There are no clinical studies that discuss gingival regeneration during extraction socket healing. However, there is continuous discussion of the management of gingival recession and how to repair it. This article will outline the principals and procedures for gingival regeneration during extraction socket healing.
The first principle of regeneration is that we must eliminate any cause of persistent inflammation.
The term ‘regeneration’ is misunderstood in dentistry. Growing tissue is not regeneration. Growing tissue is only regeneration if the tissue produced is normal in form and function. True regeneration will only occur in a non-inflammatory environment. Any tissue formed in an inflammatory environment will produce scar tissue. In our opinion, regeneration will not occur with the addition of isolated growth factors. Allogenic proteins are foreign proteins and as a result, elicit an inflammatory response inhibiting true regeneration.
The second principle of tissue regeneration is that tissue growth cannot be restrained.
Tissue regeneration cannot be guided or directed. The regenerative process must be free of outside constraints. The tissue must be permitted to grow according to the genetic makeup of the cells involved. For this reason, we do not advocate the use of tacks on membranes that constrain the regenerative process. The tissue under the membrane must be allowed to move and grow in an unrestrained manner. Likewise, tissue regeneration will not occur if the area is loaded in any manner. Any prosthetic such as a denture or flipper that applies pressure to the tissue will block regeneration.
The third principle of tissue regeneration is that the entire process of tissue formation must be stimulated.
Tissue regeneration will only occur if the entire process is stimulated. Bone and gingiva that is allowed to heal without intervention is always inferior in form and function to normal tissue. Our bodies never regenerate, and the tissue produced without intervention is always inferior to the original tissue.
One of the methods used to prevent esthetic defects post extraction is immediate implant placement with temporization. However, even in the most ideal situations this procedure still produces on average between one and two mm of gingal recession (thin phenotype 1.96 mm, thick phenotype 1.18 mm). It was also found that the more lingual the implant is placed, the greater the recession.
Extraction without grafting finds after a 6- to 8-week healing period, the total ridge thickness in the crestal midline reduced by 15% of the original dimension. The buccal plate resorbed in an “inverted V shape”. Forty-two percent of subjects had lost 4 mm or more of buccal bone in the midpoint of the extraction socket. After a 6- to 8-week healing period post-extraction, there were significant reductions in the hard and soft tissue dimensions of the ridge, most notably on the most coronal mid-buccal aspect.
When comparing no grafting to cadaver grafting and collagen membrane, a significantly greater horizontal resorption was observed at simple extraction sites (4.3+/-0.8 mm) compared to grafted sites (2.5+/-1.2 mm). The ridge height reduction at the buccal side was 3.6+/-1.5 mm for the extraction-alone group, while it was 0.7+/-1.4 mm for the ridge-preservation group. Moreover, the vertical change at the lingual sites was 0.4 mm in the ridge-preservation group and 3 mm in the extraction-alone group. Other studies have found that ridge preservation with cadaver grafts and collagen membrane show minor buccal gingival recession but complete loss of the interdental papilla.
To date, there is no therapeutic modality that predictably produces excellent esthetic and alveolar outcomes. The concept of gingival regeneration proposed here is to stimulate the regeneration of gingival tissue after extraction to produce ideal gingival esthetics.
Gingival Regeneration: Principles and Procedures
In this case, the molar was extracted and covered with a d-PTFE membrane. The gingiva and membrane are bonded in place with Oral Bond. The suture-less membrane technique is used for two reasons. First, suturing induces inflammation in the gingival tissues immediately over the regenerating tissue in the extraction socket, which violates the first principal of regeneration. Second, sutures fix the membrane in place and does not allow for the regenerating tissue to move according to its preferred growth, which violates the second principal of regeneration.
At the time of extraction and grafting, the membrane lies directly over the crest of the alveolar ridge.
However, after 5 weeks the membrane has risen approximately 3 mm above the alveolar ridge.
Four weeks after extraction.
The buccal and lingual gingiva remain significantly enlarged. The yellow material on the membrane is residual Oral Bond adhesive. The membrane is no longer over the alveolus and under the gingiva, but on top of the gingiva.
The membrane is removed at 4 weeks, exposing the regenerated tissue. This tissue in osteogenic in origin but unmineralized.
The implant is placed 4 weeks after extraction at the time of membrane removal, with the healing abutment flush with the gingival crest.
10 weeks after implant placement, the implant is ready for restoration. The crest of the gingiva is larger than the original gingival crest, which has never before been reported with any other extraction methodology.
The original gingival margin is still evident with the regenerated tissue now covered with epithelium. The crestal gingiva is now coronal to the original gingival margin with retained papilla. No recession has occurred since implant placement as the healing abutment is still flush with the gingival crest.
The gingiva around implant #10 is coronal to the original gingival margin. Genioplasty of approximately 1 mm would bring the gingival margin into symmetry with #7.
In non-esthetic areas, regeneration of ideal gingival contours via the gingival regeneration protocol outlined here promotes simple, effective oral hygiene and avoids food impaction.
The question is: what is stimulating the gingival regeneration produced in these cases?
The enlargement of the entire gingival crestal tissue after tooth extraction has never been reported. The presence of the d-PTFE membrane could be thought of as creating gingival hypertrophy, but this is not seen in ridge augmentation surgery using science-based bone grafts and it is not seen when sockets are grafted with cadaver bone grafts. For these reasons, the membrane is not simply creating gingival hypertrophy due to a foreign body reaction. The membrane is originally placed over the alveolar crest at the time of extraction, but after one month the membrane is found to be 3 to 4 mm above the alveolar crest. Also, when the membrane is placed, it is under the gingival margin. Yet 4 weeks later, it is located on top of the gingiva. From these findings, it is obvious that the membrane is being forced coronally as the socket heals.
In this radiograph, the membrane is level with the alveolar crest.
This radiograph is two weeks post extraction, showing intense mineralization in the extraction socket and the membrane has elevated off the alveolar crest.
This degree of mineralization after two weeks requires an intense amount of biologic activity involving the migration and replication of regenerative cells from none to millions. In addition, the intense biological activity requires significant vascularization to provide nutrients and remove wastes. This intense proliferation of cellular and vascular activity surely increases pressure in the contained socket that can only be relieved by tissue growing out of the extraction socket. Once this osteogenic tissue is forced out of the extraction socket, the differing cellular signals prevent mineralization and the newly formed connective tissue enlarges the gingival crest and gingival tissue is regenerated.
By following the regenerative principals listed above with a science-based bone graft material that stimulates bone formation, gingival regeneration occurs and predictable gingival esthetics are achieved.
A final note: When using this regenerative technique, the membrane must be placed deeper under the flap to compensate for the rise of the membrane during healing. We recommend placing the membrane approximately 6 mm apical to the alveolar crest so the regenerative process does not push the membrane out of the gingiva resulting in loss of the membrane and exposure of the graft material.
By following the regenerative principals listed above with a science-based bone graft material that stimulates bone formation, gingival regeneration occurs and predictable gingival esthetics are achieved.
A final note: When using this regenerative technique, the membrane must be placed deeper under the flap to compensate for the rise of the membrane during healing. We recommend placing the membrane approximately 6 mm apical to the alveolar crest so the regenerative process does not push the membrane out of the gingiva resulting in loss of the membrane and exposure of the graft material.
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American Society for Bone and Mineral Research (ASBMR)
Tissue Engineering and Regenerative Medicine International Society (TERMIS)