes, a decision was made to manipulate the abundant proximal soft tissue above the implant level during second-stage implant surgery.

1. After local anesthesia, the epithelium of soft tissue above the implant level was removed with a surgical blade (no. 15C, Swann-Morton, UK) (Figure 1).

2. A horizontal incision to the periosteum was made at the lingual or palatal corner of the zenith of alveolar ridge, which was connected to 2 parasulcular incisions placed on the adjacent teeth. Following extension to buccal aspects to a position of about half the tooth by crevicular incisions, the full-thickness flap was raised to expose the implant, ultimately reaching the labial or buccal corner of the alveolar crest (Figure 2).

3. Extreme care was taken to give sharp dissection for tension-releasing via cutback incisions by surgical blades into the labial or buccal mucosal tissue of the implant to retain the periosteal bed and form a partial-thickness flap. Then, the de-epithelized pedicled connective tissue flap was gently rolled into the artificial envelope created by the buccal semi-thick flap design. At this point, the cover screw of the implant was removed and replaced with a gingival former (Figure 3).

4. The suture for wound closure was inserted from the implant root side, and the labial or buccal tissue flap was apically repositioned with a 6-0 nonabsorbable suture (Taihe, China). Meanwhile, the obtained de-epithelized pedicled connective tissue transposition flap was rolled into the labial and buccal aspects in an artificial envelope and anchored to the periosteum and semi-thick flap medial side by suturing (Figure 4).

5. After rotation and apical reposition fixation, both flaps were sutured to each other at the alveolar ridge by penetrating the buccal double-layer tissue of the roll flap and lingual flap. The flaps and the wound closure around the healing abutments were rigidly immobilized with an interrupted suture (5-0 nonabsorbable, Taihe, China) (Figure 5).

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Case management

Each surgical site was treated by following a previously described surgical protocol. Each implant site was considered eligible for MRARF if it showed a labial and buccal deficiency and a reduced width of keratinized mucosa compared with the adjacent teeth. The sutures were removed 2 weeks after surgery, and there was stable and firm keratinized tissue over the underlying tissues and gingival former. At 6 weeks, the band of keratinized tissue was found to be healthy and stable enough to permit subsequent prosthetic procedures. A final impression was taken to produce the definitive implant-supported restoration. The augmented tissue was received, and a full ceramic restoration was performed. At 3 months, the patients were recalled for oral hygiene instructions and regular plaque control. This was followed with a 1-year recall to reinforce oral hygiene instructions and supragingival plaque control (Figure 6).

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Clinical outcomes and measurements

Four patients were recruited to receive implant-supported restoration. Of 5 implants, 2 were placed in the maxilla, and 3 were placed in the mandible. At the second-stage implant surgery, all patients received MRARF. All surgery sites healed uneventfully, and no postoperative pain or immoderate swelling was reported. The harmonious color, texture, and mucogingival junction position matched the surrounding tissue and adjacent teeth, which satisfied all patients with the final results. The modified flap design allowed for increasing the width of keratinized mucosa and its thickness with the minimally invasive technique during the 6-week and 1-year follow-up. During the observation period, all implants were stable, and none had lost osseointegration. Keratinized tissue width, soft tissue thickness, and the Pink Esthetic Score/White Esthetic Score at preoperative, 6 weeks, and 1 year of pro-operative (Tables 2 and 3) measured the gingival condition and esthetic evaluation.

Table 2 KTW and STT measured in preoperative, 6 wk, and 1 y of pro-operative*

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Table 3 PES, WES, and PES/WES scores for 4 patients at 1-y follow-up*

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Keratinized tissue width: measured from muco-gingival junction to mid-buccal gingival or peri-implant mucosal level.

Soft tissue thickness: measured from the length of a stoppered endodontic file (#30) penetrating through the facial soft tissue 2 mm below the mid-buccal peri-implant mucosal margin.

The Pink Esthetic Score and White Esthetic Score were measured for the objective aesthetics using clinical photographs taken at preoperative, 6 weeks, and 1 year of pro-operative.²⁰

Discussion

Various approaches have been proposed to augment and manipulate the peri-implant soft tissue phenotype.²¹ In 1980, the classic procedure proposed by Abrams was a palatal pedicled connective tissue flap combined with a roll technique for reducing buccal soft tissue concavity. In this surgical method, the roll flap mobility is acquired by 2 vertical incisions extended to the buccal mucosa.²² A modification introduced by Giordano et al²³ consists of 2 vertical crestal incisions 1.5 mm away from the adjacent teeth to preserve the interproximal papillae and obtain flap mobility. Pandolfi²⁴ proposed another modification of the original pouch roll envelope technique for correcting horizontal alveolar mucosa defects in implant-supported rehabilitation with a first-stage or second-stage approach. This was a report of cases describing a new flap design to address a modified protocol where stage-two implant surgeries are carried out in the circumstances of inadequate peri-implant soft tissue phenotypes. The abundant supracrestal mucosal tissue above the implant was used for de-epithelization. Then, the pedicled connective tissue flap was rolled under the buccal mucosa to increase the buccolingual dimension and improve the buccal contour. Meanwhile, the proposed combination of the buccal pedicled flap with the apically repositioned flap technique made full use of the supracrestal mucosal tissue width to increase the width of keratinized mucosa to a certain extent.

In 2013, the results of Tunkel et al²⁵ highlighted that the surgical procedures performed by the apically repositioned flap combined with a connective tissue graft could achieve the necessary keratinized mucosa width and tissue thickness at the same time. However, some possible drawbacks may be related to the connective tissue graft in terms of blood supply maintenance, additional soft tissue harvesting and trauma, and contraction of graft, which may yield increased postoperative discomfort.^26,27 In contrast, the proposed MRARF combines the apically repositioned flap with a buccal pedicled flap technique. It may be conducive to increased patient acceptance for its low morbidity, shortened surgical time, and lack of need for a palatal donor site.^28,29

The modified roll envelope technique described in this article presents advantages over other roll techniques because it includes a semi-thickness flap applied to preserve the buccal periosteum to reduce bone resorption caused by direct exposure of the bone. The roll flap procedure maximizes the amount of connective tissue that can be rolled within the buccal envelope flap and provides the benefit of increased vascular supply to the roll connective tissue, thereby gaining thickened adherent mucosa around the implant. Meanwhile, in the apically repositioned flap approach, the retention of the periosteum may provide an effective apical aspect anchor for the internal roll connective tissue flap. As described in previous reports, treatment of mucogingival deficiencies with the apically repositioned flap constituted an efficient and predictable therapeutic modality to increase the apical-coronal dimension of the attached gingiva with minimal morbidity, fast healing and good aesthetics.^30,31

Thus far, there has yet to be a consensus regarding the best technique and type of flap most suitable for peri-implant soft tissue treatment. Based on the preliminary results of this report, minimal traumatic preparation and fewer complications during the healing period can improve acceptance by patients. To this end, this paper provides clinical treatment ideas to boost the peri-implant mucosa by second-stage implant surgery and guides preliminary preparation for large sample clinical trials. Further research should focus on a longer follow-up evaluation to investigate the outcomes of this procedure, including measuring the peri-implant soft tissue phenotype outcomes.

Conclusions

This case series demonstrates the possibility of improving the peri-implant soft tissue phenotypes of patients who underwent dental implantation and GBR treatment simultaneously with MRARF applied at the second-stage implant surgery. Satisfactory results were observed in the vertical and horizontal aesthetic gingival contours, and adequate width and thickness of the keratinized mucosa around implants were achieved.