Immunohistochemical analysis of tissue regenerated from within periodontal defects treated with expanded polytetrafluoroethylene membranes
The aim of this study was to analyze regenerated soft tissue taken from five-, six-, and nine-week-old healing periodontal defects at the time of removal of ePTFE membrane. Immunochemistry using antibodies to cytoderatins, vimentin, fibrinogen, and collagens I, III, and IV was used to label cells and tissue components. Seven adult patients with moderate to advanced periodontitis were included in this study. Tissue specimens were obtained at five, six, and nine weeks and prepared for immunocytochemical analysis. All sections were incubated with a particular antibody for one hour and then washed with PBS. A second antibody was subsequently applied and washed away. Antibodies were visualized with a standard chromogenic substrate solution. All surgical sites healed with minimum patient discomfort, received 10 days of amoxicillin, and had membrane exposure.
Histological evaluation from five- to six-week retrievals showed immature granulation tissue composed of a prominent capillary network, a variable inflammatory cell infiltrate, large zones of unidentified intercellular matrix, and epithelium. At five weeks, collagen fibers staining for type I and m were evident but sparse and not well organized. Interspersed vimentin-positive cells were associated with the fiber bundles which were more mature in the six-week specimens. Type IV collagen was labeled at basement membranes associated with blood vessels and epithelium. Observation of one tooth extracted nine weeks postoperatively demonstrated vimentin positive cells, and inflammatory cell elements were no longer the predominant feature, largely due to an increase in the collagen component, the overall appearance now resembling that of adult gingival connective tissue. Epithelial cells were identified in soft tissue taken from seven of the nine defects sampled. Epithelial cells were absent from soft tissue taken from two defects that had minimal membrane exposure by the sixth week. Thus, exposure may allow more epithelial downgrowth within the granulating tissue with limited evidence of cell adhesion to the membranes. In addition, it is now widely accepted that underlying mesenchymal tissues support epithelial differentiation and maintenance, and that fibroblasts play a key role in modifying these permissive influences. [P.W.]
Pritlove-Carson, S., R.M. Palmer, P.D. Floyd, and P.M. Morgan, J Periodont, 65:86,1994