Ridge Augmentation and Concomitant Implant Placement in the Esthetic Zone Through One Surgical Site: A Clinical Report

Onlay grafting of autogenous bone block has proven to be a predictable technique with high success rates in horizontal ridge augmentation and dental implantation.^1–4  However, standard autogenous onlay bone grafting for implants often necessitates three main consecutive surgical procedures: (1) ridge augmentation, which often involves two surgical sites for both osseous recipient and donor with or without soft tissue grafting; (2) delayed implant placement; and (3) soft tissue grafting to cover the underlying bone graft (ie, at the time of bone graft placement) or to improve the keratinized gingiva around implants (ie, before or at the time of implant uncovering).^1–3  In reality, patients often express significant concerns over the duration and extent of surgery. As such, treatment options involving many consecutive surgical phases may be refused or suspended by the patient. This clinical report presents a new procedure using an autogenous block bone graft combined with a subepithelial connective tissue pedicle graft to augment a horizontal defect in the anterior maxilla for simultaneous implant placement. All of the primary surgical procedures are concentrated in one surgical procedure, and only one surgical site is involved for both the osseous recipient and donor.

A 32-year-old Chinese male was referred for the replacement of 2 maxillary teeth (teeth #8 and #9) with implants. His medical history revealed that 2 central incisors and the buccal cortex involving these teeth were avulsed in an accident 3 months previous. The patient was interested in an implant-supported fixed partial denture (FPD) and anatomical rehabilitation of the alveolar defect, rather than merely creating an illusion of a ridge through the use of a prosthesis. The patient was unwilling to undergo any surgical procedures except for the two basic surgical phases for implant placement and uncovering, and he refused additional surgical sites to obtain the bone graft.

Clinical examination showed a buccal-lingual horizontal alveolar defect and minimal keratinized gingiva at the residual site, while a protuberant anterior nasal spine could be palpated apically to the deficiency (Figure 1). Panoramic radiograph confirmed a triangular area of low osseous density corresponding to the defect and a zone of high density associated with the nasal spine (Figure 2). After the defect and remnant were scaled and evaluated, a protocol was discussed with the patient. The buccal depression was about 6 mm in width, at least 4 mm horizontally, and up to 12 mm vertically, which implied a bucket-shaped bony deficiency lacking more than half of the bucket wall. As it was difficult to maintain a stable space for ideal using of guide bone regeneration (GBR), this sort of deficiency is preferred to be restored through block bone grafting. Considering the ample bone at the anterior nasal spine, the defect would be rehabilitated through a block bone graft harvested from the anterior nasal spine so that one surgical site could cover both the donor and recipient sites. In a situation involving minimal keratinized gingiva at the donor site, a recreated bony protuberance may make primary closure over the bone graft more difficult. Therefore, a palatal split-thickness connective tissue flap was designed to simultaneously uncover the bone graft and increase the keratinized tissue. The residual crest bone were measured about 5 mm horizontally and seemed satisfactory for the placement of implants in optimal positions; therefore, the implants were expected to be inserted immediately. However, extremely thin buccal bony wall or even exposure of implants would occur at a high risk, and GBR would be necessary in this situation. The patient accepted the treatment plan options and subsequently underwent dental hygienic treatment. In case of insufficient residual bone for simultaneous implants placement, the patient was also informed of and acceded to a possible alternative method, which involved the use of GBR alone for primary augmentation, with immediate or delayed implant placement.

A horizontal incision of the edentulous ridge and two vertical releases were performed, excluding the lateral papillae at the buccal side. After elevation of a full-thick mucoperiosteal flap, a massive osseous defect and a protuberant anterior nasal spine were exposed (Figure 3). Once an appropriate graft from the donor site could be obtained that was adaptable to the size of the defect, a square bone graft was harvested from the anterior nasal spine with an osteotome (Surgerybone, Silfradent, S. Sofia, Forli, Italy) (Figure 4). When the graft was removed, the residual ridge appeared satisfactory for immediate implant placement. Two full osseotite tapered certain implants (3i Implant Innovation, Palm Beach, Fla) were placed into the located sites following the standard procedure; the #8 implant was 3.4 mm in diameter and 13 mm in length, whereas the #9 implant was 4.0 mm in diameter and 13 mm in length (Figure 5). Subsequently, the block graft was fixed to the recipient site with a screw. To attain a natural contour, one corner of the square graft was positioned supracrestally as the scaffold for the interdental papillae, and the rest of the space was packed with Bio-Oss spongiosa granules of 0.25-1 mm (Geistlich Pharma, Wolhusen, Switzerland) (Figure 6). The connective tissue flap for graft coverage was initiated using the following three incisions: (1) a horizontal incision was extended to the palatal region of tooth #13 along the tooth arch, (2) a second parallel incision was made approximately 5 mm away from the gingiva to split the palatal flap, and (3) a third distant incision was made to detach the inter flap from the palate. Below the labial full-thickness flap, the split flap was repositioned apically to cover the bone graft and the particle substitutes, while a palatal pedicle was reserved for the blood supply (Figure 7). In areas with free tension, the donor and recipient sites underwent primary closure with interrupted sutures (Figure 8).

Four months after the procedure, ridge development with improved keratinized tissue was noted, and two well osseointegrated implants were documented through periapical radiograph (Figures 9 and 10). Two healing abutments were placed, and the screw securing the graft was removed (Figure 11). Following 4 weeks of soft tissue healing for the development of gingival cuffs, a traditional prosthetic procedure was provided. According to the patient's wishes, 2 implant-supported metal-porcelain crowns were fabricated and cemented to properly seated abutments (Figure 12). The patient was satisfied with the outcome from both esthetic and functional considerations. After 2 years of follow-up, the restorations were stable and esthetic. Although vertical bone resorption about 2 mm surrounding implants was present (Figure 13), the gingival tissue represented stable positioning, improved thickness, and continual maturation (Figure 14).

GBR can be used in conjunction with alloplast, allograft, or xenograft particulates as alternatives to autogenous bone. However, these matrices are often associated with limited or poor bone formation. On the other hand, in non–space-maintaining defects, block grafts may exhibit significant advantages over particulate grafts with regard to contour reconstruction and resistance to micromovement. In this case, harvesting of bone adjacent to the defect avoided additional trauma to the donor site. Moreover, transplant of the autogenous bone block resulted in an intrabony-like space with sufficient exposure of the bone marrow, which was suitable for filling and maintaining particulate bone substitutes and provided better vascularization for bone regeneration.^5–7 

In compromised clinical situations, it is recommended that implants be placed several months after bone grafting because their placement at the time of tissue grafting is appropriate only when optimal positioning can be achieved.^8,9  In addition, implant placement usually occurs subsequent to the fixation of the graft. In this clinical report, implants were placed before graft fixation because the fixed block bone would obstruct the direct evaluation of the residual ridge and also because the screw used for graft fixation may block the osteotomy for implants in the optimal position.

A pedicle subeptithelial connective tissue graft can be designed to rebuild the gingival papillae, close the wound after immediate implant placement, and provide coverage for denuded roots or bone grafts in free tension.^10–14  With respect to blood flow, this type of tissue graft outperforms free tissue grafts. To maximize contact between the graft and host tissue, a free connective tissue is preferred for insertion between the underlying connective tissue and the overlying epithelia. Nonetheless, it is difficult to split thin gingiva supraperiosteally. Without successful vascular bridging, a free soft tissue graft can run the risk of graft necrosis, wound dehiscence, and lack of facial keratinized tissue with primary closure.¹⁵  Comparatively, a pedicle connective tissue flap may provide more reliable coverage for the bone graft with a low incidence of complications, as mentioned. Furthermore, a bony scaffold for papillae regeneration and wide facial keratinized tissue for resistance to gingiva recession can both be obtained during a single surgical appointment.^12,14 

Abbreviations

FPD

fixed partial denture

GBR

guided bone regeneration