Composition of plaque-associated lesions in the gingiva and the peri-implant mucosa in partially edentulous subjects.

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The purpose of the present investigation was to study characteristics of the plaque associated lesions in the gingiva and the adjacent periimplant mucosa sampled from the same subjects. 20 partially edentulous patients (12 female and 8 male, 30-60 years of age) volunteered to participate in the study. They had all been treated for moderate to advanced periodontal disease. Edentulous regions had been restored with implants. The restorative therapy had been completed 6-24 months prior to soft tissue biopsy. Samples of gingival tissue (GM) and periimplant mucosa (PIM) from an "interproximal surface" of one tooth site and one implant site of the same jaw were harvested. One portion of the biopsy was embedded in EPON, stained in PAS and toluidine blue and used for histometric and morphometric analyses. The 2nd portion of the biopsy was snap frozen in liquid nitrogen. 15 sections, about 5 microns thick, were prepared in a cryostat and used for immune histochemical staining. The analysis of the sections included determination of the size of the lesions as well as assessments of various cells and cell markers. In all samples of both PIM and GM discrete infiltrates of inflammatory cells (ICT) were found in the connective tissue lateral to the junctional epithelium. The ICT of PIM occupied on the average 0.17 +/- 0.14 mm2 of the soft tissue, while the corresponding lesion in GM occupied an area that was 0.25 mm2 +/- 0.21 mm2 large. The density of CD19 positive cells was 7 times higher in GM than in PIM (3.7 versus 0.5) while the densities of CD3 positive cells were 7.5 (GM) and 4.7 (PM) respectively. The density of PMN elastase positive cells was about 3 times higher in GM than in PIM (3.7 versus 1.2). Care must be exercised when these differences are interpreted. It is possible that a prolonged exposure of the implant site to the oral environment may induce both qualitative and quantitative changes of the infiltrate in PIM.