Bone Block Protection using Dense Polytetrafluoroethylene Membranes in Vertical Bone Augmentation Procedures for Atrophic Maxilla: A Case Report

1. INTRODUCTION

Rehabilitation of the posterior maxilla with dental implants necessitates a thorough evaluation of both clinical and radiographic findings in order to achieve optimal results. Tooth loss leads to the inevitable resorption of alveolar bone in all dimensions. Trauma can result in significant bone resorption, posing challenges for placing dental implants and the need for bone augmentation procedures [1]. Vertical bone defects can be managed using vertical augmentation techniques, which can be categorized into three main methods, which include bone block graft technique, guided bone regeneration, and distraction osteogenesis [2].

Autogenous bone grafts remain the gold standard for bone grafting due to their trifecta of osteogenesis, osteoinduction, and osteoconduction properties [3]. Autogenous bone grafts can be harvested from various locations, both intraoral and extraoral, with the selection based on the volume of bone required [3]. Autogenous bone grafts harvested from the anterior iliac crest offer numerous advantages, including the ability to harvest a substantial volume, particularly marrowbone, which contains ample osteoblasts and growth factors. They are easily harvested and associated with minimal complications [4].

Exposure of the bone graft to the oral environment represents the most common complication in bone augmentation procedures [5]. The likelihood of this issue escalates with the increase of the bone defect volume, particularly in cases of vertical bone defects [6]. Expertise also proves crucial in averting this complication. Its incidence can result in various repercussions, leading to the loss of bone graft material and overall procedure failure [6, 7]. We present the case of a 30-year-old patient who underwent surgery to reconstruct a significant vertical bone defect in the posterior region of the maxilla using a bone graft harvested from the anterior iliac crest. A novel aspect of our case involves covering the bone block with a dense PTFE membrane and attaching it to the fixation screws. The purpose of this addition is to protect the bone block in the event of exposure, as anticipated during surgical planning due to the size of the bone defect.

2. CASE PRESENTATION

A 30-year-old male patient was presented to the Oral and Maxillofacial Surgery department at Tishreen University Hospital following a war injury, which led to the loss of teeth in the left posterior maxilla region and a substantial portion of alveolar bone in that area (Fig. 1). The patient demonstrated good overall health, without any systemic diseases, hereditary conditions, congenital anomalies, or syndromes. He is not currently prescribed any medications. The patient was recommended an OPG and CBCT to assess the remaining bone and formulate a treatment strategy (Fig. 2). The cone beam computed tomography (CBCT) scan revealed a significant vertical defect in the lift posterior maxilla, extended from the second premolar to the molars regions. Given the crown height space of approximately 30 mm, a decision was made to opt for localized ridge augmentation utilizing an autogenous bone block with an onlay graft technique instead of a sinus lift procedure.

Under general anesthesia, a full-thickness flap mucoperiosteal was raised using two vertical incisions and one crestal incision. Additionally, the palatal flap was also elevated to fully expose the alveolar ridge. Several perforations were made at the buccal and crestal sides of the recipient bone using a small round. The iliac bone harvesting procedure commenced with an incision made on the skin, located 1.5 cm posterior to the anterosuperior iliac spine (Fig. 2). The 3–4 cm incision ran parallel to the iliac crest, with the aim of preventing damage to the lateral femoral cutaneous nerve. The exposure of the iliac crest proceeded with the elevating of the periosteum. The harvesting site was delineated with a one-mm diameter drill, a series of holes were created, and the cutting was finalized using a rotating disc (Fig. 3). An ample amount of the cancellous bone was harvested using a curette. A hemostatic sponge (Gelfoam, Pfizer, USA) was inserted into the harvested site, and the wound was sutured closed in two layers; the periosteal layer was sutured with vicryl 4/0 (SURGIReal, USA), and the skin was closed with 5/0 nylon (SURGIReal, USA).

The recipient site preparation, graft shaping, and membrane fixation were carried out utilizing a special kit (InnoGenic™ GBR Kit, Cowell Co, South Korea). The harvested thick block was contoured to fit in the recipient site. The bone block was secured in place using two tenting screws (Tenting screw, Cowell Co, South Korea). The spaces formed between the bone block and the host bone were filled using a particulate cancellous bone graft harvested from the iliac crest (Fig. 4). The d-PTFE membrane (Teflon Sheet, Cowell Co, South Korea) was secured to the tenting screws using tenting cap screws (Tenting cap, Cowell Co, South Korea) (Fig. 5). The vertical incisions were extended apically, the periosteum was scored, and the flap was mobilized to permit a tension-free primary closure, which was closed with 4/0 nylon (SURGIReal, USA) (Fig. 6). Patients were prescribed amoxicillin/clavulanate 875/125 mg (Augmentin 1000, Maatouk Pharma, Syria) twice daily for 5 days, potassium diclofenac 50 mg (Flam K, Asia Co, Syria) as required, and antimicrobial mouthwash (Fresh Mouth, BIOGHAR, Syria) for 7 days.

Although the membrane exposure was anticipated, it was less extensive than expected and occurred after 2 weeks (Fig. 7). The authors only cleaned the exposed area with a saline solution. The patient was recommended to rinse with a saline solution daily and maintain oral care. The Healing process was uneventful, with no significant complications. There were no infections or loss of bone graft material. The membrane was removed 4 weeks after the surgery. A CBCT scan was taken 6 months postoperatively to evaluate the bone height gained. The preoperative and 9-month postoperative mean height was (3.1) mm and (9.6) mm, respectively. The alveolar width gain was (6.5) mm (Fig. 8).

3. DISCUSSION

The Interest in bone grafting materials and techniques has grown significantly following the introduction of intraosseous dental implants. These implants necessitate a sufficient quantity and quality of existing bone, often leading to the need for bone grafting procedures [8, 9]. Vertical alveolar bone augmentation techniques can be categorized into four main methods: bone block graft technique (only graft), guided bone regeneration, osteoperiosteal flaps, and distraction osteogenesis [2].

Bone grafting to address vertical bone defects using bone graft harvested from the iliac crest offers numerous advantages. Firstly, the iliac crest provides a substantial amount of bone graft material, making it well-suited for extensive vertical augmentation procedures. Secondly, iliac bone grafts exhibit high osteogenic potential, facilitating new bone formation and seamless integration with the surrounding bone structures.

CONCLUSION

Based on our case report findings, it can be inferred that applying d-PTFE to cover the bone block in extensive posterior maxillary vertical augmentation procedures effectively shields the bone block from bacterial contamination, lowers the likelihood of complications, and enhances the predictability of the procedure. The incorporation of tenting screws with tenting cap screws for securing the bone block and membrane simplifies the surgical process, decreases its duration, and streamlines membrane removal.

REFERENCES