Extensive reviews have concluded that grafting of the socket reduces bone loss regardless of product or method. However, nothing has been shown to reliably and completely maintain alveolar dimensions. We advocate a biologically driven and anatomically based approach for reconstruction of the socket. There are various socket manipulations that we have found to predictably prepare a site for dental implant. The combination of graft construct design and socket management maximizes graft success for any practitioner. Each socket should be treated individually, and products or methods used that are coincident with the complexity of the defect in question.
Key points
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Each extraction socket presents unique challenges for reconstruction. These should be addressed from an anatomic, biologic, and scientific approach.
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Biologics (PRF, Bone Morphogenetic Protein, plasma) act as adjuncts to already established socket management techniques. As a socket reconstruction becomes more complex, the importance of these grafting agents is magnified.
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Implant planning should begin at the time of tooth extraction. Socket manipulations can increase the quantitative gain and the predictability of bone grafting. These aid in streamlining dental implant reconstruction for patients.
Socket grafting is an attempt to recreate the native bone and soft tissue environment, which subsequently fosters tooth replacement. To facilitate this reconstruction, an understanding of the alveolar bone structural biology, morphology, histology, and the molecular organization of its complex associated tissues is paramount. The lifecycle of alveolar bone is codependent on its relationship with developing or mature teeth. Periodontal ligament–mediated attachments between the developing tooth and alveolar bone proper leads to alveolar bone growth during eruption of primary and permanent teeth. The periodontal ligament is often classified as having supracrestal, crestal, horizontal, apical, and interradicular zones. These are all similar in composition but emphasized because of their role in maintaining bone associated with all aspects of the tooth. A dense layer of bone adjacent to root is delineated as primary alveolar bone. This layer forms the attachment for periodontal ligament fibers and is often referred to as bundle bone because of the thick insertion of Sharpey fibers and collagen bundles. , For clarity, this is the radiographically identifiable structure referred to as lamina densa. Loss of defined lamina densa radiographically often signals a pathologic or physiologic change within the bone. , Fig. 1 illustrates the individual anatomic components of the tooth-bone interface.
Fig. 2 simulates panoramic, axial, cross-sectional, and sagittal views of the maxilla or mandible that correlate with computed tomography images. These images demonstrate the extensive trabecular bone associated with tooth roots. Dental function stimulates bone to develop in an anisotropic orientation of bone trabeculae. These are generally perpendicular to the primary force on the tooth. Bone trabeculae extend from primary alveolar bone to the inner and outer cortical bone and act to fill the interdental or interradicular space. , ,
Anisotropic bone also forms to a dental implant. Fig. 3 demonstrates implant #30, 4 months postextraction and placement of immediate molar implant, with healing abutment and with platelet-rich fibrin (PRF). a
a Platelet-rich fibrin production protocol is as follows. After administration of intravenous antibiotic, the arm opposite the intravenous fluid administration, contralateral extremity used to avoid dilution with concurrently administered intravenous fluids, is palpated for a larger diameter vessel. Once isolated, the vessel is entered with an 18-gauge needle. Venous blood is collected into a 9-mL serum clot activated vaccutainer. This tube is then spun in a centrifuge for 13 minutes at 2750 rpm. PRF is then removed from the tube. It is used compressed or uncompressed depending on the application and clinician preference.
Note maintenance of bone trabeculae with anisotropic orientation between #29 lamina densa and implant surface. Also note the bone trabeculae that have developed between the distal root socket, grafted with PRF, the implant, and #31 lamina densa. Crestal bone height is maintained in association with platform switched crestal aspect of the implant.
Bone adaptation to functional forces through mechanical transduction and remodeling is part of the natural lifecycle of bone and plays an important role in the adaptation of bone to functional demands. Consider trabecular bone as agile with the capacity to rapidly remodel and adapt. Alveolar bone especially in the mandible has one of the highest natural rates of remodeling of all the bones in the body. In contrast to the internal remodeling mediated by tooth functional forces, external remodeling of the inner and outer cortex is mediated as a function of periosteum and muscular attachment. , The face is not static and continues to change throughout life. For example, the attrition of teeth may lead to occlusal and mesial drift or overt passive tooth eruption. The mandible, in particular, has some potential to respond to this by the deposition of bone along its inferior border. In contrast, the periosteum, especially of the facial surface of the alveolus, is resorptive in nature. Resorptive remodeling of the facial aspect of alveolar bone may lead to root fenestration or dehiscence.
Following tooth extraction, bundle bone or alveolar bone proper especially in the facial and crestal region undergoes rapid regressive remodeling. This is followed by bone loss from the facial and inner cortex of the alveolar bone. Accelerated loss of facial plate is most likely a function of lack of trabecular bone between the tooth root and the facial plate together with a resorptive effect from facial periosteum. , Fig. 4 highlights the resorptive periosteum of the face, as described by Enlow and coworkers.
Extensive literature is available related to socket grafting, socket preservation, and socket regeneration. Autogenous grafts, allografts, and biologics have been evaluated as sources of socket graft or reconstruction materials. All of these approaches have been shown to preserve or reconstruct socket structural biology and reduce the rate of bone loss following extraction. Extensive reviews have concluded that grafting of the socket reduces bone loss, but it does not eliminate this loss or completely maintain alveolar dimensions. Following extraction, areas of the socket, such as the facial cortical environment, devoid of marrow and bone trabeculae seem to be susceptible to rapid bone loss. This may be a factor of decreased tropic effects and vascular supply. In these areas there is essentially no separation between the primary alveolus and the facial cortex. A basic sequence of socket changes after extraction is detailed in Fig. 5 .
Recognition of these concepts suggests grafting within the socket alone may be insufficient and grafting the facial socket environment in areas susceptible to rapid bone loss may be necessary for total maintenance of alveolar architecture. , Fig. 6 demonstrates a socket that, despite grafting with rhBMP2 the facial cortical wall was not maintained. In addition, when practical it may be advisable to place immediate implants together with grafting to accelerate the return of tropic functional forces to the socket environment.
Traditional and modified approaches to management of extraction socket biologic and morphologic preservation or reconstruction should be considered on a case by case basis. Biotype, socket health, acute versus chronic infection, native bone present, and trabecular bone support for cortical bone must all be considered. Patient health factors, including oral hygiene, systemic disease, and inhaled smoke products, may variably affect outcomes. Effective socket reconstruction following tooth extraction may require a variety of approaches depending on the location of the socket, pre-extraction condition of the alveolar bone, disease state, and structural or aesthetic requirements. Biologic agents, such as PRF or Infuse (Medtronic, Minneapolis, MN), the rh-BMP2 product, are used as modulators or additives in the following techniques. They act to upregulate wound healing and maximize predictability. Used in combination with traditional methods, anatomic, systemic, or environmental challenges can be mitigated. , Several case scenarios are presented next to demonstrate some of the many variations on socket grafting and socket regeneration techniques.
Case 1
Traditional grafting sequence of teeth #8 and #9 in the esthetic zone with moderate biotype, thin fascial wall, and crestal bone defect. Treatment was by atraumatic extraction of central incisors, graft with Infuse (Medtronic), PRF, and cancellous allograft, covered by PRF membrane, and temporized with bonded ovate politics. There was subsequent guided flapless implant placement with immediate temporization. Photographs of Case 1 are detailed in Fig. 7 .
Case 2
Tooth #30 presented with acute infection with fistula and mesial buccal facial wall defect. Treatment was stage 1 extraction, debridement, and placement of PRF. In stage 2 at 12 weeks postextraction implant was placed with simultaneous facial wall graft using titanium membrane, Infuse, local autogenous bone from scrapper procurement, and PRF membrane. Photographs of Case 2 are detailed in Fig. 8 .
