Polson, A. M.; Caton, J.: Factors Influencing Periodontal Repair and Regeneration. J. Periodontol., 53 (10): 617, 1982.

Study aim:

To evaluate independently the regeneration capacity of a reduced periodontium, and the potential for new connective attachment to a periodontally exposed root surface.

Methods:

• the study utilized two young adult Rhesus monkeys where periodontitis was induce around a maxillary central incisor of each animal to produce approximately 60% loss of attachment and formation of an intrabony pocket while the contralateral incisor was left without disease.
• To evaluate the regenerative potential transplantion of the central incisors occured by extration and transplantation with the removal of gingival tissues by reverse bevel incision.
• Forty days post transplantation histologic evaluation occured.

Results:

• Forty days later, there was noticeable loss of crestal bone associated with the periodontitis root whcih had been placed into the normal periodontium.
• The control specimens findings w3ere consistent irrespective of whether the normal tooth had been reimplanted or transplanted into a normal socket.
• The apical end of the sulcular epithelium approximated the level of the cementoenamel junctions, its original location on these root surfaces.
• The periodontal ligaments were well oriented, new cellul;ar cementum was discernible on the root surface, and new bone formation was evident.
• In some cases the new bone extended the width of the periodontal ligament and ankylosis was present.
• Exposed roots to periodontitis to normal periodontium
• Epithelium extended down the root surface to a point well apical to the crest of the alveolar bone, indicating that new connective tissue attachment had not occurred.
• The crest of the alveolar bone adjacent to the epithlium lining the root surface was undergoing reorption.
• The ligament fibers were aligned approximately parallel to the root surface and alveolar bone appeared to be present. There were some area of ankylosis and root resorption.

Discussion:

• Control specimens all showed a distinct layer of new cementum; however, new cementum formation was apparent on some, but not all, supracrestal root surfaces. Repopulation was thought to be derived from adjacent periodontal ligament cells.
• The normal tooth transplanted into the diseased site healed well because the fibers are retained on the root surface and that tissue reattachment can occur through linkage between fiber ends on the root surface with fibers form the soft tissue wound edge. Also no supracrestal cementum was observed due to lack of progenitor cells in this diseased site.
• The presence of epithelium extending along the root sufrace to a level far apical to the crest of the alveolaar bone in the specimens of periodontitis exposed roots transplanted into a normal periodontium indicated that root surface alterations, rather than lack of adjacent progenitor cell populations, inhibited the potential for new connective tissue attachment: denudation of fiber attachment, contamination of the root surface, and alterations in mineral density.

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