10

Extraction Socket Treatment

In nature, the healing of a tooth extraction defect is optimized for rapid, bacteria-tight closure; for example, the bundle bone at the alveolar margin is rapidly resorbed after tooth extraction so that the soft tissue can shrink more easily over the defect. However, this natural optimization does not coincide with the requirements of function and esthetics of dental implants. Several therapeutic approaches exist with the goal of compensating for the resorption of the bundle bone and facial bone lamella, thus fully transferring the contour of the emergence profile of the natural tooth to the implant reconstruction. These include immediate implant placement, ridge preservation, and simultaneous contour augmentation by GBR.

10.1 Gentle Tooth Extraction and Surgical Treatment of the Extraction Wound

Good conditions for undisturbed wound healing of the alveolus are provided by atraumatic, preferably axial, extraction of the tooth. The marginal gingiva should not be mobilized, because the detachment of a periosteal flap leads to surface resorption of the underlying bone. Therefore, surgical tooth extractions should be performed completely within the alveolar socket rather than by raising a flap, if possible. Granulation tissue and the inner marginal epithelium in the presence of marginal periodontitis of the extracted tooth should be completely excised with sharp scalpel blades. The blood coagulum can be stabilized at the entrance of the alveolus by a piece of moistened collagen fleece, so that decomposition of the coagulum by bacteria is prevented as much as possible.¹ It is useful to adapt the marginal gingiva over the collagen fleece with some sutures to stop the bleeding as well. If these conditions are met, rapid soft tissue coverage by annular shrinkage of the buccal and interdental soft tissues over the bone defect can be expected within about 3 weeks in healthy patients. Complete bony consolidation takes about 3 months in the maxilla and often somewhat longer in the mandible. Disturbances occur, for example, in the case of inflammation due to plasmin activation by the urokinase plasminogen activator (uPA), by bacterial streptokinase, or by endogenously induced hyperactivity of fibrinolysis, eg, with oral contraceptives.² The so-called dry socket is a fibrinolytic alveolitis, ie, it results from secondary dissolution of the blood coagulum.

Fig 10-1 Principle of ridge preservation. Replacement of the resorbed bundle bone with socket grafting material.

10.2 Goals of Ridge Preservation

The aim of ridge preservation is to maintain the mid-buccal mucosal level (MBML) for a subsequent dental implant. This goal is to be achieved by influencing the facial socket wall. When a tooth is extracted, the marginal bone resorbs physiologically, primarily by reducing the height of the facial bone lamella. This is explained by the concept of bundle bone (see chapter 1), a type of bone at the insertion site of ligaments and tendons, in this case the periodontal ligament. When the ligament disappears, the bundle bone also shrinks. This shrinkage is physiologically preprogrammed and cannot be stopped with the exception of the socket-shield technique (see also section 9.2 in chapter 9 and section 10.8). The extent and speed of resorption is variable between individuals.

The principle of ridge preservation is the early establishment of a resorption-stable bone structure inside the alveolus, which can take over the soft tissue support of the buccal gingiva internally before the bundle bone shrinks (Fig 10-1). Thus, indirectly, the circular fiber system of the marginal periodontium should also be prevented from collapsing, preserved, and ideally transferred from the extracted tooth to the dental implant without loss in soft tissue height and quality (keratinization; Fig 10-2). This is done by filling the extraction socket with a bone graft or other bone substitute. In the case of an alveolar defect, not only can resorption be reduced in this way, but the defect can even be filled from the inside. This corresponds to primary alveolar reconstruction (Fig 10-3).

One modification is ridge preservation together with guided bone regeneration (GBR), in which bone substitute material and a membrane are applied buccally to the alveolar wall. This is usually associated with flap elevation, soft tissue scarring, and periosteal detachment, which would contradict the actual goal of ridge preservation, which is why as little soft tissue as possible should be mobilized.

With regard to the goal of transferring the soft tissue contour of the extracted tooth to the implant reconstruction without loss of quality and height, two other procedures compete with ridge preservation: immediate implant placement and early implant placement with contour augmentation.⁴ In immediate implant placement, the implant is placed at the palatal alveolar margin, and the space between the implant and the buccal wall is filled with a bone graft, similar to ridge preservation. Advantages are that the implant can be immediately restored with a provisional restoration and that the patient saves time and money. The disadvantage of immediate implant placement is that the immediately placed implant still has the remodeling phase of the extraction socket ahead of it, with uncertain predictability of the extent of this remodeling. A meta-analysis showed a higher implant loss rate with immediate implant placement than with early implant placement.⁵ Remodeling, which cannot be well calculated, may also result in soft tissue recession and esthetic failure, especially in a thin gingival type.

Fig 10-2 Feneis fiber apparatus. Original drawing from the article by Heinz Feneis (anatomist, Tübingen).³ This work was the basis for the development of immediate implant placement by Willi Schulte (oral surgeon, Tübingen).

Fig 10-3 Principle of primary alveolar reconstruction. Filling of a socket wall defect from the inside.

In contrast, with early implant placement with contour augmentation, after 8 weeks, most of the remodeling has already been completed, and the resulting loss of bundle bone can be assessed and compensated for under visualization as needed with a stable bone graft with a low substitution rate. This results in increased safety for the esthetics and function of the implant. This discussion is currently ongoing.

10.3 Socket Grafting in Intact Alveoli

The aim of healing after tooth extraction from an implantology point of view, especially in the esthetic field, is to preserve the bone volume of the alveolar process. This is attempted in ridge preservation by filling the alveolus with various graft materials. Ridge preservation involves not only filling but also covering the extraction socket. Studies do not show that soft tissue coverage by flap mobilization is beneficial, but rather the opposite: bone resorption is increased by flap formation, and scars and flattening of the vestibule and more bone loss occur than without flap formation.

The various filling materials have been scientifically compared largely in randomized trials against unfilled spontaneous healing. In these studies, the effect size is interesting for comparing the materials. Although the buccal lamella also resorbs in ridge preservation, it resorbs less than in spontaneous healing. This difference to spontaneous healing is the effect size. In a large meta-analysis, the effect size of recombinant human bone morphogenetic protein (rhBMP)-2 was highest with a 2.7-mm difference in resorption from spontaneous healing.⁶ When filling materials were used, xenogeneic bone graft substitute was the most effective in the included studies, surpassed only by rhBMP-2. Alloplastic materials performed worse, and leukocyte- and platelet-rich fibrin (L-PRF) showed only a small additional effect over spontaneous healing. The mean of all studies showed an average of 1.65-mm resorption reduction in the vertical direction and 1.62 mm in the horizontal direction.⁷ It has been scientifically proven with moderate evidence from a Cochrane Report that ridge preseravtion is basically useful for bone preservation, but no evidence was found for better esthetics of the subsequent implant, and a reduced need for augmentation was not established.⁸ Whether an intact alveolus should be filled with bone substitute material, even if no defects are present, is quite controversial and partially rejected.⁹ There is an argument that complete filling may also limit the good natural bone healing tendency of the socket via obstruction of angiogenesis and is therefore only really useful in socket defects. In addition, a systematic review pointed out the high rate of inflammation and fibrous encapsulated bone substitute particles.¹⁰

In most studies, a barrier membrane was used for covering the graft, which may or may not be resorbable. This membrane is intended to separate the bone regeneration space of the bone graft from the bacterial influences of the oral cavity for some time, so that vascularization and ossification of the bone grafts can occur undisturbed. It is also possible to replace the membrane with a piece of collagen fleece (Fig 10-4). It is advisable to place a pontic-type provisional over the entrance to the socket so that the papillae remain supported.

10.4 Socket Grafting with an Alveolar Defect

A clear indication for ridge preservation is an alveolar defect. Even in the case of severe wall defects following marginal periodontitis, one study showed that 91.2% of the alveolar bone volume could be regenerated.¹¹ It is scientifically elegant to plug defects of the buccal alveolar wall from the inside and allow them to heal before the soft tissue collapses into the defect (Fig 10-5).

This saves the patient possibly time-consuming subsequent secondary reconstructions. This ridge preservation is also referred to as immediate reconstruction of the alveolar process, analogous to immediate implant placement.

Fig 10-4 Ridge preservation. a. Initial situation with the maxillary left canine ready for extraction with root resorption and buccal wall defect of the alveolus. b. Axial tooth extraction without touching the marginal gingiva if possible. c. Scraper chips obtained at the external oblique ridge. d. The alveolar socket is filled with purely autogenous scraper chips. e. Bone substitute material mixed with scraper chips and venous blood. The material is coagulated by polymerization of the fibrin. f. The entrance to the alveolar socket and buccal wall defect is lined with a plug of the mixed bone substitute material.

Fig 10-4 Ridge preservation. g. Collagen fleece (Resorba). h. The collagen fleece is slightly moistened externally so that it does not stick to the instruments. i. Socket filled above bone level for overcompensation. j.

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