Collagen plug application in extraction sockets

Drs. Jon B. Suzuki and Diana Bronstein explore the efficacy of a collagen plug-in


Post-extraction healing is characterized by osseous resorption and significant contour changes in buccal-lingual and apico-coronal width of the residual alveolar ridge.1 Research suggests that an extraction socket augmentation carried out at the time of tooth removal is a reliable and predictable method to reduce significantly crestal bone resorption and atrophy, aid socket fill, and minimize loss of horizontal ridge height.


Ultimately, it helps patient and practitioner to reduce or eliminate the need for further costly and traumatic ridge defect augmentation at the time of esthetic rehabilitation or implant placement.1 Clinicians today are aware that sufficient alveolar bone volume and favorable architecture of the alveolar ridge are essential to achieve ideal functional and esthetic prosthetic reconstruction.

Ridge preservation procedures that are carried out immediately after extractions significantly reduce the three-dimensional alveolar bone loss that inevitably follows tooth extraction alone..2 Patients undergoing this procedure benefit from a ridge form that allows for better esthetics, contour of fixed or removable prosthesis, and implant placement.1

This article will discuss the efficacy of a collagen plug-in, preserving alveolar ridge dimensions in immediate extraction sites and present the data from the literature that involves flapless ridge preservation procedures with the use of specially heat-treated collagen plugs for occlusion of the extraction socket.3


Traditional methods of tooth extraction often result, at the least, in loss of the labial plate of the alveolar bone. Atraumatic extraction focuses on gently severing the periodontal ligament using micro instrumentation, e.g., periotomes, intending to preserve alveolar crestal height in all three dimensions.1 Already before 1970, the first attempt for the reasonable studying and the prevention of the ridge resorption phenomenon had started.4 The submerged root concept was introduced as a ridge preservation technique.7,13

The trauma of the extraction brings a cascade of cellular events to fill the socket with bone. Grafting at the same time takes advantage of this phenomenon. Contemporary socket preservation techniques involve the placement of different biomaterials into the socket.5,8 Dr. B.K. Bartee proposed a classification of application techniques depending on the purpose of the ridge preservation. This classification is based on the resorbability pattern of the bone graft, and three categories were identified as follows.37

As far as primary wound closure is concerned, soft tissue coverage of the graft with or without membrane, sealing of the socket with a free gingival graft, or a connective tissue graft, and placement of a collagen plug for socket occlusion have all been proposed.14,15,36,38 Barrier membranes as used for GBR have been employed, showing good results in ridge preservation.17,18,19 The need for primary soft tissue closure presents the main drawback associated with this technique.3 It requires significant coronal flap advancement causing coronal displacement of the mucogingival junction and of the keratinized gingiva toward the crest, and increases postoperative swelling and discomfort due to periosteal scoring and/or relieve incisions.20 Furthermore, if membrane exposure occurs, risk for infection of the graft increases, and the outcome of the preservation procedure becomes less predictable,21 even though one study by Nam and Park in 200911 showed that membrane exposure during the healing period did not affect the efficacy of ridge preservation procedures.

In full-thickness buccal and palatal/lingual mucoperiosteal flaps, which are raised to facilitate barrier membrane placement over sound alveolar bone, the vascular innervation via the bone-periosteum continuity is disrupted, and a marginal bone resorption of approximately 1 mm should be anticipated.6

Based on this, for predictable post-extraction ridge preservation, flapless techniques should be favored. Reflecting a flap may initiate further bone resorption due to disruption in the blood supply to the cortical bone under the periosteum. Further ridge atrophy would occur additional to the natural bundle bone resorption of the alveolar post-extraction healing socket.1



The “socket seal surgery” technique, a ridge preservation technique that does not require flap advancement, was introduced to counter these procedure-inherent drawbacks.22 This minimally invasive ridge preservation procedure involves bone and soft tissue grafting. The extraction socket is filled with bone graft, and then an autogenous soft tissue graft of adequate size is harvested from the palate and is placed over the bone graft in order to seal the socket.23 Even though the “socket seal surgery” technique was innovative in introducing a ridge preservation procedure that would not require advancement of mucoperiosteal flaps for primary wound closure, it still did not minimize the postoperative discomfort due to the graft harvesting at the donor site.3 Recent work by Araujo and Lindhe37 in a dog model showed using a subepithelial connective tissue graft taken by a window or envelope procedure from the palate may increase soft tissue coverage, but this did not result in increased bone fill.3

Then, the Bio-Col technique was introduced shortly afterwards, using the same principles as the “socket seal surgery,” but specifically using anorganic slow-resorbing bovine bone particulates as a socket graft and replacing the soft tissue graft with the use of a collagen plug to occlude the wound.24 This new technique reduced postoperative morbidity, as there was no need for flap elevation or graft harvesting.3 After the introduction of this concept, many modifications were proposed in the literature, differing either in the graft that was used (Alloplug technique, Nu-mem technique) or in the placement of the collagen plug (modified Bio-Col technique ).25-27

Because of the configuration of the extraction socket, the majority of bone graft may be lost if no protection is provided.1 Therefore, the use of collagen wound-dressing material was suggested, not only to protect the graft material, but also to  induce blood clot formation and stabilize the wound.8 A collagen dressing material is preferable due to its high biocompatibility and hemostatic ability that can enhance platelet aggregation, and thus, facilitate clot formation and wound stabilization.9 Collagen also has a high chemotactic function for fibroblasts. This might promote cell migration and accelerate primary wound coverage.10

Variations of the “socket-plug” technique have been also used for more than a decade to help minimize the amount of bone loss and ensure the esthetics of the future restoration.24 One contraindication to the application of this technique is severe buccal plate dehiscence.3 In such cases, a barrier membrane should be employed in order to contain the graft and exclude the soft tissue from invading the buccal space.39

The cases presented will illustrate the basic steps used in this technique:3

  • Atraumatic tooth extraction
  • Preservation of soft tissue architecture with the flapless technique
  • Placement of the appropriate biomaterials in the extraction site
  • Collagen plug stabilization


Case 1

Dr. Yueh Hsiao, Temple University
Fractured No. 19 was extracted atraumatically, and ridge preservation with Foundation® Bone Filling Augmentation Material was performed for future implant placement.

Figure 1 depicts preserved socket after careful extraction of tooth No.19 with intact buccal plate and interdental septum.

Figures 2 and 3 depict J. Morita’s Foundation®.31 It is a bone-filling augmentation material indicated for use after extractions, providing support for implants, bridges, and dentures. According to the manufacturer, the bovine-collagen-based material is formulated to stimulate growth of the patient’s own bone at an accelerated rate while minimizing antigenicity. Foundation® comes in two sizes of solid bullet-shaped plugs, designed for easy handling and placement in the extraction socket. If desired, the plugs can be trimmed or shaped for a better fit. It is radiolucent and resorbable.

31The Foundation bullet-shaped plugs come in two sizes — small (8 mm x 25 mm) and medium (15 mm x 25 mm) — and are individually packaged in sterile containers.

Figure 4 depicts the Foundation collagen plug placed in extraction socket and held by non-resorbable sutures. Immediately after extraction and socket curettage, forceps are used to place the Foundation plug on a 2 x 2 gauze pad before insertion into the extraction socket. There is no need to remove the product once it’s placed, and no membrane is required. The plugs can be shaped to mimic the root tip when needed. After placement, the Foundation plug is gently condensed into the socket.

Figure 5 depicts 1 week post-op healing after suture removal with ridge maintaining width and height.31 According to the manufacturer, implants may be placed as soon as 8 to 12 weeks after Foundation is placed in the extraction socket.

Case 2

Dr. Masa Suzuki, Suzuki Dental Clinic, Japan
Figure 6 depicts ridge preservation with Foundation® immediately following extraction of tooth No. 8 and socket debridement. Figure 7 depicts excellent healing after several weeks with keratinized tissue buccal and no loss of vestibulum. Alveolar ridge height and width appear adequate for prosthetic restoration.

Case 3

Dr. Masa Suzuki, Suzuki Dental Clinic, Japan
Case 3 pertains to teeth Nos. 17, 18, 20, and 21 due to secondary occlusal trauma in a bruxing patient with past periodontal disease. After the atraumatic extraction, granulomatous tissue was curetted out, and bone surface was exposed. Two pieces of S size and two pieces of SS size Foundation were placed in the sockets and sutured. In the lower right, GBR was performed to increase ridge width, and implants were placed 6 weeks after the extractions on the left side. Ten weeks after the extraction, the lower left side filled with Foundation was restored with implants, which were immediately loaded by a provisional prosthesis. Four months later, the final prosthesis was inserted.

Figure 8 depicts patient panoramic radiograph 2 weeks after the extractions and the placement of Foundation into the extraction sockets of the posterior lower left teeth.

Figures 9 and 10 depict patient panoramic radiograph 6 and 10 weeks after the post-extraction ridge preservation procedure in the posterior lower left. Implants were also placed lower right.

Figure 11 depicts patient panoramic radiograph 4 months after implant placement with definitive restoration in place.

Figure 12 depicts patient 4 months after implant placement, and Figure 13 shows definitive restoration in place.

Case 4

Dr. Arthur Greenspoon, Montreal, Quebec, Canada
Figure 14 depicts pre-extraction PA of tooth No. 13 after failed endodontic treatment and apicoectomy, post and core in place with defective restoration.

Figure 15 depicts immediate post-extraction PA of tooth No. 13

Figure 16 depicts placement of Foundation after the extraction of No. 13 and future implant planning.

Figures 16 and 17 depict grafted extraction socket at 4 weeks and 8 weeks

Figure 18 depicts implant in place at about 3 months after extraction and grafting with slight mesial angulation of the coronal part to improve prosthetic access and engage more of the native bone apically.


Case 5

Dr. Arthur Greenspoon, Montreal, Quebec, Canada

Figure 19 depicts tooth No. 19 with sinus tract and radiolucent J-form lesion apically with inflammatory resorption, possibly mesial root fracture

Figure 20 depicts tooth No.19 after root amputation and placement of Foundation into the mesial root socket

Figure 21 depicts tooth No. 19 post-op radiograph after definitive restoration and splint to adjacent premolar with PFM


Not many studies have documented the histology of extraction-socket healing in human subjects, and most research involving extraction-socket healing has been performed on animals, which regenerate oral tissues much faster and more completely than humans.38 Accordingly, studies of extraction-socket healing in animals cannot be equated to human extraction-socket healing.

Amler, et al.41 found that the blood clot filling the socket after extraction was replaced with granulation tissue after 7 days. After 20 days, the granulation tissue was replaced by collagen, and bone began forming at the base and the periphery of the extraction socket and at 5 weeks, two-thirds of the extraction socket had filled with bone.38 Epithelium was found to require a minimum of 24 days to completely cover the extraction socket, with some extraction sites requiring up to 35 days to completely cover the socket.41 The epithelium was found to grow progressively, enveloping islands of granulation tissue, debris, and bone splinters. 38Amler noted that all stages of bone regeneration progressed from the apex and periphery, and proceeded finally to the center and crest of the extraction socket.

Boyne found new bone formation after extraction only after 8 days under the socket wall but not on the surface of the bone lining the extraction socket.42 After 10 days, bone formation was occurred on the surface of the socket wall, and after 12 days, new bone formation continued along the socket wall and in the trabecular spaces surrounding the extraction site.42

In their histological samples, Devon and Sloan noted woven bone trabecula at the periphery of the socket 2 weeks after extraction. Osteoprogenitor cells, preosteoblasts, and osteoblasts surrounded the trabecula. The periodontal ligament was displaced to the center of the extraction socket and not attached to the socket wall.40

These findings indicate that, in humans, the first phase of extraction-socket healing is most likely osteoclastic undermining and rejection of the original socket wall into the healing socket.38

While it is generally assumed that after extraction bone lining the socket wall is stimulated into new bone growth, this contention is at odds with what is known about how bone responds to trauma and surgical exposure.38 During gingival flap surgery, raising the soft tissue off the bone will result in resorption of bone from the bone surface.6,43 Usualy after extraction the buccal plate is significantly resorbed, and the bony socket wall is exposed to bacterial colonization, while the body attempts to form a fibrin clot.41,44-46

Inflammatory cells trying to prevent infection infiltrate the fibrin clot. As seen in periodontal and endodontic diseases, bone is resorbed in the presence of inflammatory cells.47,48

It is more plausible that the socket wall will proceed through a phase of resorption before regeneration.38

The possible origins of osteoblasts in the human tooth extraction socket are Pericytes, Adipocytes, the periodontal ligament fibroblasts, the marrow stem cells, and the periosteum.

We know that the periodontal ligament can regenerate alveolar bone, although guided tissue regeneration techniques, which allow further osteogenic differentiation of these cells, produce unpredictable clinical results. Osteoprogenitor cells in the periodontal ligament and bone marrow may contribute to bone regeneration following tooth extraction.40


The resorption of alveolar bone following extractions results in a narrowing and shortening of the residual ridge.2 According to the literature, alveolar ridge resorption can be limited but not avoided. Complete preservation of the pre-extraction ridge dimensions should not be anticipated, even when alveolar ridge preservation techniques involving post-extraction socket grafting are applied. Ridge preservation requires thorough comprehension of tissue-healing procedures after the extraction of one or more teeth, as well as deep knowledge of bone substitute properties. The “socket-plug” technique can help the clinician to provide the best possible outcome with the least patient discomfort. The results not only depend on the delicate handling of the tissues, but also on the resorption rate of the graft material and its replacement by mature bone capable of withstanding functional loading.3 Obviously, the different anatomical and dimensional characteristics of hard tissue and soft tissue quantities, qualities, and gingival tissue biotypes, together with several other factors (e.g., reason for extraction, tooth location, etc.), may influence the final outcome of any socket preservation procedure and may be important in making the decision of whether or not a ridge preservation technique is indicated. Ultimately, the ridge preservation approach significantly limits the osseous resorption of the alveolar post-extraction ridge compared to extraction alone.1


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