INTRODUCTION
Over the past 25 years, the market for biologics used in conjunction with bone grafting has exploded. Clinicians providing extractions for their patients are faced with a plethora of choices when deciding what they should use and when. This article’s intent is to simplify the decision tree. The type of bone defect remaining after removing the tooth dictates the type of bone and membrane we should utilize for a given socket or bone defect. We will assume that in each of the clinical scenarios discussed, the clinician will want to place an implant. It is noteworthy that even in the absence of implant treatment planning, preserving as much of the alveolus—in other words, ridge preservation—is equally beneficial for patients receiving either conventional crown and bridge or removable prosthetics (Figure 1).
In this article, we will discuss 3 common clinical scenarios and their treatment approaches based on current literature review as well as anecdotal evidence. There are 5 common denominators that are essential to successful bone regeneration. One can be certain that failure of a graft will always be traced to inadequate execution of one of the 5. Let’s examine the influence of these factors with each of the clinical scenarios provided.1
1. Adequate blood supply
2. Appropriate graft selection
3. Graft stabilization
4. Proper socket seal
5. Tension-free flap (if required) closure
CASE TYPE 1: THE INTACT 5-WALL EXTRACTION SOCKET
The number of bony walls remaining following tooth removal directly impacts the recommended grafting protocol. Five intact walls indicate an atraumatic extraction—no loss of bony walls (Figure 2). A bone graft requires an adequate blood supply to provide osteoprogenitor cells and their associated growth factors. The act of removing the tooth exposes bone rich in vascular supply. It is known as reginal acceleratory phenomenon (RAP).2 Specifically, RAP is a tissue reaction to a noxious stimulus that increases the healing capacity of the affected tissues. It is characterized by acceleration of the normal cellular activities—an “SOS” phenomenon of the body in reaction to trauma.3
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| Figure 1. At 16 weeks postoperative, teeth Nos. 7 to 9 were extracted. Grafting was done with MinerOss (BioHorizons) for crown and bridge pontic site development. | Figure 2. A 5-wall post-extraction socket. |
The second foundation for regeneration is appropriate graft selection. It is important to understand that with any bone graft choice, incorporating the patient’s own bone maximizes the graft’s ability to induce new bone formation.4 Common devices used to collect autogenous bone include bone scrapers and bone mills (Figures 3 and 4). Although there are many opinions on which graft material is best for a 5-wall socket, a mineralized allograft will always serve as an excellent choice. The primary advantage of mineralized bone allograft is that it undergoes slower resorption than DFDBA (demineralized), thus maintaining the space for regeneration.5
Relative to factor 4 (proper socket seal), the clinician has 3 basic choices to “seal” the socket. The ideal membrane should prevent soft-tissue cells from infiltrating the graft material, stabilize the graft material beneath it, and reduce bacterial infusion while enabling oxygen diffusion and the transfusion of small molecules.
Dense polytetrafluoroethylene (d-PTFE) is a newer option and a safe choice. The primary advantage of d-PTFE is that it functions to facilitate the ideal membrane requirements listed above and can be exposed to the oral cavity. This eliminates the need for primary closure6 (Figure 5). Although d-PTFE yields highly predictable outcomes, it requires a second procedure for removal. A second method to contain the graft is a collagen plug. Biocompatible and resorbable, collagen plugs are available in multiple forms and are easy to use. Lastly, platelet-rich fibrin (PRF) has become a popular choice and is associated with rapid increase in soft-tissue healing. It does require extra time and preparation via a blood draw prior to the surgery.7
Literature shows that all 3 methods of containing the graft result in significantly reduced bone resorption.8 Primary selection should come from documenting (including photography) the outcomes of each modality over the course of the clinician’s experience. Regardless of the membrane used, it should be secured with a non-resorbable suture that minimizes wicking. The sutures are typically removed in 2 weeks.
CASE TYPE 2: THE 4-WALL SOCKET
There are a number of clinical scenarios where a portion of the buccal wall is lost. This can precede the extraction by way of a buccal fistula secondary to infection. In other cases, it is the result of the extraction process itself. There are clinical scenarios in which even meticulous protocol still results in a lost portion of the buccal plate.
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| Figure 3. Bone mill. | Figure 4. Bone scraper. |
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| Figure 5. A classic 5-wall socket graft, featuring mineralized bone graft, non-resorbable Cytoplast (not seen), and L-PRF (leukocyte- and platelet-rich fibrin). | Figure 6. A titanium-reinforced membrane (Cytoplast Ti-Reinforced dPTFE Membrane [BioHorizons]) tacked with 2 self-tapped screws. |
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| Figure 7. L-PRF overlying the Cytoplast membrane (membranes prepared with IntraSpin [BioHorizons]). | Figure 8. The results achieved with the titanium-reinforced membrane. |
The approach to regenerate the buccal wall is much more demanding and less forgiving. It requires further classification of the damaged extraction socket.
• The buccal wall is thin (< 1.0 mm) or slightly perforated. In this case, I recommend an internal approach. In their 2007 paper, Elian et al8 described a flapless approach to repairing this defect. This preserves the mucogingival junction, which is especially relevant in aesthetic zone extractions. With this technique, a membrane is slid down the buccal, folded occlusally over the bone graft, and sutured to the palatal tissue.
The ideal membrane for this procedure is a cross-linked, long-lasting resorbable collagen membrane that typically resorbs at 36 weeks. The graft material utilized in this case would again be a mineralized bone graft with some autogenous bone, if possible.
• The buccal wall defect is significant (> 6.0 mm wide and long). This defect requires even stricter adherence to protocol. It requires a buccal flap. These flaps are typically at least one tooth away on either side of the defect. Often, a vertical, oblique-releasing incision is necessary to gain access for the repair. Prior to membrane placement, the appropriate graft selection is made. Within the socket, a mineralized graft is used once again. Since this protocol requires a flap, the procedure should include some autogenous bone harvested with a scraper. The outer wall of the defect should be layered with 2.0 mm of xenograft. Xenografts are bone substitutes from animals or plants. Although they have a poor ability to form bone, they maintain their volume, making them the perfect selection for the outer contour of a bone defect. This 2-layer approach has been shown to yield stable bone volume on the facial aspect, even years after surgery.4 Once the graft material is in its proper place, a titanium-reinforced cytoplastic membrane is utilized. This membrane fulfills a multitude of requirements. It is an excellent barrier to prevent soft-tissue ingrowth in the socket. It is highly biocompatible and helps reduce the possibility of infection. The added titanium has a critical function in maintaining space to prevent the newly generated buccal plate from collapsing into the socket. It is necessary to stabilize this membrane with screws (Figures 6 and 7). Many clinicians report great success with a self-tapping (no drill required) system (Osteogenics). Two screws are necessary, and it is critical that the clinician be aware of the underlying anatomy (ie, the roots of adjacent teeth) when planning the fixation. Ideally, this membrane should be covered by PRF, followed by meticulous tension-free suturing with a non-resorbable suture. The sutures are removed 14 days later, and a second procedure is required 4 months after that to remove the membrane and fixation screws. An alternative membrane with this defect would be a titanium mesh. These are typically porous and thin enough to be malleable. They also require bone fixation screws.
A significant advantage of this membrane is the ability to maintain space between the membrane and the defect. It is also known to be highly biocompatible. The presence of the pores enables blood support both to the mucosa and the bone during the regeneration phase.9 The disadvantages associated with the use of this mesh are the need for a second surgery for removal and its tendency to become exposed. Several studies have revealed that these meshes can result in successful bone grafting, even in the presence of an exposure10 (Figure 8).
CLOSING COMMENTS
Regardless of the membrane, soft-tissue outcomes are enhanced by using PRF as the final layer prior to suturing. Suturing for GBR is further enhanced by employing non-resorbable PTFE-types of sutures due to their lack of bacterial wicking. The GBR technique utilized to address the above osseous defect requires advanced surgical skills, which include soft-tissue regenerative procedures as well.
Selecting the best membrane and method can be overwhelming. The intent of this article is to narrow down the selection to a modest number of biologics that produce predictable outcomes. Every surgery demands uncompromising attention to detail and execution. The decision tree ultimately should be influenced by each clinician’s results, which mandates careful photo documentation of each GBR method utilized.
References
- Goldstep F. Bone grafts for implant dentistry: the basics. Oral Health. December 9, 2015. https://www.oralhealthgroup.com/features/1003918360/. Accessed November 18, 2019.
- Misch CE. Contemporary Implant Dentistry. 2nd ed. St. Louis, MO: Mosby; 1999:462.
- Verna C. Regional acceleratory phenomenon. Front Oral Biol. 2016;18:28-35.
- Miron RJ, Zhang Y, eds. Next-Generation Biomaterials for Bone & Periodontal Regeneration. Chicago, IL: Quintessence Publishing; 2019.
- Liu J, Kerns DG. Mechanisms of guided bone regeneration: a review. Open Dent J. 2014;8:56-65.
- Ghensi P, Stablum W, Bettio E, et al. Management of the exposure of a dense PTFE (d-PTFE) membrane in guided bone regeneration (GBR): a case report. Oral Implantol (Rome). 2017;10:335-342.
- Hamdoun R, Ennibi OK, Ismaili Z, et al. PRF in oral surgery: a literature review. Journal of Medical Implants and Surgery. 2016;1:1-4.
- Elian N, Cho SC, Froum S, et al. A simplified socket classification and repair technique. Pract Proced Aesthet Dent. 2007;19:99-104.
- Celletti R, Davarpanah M, Etienne D, et al. Guided tissue regeneration around dental implants in immediate extraction sockets: comparison of e-PTFE and a new titanium membrane. Int J Periodontics Restorative Dent. 1994;14:242-253.
- Louis PJ, Gutta R, Said-Al-Naief N, et al. Reconstruction of the maxilla and mandible with particulate bone graft and titanium mesh for implant placement. J Oral Maxillofac Surg. 2008;66:235-245.
Dr. Rasner earned his DMD degree at the University of Pennsylvania. He has completed the Misch International Implant Institute curriculum and the Pikos Institute continuum. Dr. Rasner has been teaching for 20 years. His courses, “Atraumatic Extractions for the GP” and “The Bulletproof Guide to Implant Success,” have been popular at ADA and AGD component society meetings, as well as at the national ADA meeting. His newest course, “Hands-on Atraumatic Extractions for the GP”, features 2 days of live-patient experience in his office. He has authored 3 books and more than 50 industry and journal publications. He can be reached at drrasner@aol.com.
Disclosure: Dr. Rasner has an in-kind sponsor relationship with Osteogenics.
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