New Attachment and Reattachment in Periodontal Therapy
by Dinh X. Bui, D.D.S., M.S.

New Attachment and Reattachment in Periodontal Therapy
The goal of Periodontal therapy is to halt the disease progression and prevent its recurrence, and restore the lost periodontal structure which occured as the result of the disease destruction. The later goal prompts us to evaluate the concept of “new attachment” or “regeneration”, and “reattachment” or “repair”. Each concepts will lead to different mode of periodontal therapy, and ultimately different result. New attachment is the ideal, desired goal, which each periodontist today are trying to achieve in every possible way.
Reattachment of the soft tissues to the tooth, with or without bone regeneration, has been observed clinically as far back as 1893 by Allport and 1894 by Younger, Leonard, and ohters. Box and Beube have shown histologic confirmation of reattachment in human material. Glickman and Lazansky demonstrated that it is possible for epithelium to attach itself to a higher crownward level rather than point of incision. Linghorn and O’Connel observed reattachment of connective tissue and the formation of new bone and cementum in surgically defected in dogs. Finally, Ramfjord demonstrated reattachment histologically in pathologic pockets experimentally produced in monkey. Ramfjord showed that histologic examination reveals formation of new bone, periodontal membrane, cementum, and the epithelial reattachment at a more crownward level.
In 1948, Orban in his classical article “Pocket Elimination or Reattachment” defines reattachment as the establishment of an organic connection between connective tissue and cementum in the area of gingival or periodontal pocket. He also states that repair is the
healing of an injury to cementum, periodontal membrane, and bone area which is not in communication with the pocket. According to this definition, one can see that repair cannot occur as the result of scaling and root planing since the area of healing is inside the pocket. In 1969, Melcher arrives at a more accurate definition. He states that regeneration is a biologic process by which the architecture and function of lost tissue is completely renewed. He alos pointed out that regeneration of the periodontal ligament is the key to new attachment, because it provides the continuity between the alveolar bone and the cementum and also because it contains cells that can synthesize and remodel the three connective tissues of the alveolar part of the periodontium . Repair, on the other hand, is the biologic process by which continuity of disrupted tissue is restored by new tissues which do not replicate the structure and function of the lost tissue. According to this definition, new attachment, or regeneration, will result in a completely new exact duplicate of the periodontal structures (periodontal ligament, alveolar bone , and cementum) which were there before the disease destruction, where as repair brings about the “scar” tissue, with anticipated lost of function. Caranza in his book of clinical periodontology, defined regeneration as the growth and differentiation of new cells and intercellular substances to form new tissues or parts. The final endpoint of regeneration is the complete tissue restoration. In the periodontium, gingival epithelium is replaced by epithelium, and the underlying connective tissue and periodontal ligament are derived from connective tissue. Bone and cementum are replaced by connective tissue, which is the precursor of both bone and cementum. Undifferentiate connective tissue stem cells develop into osteoblasts and cementoblasts, which form bone and cementum. Regeneration occured everyday, as the process is continuous to replace mature and dead cell. This kind of regeneration also termed wear and tear repair. Regeneration also occured in present of disease destruction. One must keep in mind that with regeneration, there is a complete restoration of tissue and function. Caranza also defined repair as “healing by scar”, of which disease progression is halted. There is no increase in bone height. The destroyed periodontium is replaced by mobilization of epithelial and connective tissue cells into damaged area and increase local mitotic divisions to provide the sufficient number of cell. Caranza defines new attachment as the embedding of new periodontal ligament fibers into new cementum and attachment of the gingival epithelium to a tooth surface previously denuded by disease. In the past reattachment was used to refer to the restoration of the marginal periodontium, but because it is not the existing fibers that reattach but the new fibers that are formed and attach to the new cementum, the term has been replaced by the term new attachment. Reattachment are now only used as repair in areas of the root not previously exposed to the pocket, such as after surgical detachment of the tissues or after traumatic tears in the cementum, tooth fractures, or treatment of periapical lesion. Finally, the definitions these process have been presented in the American Academy of Periodontology’s Glossary of Periodontic Terms. Repair is the healing of a wound tissue that does not fully restore the architecture or the function of the part. Regeneration is the reproduction or reconstitution of a lost or injured part. New attachment is the reunion of connective tissue with a root surface that has been deprived of its peridontal ligament. This reunion occurs by the formation of a new cementum with inserting collagen fibers. Finally, reattachment is the reunion of connective tissue with a root surface on which viable periodontal tissue is present. Not to be confused with New attachment.

With these concept in mind, let us review the histology of the periodontal pocket, especially in the area of tissue destruction and healing after the periodontal therapy instituted. The periodontal pocket is described as one which occured with destruction of the supporting periodontal tissues. Progressive pocket deepening leads to destruction of the supporting periodontal tissues and loosening and exfoliation of the teeth. The suprabony pockets are those which the bottom of the pocket is coronal to the underlying alveolar bone. The infrabony pockets are those which the bottom of the pocket is apical to the level of the adjacent alveolar bone and the lateral pocket wall lies between the tooth surface and the alveolar bone. Pocket formation starts as an inflammatory change in the connective tissue wall of the gingival sulcus caused by the bacterial plaque. Gingival fibers became degenerate, and the area of the destroyed collagen fibers develops just apical to the junctional epithelium. The coronal portion of the junctional epithelium detaches from the root as the apical portion migrates. Thus the initial deepening of the pocket has been described as occuring between the junctional epithelium and the tooth, or within the junctional and the tooth. During the healing of the periocontal, cells from four different areas compete for repopulation of the pocket. They are: oral epithelium, gingival connective tissue, bone, and periodontal ligament. If the oral epithelium arrives the tooth surface before all other tissues, the result will be long junctional epithelium. If the cells from the gingival connective are first to repopulate the area, the result will be fibers parallel to the tooth surface and remodeling of the alveolar bone, with no attachment to the cementum. External resorption may or may not occur. If bone cells are allowed to repopulate the area, root resorption and ankylosis may occur. Finally, when only the cells from the periodontal ligament proliferate coronally is there new formation of cementum and peridontal ligament. Thus in the last case, the ultimate goal of regeneration and new attachment has been achieved. In the normal circumstance, the cell of oral epithelium almost always is the first to repopulate the area, thus the common result after the conservative treatment of periodontal therapy would be the establishment of long junctional epithelium. Whereas when the more aggressive or surgical therapy are used such as in the case of guided tissue regeneration (GTR) or guided bone regeneration (GBR), oral epithelium downgrowth is prevented, which allows cells of the periodontal ligament to repopulate the area, aiming to achieve new attachment with osseous regeneration.
Orban in 1948 pointed out that the reattachment of the epithelium always apically from the deepest point of the epithelial attachment. This statement is no longer valid since it negates the repair or regeneration of a tooth/soft tissue interface at any site of a previously existing pocket. To understand fully the concept of new attachment, reattachment, one must examine the histologic evidence of healing following surgical periodontal therapy at two crucial sites, namely, in the area apical to the crest of the alveolar bone (infrabony pocket) and in the area of the supra crestal tissue: the epithelium/connective tissue/tooth wall unit. Further, we will clarify whether healing at these two areas represent repair or regeneration phenomenon. Taylor and Campbell in 1972 suggested a dynamic attachment in which newly proliferated epithelial cells near cervix attach themselves to the tooth and migrate occlusally along its surface. The connective tissue, in its healing, remodels and creates a new margin occlusal to the initial excision. Thus this phenomenon are term “creeping” reattachment. This concept overturn the statement made by Orban as described above. The reattachment did occur above the deepest point of the epithelial attachment. The remodeling of the gingival margin or papilla produced a small gain in an occlusal direction. When the inverse bevel was used, ther is also a long connective tissue interfaced exposed. Since connective tissue insertion suparcrestally almost never occurred, clinical healing can only be the result of epithelial adherence of the epithelium covering the connective tissue to the root, ero, a long junctional adhesion, or a long junctional epthithelial adhesion and some collagen adhesion to the root. Next we will explore the connective tissue/tooth adherence. A common observed response in this case is the allignment of fibers parallel to the root in the area immediately below the most apical position of the junctional epithelium. This is where contact inhibition of epithelial downgrowth. Supracrestal fibers filled the infraosseous defect and adhered to tooth surface. It is possible that the supracrestal healig response following flap surgery is a connective tissue adherence over a limited space immediately apical to the junctional epithelial adherence. Another mode of healing via connective tissue/tooth attahment is the fiber splicing, or “renewed attachment is the result from linkage and splicing of new and old collagen... the collagen fibrils of the new connective tissue allign in a close opposition to the exposed root surface fibrils. This is the same phenomenon as seen in reimplanted teeth into the socket. This process, since it involves the reattachment or splicing between the “old” fiber ends from the tooth surface and the “new” fibers from the healing flap wound edge, is better classified as “repair” rather than regeneration. Regeneration can only be achieved if the oral epithelium and the gingival connective tissue are prevented from repopulate the area of the lesion and allowed for the cell of the periodontal ligament to repopulate. In the successful regenerative therapy, there is remodeling and regeneration of the alveolar vertical defect with crestal resorption, formation of functional periodontal ligament withen the defect site and the deposition of the cementumlike material on the tooth wall within the defect. In other word, the entire attachment apparatus is regenerated, and take place of a normal healing response. Cementum deposition coronally to the crest of the bone margin ( about 1mm limit) serves as the anchor for the attached fibrils. We cannot speculate whether the new cementum seen supracrestally is the result of the alveolar crest resorption or whether it is truely the new regenerative response that occur during healing. Histological study has been made concerning this new deposited material. Hawley and Miller in 1975 described the new cementum as “repair cementum”. Listgarten in 1972 states that the newly deposited cementum is often devoid of well defined fiber bundles. The initial cementum deposited over the tooth structure consist of individual collagen fibers frequently running parallel to the tooth surface. Due to this reason, again, the healing is better characterized as the repair in the vertical lesions including formation of a newly formed portion of the periodontal attachment apparatus occlusal to the base of the original pocket. Perhaps true regeneration is very hard to achieve. A more practical view of a successful healing response would be a large major area of healing occurs with regeneration with a small areas of repair also found.
Thus far we have defined that new attachment is only possible in regions where pathological detachment of tissue has occurred and should not be confused with reattachment, which defines reunion of connective tissue with the root surface on which viable periodontal tissue is present. Historically, three general procedures have been used to achieve new attachment in periodontal therapy. They are gingival curettage, excisional new attachment procedure (ENAP), and flap debridement surgery. In gingival curettage, the healing is complete clinically in 6 to 10 days with the establishment of long junctional epithelium , not by new connective tissue attachment. In the event of connective tissue repair, healing may take up to 21 days. Complete removal of epithelial lining is advocated to achieve successful result. Different methods have been employed including the use of curettes, ultrasonics, and chemical agents. Nevertheless, to date, no histological evaluation has predictably demonstrated new attachment following gingival curettage. Excsional New Attachment Procedure (ENAP) is also utilized in an attempt to achieve new attachment. In animal study on Rhesus monkey, mean probing depth reduction was between 2.82 and 5.02 mm; with 73.6% of this reduction was defined as clinical new attachment. However, histological findingss have shown that healing occurred by formation of long, thin junctional epithelium. It is not possible to completely remove all the crevicular epithelium with an ENAP. Healing event takes place approximately 2 weeks to establish crevicular epithelium and 35 days to completely heal histologically. Finally, flap surgery has been evaluated concerning its use in obtaining new attachment. The response to flap debridement surgery has been extensively evaluated. Some have report that flap debridement did not induce bone formation, while others have describe reentry data demonstrating a mean of 1.2mm bone fill. Nevertheless, various human studies have indicated that gain in attachment in deep probing depth site were obtained. Clinical healing following flap debridement surgery is completed by 21 days, but is dependent on the degree of wound closure during surgery. Flap debridement surgery again demonstrated that healing was by formation of a long, thin, junctional epithelium, not by new attachment. Reattachment occur if connective tissue fibers are left on the root surface when a flap is elevated. The primary healing response is soft tissue adhesion. In short, gingival curettage, ENAP, and flap debridement surgery do not result in new attachment but rather reattachment via establishment of long junctional epithelium.
Today, efforts and advance have been made in the area of guided tissue regeneration. Regeneration procedures involves the use of barrier membrane (alone or with bone graft) to prevent oral and connective tissue epithelium from repopulate the area and allowed the cells of periodontal ligaments to arrive first at the defect site. Favorable results have been achieve with formation of new alveolar bone, deposition of new cementum, and the formation, insertion, and functional arrangement of periodontal ligament fibers. Periodontal regeneration is a goal that attracts almost all those involved in the periodontics and periodontology. The result can be obtain, but varied greatly in quality and quantity of gain. Perhaps in the future, predictable results in clearly specified areas of periodontal defects can be obtain with commanding control.